VARIABLE POWER OPTICAL SYSTEM AND IMAGE PICKUP APPARATUS HAVING THE SAME

This application claims benefits of Japanese Application No. 2009-212134 filed in Japan on Sep. 14, 2009, No. 2009-212135 filed in Japan on Sep. 14, 2009 and No. 2009-212136 filed in Japan on Sep. 14, 2009, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to a variable power optical system in which aberrations are corrected well while the value of the total length of the optical system relative to image height is being made to become small, and to an image pickup apparatus having the same.

2. Description of the Related Art

Digital cameras, which are provided with a solid-state imaging sensor like CCD (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor), have become mainstream instead of film-based cameras in recent years. These digital cameras include various kinds of digital cameras which range from high performance-type digital camera for business to compact popular-type digital camera.

And, in such digital cameras, compact popular-type digital cameras have improved in downsizing because of desires that users easily enjoy photography, so that digital cameras which can be put well in pockets of clothes or bags and are convenient to be carried have appeared. Accordingly, it has become necessary to downsize variable power optical systems for such digital cameras yet more. However, it has been required that variable power optical systems for such digital cameras have not only a small size but also high optical performance (aberrations are corrected well in such variable power optical systems).

Variable power optical systems which meet such requirements include variable power optical systems which are disclosed in International Publication WO 2006/115107 and Japanese Patent Kokai No. 2008-233611 respectively. International Publication WO 2006/115107 relates to a variable power optical system for correcting chromatic aberration of magnification. When an attempt to achieve a super-small-sized variable power optical system is made, the refractive power of a second lens group becomes strong, so that chromatic aberration of magnification at the telephoto end position becomes a problem. In International Publication WO 2006/115107, this problem is corrected by making the Abbe's number of a fourth lens group proper. Japanese Patent Kokai No. 2008-233611 relates to a variable power optical system which has high performances and is downsized and the first lens group of which consists of two lens.

SUMMARY OF THE INVENTION

A variable power optical system according to the present first invention is characterized in that: the variable power optical system at least includes, in order from the object side, a first lens group with negative refractive power, a magnification-changing group with positive refractive power, and a last lens group with positive refractive power; the magnification-changing group includes a first lens element with positive refractive power, a second lens element, and a third lens element in that order from the object side; the second lens element has a convex shape on the object side; the last lens group includes a positive lens; and the following conditions (1) and (2) are satisfied:

10≦VdLg≦45 (1)

−1.0<(R2a−R2b)/(R2a+R2b)<1.0 (2)

where VdLg denotes the Abbe' Number of the positive lens of the last lens group with respect to the d line, R2a denotes the radius of curvature of the object-side surface of the second lens element, and R2b denotes the radius of curvature of the image-side surface of the third lens element.

Also, in a variable power optical system according to the present first invention, it is preferred that: the variable power optical system consists of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power, in that order from the object side; and the magnification-changing group is the second lens group and the last lens group is the fourth lens group.

Also, in a variable power optical system according to the present first invention, it is preferred that the following condition (3) is satisfied:

0.45≦|f1|/(FLw×FLt)^1/2≦1.60 (3)

where f1 denotes the focal length of the first lens group, FLw denotes the focal length of the whole of the variable power optical system in the wide angle end position, and FLt denotes the focal length of the whole of the variable power optical system in the telephoto end position.

Also, in a variable power optical system according to the present first invention, it is preferred that the following condition (4) is satisfied:

0.30≦fv/(FLw×FLt)^1/2≦1.10 (4)

where fv denotes the focal length of the magnification-changing group, FLw denotes the focal length of the whole of the variable power optical system in the wide angle end position, and FLt denotes the focal length of the whole of the variable power optical system in the telephoto end position.

Also, in a variable power optical system according to the present first invention, it is preferred that: the positive lens in the last lens group has a concave shape on the object side; and the following condition (5) is satisfied:

0.1≦(RLa−RLb)/(RLa+RLb)<1.0 (5)

where RLa denotes the radius of curvature of the object-side surface of the positive lens in the last lens group, and RLb denotes the radius of curvature of the image-side surface of the positive lens in the last lens group.

Also, an image pickup apparatus according to the present first invention is characterized in that: the image pickup apparatus includes one of the above-described variable power optical systems according to the present first invention, and an imaging sensor; and the following condition (6) is satisfied:

1.0≦|f1|/IH≦2.8 (6)

where f1 denotes the focal length of the first lens group, and IH denotes the image height of the imaging sensor.

Also, an image pickup apparatus according to the present first invention is characterized in that the image pickup apparatus includes one of the above described variable power optical systems according to the first present invention, and an imaging sensor; and the following condition (7) is satisfied:

0.2≦|fv|/IH≦1.8 (7)

where fv denotes the focal length of the magnification-changing group, and IH denotes the image height of the imaging sensor.

Also, a variable power optical system according to the present second invention is characterized in that: the variable power optical system includes, in order from the object side, a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power; the second lens group includes at least one positive lens and a negative lens; the fourth lens group includes a positive lens; and the following conditions (8), (9), and (10) are satisfied:

10≦Vd4g≦45 (8)

2.2≦|α/f1|+(α/f2)−0.026×Vd4g≦5.0 (9)

10≦Vdmax−Vdmin≦80 (10)

where α=(FLw×FLt)^1/2, FLw denotes the focal length of the whole of the variable power optical system in the wide angle end position, FLt denotes the focal length of the whole of the variable power optical system in the telephoto end position, f1 denotes the focal length of the first lens group, f2 denotes the focal length of the second lens group, Vd4g denotes the Abbe'Number of the positive lens of the fourth lens group with respect to the d line, Vdmax denotes the Abbe's Number of a glass material having the lowest dispersion characteristic of those of glass materials which are used for lenses of the second lens group, with respect to the d line, and Vdmin denotes the Abbe's Number of a glass material having the highest dispersion characteristic of those of glass materials which are used for lenses of the second lens group, with respect to the d line.

Also, in a variable power optical system according to the present second invention, it is preferred that the following condition (3) is satisfied:

0.45≦|f1|/(FLw×FLt)^1/2≦1.60 (3)

Also, in a variable power optical system according to the present second invention, it is preferred that the following condition (11) is satisfied:

0.30≦f2/(FLw×FLt)^1/2≦1.10 (11)

where f2 denotes the focal length of the second lens group, FLw denotes the focal length of the whole of the variable power optical system in the wide angle end position, and FLt denotes the focal length of the whole of the variable power optical system in the telephoto end position.

Also, in a variable power optical system according to the present second invention, it is preferred that: the second lens group consists of a first lens element with positive refractive power, a second lens element, and a third lens element in that order from the object side; the first lens element has a convex shape on the object side; and the following condition (2) is satisfied:

−1.0<(R2a−R2b)/(R2a+R2b)<1.0 (2)

where R2a denotes the radius of curvature of the object-side surface of the second lens element, and R2b denotes the radius of curvature of the image-side surface of the third lens element.

Also, in a variable power optical system according to the present second invention, it is preferred that: the positive lens in the fourth lens group has a concave shape on the object side; and the following condition (12) is satisfied:

0<(R4a−R4b)/(R4a+R4b)<1.0 (12)

where R4a denotes the radius of curvature of the object-side surface of the positive lens in the fourth lens group, and R4b denotes the radius of curvature of the image-side surface of the positive lens in the fourth lens group.

Also, an image pickup apparatus according to the present second invention is characterized in that: the image pickup apparatus includes one of the above-described variable power optical systems according to the second present invention, and an imaging sensor.

Also, in an image pickup apparatus according to the present second invention, it is preferred that: the image pickup apparatus includes a variable power optical system forming an optical image of an object, and an imaging sensor; the imaging sensor transforms the optical image formed by the variable power optical system into electrical image signals; the variable power optical system includes, in order from the object side, a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power; the second lens group includes at least one positive lens and a negative lens; the fourth lens group includes a positive lens; and the following conditions (8), (13), and (10) are satisfied:

10≦Vd4g≦45 (8)

−0.27≦|IH/f1|+(IH/f2)−0.05×Vd4g≦3.0 (13)

10≦Vdmax−Vdmin≦80 (10)

where IH denotes the image height of the imaging sensor, f1 denotes the focal length of the first lens group, f2 denotes the focal length of the second lens group, Vd4g denotes the Abbe' Number of the positive lens of the fourth lens group with respect to the d line, Vdmax denotes the Abbe's Number of a glass material having the lowest dispersion characteristic of those of glass materials which are used for lenses of the second lens group, with respect to the d line, and Vdmin denotes the Abbe's Number of a glass material having the highest dispersion characteristic of those of glass materials which are used for lenses of the second lens group, with respect to the d line.

Also, in an image pickup apparatus according to the present second invention, it is preferred that the following condition (6) is satisfied:

1.0≦|f1|/IH≦2.8 (6)

where f1 denotes the focal length of the first lens group, and IH denotes the image height of the imaging sensor.

Also, in an image pickup apparatus according to the present second invention, it is preferred that the following condition (14) is satisfied:

0.2≦|f2|/IH≦1.8 (14)

where f2 denotes the focal length of the second lens group, and IH denotes the image height of the imaging sensor.

Also, in an image pickup apparatus according to the present second invention, it is preferred that: the second lens group consists of a first lens element with positive refractive power, a second lens element, and a third lens element in that order from the object side; the first lens element has a convex shape on the object side; and the following condition (2) is satisfied:

−1.0<(R2a−R2b)/(R2a+R2b)<1.0 (2)

where R2a denotes the radius of curvature of the object-side surface of the second lens element, and R2b denotes the radius of curvature of the image-side surface of the third lens element.

Also, in an image pickup apparatus according to the present second invention, it is preferred that: the positive lens in the fourth lens group in the variable power optical system has a concave shape on the object side; and the following condition (12) is satisfied:

0<(R4a−R4b)/(R4a+R4b)<1.0 (12)

Also, a variable power optical system according to the present third invention is characterized in that: the variable power optical system includes, in order from the object side, a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power; the first lens group includes one negative lens and one positive lens in that order from the object side, and an air distance is provided between the negative and positive lenses of the first lens group; and the following conditions (15), (16), and (17) are satisfied:

1.75≦Nd1g≦2.50 (15)

15≦Vd1g≦43 (16)

3≦VdN−VdP≦28 (17)

where Nd1g denotes the refractive index of each of lenses constituting the first lens group, with respect to the d line, Vd1g denotes the Abbe's Number of each of lenses constituting the first lens group, with respect to the d lines, VdN denotes the Abbe's Number of the negative lens in the first lens group, with respect to the d lines, and VdP denotes the Abbe's Number of the positive lens in the first lens group, with respect to the d lines. Also, in a variable power optical system according to the present third invention, it is preferred that the following condition (18) is satisfied:

0.03≦D/(FLw×FLt)^1/2≦0.26 (18)

where D denotes the axial air distance between the negative and positive lenses of the first lens group, FLw denotes the focal length of the whole of the variable power optical system in the wide angle end position, and FLt denotes the focal length of the whole of the variable power optical system in the telephoto end position.

Also, in a variable power optical system according to the present third invention, it is preferred that: an air lens which has a convex shape on the object side is formed nearer to the image-plane side than the negative lens of the first lens group; and the following condition (19) is satisfied:

−0.25≦(r2−r3)/(r2+r3)≦−0.07 (19)

where r2 denotes the radius of curvature of the image-side surface of the negative lens of the first lens group, and r3 denotes the radius of curvature of the object-side surface of the positive lens of the first lens group.

Also, in a variable power optical system according to the present third invention, it is preferred that the following condition (3) is satisfied:

0.45≦|f1|/(FLw×FLt)^1/2≦1.60 (3)

Also, in a variable power optical system according to the present third invention, it is preferred that the following condition (20) is satisfied:

−0.5≦FLn/FLp≦−0.3 (20)

where FLn denotes the focal length of the negative lens of the first lens group, and FLp denotes the focal length of the positive lens of the first lens group.

Also, in a variable power optical system according to the present third invention, it is preferred that the following condition (11) is satisfied:

0.30≦f2/(FLw×FLt)^1/2≦1.10 (11)

Also, in a variable power optical system according to the present third invention, it is preferred that: the negative lens of the first lens group has a convex shape on the object side; and the following condition (21) is satisfied:

0.2≦(r1−r2)/(r1+r2)<1.0 (21)

where r1 denotes the radius of curvature of the object-side surface of the negative lens of the first lens group, and r2 denotes the radius of curvature of the image-side surface of the negative lens of the first lens group.

Also, in a variable power optical system according to the present third invention, it is preferred that: the fourth lens group consists of one lens with positive refractive power; and the following condition (22) is satisfied:

10≦Vd4g≦40 (22)

where Vd4g denotes the Abbe's Number of the positive lens of the fourth lens group with respect to the d line.

Also, an image pickup apparatus according to the present third invention is characterized in that: the image pickup apparatus includes one of the above-described variable power optical systems according to the present third invention, and an imaging sensor; and the following condition (6) is satisfied:

1.0≦|f1|/IH≦2.8 (6)

where f1 denotes the focal length of the first lens group, and IH denotes the image height of the imaging sensor.

0.2≦|f2|/IH≦1.8 (14)

where f2 denotes the focal length of the second lens group, and IH denotes the image height of the imaging sensor.

The present invention can offer a variable power optical system in which aberrations are corrected well while the value of the total length of the variable power optical system relative to image height is being made to become small, and an image pickup apparatus having the same.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a variable power optical systems of an embodiment 1 according to the present invention, taken along the optical axis, FIG. 1A shows the configuration of lenses in the wide angle end position, FIG. 1B shows the configuration of lenses in the middle position, and FIG. 1C shows the configuration of lenses in the telephoto end position.

FIG. 2 are aberration diagrams in focusing at infinity in the embodiment 1, FIGS. 2A to 2D show a state in the wide angle end position, FIGS. 2E to 2H show a state in the middle position, and FIGS. 2I to 2L show a state in the telephoto end position.

FIG. 3 are aberration diagrams in focusing at close range in the embodiment 1, FIGS. 3A to 3D show a state in the wide angle end position, FIGS. 3E to 3H show a state in the middle position, and FIGS. 3I to 3L show a state in the telephoto end position.

FIG. 4 are aberration diagrams showing coma in the embodiment 1, FIG. 4A shows a state in focusing at infinity in the wide angle end position, FIG. 4B shows a state in focusing at infinity in the middle position, FIG. 4C shows a state in focusing at infinity in the telephoto end position, FIG. 4D shows a state in focusing at close range in the wide angle end position, FIG. 4E shows a state in focusing at close range in the middle position, and FIG. 4F shows a state in focusing at close range in the telephoto end position.

FIG. 5 is a sectional view showing a variable power optical system of an embodiment 2 according to the present invention, taken along the optical axis, FIG. 5A shows the configuration of lenses in the wide angle end position, FIG. 5B shows the configuration of lenses in the middle position, and FIG. 5C shows the configuration of lenses in the telephoto end position.

FIG. 6 are aberration diagrams in focusing at infinity in the embodiment 2, FIGS. 6A to 6D show a state in the wide angle end position, FIGS. 6E to 6H show a state in the middle position, and FIGS. 6I to 6L show a state in the telephoto end position.

FIG. 7 are aberration diagrams in focusing at close range in the embodiment 2, FIGS. 7A to 7D show a state in the wide angle end position, FIGS. 7E to 7H show a state in the middle position, and FIGS. 7I to 7L show a state in the telephoto end position.

FIG. 8 are aberration diagrams showing coma at 70 percent of image height in the embodiment 2, FIG. 8A shows a state in focusing at infinity in the wide angle end position, FIG. 8B shows a state in focusing at infinity in the middle position, FIG. 8C shows a state in focusing at infinity in the telephoto end position, FIG. 8D shows a state in focusing at close range in the wide angle end position, FIG. 8E shows a state in focusing at close range in the middle position, and FIG. 8F shows a state in focusing at close range in the telephoto end position.

FIG. 9 is a sectional view showing a variable power optical system of an embodiment 3 according to the present invention, taken along the optical axis, FIG. 9A shows the configuration of lenses in the wide angle end position, FIG. 9B shows the configuration of lenses in the middle position, and FIG. 9C shows the configuration of lenses in the telephoto end position.

FIG. 10 are aberration diagrams in focusing at infinity in the embodiment 3, FIGS. 10A to 10D show a state in the wide angle end position, FIGS. 10E to 10H show a state in the middle position, and FIGS. 10I to 10L show a state in the telephoto end position.

FIG. 11 are aberration diagrams in focusing at close range in the embodiment 3, FIGS. 11A to 11D show a state in the wide angle end position, FIGS. 11E to 11H show a state in the middle position, and FIGS. 11I to 11L show a state in the telephoto end position.

FIG. 12 are aberration diagrams showing coma at 70 percent of image height in the embodiment 3, FIG. 12A shows a state in focusing at infinity in the wide angle end position, FIG. 12B shows a state in focusing at infinity in the middle position, FIG. 12C shows a state in focusing at infinity in the telephoto end position, FIG. 12D shows a state in focusing at close range in the wide angle end position, FIG. 12E shows a state in focusing at close range in the middle position, and FIG. 12F shows a state in focusing at close range in the telephoto end position.

FIG. 13 is a sectional view showing a variable power optical system of an embodiment 4 according to the present invention, taken along the optical axis, FIG. 13A shows the configuration of lenses in the wide angle end position, FIG. 13B shows the configuration of lenses in the middle position, and FIG. 13C shows the configuration of lenses in the telephoto end position.

FIG. 14 are aberration diagrams in focusing at infinity in the embodiment 4, FIGS. 14A to 14D show a state in the wide angle end position, FIGS. 14E to 14H show a state in the middle position, and FIGS. 14I to 14L show a state in the telephoto end position.

FIG. 15 are aberration diagrams in focusing at close range in the embodiment 4, FIGS. 15A to 15D show a state in the wide angle end position, FIGS. 15E to 15H show a state in the middle position, and FIGS. 15I to 15L show a state in the telephoto end position.

FIG. 16 are aberration diagrams showing coma at 70 percent of image height in the embodiment 4, FIG. 16A shows a state in focusing at infinity in the wide angle end position, FIG. 16B shows a state in focusing at infinity in the middle position, and FIG. 16C shows a state in focusing at infinity in the telephoto end position, FIG. 16D shows a state in focusing at close range in the wide angle end position, FIG. 16E shows a state in focusing at close range in the middle position, and FIG. 16F shows a state in focusing at close range in the telephoto end position.

FIG. 17 is a sectional view showing a variable power optical system of an embodiment 5 according to the present invention, taken along the optical axis, FIG. 17A shows the configuration of lenses in the wide angle end position, FIG. 17B shows the configuration of lenses in the middle position, and FIG. 17C shows the configuration of lenses in the telephoto end position.

FIG. 18 are aberration diagrams in focusing at infinity in the embodiment 5, FIGS. 18A to 18D show a state in the wide angle end position, FIGS. 18E to 18H show a state in the middle position, and FIGS. 18I to 18L show a state in the telephoto end position.

FIG. 19 are aberration diagrams in focusing at close range in the embodiment 5, FIGS. 19A to 19D show a state in the wide angle end position, FIGS. 19E to 19H show a state in the middle position, and FIGS. 19I to 19L show a state in the telephoto end position.

FIG. 20 are aberration diagrams showing coma at 70 percent of image height in the embodiment 5, FIG. 20A shows a state in focusing at infinity in the wide angle end position, FIG. 20B shows a state in focusing at infinity in the middle position, FIG. 20C shows a state in focusing at infinity in the telephoto end position, FIG. 20D shows a state in focusing at close range in the wide angle end position, FIG. 20E shows a state in focusing at close range in the middle position, and FIG. 20F shows a state in focusing at close range in the telephoto end position.

FIG. 21 is a sectional view showing a variable power optical system of an embodiment 6 according to the present invention, taken along the optical axis, FIG. 21A shows the configuration of lenses in the wide angle end position, FIG. 21B shows the configuration of lenses in the middle position, and FIG. 21C shows the configuration of lenses in the telephoto end position.

FIG. 22 are aberration diagrams in focusing at infinity in the embodiment 6, FIGS. 22A to 22D show a state in the wide angle end position, FIGS. 22E to 22H show a state in the middle position, and FIGS. 22I to 22L show a state in the telephoto end position.

FIG. 23 are aberration diagrams in focusing at close range in the embodiment 6, FIGS. 23A to 23D show a state in the wide angle end position, FIGS. 23E to 23H show a state in the middle position, and FIGS. 23I to 23L show a state in the telephoto end position.

FIG. 24 are aberration diagrams showing coma at 70 percent of image height in the embodiment 6, FIG. 24A shows a state in focusing at infinity in the wide angle end position, FIG. 24B shows a state in focusing at infinity in the middle position, FIG. 24C shows a state in focusing at infinity in the telephoto end position, FIG. 24D shows a state in focusing at close range in the wide angle end position, FIG. 24E shows a state in focusing at close range in the middle position, and FIG. 24F shows a state in focusing at close range in the telephoto end position.

FIG. 25 is a sectional view showing a variable power optical system of an embodiment 7 according to the present invention, taken along the optical axis, FIG. 25A shows the configuration of lenses in the wide angle end position, FIG. 25B shows the configuration of lenses in the middle position, and FIG. 25C shows the configuration of lenses in the telephoto end position.

FIG. 26 are aberration diagrams in focusing at infinity in the embodiment 7, FIGS. 26A to 26D show a state in the wide angle end position, FIGS. 26E to 26H show a state in the middle position, and FIGS. 26I to 26L show a state in the telephoto end position.

FIG. 27 are aberration diagrams showing coma at 70 percent of image height in the embodiment 7, FIG. 27A shows a state in focusing at infinity in the wide angle end position, FIG. 27B shows a state in focusing at infinity in the middle position, and FIG. 27C shows a state in focusing at infinity in the telephoto end position.

FIG. 28 is a sectional view showing a variable power optical system of an embodiment 8 according to the present invention, taken along the optical axis, FIG. 28A shows the configuration of lenses in the wide angle end position, FIG. 28B shows the configuration of lenses in the middle position, and FIG. 28C shows the configuration of lenses in the telephoto end position.

FIG. 29 are aberration diagrams in focusing at infinity in the embodiment 8, FIGS. 29A to 29D show a state in the wide angle end position, FIGS. 29E to 29H show a state in the middle position, and FIGS. 29I to 29L show a state in the telephoto end position.

FIG. 30 are aberration diagrams showing coma at 70 percent of image height in the embodiment 8, FIG. 30A shows a state in focusing at infinity in the wide angle end position, FIG. 30B shows a state in focusing at infinity in the middle position, and FIG. 30C shows a state in focusing at infinity in the telephoto end position.

FIG. 31 is a sectional view showing a variable power optical system of an embodiment 9 according to the present invention, taken along the optical axis, FIG. 31A shows the configuration of lenses in the wide angle end position, FIG. 31B shows the configuration of lenses in the middle position, and FIG. 31C shows the configuration of lenses in the telephoto end position.

FIG. 32 are aberration diagrams in focusing at infinity in the embodiment 9, FIGS. 32A to 32D show a state in the wide angle end position, FIGS. 32E to 32H show a state in the middle position, and FIGS. 32I to 32L shows a state in the telephoto end position.

FIG. 33 are aberration diagrams showing coma at 70 percent of image height in the embodiment 9, FIG. 33A shows a state in focusing at infinity in the wide angle end position, FIG. 33B shows a state in focusing at infinity in the middle position, and FIG. 33C shows a state in focusing at infinity in the telephoto end position.

FIG. 34 is a sectional view showing a variable power optical system of an embodiment 10 according to the present invention, taken along the optical axis, FIG. 34A shows the configuration of lenses in the wide angle end position, FIG. 34B shows the configuration of lenses in the middle position, and FIG. 34C shows the configuration of lenses in the telephoto end position.

FIG. 35 are aberration diagrams in focusing at infinity in the embodiment 10, FIGS. 35A to 35D show a state in the wide angle end position, FIGS. 35E to 35H show a state in the middle position, and FIGS. 35I to 35L show a state in the telephoto end position.

FIG. 36 are aberration diagrams showing coma at 70 percent of image height in the embodiment 10, FIG. 36A shows a state in focusing at infinity in the wide angle end position, FIG. 36B shows a state in focusing at infinity in the middle position, and FIG. 36C shows a state in focusing at infinity in the telephoto end position.

FIG. 37 is a sectional view showing a variable power optical system of an embodiment 11 according to the present invention, taken along the optical axis, FIG. 37A shows the configuration of lenses in the wide angle end position, FIG. 37B shows the configuration of lenses in the middle position, and FIG. 37C shows the configuration of lenses in the telephoto end position.

FIG. 38 are aberration diagrams in focusing at infinity in the embodiment 11, FIGS. 38A to 38D show a state in the wide angle end position, FIGS. 38E to 38H show a state in the middle position, and FIGS. 38I to 38L show a state in the telephoto end position.

FIG. 39 are aberration diagrams showing coma at 70 percent of image height in the embodiment 11, FIG. 39A shows a state in focusing at infinity in the wide angle end position, FIG. 39B shows a state in focusing at infinity in the middle position, and FIG. 39C shows a state in focusing at infinity in the telephoto end position.

FIG. 40 is a sectional view showing a variable power optical system of an embodiment 12 according to the present invention, taken along the optical axis, FIG. 40A shows the configuration of lenses in the wide angle end position, FIG. 40B shows the configuration of lenses in the middle position, and FIG. 40C shows the configuration of lenses in the telephoto end position.

FIG. 41 are aberration diagrams in focusing at infinity in the embodiment 12, FIGS. 41A to 41D show a state in the wide angle end position, FIGS. 41E to 41H show a state in the middle position, and FIGS. 41I to 41L show a state in the telephoto end position.

FIG. 42 are aberration diagrams showing coma at 70 percent of image height in the embodiment 12, FIG. 42A shows a state in focusing at infinity in the wide angle end position, FIG. 42B shows a state in focusing at infinity in the middle position, and FIG. 42C shows a state in focusing at infinity in the telephoto end position.

FIG. 43 is a front perspective view showing the appearance of a digital camera into which a variable power optical system of one of the embodiments according to the present invention is incorporated.

FIG. 44 is a rear perspective view showing the appearance of the digital camera which is shown in FIG. 43.

FIG. 45 is a perspective view schematically showing the constitution of the digital camera which is shown in FIG. 43.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Prior to the description of the embodiments, operation and its effect in variable power optical systems according to the present invention and in image pickup apparatuses having the same will be explained.

A variable power optical system of the first embodiment is characterized in that: the variable power optical system at least includes, in order from the object side, a first lens group with negative refractive power, a magnification-changing group with positive refractive power, and a last lens group with positive refractive power; the magnification-changing group includes a first lens element with positive refractive power, a second lens element, and a third lens element in that order from the object side; the second lens element has a convex shape on the object side; the last lens group includes a positive lens; and the following conditions (1) and (2) are satisfied:

10≦VdLg≦45 (1)

−1.0<(R2a−R2b)/(R2a+R2b)<1.0 (2)

The condition (1) shows the Abbe's Number of the positive lens of the last lens group. The condition (2) shows the shape factor for the second lens element and the third lens element. When the position of the principal point of a positive group that is the magnification-changing group is moved near the object side in retrofocus-type optical systems in general, it is possible to shorten the total lengths of the retrofocus-type optical systems while the positive group is not physically intercepting with the negative group. Also, the magnification-changing group has a meniscus shape which becomes convex on the object side, by making the optical systems satisfy the condition (2). In this case, the principal point of the magnification-changing group can be moved near the object side. As a result, it is possible to control the variations in various aberrations.

If VdLg is below the lower limit of the condition (1), there is no actual glass material for the positive lens, so that it is impossible to achieve desired optical systems. On the other hand, if VdLg is beyond the upper limit of the condition (1), it becomes difficult to correct chromatic aberration of magnification well in the telephoto end position.

If (R2a−R2b)/(R2a+R2b) is below the lower limit of the condition (2), it is impossible to control the variations in spherical aberration and coma in changing magnification. On the other hand, if (R2a−R2b)/(R2a+R2b) is beyond the upper limit of the condition (2), it is impossible to move near the object side the principal point of the magnification-changing group. In addition, it is impossible to control the variations in spherical aberration and coma in changing magnification.

When the conditions (1) and (2) are satisfied at the same time as described above, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is made to become small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which chromatic aberration of magnification in the telephoto end position and the variations in spherical aberration and coma in changing magnification are particularly corrected well (in particular, the variations in spherical aberration and coma are controlled better).

Also, it is preferred that the variable power optical system of the first embodiment satisfies the following conditions (1-1) and (2-1) instead of the conditions (1) and (2):

15≦VdLg≦40 (1-1)

−0.8<(R2a−R2b)/(R2a+R2b)<0.88 (2-1)

When the conditions (1-1) and (2-1) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which chromatic aberration of magnification in the telephoto end position and the variations in spherical aberration and coma in changing magnification are particularly corrected better.

Also, in a variable power optical system of the first embodiment, it is preferred that the second lens element in the magnification-changing group has positive refractive power and the third lens element in the magnification-changing group has negative refractive power.

Also, in a variable power optical system of the first embodiment, it is preferred that: the variable power optical system consists of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power, in that order from the object side; and the magnification-changing group is the second lens group and the last lens group is the fourth lens group.

Also, in a variable power optical system of the first embodiment, it is preferred that the first lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by switching from shooting at infinity to shooting in close range.

Because the total length is fixed in changing magnification, it is possible to easily secure the strength of a lens frame. In addition, because the structure of the lens frame can be simplified, it is possible to downsize the optical system.

Also, in a variable power optical system of the first embodiment, it is preferred that the fourth lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by switching from shooting at infinity to shooting in close range.

It is possible to make the movable components with two lens groups the number of which is the minimum number, by fixing the fourth lens group. As a result, the structure of the lens frame can be simplified, so that it is possible to downsize the optical system. In addition, it is possible to control the variations in aberrations, by arranging fixed groups on the object side and the image plane side of the two movable groups.

Also, in a variable power optical system according to the first embodiment, it is preferred that the following condition (3) is satisfied:

0.45≦|f1|/(FLw×FLt)^1/2≦1.60 (3)

Because the refractive power of the first lens group is strong, it is possible to move near the image plane side the point at which a virtual image is formed by the first lens group. As a result, it is possible to shorten the total length of the optical system. However, when the refractive power becomes large, it generally becomes difficult to correct aberrations. When the condition (3) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) well.

If |f1|/(FLw×FLt)^1/2is below the lower limit of the condition (3), it is impossible to control the variations in spherical aberration and coma in changing magnification. On the other hand, if |f1|/(FLw×FLt)^1/2is beyond the upper limit of the condition (3), it becomes difficult to move near the image plane side the point at which the virtual image is formed by the first lens group, which is undesirable.

Also, in a variable power optical system according to the first embodiment, it is preferred that the following condition (3-1) is satisfied instead of the condition (3):

0.50≦|f1|/(FLw×FLt)^1/2≦1.04 (3-1)

When the condition (3-1) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) better.

Also, in a variable power optical system according to the first embodiment, it is preferred that the first lens group consists of two or less lens elements.

Also, in a variable power optical system according to the first embodiment, it is preferred that the following condition (4) is satisfied:

0.30≦fv/(FLw×FLt)^1/2≦1.10 (4)

The condition (4) shows the focal length of the magnification-changing group. It generally becomes possible to reduce an amount of movement of the magnification-changing group in changing magnification by making the magnification-changing group have sufficiently strong refractive power. As a result, it is possible to shorten the total length of the optical system. However, when the refractive power becomes large, it generally becomes difficult to correct aberrations. When the condition (4) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected well.

If fv/(FLw×FLt)^1/2is below the lower limit of the condition (4), spherical aberration inevitably becomes worse, which is undesirable. On the other hand, if fv/(FLw×FLt)^1/2is beyond the upper limit of the condition (4), an amount of movement of the magnification-changing group inevitably increases in changing magnification, which is undesirable.

Also, in a variable power optical system according to the first embodiment, it is preferred that the following condition (4-1) is satisfied instead of the condition (4):

0.35≦fv/(FLw×FLt)^1/2≦0.62 (4-1)

When the condition (4-1) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected better.

Also, in a variable power optical system according to the present first invention, it is preferred that the last lens group consists of one lens element having positive refractive power.

Also, in a variable power optical system according to the first embodiment, it is preferred that: the positive lens in the last lens group has a concave shape on the object side; and the following condition (5) is satisfied:

0.1≦(RLa−RLb)/(RLa+RLb)≦1.0 (5)

The condition (5) shows the shape factor of the positive lens of the last lens group. When the condition (5) is satisfied, the shape of the positive lens becomes a meniscus shape which becomes convex on the object side. As a result, it is possible to achieve a variable power optical system in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variation in field curvature in changing magnification is particularly corrected (controlled) well. On the other hand, if the condition (5) is not satisfied, it is impossible to control the variation in field curvature in changing magnification.

Also, in a variable power optical system according to the first embodiment, it is preferred that the following condition (5-1) is satisfied instead of the condition (5):

0.1≦(RLa−RLb)/(RLa+RLb)<0.9 (5-1)

When the condition (5-1) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variation in field curvature in changing magnification is particularly corrected (controlled) better.

Also, an image pickup apparatus of a first embodiment according to the present invention is characterized in that: the image pickup apparatus includes one of the above-described variable power optical systems according to the first embodiment, and an imaging sensor; and the following condition (6) is satisfied:

1.0≦|f1|/IH≦2.8 (6)

where f1 denotes the focal length of the first lens group, and IH denotes the image height of the imaging sensor.

Because the refractive power of the first lens group is strong, it is possible to move near the image plane side the point at which a virtual image is formed by the first lens group. As a result, it is possible to shorten the total length of the optical system. However, when the refractive power becomes large, it generally becomes difficult to correct aberrations. When the condition (6) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) well.

In this case, IH denotes the image height of the imaging sensor. In a more detailed explanation, IH is half as long as the diagonal length of the image plane of the imaging sensor.

Besides, the height of an image formed on the imaging sensor may be used as IH (where the height of an image formed on the imaging sensor is the distance between the optical axis and the maximum image height).

If |f1|/IH is below the lower limit of the condition (6), it is impossible to control the variations in spherical aberration and coma in changing magnification. On the other hand, if|f1|/IH is beyond the upper limit of the condition (6), it is becomes difficult to move near the image plane side the point at which a virtual image is formed by the first lens group, which is undesirable.

Also, in an image pickup apparatus according to the first embodiment, it is preferred that the following condition (6-1) is satisfied instead of the condition (6):

1.8≦|f1|/IH≦2.6 (6-1)

When the condition (6-1) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) better.

Also, an image pickup apparatus according to the first embodiment is characterized in that the image pickup apparatus includes one of the above described variable power optical systems according to the first embodiment, and an imaging sensor; and the following condition (7) is satisfied:

0.2≦|fv|/IH≦1.8 (7)

where fv denotes the focal length of the magnification-changing group, and IH denotes the image height of the imaging sensor.

It is generally possible to reduce an amount of movement of the magnification-changing group in changing magnification by making the magnification-changing group have sufficiently strong refractive power. As a result, it is possible to shorten the total length of the optical system. However, when the refractive power becomes large, it generally becomes difficult to correct aberrations. When the condition (7) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected better. Besides, IH (image height) is as described above.

If |fv|/IH is below the lower limit of the condition (7), spherical aberration inevitably becomes worse, which is undesirable. On the other hand, if |fv|/IH is beyond the upper limit of the condition (7), an amount of movement of the magnification-changing group inevitably increases in changing magnification, which is undesirable.

Also, in an image pickup apparatus according to the first embodiment, it is preferred that the following condition (7-1) is satisfied instead of the condition (7):

1.0≦|fv|/IH≦1.5 (7-1)

When the condition (7-1) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected better.

Also, a variable power optical system according to the second embodiment is characterized in that: the variable power optical system includes, in order from the object side, a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power; the second lens group includes at least one positive lens and a negative lens; the fourth lens group includes a positive lens; and the following conditions (8), (9), and (10) are satisfied:

10≦Vd4g≦45 (8)

2.2≦|α/f1|+(α/f2)−0.026×Vd4g≦5.0 (9)

10≦Vdmax−Vdmin≦80 (10)

where α=(FLw×FLt)^1/2, FLw denotes the focal length of the whole of the variable power optical system in the wide angle end position, FLt denotes the focal length of the whole of the variable power optical system in the telephoto end position, f1 denotes the focal length of the first lens group, f2 denotes the focal length of the second lens group, Vd4g denotes the Abbe' Number of the positive lens of the fourth lens group with respect to the d line, Vdmax denotes the Abbe's Number of a glass material having the lowest dispersion characteristic of those of glass materials which are used for lenses of the second lens group, with respect to the d line, and Vdmin denotes the Abbe's Number of a glass material having the highest dispersion characteristic of those of glass materials which are used for lenses of the second lens group, with respect to the d line.

In order to achieve an optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well, various aberrations have to be corrected in each of the lens groups while the power of each of the lens groups is being strengthened. For example, in the case where the fourth lens groups is composed of one positive lens, the positive lens should be made of a low dispersion material in order to control the occurrence of chromatic aberration by a single lens. However, if the value of the total length of the variable power optical system relative to image height is made to become smaller, the required power of each of the first and second lens groups increases, so that it becomes impossible to balance the power with the corrections of various aberrations (monochromatic aberration/chromatic aberration) in each of the lens groups.

Specifically, required power in the first lens group increases, so that the variations in monochromatic aberrations (spherical aberration/coma) become large in changing magnification. Accordingly, in order to correct the monochromatic aberrations, the variations in monochromatic aberrations (spherical aberration/coma) are mainly controlled in the first lens group. However, the occurrence of chromatic aberration in the first lens group becomes frequent with the control of the variations in monochromatic aberrations. In addition, required power in the second lens group increases and chromatic aberration frequently occurs.

Accordingly, in the variable power optical system of the second embodiment, the fourth lens group is made to satisfy the condition (8) in order to correct these aberrations well. The condition (8) shows the Abbe's Number of the positive lens in the fourth lens group. The condition (9) shows the relation between the Abbe's Number of the positive lens in the fourth lens group and the powers of the first and second lens groups. The condition (10) shows the difference between a glass material having the lowest dispersion characteristic of those of grass materials for the second lens group and a glass material having the highest dispersion characteristic of those of the grass materials for the second lens group.

When both of the conditions (8) and (9) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. In addition, when the condition (10) is also satisfied, it is possible to achieve a variable power optical system in which various aberrations are corrected better.

If Vd4g is below the lower limit of the condition (8), there is no grass material, so that it is impossible to achieve a desired optical system. On the other hand, if Vd4g is beyond the upper limit of the condition (8), it becomes difficult to correct chromatic aberration of magnification well in the telephoto end position.

If |α/f1|+(α/f2)−0.026×Vd4g is below the lower limit of the condition (9), the powers of the first and second lens group are inadequate, so that it is impossible to shorten the total length of the optical system. On the other hand, if |α/f1|+(α/f2)−0.026×Vd4g is beyond the upper limit of the condition (9), the powers of the first and second lens groups become too strong, so that it is impossible to control the variations in spherical aberration and coma in changing magnification.

If Vdmax−Vdmin is below the lower limit of the condition (10), the correction of chromatic aberration in the second lens group mainly becomes inadequate. On the other hand, if Vdmax−Vdmin is beyond the upper limit of the condition (10), the correction of chromatic aberration in the second lens group mainly becomes surplus.

As described above, when the conditions (8), (9), and (10) are satisfied at the same time, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification and chromatic aberration are corrected particularly well.

Also, in a variable power optical system according to the second embodiment, it is preferred that the following conditions (8-1), (9-1), and (10-1) are satisfied instead of the conditions (8), (9), and (10):

15≦Vd4g≦40 (8-1)

2.25≦|α/f1|+(α/f2)−0.026×Vd4g≦4.5 (9-1)

15≦Vdmax−Vdmin≦70 (10-1)

When the conditions (8-1), (9-1), and (10-1) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification and chromatic aberration are particularly corrected better.

Also, in a variable power optical system according to the second embodiment, it is preferred that the first lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by changing shooting at infinity to shooting in close range.

Because the total length of the variable power optical system is fixed in changing magnification, it is possible to easily secure the strength of a lens frame. In addition, because the structure of the lens frame can be simplified, it is possible to downsize the optical system.

Also, in a variable power optical system according to the second embodiment, it is preferred that the fourth lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by changing shooting at infinity to shooting in close range.

Because the fourth lens group is fixed in changing magnification, a minimum of two lens groups can be used as movable components. As a result, the structure of the lens frame can be simplified, so that it is possible to downsize the optical system. In addition, when fixed lens groups are arranged on the object and image-plane sides of the two movable lens groups, it is possible to control the variations in aberrations.

Also, in a variable power optical system according to the present second embodiment, it is preferred that the following condition (3) is satisfied:

0.45≦|f1|/(FLw×FLt)^1/2≦1.60 (3)

Also, in a variable power optical system according to the second embodiment, it is preferred that the following condition (3-1) is satisfied instead of the condition (3):

0.50≦|f1|/(FLw×FLt)^1/2≦1.04 (3-1)

Also, in a variable power optical system according to the second embodiment, it is preferred that the first lens group consists of two or less lens elements.

Also, in a variable power optical system according to the second embodiment, it is preferred that the following condition (11) is satisfied:

0.30≦f2/(FLw×FLt)^1/2≦1.10 (11)

When the refractive power of the second lens group is strong, it is generally possible to reduce an amount of movement of the lens group in changing magnification. As a result, it is possible to shorten the total length of the optical system. However, when the refractive power becomes large, it generally becomes difficult to correct aberrations. When the condition (11) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected well.

If f2/(FLw×FLt)^1/2is below the lower limit of the condition (11), spherical aberration inevitably becomes worse, which is undesirable. On the other hand, if f2/(FLw×FLt)^1/2is beyond the upper limit of the condition (11), an amount of movement of the lens group inevitably increases in changing magnification, which is undesirable.

Also, in a variable power optical system according to the second embodiment, it is preferred that the following condition (11-1) is satisfied instead of the condition (11):

0.35≦f2/(FLw×FLt)^1/2≦0.62 (11-1)

When the condition (11-1) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected better.

Also, in a variable power optical system according to the second embodiment, it is preferred that: the second lens group consists of a first lens element (L21) with positive refractive power, a second lens element (L22), and a third lens element (L23) in that order from the object side; the first lens element (L21) has a convex shape on the object side; and the following condition (2) is satisfied:

−1.0<(R2a−R2b)/(R2a+R2b)<1.0 (2)

where R2a denotes the radius of curvature of the object-side surface of the second lens element (L22), and R2b denotes the radius of curvature of the image-side surface of the third lens element (L23).

The condition (2) shows the shape factor for the second lens element (L22) and the third lens element (L23). When the position of the principal point of a positive group that is the main magnification-changing group is moved near the object side in retrofocus-type optical systems in general, it is possible to shorten the total lengths of the retrofocus-type optical systems while the positive group is not physically intercepting with the negative group.

When the condition (2) is satisfied, the magnification-changing group has a meniscus shape which becomes convex on the object side, so that the principal point of the second lens group can be moved near the object side. As a result, it is possible to achieve a variable power optical system in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected well.

If (R2a−R2b)/(R2a+R2b) is below the lower limit of the condition (2), it is impossible to control the variations in spherical aberration and coma in changing magnification. On the other hand, if (R2a−R2b)/(R2a+R2b) is beyond the upper limit of the condition (2), it is impossible to move near the object side the position of the principal point of the second lens group. In addition, it is impossible to control the variations in spherical aberration and coma in changing magnification.

Also, it is preferred that the variable power optical system of the second embodiment satisfies the following condition (2-1) instead of the condition (2):

−0.8<(R2a−R2b)/(R2a+R2b)<0.72 (2-1)

When the condition (2-1) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected better.

Also, in a variable power optical system of the second embodiment, it is preferred that the second lens element (L22) has positive refractive power, and the third lens element (L23) has negative refractive power.

Also, in a variable power optical system of the second embodiment, it is preferred that the fourth lens group consists of one lens element with positive refractive power.

Also, in a variable power optical system according to the second embodiment, it is preferred that: the positive lens in the fourth lens group has a concave shape on the object side; and the following condition (12) is satisfied:

0<(R4a−R4b)/(R4a+R4b)<1.0 (12)

The condition (12) shows the shape factor for the positive lens of the fourth lens group. When the condition (12) is satisfied, the shape of the positive lens becomes a meniscus shape which becomes concave on the object side. As a result, it is possible to achieve a variable power optical system in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variation in field curvature in changing magnification is particularly corrected (controlled) well. On the other hand, if the condition (12) is not satisfied, it is impossible to control the variation in field curvature in changing magnification.

Also, it is preferred that the variable power optical system of the second embodiment satisfies the following condition (12-1) instead of the condition (12):

0.1≦(R4a−R4b)/(R4a+R4b)<0.9 (12-1)

When the condition (12-1) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variation in field curvature in changing magnification is particularly corrected (controlled) better.

Also, an image pickup apparatus according to the second embodiment includes one of the above-described variable power optical systems according to the second embodiment, and an imaging sensor.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that: the image pickup apparatus includes a variable power optical system forming an optical image of an object, and an imaging sensor; the imaging sensor transforms the optical image formed by the variable power optical system into electrical image signals; the variable power optical system includes, in order from the object side, a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power; the second lens group includes at least one positive lens and a negative lens; the fourth lens group includes a positive lens; and the following conditions (8), (13), and (10) are satisfied:

10≦Vd4g≦45 (8)

−0.27≦|IH/f1|+(IH/f2)−0.05×Vd4g≦3.0 (13)

10≦Vdmax−Vdmin≦80 (10)

When both of the conditions (8) and (13) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. In addition, when the condition (10) is also satisfied, it is possible to achieve a variable power optical system in which various aberrations are also corrected better. In this case, IH denotes the image height of the imaging sensor. In a more detailed explanation, IH is half as long as the diagonal length of the image plane of the imaging sensor. Besides, the height of an image formed on the imaging sensor may be used as IH (where the height of an image formed on the imaging sensor is the distance between the optical axis and the maximum image height).

The conditions (8) and (10) have been already explained. Also, the condition (13) has the same technical significance and the same operation effects as the condition (9) does.

As described above, when the conditions (8), (13), and (10) are satisfied at the same time, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification and chromatic aberration are particularly corrected well.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the following conditions (8-1), (13-1), and (10-1) are satisfied instead of the conditions (8), (13), and (10):

15≦Vd4g≦40 (8-1)

−0.25≦|α/f1|+(α/f2)−0.026×Vd4g≦2.5 (13-1)

15≦Vdmax−Vdmin≦70 (10-1)

When the conditions (8-1), (13-1), and (10-1) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification and chromatic aberration are particularly corrected better.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the image pickup apparatus includes a variable power optical system in which the first lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by changing shooting at infinity to shooting in close range. Also, in an image pickup apparatus according to the present embodiment, it is preferred that the image pickup apparatus includes a variable power optical system in which the fourth lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by changing shooting at infinity to shooting in close range. The matter of the constitution in which the first and fourth lens groups are fixed has been already explained.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the following condition (6) is satisfied:

1.0≦|f1|/IH≦2.8 (6)

where f1 denotes the focal length of the first lens group, and IH denotes the image height of the imaging sensor.

The condition (6) has the same technical significance and the same operation effects as the condition (3) does. Besides, the explanation about the image height has been described above.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the following condition (6-1) is satisfied instead of the condition (6):

1.8≦|f1|/IH≦2.6 (6-1)

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the first lens group in the variable power optical system consists of two or less lens elements.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the following condition (14) is satisfied:

0.2≦|f2|/IH≦1.8 (14)

where f2 denotes the focal length of the second lens group, and IH denotes the image height of the imaging sensor.

The condition (14) has the same technical significance and the same operation effects as the condition (11) does. Besides, the explanation about IH has been described above.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the following condition (14-1) is satisfied instead of the condition (14):

1.0≦|f2|/IH≦1.5 (14-1)

Also, in an image pickup apparatus according to the second embodiment, it is preferred that: the second lens group in the variable power optical system consists of a first lens element with positive refractive power, a second lens element, and a third lens element in that order from the object side; the first lens element has a convex shape on the object side; and the following condition (2) is satisfied:

−1.0<(R2a−R2b)/(R2a+R2b)<1.0 (2)

where R2a denotes the radius of curvature of the object-side surface of the second lens element, and R2b denotes the radius of curvature of the image-side surface of the third lens element.

The technical significance and the operation effects of the condition (2) have been already explained.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the following condition (2-1) is satisfied instead of the condition (2):

−0.8<(R2a−R2b)/(R2a+R2b)<0.72 (2-1)

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the second lens element in the variable power optical system has positive refractive power and the third lens element in the variable power optical system has negative refractive power, respectively.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the fourth lens group in the variable power optical system consists of one lens element with positive refractive power.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that: the positive lens in the fourth lens group in the variable power optical system has a concave shape on the object side; and the following condition (12) is satisfied:

0<(R4a−R4b)/(R4a+R4b)<1.0 (12)

The technical significance and the operation effects of the condition (12) have been already explained.

Also, in an image pickup apparatus according to the second embodiment, it is preferred that the following condition (12-1) is satisfied instead of the condition (12):

0.1≦(R4a−R4b)/(R4a+R4b)<0.9 (12-1)

Also, a variable power optical system according to the third embodiment is characterized in that: the variable power optical system includes, in order from the object side, a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power; the first lens group includes one negative lens and one positive lens in that order from the object side, and an air distance is provided between the negative and positive lenses of the first lens group; and the following conditions (15), (16), and (17) are satisfied:

1.75≦Nd1g≦2.50 (15)

15≦Vd1g≦43 (16)

3≦VdN−VdP≦28 (17)

where Nd1g denotes the refractive index of each of lenses constituting the first lens group, with respect to the d line, Vd1g denotes the Abbe's Number of each of lenses constituting the first lens group, with respect to the d lines, VdN denotes the Abbe's Numbers of the negative lens in the first lens group, with respect to the d lines, and VdP denotes the Abbe's Numbers of the positive lens in the first lens group, with respect to the d lines.

The variable power optical system according to the third embodiment is characterized in that both of the negative and positive lenses constituting the first lens group have high refractive index and high dispersion characteristic. The condition (15) shows the refractive index of each of the lenses constituting the first lens group. The condition (16) shows the Abbe's Number of each of the lenses constituting the first lens group. The condition (17) shows the difference between the Abbe's Numbers of the negative and positive lenses constituting the first lens group.

When the condition (15) is satisfied, it is possible to strengthen the refractive power while the radius of curvature of each of the lenses constituting the first lens group is being made to become large. Small radius of curvature generally makes the variations in various aberrations large. That is to say, it is possible to control the variations in various aberrations and it is possible to achieve desired refractive power, by making the radius of curvature large. In addition, when both of the conditions (16) and (17) are satisfied, it is possible to correct various aberrations in the first lens group well while desired refractive power is being achieved in the first lens group.

If Nd1g is below the lower limit of the condition (15), it is impossible to achieve desired refractive power with the variations in various aberrations in each of the lenses being controlled. On the other hand, if Nd1g is beyond the upper limit of the condition (15), there is no glass material for the lenses constituting first lens group, so that it is impossible to achieve a desired optical system.

If Vd1g is below the lower limit of the condition (16), there is no glass material for the lenses constituting the first lens group, so that it is impossible to achieve a desired optical system. On the other hand, if Vd1g is beyond the upper limit of the condition (16), actual glass materials cause a decline in the refractive power, so that it is impossible to achieve a desired refractive index of the first lens group.

If VdN−VdP is below the lower limit of the condition (17), the correction of chromatic aberration inevitably becomes inadequate. On the other hand, if VdN−VdP is beyond the upper limit of the condition (17), the correction of chromatic aberration inevitably becomes surplus.

As described above, when the conditions (15), (16), and (17) are satisfied at the same time, it is possible to achieve a variable power optical system in which the value of the total length of the variable power optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which chromatic aberration is particularly corrected well.

Also, in a variable power optical system according to the third embodiment, it is preferred that the following conditions (15-1), (16-1), and (17-1) are satisfied instead of the conditions (15), (16), and (17):

1.82≦nd1g≦2.40 (15-1)

16≦vd1g≦38.7 (16-1)

9≦vdN−vdP≦22.7 (17-1)

When the conditions (15-1), (16-1), and (17-1) are satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which chromatic aberration is particularly corrected better.

In a variable power optical system according to the third embodiment, it is preferred that the following condition (18) is satisfied:

0.03≦D/(FLw×FLt)^1/2≦0.26 (18)

When the condition (18) is satisfied, it is possible to achieve a variable power optical system in which various aberrations are corrected well while the thickness of the first lens group is being thinned. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) well.

If D/(FLw×FLt)^1/2is below the lower limit of the condition (18), it is impossible to control the variations in spherical aberration and coma in changing magnification. On the other hand, if D/(FLw×FLt)^1/2is beyond the upper limit of the condition (18), the thickness of the first lens group increases, so that it is impossible to achieve a desired optical system.

Also, in a variable power optical system according to the third embodiment, it is preferred that the following condition (18-1) is satisfied instead of the condition (18):

0.05≦D/(FLw×FLt)^1/2≦0.20 (18-1)

When the condition (18-1) is satisfied, it is possible to achieve a variable power optical system in which various aberrations are corrected better while the thickness of the first lens group is being thinned. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) better.

Also, in a variable power optical system according to the third embodiment, it is preferred that: an air lens which has a convex shape on the object side is formed nearer to the image-plane side than the negative lens of the first lens group; and the following condition (19) is satisfied:

−0.25≦(r2−r3)/(r2+r3)≦−0.07 (19)

The condition (19) shows the shape factor of the air lens of the first lens group. When the condition (19) is satisfied, it is shown that the air lens becomes a meniscus lens having a convex shape on the object side and having positive refractive power. As a result, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are corrected (controlled) well.

If (r2−r3)/(r2+r3) is below the lower limit of the condition (19), the refractive power of the air lens is reduced, so that it is impossible to control the variations in spherical aberration and coma in changing magnification. On the other hand, if (r2−r3)/(r2+r3) is beyond the upper limit of the condition (19), the refractive index of the air lens becomes high. That is to say, the radius of curvature of the object-side surface of the positive lens in the first lens group becomes large, so that it is impossible to correct various aberrations well while desired refractive power of the first lens group is being achieved.

Also, in a variable power optical system according to the third embodiment, it is preferred that the following condition (19-1) is satisfied instead of the condition (19):

−0.20≦(r2−r3)/(r2+r3)≦−0.10 (19-1)

When the condition (19-1) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) better.

Also, in a variable power optical system of the third embodiment, it is preferred that the first lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by switching from shooting at infinity to shooting in close range.

Also, in a variable power optical system of the third embodiment, it is preferred that the fourth lens group is made to keep still in changing magnification from the wide angle end position to the telephoto end position or in performing shooting by switching from shooting at infinity to shooting in close range.

It is possible to use a minimum of two lens groups as movable components by fixing the fourth lens group. As a result, the structure of the lens frame can be simplified, so that it is possible to downsize the optical system. In addition, it is possible to control the variations in aberrations, by arranging fixed groups on the object side and the image-plane side of the two movable groups.

Also, in a variable power optical system according to the present third embodiment, it is preferred that the following condition (3) is satisfied:

0.45≦|f1|/(FLw×FLt)^1/2≦1.60 (3)

The first lens group has high refractive power, so that it is possible to move near the image plane side a point at which a virtual image is formed by the first lens group. As a result, it is possible to shorten the total length of the optical system. However, when refractive power becomes high, it generally becomes difficult to correct aberrations. When the condition (3) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve an optical system in which variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) well.

If |f1|/(FLw×FLt)^1/2is below the lower limit value of the condition (3), it becomes impossible to control variations in spherical aberration and coma in changing magnification. On the other hand, if |f1|/(FLw×FLt)^1/2is beyond the upper limit value of the condition (3), it becomes difficult to move near the image-plane side a point at which a virtual image is formed by the first lens group, which is undesirable.

Also, in a variable power optical system according to the present third invention, it is preferred that the following condition (3-2) is satisfied instead of the condition (3):

0.70≦|f1|/(FLw×FLt)^1/2≦1.20 (3-2)

When the condition (3-2) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve an optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) better.

Also, in a variable power optical system according to the present third embodiment, it is preferred that the following condition (20) is satisfied:

−0.5≦FLn/FLp≦−0.3 (20)

where FLn denotes the focal length of the negative lens of the first lens group and FLp denotes the focal length of the positive lens of the first lens group.

The condition (20) shows the ratio of power of the negative lens to power of the positive lens in the first lens group. When the condition (20) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which chromatic aberration is particularly corrected well.

If FLn/FLp is below the lower limit value of the condition (20), a correction of chromatic aberration inevitably becomes surplus one. On the other hand, if FLn/FLp is beyond the upper limit value of the condition (20), a correction of chromatic aberration inevitably becomes insufficient one.

Also, in a variable power optical system according to the third embodiment, it is preferred that the following condition (11) is satisfied:

0.30≦f2/(FLw×FLt)^1/2≦1.10 (11)

When the refractive power of the second lens group is sufficiently strong, it is generally possible to reduce an amount of movement of the lens group in changing magnification. As a result, it is possible to shorten the total length of the optical system. However, when the refractive power becomes high, it generally becomes difficult to correct aberrations. When the condition (11) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected well.

If f2/(FLw×FLt)^1/2is below the lower limit value of the condition (11), spherical aberration inevitably becomes worse, which is undesirable. On the other hand, if f2/(FLw×FLt)^1/2is beyond the upper limit value of the condition (11), an amount of movement of the lens group inevitably increases in changing magnification, which is undesirable.

Also, in a variable power optical system according to the third embodiment, it is preferred that the following condition (11-2) is satisfied instead of the condition (11):

0.45≦f2/(FLw×FLt)^1/2≦0.70 (11-2)

When the condition (11-2) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected better. Specifically, it is possible to achieve a variable power optical system in which spherical aberration is particularly corrected better.

Also, in a variable power optical system according to the third embodiment, it is preferred that: the negative lens in the first lens group has a convex shape on the object side; and the following condition (21) is satisfied:

0.2≦(r1−r2)/(r1+r2)≦1.0 (21)

where r1 denotes the radius of curvature of the object-side surface of the negative lens of the first lens group and r2 denotes the radius of curvature of the image-side surface of the negative lens of the first lens group.

The condition (21) shows the shape factor of the negative lens of the first lens group. When the condition (21) is satisfied, it is possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which the variations in spherical aberration and coma in changing magnification are particularly corrected (controlled) well.

If (r1−r2)/(r1+r2) is below the lower limit of the condition (21), the power of the negative lens of the first lens group is reduced. In this case, it becomes difficult to move near the image-plane side the point at which a virtual image is formed by the first lens group, which is undesirable. On the other hand, if (r1−r2)/(r1+r2) is beyond the upper limit of the condition (21), the negative lens of the first lens group inevitably has a biconcave shape, so that it is impossible to control the variations in spherical aberration and coma in changing magnification.

Also, in a variable power optical system according to the third embodiment, it is preferred that: the fourth lens group consists of one lens with positive refractive power; and the following condition (22) is satisfied:

10≦Vd4g≦40 (22)

where Vd4g denotes Abbe's Number of the positive lens of the fourth lens group with respect to the d line.

The condition (22) shows the Abbe's Number of the positive lens of the fourth lens group. The achievement of the condition (22) makes it possible to achieve a variable power optical system in which the value of the total length of the optical system relative to image height is small and in which various aberrations are corrected well. Specifically, it is possible to achieve a variable power optical system in which chromatic aberration of magnification is particularly corrected well in the telephoto end position.

If Vd4g is below the lower limit of the condition (22), there is no actual glass material, so that it is impossible to achieve a desired optical system. On the other hand, if Vd4g is beyond the upper limit of the condition (22), it becomes difficult to correct chromatic aberration of magnification well in the telephoto end position.

Also, in an image pickup apparatus according to the third embodiment, it is preferred that: the image pickup apparatus includes one of the above-described variable power optical systems according to the third embodiment, and an imaging sensor; and the following condition (6) is satisfied:

1.0≦|f1|/IH≦2.8 (6)

where f1 denotes the focal length of the first lens group, and IH denotes the image height of the imaging sensor.

The condition (6) has the same technical significance and the same operation effect as the condition (3) does. In this case, IH denotes the image height of the imaging sensor. In a more detailed explanation, IH is half as long as the diagonal length of the image plane of the imaging sensor. Besides, the height of an image formed on the imaging sensor (the distance between the optical axis and the maximum image height) may be used as IH.

Also, in an image pickup apparatus according to the third embodiment, it is preferred that the following condition (6-1) is satisfied instead of the condition (6):

1.8≦|f1|/IH≦2.6 (6-1)

0.2≦|f2|/IH≦1.8 (14)

where f2 denotes the focal length of the second lens group, and IH denotes the image height of the imaging sensor.

The condition (14) has the same technical significance and the same operation effects as the condition (11) does. Besides, the explanation about IH has been described above.

Also, in an image pickup apparatus according to the third embodiment, it is preferred that the following condition (14-1) is satisfied instead of the condition (14):

1.0≦|f2|/IH≦1.5 (14-1)

EMBODIMENT

Embodiments for variable power optical systems according to the present invention and image pickup apparatuses having the same are explained using the drawings, below.

First, the embodiments 1 to 12 for variable power optical systems according to the present invention will be explained.

The sectional view of the variable power optical system of the embodiment 1 is shown in FIG. 1, the sectional view of the variable power optical system of the embodiment 2 is shown in FIG. 5, the sectional view of the variable power optical system of the embodiment 3 is shown in FIG. 9, the sectional view of the variable power optical system of the embodiment 4 is shown in FIG. 13, the sectional view of the variable power optical system of the embodiment 5 is shown in FIG. 17, the sectional view of the variable power optical system of the embodiment 6 is shown in FIG. 21, the sectional view of the variable power optical system of the embodiment 7 is shown in FIG. 25, the sectional view of the variable power optical system of the embodiment 8 is shown in FIG. 28, the sectional view of the variable power optical system of the embodiment 9 is shown in FIG. 31, the sectional view of the variable power optical system of the embodiment 10 is shown in FIG. 34, the sectional view of the variable power optical system of the embodiment 11 is shown in FIG. 37, and the sectional view of the variable power optical system of the embodiment 12 is shown in FIG. 40.

In the embodiment 1, the image height (IH) is 2.9 mm, and the pixel pitch of the imaging sensor is 1.4 μm. In the embodiment 10, the image height (IH) is 2.25 mm, and the pixel pitch of the imaging sensor is 1.1 μm, in the below explanation. However, the image height and the pixel pitch in each of the below-described embodiments are not limited to these numerical values. For example, the pixel pitch of the imaging sensor may be 2.00 μm, 1.75 μm, 1.40 μm, or 1.1 μm. The diameter of the aperture stop in the telephoto end position is larger than that of the aperture stop in the wide angle end position. As a result, it is possible to prevent the deterioration of the performance due to the diffraction limit, in the telephoto end position. However, the aperture diameter may be unchangeable if there is no practical problem.

Embodiment 1

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 1. The total length of the variable power optical system of the present embodiment is about 13 mm. The variable power optical system of the present embodiment includes, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, and a fourth lens group G4 with positive refractive power, these lens groups being located on the optical axis Lc.

The first lens group G1 is composed of a negative meniscus lens L11 the convex surface of which faces toward the object side and a positive meniscus lens L12 the convex surface of which faces toward the object side, in that order from the object side. And, the first lens group G1 as a whole has negative refractive power.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group is composed of a biconvex positive lens L21 which becomes the first lens element, an aperture stop S, a biconvex positive lens L22 which becomes the second lens element, and a biconcave negative lens L23 which becomes the third lens element and is joined to the biconvex positive lens L22, in that order from the object side. And, the second lens group G2 has positive refractive power as a whole and has a main magnification change function.

The third lens group G3 is composed of one biconcave negative lens L3. Besides, the biconcave negative lens L3 may be replaced with a negative meniscus lens the convex surface of which faces toward the object side or with a negative meniscus lens the concave surface of which faces toward the object side.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

In changing magnification from the wide angle end position to the telephoto end position, the first lens group G1 and the fourth lens group G4 keep still, and the second lens group G2 and the third lens group G3 move toward the object side. In changing from an object point at infinity to a close object point to focus the optical system on the close object point, both of the second and third lens groups G2 and G3 may be moved.

Embodiment 2

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 5. The total length of the variable power optical system of the present embodiment is about 13 mm.

The variable power optical system of the present embodiment includes, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, and a fourth lens group G4 with positive refractive power, these lens group being located on the optical axis Lc.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group G2 is composed of a biconvex positive lens L21 which becomes the first lens element, an aperture stop S, a biconvex positive lens L22 which becomes the second lens element, and a biconcave negative lens L23 which becomes the third lens element and is joined to the biconvex positive lens L22, in that order from the object side. And, the second lens group G2 has positive refractive power as a whole and has a main magnification change function.

The third lens group G3 is composed of one negative meniscus lens L3 the concave surface of which faces toward the object side. Besides, the negative meniscus lens element L3 the concave surface of which faces toward the object side may be replaced with a negative meniscus lens the convex surface of which faces toward the object side or with a biconcave negative lens.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

It is possible to correct variation in field curvature well in focusing on an object, by moving the both lens groups.

Embodiment 3

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 9. The total length of the variable power optical system of the present embodiment is about 16 mm.

The variable power optical system of the present embodiment includes, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power, these lens groups being located on the optical axis Lc.

The first lens group G1 is composed of one biconcave negative lens L1.

The second lens group G2 is composed of one positive meniscus lens L2 the convex surface of which faces toward the object side.

The third lens group G3 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The second lens element has a convex shape on the object side. Specifically, the second lens group G3 is composed of an aperture stop S, a biconvex positive lens L31 which becomes the first lens element, a negative meniscus lens L32 which becomes the second lens element and the convex surface of which faces toward the object side, and a negative meniscus lens L33 which becomes the third lens element and the convex surface of which faces toward the object side, in that order from the object side. And, the third lens group G3 as a whole has positive refractive power.

The fourth lens group G4 is composed of one biconvex positive lens L4.

In changing from an object point at infinity to a close object point to focus the optical system on the close object point, both of the second and third lens groups G2 and G3 may be moved.

It is possible to correct variation in field curvature well in focusing on an object, by moving the both lens groups.

Embodiment 4

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 13. The total length of the variable power optical system of the present embodiment is about 13 mm.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group G2 is composed of a biconvex positive lens L21 which becomes the first lens element, an aperture stop S, a biconvex positive lens L22 which becomes the second lens element, and a biconcave negative lens L23 which becomes the third lens element and is joined to the biconvex positive lens L22, in that order from the object side. And, the second lens group G2 has positive refractive power as a whole and has a main magnification change function.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

In changing from an object point at infinity to a close object point to focus the optical system on the close object point, both of the second and third lens groups G2 and G3 may be moved.

Embodiment 5

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 17. The total length of the variable power optical system of the present embodiment is about 13 mm.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

Embodiment 6

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 21. The total length of the variable power optical system of the present embodiment is about 13.5 mm.

The first lens group G1 is composed of a biconcave negative lens L11 and a positive meniscus lens L12 which is jointed to the biconcave negative lens L11 and the convex surface of which faces toward the object side, in that order from the object side. And, the first lens group G1 as a whole has negative refractive power. When the L12 is made of energy curable resin, it is possible to make the first lens group G1 thin, so that it is possible to sufficiently secure an amount of movement of the second lens group G2 in changing magnification. As a result, it is possible to shorten the total length of the optical system while good performance of the optical system is being maintained.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group G2 is composed of a biconvex positive lens L21 which becomes the first lens element, an aperture stop S, a biconvex positive lens L22 which becomes the second lens element, and a biconcave negative lens L23 which becomes the third lens element and is joined to the biconvex positive lens L22, in that order from the object side. And, the second lens group G2 as a whole has positive refractive power.

The third lens group G3 is composed of one biconcave negative lens L3. Besides, the biconcave negative lens element L3 may be replaced with a negative meniscus lens the convex surface of which faces toward the object side or with a negative meniscus lens the concave surface of which faces toward the object side.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

In changing magnification from the wide angle end position to the telephoto end position, the first lens group G1 and the fourth lens group G4 keep still, the second lens group G2 moves toward the object side, and the third lens group G3 moves to the position nearest to the object side in the middle of the optical system.

In changing from an object point at infinity to a close object point to focus the optical system on the close object point, both of the second and third lens groups G2 and G3 may be moved.

Embodiment 7

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 25. The total length of the variable power optical system of the present embodiment is about 13 mm.

When the L12 is made of energy curable resin, it is possible to make the first lens group G1 thin, so that it is possible to sufficiently secure an amount of movement of the second lens group G2 in changing magnification. As a result, it is possible to shorten the total length of the optical system while good performance of the optical system is being maintained.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group G2 is composed of a biconvex positive lens L2 which becomes the first lens element, an aperture stop S, the biconvex positive lens L22 which becomes the second lens element, a biconcave negative lens L23 which becomes the third lens element and is jointed to the biconvex positive lens L22, in that order from the object side. And, the second lens group G2 has positive refractive power as a whole and has a main magnification change function.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

In changing magnification from the wide angle end position to the telephoto end position, the first lens group G1 and the fourth lens group G4 keep still, and the second lens group G2 moves toward the object side, and the third lens group G3 moves to the position nearest to the object side in the middle of the optical system.

In changing from an object point at infinity to a close object point to focus the optical system on the close object point, both of the second and third lens groups G2 and G3 may be moved.

Embodiment 8

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 28. The total length of the variable power optical system of the present embodiment is about 13 mm.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group G2 is composed of a biconvex positive lens L21 which becomes the first lens element, an aperture stop S, a biconvex positive lens L22 which becomes the second lens element, and a biconcave negative lens L23 which becomes the third lens element and is joined to the biconvex positive lens L22, in that order from the object side. And, the second lens group G2 has positive refractive power as a whole and has a main magnification change function.

The third lens group G3 is composed of one negative meniscus lens L3 the convex surface of which faces toward the object sides. Besides, the negative meniscus lens L3 the convex surface of which faces toward the object side may be replaced with a negative meniscus lens the concave surface of which faces toward the object side or with a biconcave negative lens.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

Embodiment 9

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 31. The total length of the variable power optical system of the present embodiment is about 13.5 mm.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

In changing magnification from the wide angle end position to the telephoto end position, the first lens group G1 keeps still, the second lens group G2 moves toward the object side, the third lens group G3 moves to the position nearest to the object side in the middle of the optical system, and the fourth lens group G4 moves toward the image side.

Embodiment 10

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 34. The total length of the variable power optical system of the present embodiment is about 10 mm.

The first lens group G1 is composed of a biconcave negative lens L11 and a positive meniscus lens L12 the convex surface of which faces toward the object side, in that order from the object side. And, the first lens group G1 as a whole has negative refractive power.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group G2 is composed of a biconvex positive lens L21 which becomes the first lens element, an aperture stop S, a biconvex positive lens L22 which becomes the second lens element, and a biconcave negative lens L23 which becomes the third lens element and is joined to the biconvex positive lens L22, in that order from the object side. And, the second lens group G2 has positive refractive power as a whole and has a main magnification change function.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

Embodiment 11

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 37 The total length of the variable power optical system of the present embodiment is about 10 mm.

The second lens group G2 includes a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first and second lens elements have convex shapes on the object side, respectively. Specifically, the second lens group G2 is composed of a biconvex positive lens L21 which becomes the first lens element, an aperture stop S, a biconvex positive lens L22 which becomes the second lens element, and a biconcave negative lens L23 which becomes the third lens element and is jointed to the biconvex positive lens L22, in that order from the object side. And, the third lens group G2 has positive refractive power as a whole and has a main magnification change function.

The third lens group G3 is composed of one negative meniscus lens L3 the concave surface of which faces toward the object side. Besides, the negative meniscus lens L3 the concave surface of which faces toward the object side may be replaced with a negative meniscus lens the convex surface of which faces toward the object side or with a biconcave negative lens.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

Embodiment 12

The optical constitution of the variable power optical system of the present embodiment is explained using FIG. 40. The total length of the variable power optical system of the present embodiment is about 14 mm.

The first lens group G1 is composed of one biconcave negative lens L1.

The second lens group G2 is composed of a first lens element with positive refractive power, a second lens element, and a third lens element, in that order from the object side. The first lens element has a convex shape on the object side. Specifically, the second lens group G2 is composed of a biconvex positive lens L21 which becomes the first lens element, a biconcave negative lens L22 which becomes the second lens element and is joined to the biconvex positive lens L21, an aperture stop S, and a biconvex positive lens L23 which becomes the third lens element, in that order from the object side. And, the second lens group G2 has positive refractive power as a whole and has a main magnification change function.

The third lens group G3 is composed of one negative meniscus lens L3 the convex surface of which faces toward the object side. Besides, the negative meniscus lens L3 the convex surface of which faces toward the object side may be replaced with a negative meniscus lens the concave surface of which faces toward the object side or with a biconcave negative lens.

The fourth lens group G4 is composed of one positive meniscus lens L4 the convex surface of which faces toward the image side.

Next, in each of the embodiments 1 to 12, the numerical data of the optical members constituting each of the variable power optical systems will be given. The embodiment 1 corresponds to a numerical embodiment 1. The embodiment 2 corresponds to a numerical embodiment 2. The embodiment 3 corresponds to a numerical embodiment 3. The embodiment 4 corresponds to a numerical embodiment 4. The embodiment 5 corresponds to a numerical embodiment 5. The embodiment 6 corresponds to a numerical embodiment 6. The embodiment 7 corresponds to a numerical embodiment 7. The embodiment 8 corresponds to a numerical embodiment 8. The embodiment 9 corresponds to a numerical embodiment 9. The embodiment 10 corresponds to a numerical embodiment 10. The embodiment 11 corresponds to a numerical embodiment 11. The embodiment 12 corresponds to a numerical embodiment 12.

Besides, in the numerical data and the drawings, r denotes the radius of curvature of each of lens surfaces, d denotes the thickness of each of lenses or air spacing between lenses, nd denotes the refractive index of each of lenses with respect to the d line (587.56 nm), vd denotes the Abbe's number of each of lenses with respect to the d line (587.56 nm), and * (asterisk) expresses aspherical surface. A unit of length is mm in the numerical data.

Also, when z is taken as a coordinate in the direction along the optical axis, y is taken as a coordinate in the direction perpendicular to the optical axis, K denotes a conic constant, and A4, A6, A8, and A10 denote an aspherical coefficient, the shapes of aspherical surfaces are expressed by the following formula (I):

z=(y²/r)/[1+{1−(1+K)(y/r)²}^1/2]+A4y⁴+A6y⁶+A8y⁸+A10y¹⁰ (I)

Also, e denotes a power of ten. Besides, these symbols for these various values are also common to the following numerical data of the embodiments.

Besides, BF denotes the distance from the last surface in lenses to a paraxial image plane in the form of air equivalent amount, and lens total length denotes a value obtained by adding the distance between the first surface and the last surface in lenses to BF. On the other hand, BF# denotes the distance from the last surface in lenses to an image plane in the form of air equivalent amount, and lens total length# denotes a value obtained by adding the distance between the first surface and the last surface in lenses to BF#.

Numerical Embodiment 1

Surface data

Unit: mm

Surface No.
r
d
nd
vd
Effective diameter

Object plane
∞
∞

1*
29.7496
0.5421
1.90270
31.00
2.690

2*
2.6180
0.5723

2.165

3*
3.5600
0.7172
2.10223
16.77
2.185

4*
5.6420
D4

2.097

5*
2.1763
0.9187
1.59201
67.02
1.427

6*
−44.5379
0.2000

1.318

7 (Stop)
∞
0.0000

(Variable)

8*
5.9838
0.6894
1.85135
40.10
1.207

9
−6.5431
0.5215
1.82114
24.06
1.137

10*
5.0933
D10

1.011

11*
−4.9399
0.4461
1.77377
47.17
1.198

12*
53.6530
D12

1.427

13*
−14.4249
0.8801
1.82114
24.06
2.808

14*
−5.0670
0.2353

2.868

15
∞
0.3000
1.51633
64.14
2.929

16
∞
0.4000

2.947

Image plane
∞

Aspherical surface data

The first surface

K = −224.489, A4 = 6.10008e−03, A6 = −1.22957e−03,

A8 = 5.75218e−05

The second surface

K = 0.086, A4 = −6.58139e−03, A6 = 3.39688e−03,

A8 = −7.32903e−04

The third surface

K = −6.605, A4 = −3.67877e−03, A6 = 1.95938e−03,

A8 = −8.93682e−05

The fourth surface

K = −21.342, A4 = −4.83678e−03, A6 = 6.39538e−04,

A8 = 5.70942e−05

The fifth surface

K = −0.989, A4 = 2.50732e−03, A6 = 7.21049e−04,

A8 = 3.61962e−04

The sixth surface

K = −791.631, A4 = −1.12792e−02, A6 = 8.93540e−03,

A8 = −1.87646e−03

The eighth surface

K = 4.845, A4 = −9.49342e−04, A6 = 9.01956e−03,

A8 = −2.80204e−03

The tenth surface

K = −32.788, A4 = 6.96684e−02, A6 = −4.68501e−03,

A8 = 9.73012e−03

The eleventh surface

K = −3.112, A4 = 3.30281e−03, A6 = −6.05974e−03,

A8 = −4.24602e−03

The twelfth surface

K = −40363.004, A4 = 2.29435e−02, A6 = −1.24625e−02,

A8 = 9.19254e−04

The thirteenth surface

K = −1.394, A4 = 4.97914e−03, A6 = −1.14929e−03,

A8 = 9.38867e−05

The fourteenth surface

K = −2.722, A4 = 1.16889e−02, A6 = −2.73333e−03,

A8 = 1.79573e−04

Various data

Zoom ratio: 2.850

Wide

Tele-

Wide

Tele-
angle

photo

angle

photo
end
Middle
end

end
Middle
end
(focusing on a close range)

Focal length
3.754
6.025
10.699

F No.
3.200
4.369
5.200

Angle of view
82.828
51.090
29.527

2ω

Image height
2.900
2.900
2.900

BF
0.833
0.833
0.833

Lens total
12.898
12.898
12.898

length

(Distance from
∞
∞
∞
100.00
500.00
800.00

an object

point)

D4
3.941
2.207
0.200
3.225
2.257
0.483

D10
1.025
0.863
1.714
0.969
0.883
1.519

D12
1.611
3.507
4.664
2.384
3.438
4.575

Stop diameter
0.987
0.987
1.215

(Entrance
3.159
2.655
1.791

pupil

position)

(Exit pupil
−6.368
−14.458
−35.576

position)

(The position
4.966
6.304
9.349

of the front

side principle

point)

(The position
−3.317
−5.641
−10.271

of the rear

side principle

point)

Lens
The first surface of lens
Focal length of lens

L11
1
−3.210

L12
3
7.413

L21
5
3.531

L22
8
3.767

L23
9
−3.419

L3
11
−5.827

L4
13
9.125

Zoom lens group data

The first
Focal
Composition
The position
The position

surface
length
length
of the front
of the rear

of lens
of lens
of lens
side prin-
side prin-

Group
group
group
group
ciple point
ciple point

G1
1
−5.731
1.832
0.276
−0.873

G2
5
3.191
2.330
−0.304
−1.515

G3
11
−5.827
0.446
0.021
−0.230

G4
13
9.125
0.880
0.715
0.251

Magnification of lens group

Wide

Tele-

Wide

Tele-
angle

photo

angle

photo
end
Middle
end

end
Middle
end
(focusing on a close range)

G1
0.000
0.000
0.000
0.054
0.011
0.007

G2
−0.453
−0.600
−0.964
−0.530
−0.602
−0.898

G3
1.553
1.868
2.075
1.689
1.859
2.063

G4
0.932
0.938
0.933
0.930
0.936
0.931

Numerical embodiment 2

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
31.1191
0.5500
1.85135
40.10
2.825

2*
2.5330
0.5132

2.187

3*
3.1051
0.8424
1.82114
24.06
2.203

4*
5.5712
D4

2.110

5*
2.0868
1.0720
1.59201
67.02
1.438

6*
−181.2845
0.2000

1.296

7 (Stop)
∞
0.0000

(Variable)

8*
5.2934
0.6793
1.85135
40.10
1.161

9
−9.4008
0.4687
1.82114
24.06
1.086

10*
4.3096
D10

0.980

11*
−4.5361
0.4000
1.77377
47.17
1.185

12*
−4863.2721
D12

1.405

13*
−15.0779
0.8960
1.82114
24.06
2.787

14*
−4.9623
0.2027

2.854

15
∞
0.3000
1.51633
64.14
2.920

16
∞
0.4000

2.953

Image plane
∞

Aspherical surface data

The first surface

K = 9.975, A4 = 5.45942e−03, A6 = −1.17913e−03, A8 = 6.14112e−05

The second surface

K = 0.028, A4 = −5.92450e−03, A6 = 3.54360e−03, A8 = −7.18809e−04

The third surface

K = −4.944, A4 = −2.93256e−03, A6 = 2.56724e−03,

A8 = −1.52620e−04

The fourth surface

K = −16.419, A4 = −5.87501e−03, A6 = 9.32666e−04,

A8 = 4.10944e−05

The fifth surface

K = −0.869, A4 = 3.97321e−03, A6 = 4.46620e−04, A8 = 3.23707e−04

The sixth surface

K = −9645.985, A4 = −2.36383e−02, A6 = 1.14055e−02,

A8 = −2.04346e−03

The eighth surface

K = −2.017, A4 = −1.25319e−02, A6 = 1.04830e−02,

A8 = −2.75134e−03

The tenth surface

K = −37.283, A4 = 8.97816e−02, A6 = −2.64567e−02,

A8 = 2.13844e−02

The eleventh surface

K = −3.217, A4 = 3.81585e−03, A6 = −1.49213e−02, A8 = 1.03508e−03

The twelfth surface

K = −14369395.106, A4 = 1.43170e−02, A6 = −1.10677e−02,

A8 = 1.12467e−03

The thirteenth surface

K = −1.990, A4 = 5.00050e−03, A6 = −1.15848e−03, A8 = 9.16097e−05

The fourteenth surface

K = −2.578, A4 = 1.16150e−02, A6 = −2.73641e−03, A8 = 1.80048e−04

Various data

Zoom ratio: 2.850

Wide

Wide

angle

Telephoto

angle

Telephoto
end
Middle
end

end
Middle
end
(focusing on a close range)

Focal
3.754
6.021
10.699

length

F No.
3.200
4.384
5.200

Angle of
82.691
50.978
29.424

view 2ω

Image
2.900
2.900
2.900

height

BF
0.801
0.801
0.801

Lens total
12.898
12.898
12.898

length

(Distance
∞
∞
∞
100.00
500.00
800.00

from an

object

point

D4
3.931
2.208
0.200
3.736
2.222
0.266

D10
0.964
0.788
1.612
0.981
0.811
1.598

D12
1.581
3.480
4.663
1.759
3.443
4.612

Stop
0.944
0.944
1.173

diameter

(Entrance
3.288
2.795
1.956

pupil

position)

(Exit pupil
−6.289
−14.879
−41.689

position)

(The
5.061
6.495
9.958

position of

the front

side

principle

point)

(The
−3.330
−5.679
−10.344

position of

the rear

side

principle

point)

Lens
The first surface of lens
Focal length of lens

L11
1
−3.268

L12
3
7.403

L21
5
3.492

L22
8
4.064

L23
9
−3.544

L3
11
−5.868

L4
13
8.662

Zoom lens group data

The

The position
position

of the
of the

The first
Focal
Composition
front side
rear side

surface of
length of
length of
principle
principle

Group
lens group
lens group
lens group
point
point

G1
1
−5.825
1.906
0.340
−0.873

G2
5
3.180
2.420
−0.387
−1.600

G3
11
−5.868
0.400
−0.000
−0.226

G4
13
8.662
0.896
0.705
0.232

Magnification of lens group

Wide

Wide

angle

Telephoto
angle end
Middle
Telephoto end

end
Middle
end
(focusing on a close range)

G1
0.000
0.000
0.000
0.055
0.012
0.007

G2
−0.450
−0.596
−0.954
−0.486
−0.601
−0.948

G3
1.536
1.844
2.048
1.576
1.842
2.043

G4
0.932
0.941
0.940
0.926
0.939
0.938

Numerical embodiment 3

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
−51.6608
0.5500
1.53071
55.67
3.911

2*
3.8768
D2

2.973

3*
4.5535
0.7634
1.63493
23.89
2.471

4*
8.1682
D4

2.332

5 (Stop)
∞
0.0000

(Variable)

6*
2.2847
1.2110
1.53071
55.67
1.442

7*
−4.8589
0.2000

1.407

8*
27.5864
0.5000
1.63493
23.89
1.317

9*
1.9602
0.5251

1.202

10*
1.9235
0.7100
1.53071
55.67
1.500

11*
1.9019
D11

1.610

12*
13.5849
1.5632
1.63493
23.89
2.944

13*
−23.9264
1.2468

2.814

14
∞
0.4000
1.51633
64.14
2.946

15
∞
0.4000

2.973

Image plane
∞

Aspherical surface data

The first surface

K = 5.000, A4 = −2.36892e−03, A6 = 2.28612e−04, A8 = −5.01395e−06

The second surface

K = −5.000, A4 = 6.35893e−03, A6 = −6.43852e−04, A8 = 6.13916e−05

The third surface

K = −4.992, A4 = 2.91448e−03, A6 = −7.05027e−04, A8 = 8.65670e−05

The fourth surface

K = −1.084, A4 = −3.57126e−03, A6 = −4.87021e−05,

A8 = 6.46356e−05

The sixth surface

K = −1.312, A4 = 5.44552e−03, A6 = 3.11419e−03, A8 = −8.98067e−04

The seventh surface

K = −4.146, A4 = 2.83431e−02, A6 = −1.00090e−02, A8 = 6.33877e−04

The eighth surface

K = 0.000, A4 = 2.55526e−02, A6 = −8.57471e−03

The ninth surface

K = −3.832, A4 = 3.21058e−02, A6 = 7.16734e−03, A8 = 7.08642e−04

The tenth surface

K = −3.755, A4 = −1.67129e−02, A6 = −5.64958e−03,

A8 = 3.28290e−03

The eleventh surface

K = −1.122, A4 = −4.68131e−02, A6 = 2.86083e−03, A8 = 8.24444e−04

The twelfth surface

K = 0.756, A4 = −3.58875e−03, A6 = 7.72697e−04, A8 = −1.41169e−05

The thirteenth surface

K = −5.000, A4 = −5.33300e−03, A6 = 7.14335e−04, A8 = 2.85829e−05

Various data

Zoom ratio: 2.862

Wide

Wide

angle

Telephoto

angle

Telephoto
end
Middle
end

end
Middle
end
(focusing on a close range)

Focal
4.156
6.693
11.893

length

F No.
3.200
4.396
5.200

Angle of
77.136
47.218
26.480

view 2ω

Image
2.900
2.900
2.900

height

BF
1.911
1.911
1.911

Lens total
15.864
15.864
15.864

length

(Distance
∞
∞
∞
100.00
500.00
800.00

from an

object

point)

D2
3.202
0.703
0.327
2.875
0.774
0.401

D4
3.820
3.980
0.909
3.675
3.824
0.787

D11
0.909
3.247
6.694
1.381
3.333
6.742

Stop
1.080
1.080
1.292

diameter

(Entrance
4.327
3.912
1.855

pupil

position)

(Exit pupil
−4.270
−9.011
−23.780

position)

(The
5.704
6.491
8.219

position of

the front

side

principle

point)

(The
−3.721
−6.324
−11.604

position of

the rear

side

principle

point)

Lens
The first surface of lens
Focal length of lens

L1
1
−6.772

L2
3
14.977

L31
6
3.111

L32
8
−3.349

L33
10
30.688

L4
12
13.872

Zoom lens group data

The

The position
position

of the
of the

The first
Focal
Composition
front side
rear side

surface of
length of
length of
principle
principle

Group
lens group
lens group
lens group
point
point

G1
1
−6.772
0.550
0.333
−0.025

G2
3
14.977
0.763
−0.544
−0.975

G3
5
6.085
3.146
−2.433
−3.367

G4
12
13.872
1.563
0.352
−0.620

Magnification of lens group

Wide angle

Telephoto

Wide

Telephoto
end
Middle
end

angle end
Middle
end
(focusing on a close range)

G1
0.000
0.000
0.000
0.063
0.013
0.008

G2
2.712
1.867
1.784
2.386
1.863
1.787

G3
−0.278
−0.646
−1.193
−0.360
−0.661
−1.208

G4
0.815
0.820
0.826
0.814
0.819
0.823

Numerical embodiment 4

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
24.9824
0.4982
1.90270
31.00
2.680

2*
2.6593
0.5867

2.159

3*
3.7965
0.6883
2.10223
16.77
2.159

4*
5.9430
D4

2.120

5*
2.1596
0.9525
1.59201
67.02
1.435

6*
−48.6138
0.2000

1.322

7 (Stop)
∞
0.0000

(Variable)

8*
6.5103
0.6801
1.85135
40.10
1.201

9
−7.3491
0.5708
1.82114
24.06
1.134

10*
5.5872
D10

1.015

11*
−4.6844
0.4504
1.77377
47.17
1.212

12*
100.7637
D12

1.437

13*
−13.7627
0.8839
1.90270
31.00
2.801

14*
−5.1236
0.2065

2.866

15
∞
0.3000
1.51633
64.14
2.928

16
∞
0.4000

2.946

Image plane
∞

Aspherical surface data

The first surface

K = −397.963, A4 = 6.59381e−03, A6 = −1.17236e−03,

A8 = 5.02427e−05

The second surface

K = 0.088, A4 = −6.56207e−03, A6 = 3.84046e−03, A8 = −7.40701e−04

The third surface

K = −7.634, A4 = −3.69106e−03, A6 = 1.79132e−03,

A8 = −1.86618e−04

The fourth surface

K = −23.212, A4 = −5.62260e−03, A6 = 5.95203e−04,

A8 = −6.89594e−05

The fifth surface

K = −0.956, A4 = 2.77532e−03, A6 = 7.11842e−04, A8 = 9.68824e−05

The sixth surface

K = 218.608, A4 = −1.28903e−02, A6 = 7.79247e−03,

A8 = −1.56315e−03

The eighth surface

K = 0.801, A4 = −2.76409e−03, A6 = 7.97038e−03, A8 = −2.01303e−03

The tenth surface

K = −38.926, A4 = 6.44034e−02, A6 = −6.22281e−03,

A8 = 1.13101e−02

The eleventh surface

K = −3.245, A4 = 4.36822e−03, A6 = −5.62552e−03,

A8 = −2.76127e−03

The twelfth surface

K = −575054.125, A4 = 1.94775e−02, A6 = −8.94047e−03,

A8 = 3.15805e−04

The thirteenth surface

K = −0.780, A4 = 4.95196e−03, A6 = −1.14942e−03, A8 = 9.43150e−05

The fourteenth surface

K = −2.819, A4 = 1.17394e−02, A6 = −2.72948e−03, A8 = 1.79738e−04

Various data

Zoom ratio: 2.849

Wide

Wide

angle

Telephoto

angle

Telephoto
end
Middle
end

end
Middle
end
(focusing on a close range)

Focal
3.754
6.019
10.695

length

F No.
3.200
4.367
5.200

Angle of
82.905
51.227
29.493

view 2ω

Image
2.900
2.900
2.900

height

BF
0.804
0.804
0.804

Lens total
12.898
12.898
12.898

length

(Distance
∞
∞
∞
100.00
500.00
800.00

from an

object

point)

D4
3.931
2.207
0.200
3.137
2.256
0.534

D10
1.026
0.876
1.749
0.968
0.895
1.511

D12
1.626
3.500
4.633
2.478
3.432
4.537

Stop
0.983
0.983
1.210

diameter

(Entrance
3.137
2.642
1.790

pupil

position)

(Exit pupil
−6.729
−16.061
−45.914

position)

(The
5.032
6.511
10.036

position of

the front

side

principle

point)

(The
−3.308
−5.634
−10.298

position

of the

rear side

principle

point)

Lens
The first surface of lens
Focal length of lens

L11
1
−3.332

L12
3
8.164

L21
5
3.517

L22
8
4.149

L23
9
−3.790

L3
11
−5.774

L4
13
8.624

Zoom lens group data

The

The position
position

of the
of the

The first
Focal
Composition
front side
rear side

surface of
length of
length
principle
principle

Group
lens group
lens group
of lens group
point
point

G1
1
−5.700
1.773
0.255
−0.878

G2
5
3.194
2.403
−0.286
−1.548

G3
11
−5.774
0.450
0.011
−0.242

G4
13
8.624
0.884
0.706
0.263

Magnification of lens group

Wide angle

Telephoto

Wide

Telephoto
end
Middle
end

angle end
Middle
end
(focusing on a close range)

G1
0.000
0.000
0.000
0.054
0.011
0.007

G2
−0.454
−0.602
−0.969
−0.539
−0.604
−0.889

G3
1.555
1.867
2.066
1.705
1.859
2.055

G4
0.932
0.939
0.937
0.930
0.937
0.934

Numerical embodiment 5

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
32.5181
0.4000
1.90270
31.00
2.662

2*
2.6859
0.5841

2.171

3*
3.9263
0.7023
2.10223
16.77
2.172

4*
6.3251
D4

2.123

5*
2.3656
0.8877
1.59201
67.02
1.442

6*
−19.9615
0.2000

1.349

7 (Stop)
∞
0.0000

(Variable)

8*
5.6753
0.6799
1.85135
40.10
1.257

9
−8.0095
0.5194
1.82114
24.06
1.184

10*
5.2122
D10

1.039

11*
−4.7550
0.4439
1.77377
47.17
1.186

12*
241.8954
D12

1.373

13*
−17.7526
1.0020
1.58347
30.25
2.836

14*
−5.0153
0.2387

2.891

15
∞
0.3000
1.51633
64.14
2.940

16
∞
0.4000

2.952

Image plane
∞

Aspherical surface data

The first surface

K = −204.602, A4 = 6.38593e−03, A6 = −1.31082e−03,

A8 = 6.42265e−05

The second surface

K = 0.140, A4 = −4.48908e−03, A6 = 3.35561e−03, A8 = −7.34479e−04

The third surface

K = −8.010, A4 = −3.58577e−03, A6 = 2.02086e−03,

A8 = −1.85601e−04

The fourth surface

K = −27.131, A4 = −5.26129e−03, A6 = 7.06800e−04,

A8 = −5.83212e−05

The fifth surface

K = −1.224, A4 = −2.34964e−04, A6 = 1.88499e−08, A8 = 3.10798e−04

The sixth surface

K = −178.856, A4 = −8.86247e−03, A6 = 7.81377e−03,

A8 = −1.53400e−03

The eighth surface

K = 6.120, A4 = 6.42116e−03, A6 = 8.89900e−03, A8 = −2.09052e−03

The tenth surface

K = −38.050, A4 = 7.18749e−02, A6 = −5.04696e−03,

A8 = 1.13516e−02

The eleventh surface

K = −3.616, A4 = 4.31319e−03, A6 = −1.04263e−03,

A8 = −3.53360e−03

The twelfth surface

K = −1640587.993, A4 = 1.96904e−02, A6 = −4.81382e−03,

A8 = −6.24215e−04

The thirteenth surface

K = −5.864, A4 = 5.12076e−03, A6 = −1.13861e−03, A8 = 9.49549e−05

The fourteenth surface

K = −2.353, A4 = 1.15022e−02, A6 = −2.74683e−03, A8 = 1.78418e−04

Various data

Zoom ratio: 2.850

Wide

Wide

angle

Telephoto

angle

Telephoto
end
Middle
end

end
Middle
end
(focusing on a close range)

Focal
3.754
6.038
10.699

length

F No.
3.200
4.349
5.200

Angle of
82.899
51.642
29.898

view 2ω

Image
2.900
2.900
2.900

height

BF
0.837
0.837
0.837

Lens total
12.898
12.898
12.898

length

(Distance
∞
∞
∞
100.00
500.00
800.00

from an

object

point)

D4
3.975
2.194
0.200
3.198
2.281
0.556

D10
1.006
0.888
1.793
0.960
0.900
1.528

D12
1.661
3.560
4.649
2.484
3.461
4.557

Stop
1.033
1.033
1.255

diameter

(Entrance
3.012
2.510
1.668

pupil

position)

(Exit pupil
−5.919
−11.530
−20.540

position)

(The
4.693
5.589
7.011

position

of the

front side

principle

point)

(The
−3.312
−5.686
−10.305

position

of the

rear side

principle

point)

Lens
The first surface of lens
Focal length of lens

L11
1
−3.264

L12
3
8.143

L21
5
3.626

L22
8
3.993

L23
9
−3.778

L3
11
−6.022

L4
13
11.643

Zoom lens group data

The

The position
position

of the
of the

The first
Focal
Composition
front side
rear side

surface of
length of
length
principle
principle

Group
lens group
lens group
of lens group
point
point

G1
1
−5.552
1.686
0.169
−0.919

G2
5
3.194
2.287
−0.238
−1.451

G3
11
−6.022
0.444
0.005
−0.245

G4
13
11.643
1.002
0.857
0.242

Magnification of lens group

Wide angle

Telephoto

Wide

Telephoto
end
Middle
end

angle end
Middle
end
(focusing on a lose range)

G1
0.000
0.000
0.000
0.053
0.011
0.007

G2
−0.455
−0.610
−0.986
−0.537
−0.607
−0.898

G3
1.571
1.870
2.058
1.707
1.857
2.046

G4
0.945
0.953
0.949
0.945
0.951
0.948

Numerical embodiment 6

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
−20.7452
0.4261
1.76802
49.24
2.660

2*
3.1798
0.5199
1.63387
23.38
2.348

3*
11.5413
D3

2.338

4*
2.5653
0.7836
1.69350
53.21
1.425

5*
−9.5581
0.1627

1.304

6 (Stop)
∞
0.1056

(Variable)

7*
6.3829
0.6523
1.77377
47.17
1.173

8
−16.9084
0.3267
1.84666
23.78
1.048

9*
2.6017
D9

0.900

10*
−1663.5639
0.3688
1.58913
61.14
1.798

11*
9.0733
D11

1.796

12*
−6.3464
0.7403
1.82114
24.06
2.400

13*
−4.0025
2.2296

2.510

14
∞
0.3796
1.51633
64.14
2.909

15
∞
0.4000

2.942

Image plane
∞

Aspherical surface data

The first surface

K = −375.930, A4 = −1.15480e−02, A6 = 2.04009e−03,

A8 = −2.03463e−04, A10 = 9.13064e−06

The second surface

K = −4.767

The third surface

K = 19.716, A4 = −8.39462e−03, A6 = 8.74090e−04,

A8 = −3.16644e−05, A10 = −9.08607e−06

The fourth surface

K = −5.335, A4 = 3.95944e−02, A6 = −2.26682e−04, A8 = 1.21738e−03,

A10 = −2.20735e−05

The fifth surface

K = −1.433, A4 = 5.93078e−02, A6 = −5.72481e−03,

A8 = −1.00605e−05, A10 = −4.23420e−04

The seventh surface

K = 0.827, A4 = 7.27634e−02, A6 = −2.04547e−02, A8 = 2.74787e−03,

A10 = −2.76359e−03

The ninth surface

K = 3.493, A4 = 2.51814e−02, A6 = −9.44244e−04, A8 = −9.17287e−03,

A10 = −9.81182e−03

The tenth surface

K = 0.000, A4 = 2.01378e−02, A6 = 2.42834e−03, A8 = −6.61110e−04,

A10 = −3.37042e−05

The eleventh surface

K = 1.229, A4 = 2.32836e−02, A6 = 1.19434e−03, A8 = −5.32506e−05,

A10 = −1.30308e−04

The twelfth surface

K = −0.983, A4 = 3.30959e−03, A6 = 1.23354e−04

The thirteenth surface

K = −1.651, A4 = −8.10707e−05, A6 = −7.42911e−05,

A8 = 1.46926e−05

Various data

Zoom ratio: 2.849

Wide

Wide

angle

Telephoto

angle

Telephoto
end
Middle
end

end
Middle
end
(focusing on a close range)

Focal
4.521
7.640
12.880

length

F No.
3.757
4.702
5.248

Angle of
70.567
43.949
24.572

view 2ω

Image
2.900
2.900
2.900

height

BF
2.880
2.880
2.880

Lens total
13.374
13.371
13.371

length

(Distance
∞
∞
∞
100.00
500.00
800.00

from an

object

point)

D3
4.604
2.224
0.151
3.959
2.507
0.265

D9
0.557
0.550
4.157
0.781
0.549
4.037

D11
1.247
3.631
2.097
1.665
3.348
2.102

Stop
0.900
1.000
1.250

diameter

(Entrance
3.479
2.544
1.301

pupil

position)

(Exit
−4.272
−11.074
−15.850

pupil

position)

(The
5.143
6.001
5.324

position

of the

front side

principle

point)

(The
−4.121
−7.240
−12.480

position

of the

rear side

principle

point)

Lens
The first surface of lens
Focal length of lens

L11
1
−3.562

L12
2
6.761

L21
4
2.996

L22
7
6.063

L23
8
−2.643

L3
10
−15.316

L4
12
11.553

Zoom lens group data

The

The position
position

of the
of the

The first
Focal
Composition
front side
rear side

surface of
length of
length
principle
principle

Group
lens group
lens group
of lens group
point
point

G1
1
−7.332
0.946
0.301
−0.251

G2
4
4.054
2.031
−1.113
−1.816

G3
10
−15.316
0.369
0.231
−0.001

G4
12
11.553
3.349
0.963
−1.872

Magnification of lens group

Wide

Telephoto

Wide

Telephoto
angle end
Middle
end

angle end
Middle
end
(focusing on a close range)

G1
0.000
0.000
0.000
0.068
0.014
0.009

G2
−0.578
−0.874
−1.579
−0.690
−0.842
−1.551

G3
1.329
1.485
1.385
1.356
1.466
1.385

G4
0.803
0.803
0.803
0.803
0.803
0.803

Numerical embodiment 7

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
−11.1356
0.4975
1.76802
49.24
2.436

2*
4.3635
0.2782
1.68086
20.03
2.161

3*
13.0403
D3

2.143

4*
2.4354
1.1497
1.69350
53.21
1.500

5*
−10.2972
0.0965

1.338

6 (Stop)
∞
0.1122

(Variable)

7*
6.9467
0.6344
1.76802
49.24
1.209

8
−10.0264
0.3871
1.84666
23.78
1.142

9*
2.7369
D9

1.053

10*
−1593.9529
0.4096
1.58913
61.14
1.938

11*
7.2355
D11

1.949

12*
−7.0449
1.0575
1.92286
20.88
2.686

13*
−3.9192
0.8750

2.866

14
∞
0.3796
1.51633
64.14
2.965

15
∞
0.4000

2.977

Image plane
∞

Aspherical surface data

The first surface

K = −43.263, A4 = −1.24712e−02, A6 = 1.73364e−03,

A8 = −6.78483e−05

The second surface

K = −13.143

The third surface

K = 11.728, A4 = −8.61588e−03, A6 = 1.31833e−03, A8 = 3.44649e−05

The fourth surface

K = −1.810, A4 = 1.47470e−02, A6 = 1.63827e−03, A8 = 1.52183e−04

The fifth surface

K = 10.732, A4 = 1.76981e−02, A6 = −3.95829e−03, A8 = 3.18646e−04

The seventh surface

K = −0.652, A4 = 6.62402e−03, A6 = −8.64488e−03,

A8 = −8.05063e−04

The ninth surface

K = 3.404, A4 = −4.48263e−03, A6 = −5.81944e−03,

A8 = −5.86170e−03

The tenth surface

K = 0.000, A4 = 6.85162e−03, A6 = 5.94218e−04

The eleventh surface

K = 1.002, A4 = 8.32696e−03, A6 = 6.31067e−04, A8 = −4.05088e−05

The twelfth surface

K = −4.931

The thirteenth surface

K = −3.651, A4 = −2.91002e−03, A6 = −8.23036e−05,

A8 = −3.97711e−07

Various data

Zoom ratio: 2.846

Wide angle

Telephoto

end
Middle
end

Focal length
4.526
7.640
12.878

F No.
3.590
5.050
5.131

Angle of view 2ω
72.782
43.815
24.659

Image height
2.900
2.900
2.900

BF
1.525
1.525
1.525

Lens total length
12.867
12.873
12.875

Distance from an object point
∞
∞
∞

D3
4.309
2.213
0.196

D9
1.296
1.055
4.311

D11
1.114
3.457
2.220

Stop diameter
0.900
0.900
1.250

Entrance pupil position
3.292
2.510
1.389

Exit pupil position
−7.123
−23.689
−42.013

The position of the front side
5.450
7.835
10.458

principle point

The position of the rear side principle
−4.122
−7.242
−12.481

point

Lens
The first surface of lens
Focal length of lens

L11
1
−4.026

L12
2
9.508

L21
4
2.949

L22
7
5.431

L23
8
−2.505

L3
10
−12.225

L4
12
8.235

Zoom lens group data

The
The

position
position

of the
of the rear

The first

Composition
front side
side

surface of
Focal length
length
principle
principle

Group
lens group
of lens group
of lens group
point
point

G1
1
−6.977
0.776
0.202
−0.239

G2
4
3.819
2.380
−1.106
−1.918

G3
10
−12.225
0.410
0.257
−0.001

G4
12
8.235
2.312
1.066
−0.532

Magnification of lens group

Wide angle end
Middle
Telephoto end

G1
0.000
0.000
0.000

G2
−0.579
−0.848
−1.536

G3
1.265
1.456
1.355

G4
0.886
0.887
0.887

Numerical embodiment 8

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
−5.6531
0.5000
1.58913
61.14
2.376

2
9.8000
0.2500
1.63494
23.22
2.159

3*
16.8078
D3

2.137

4*
2.9908
0.9110
1.85135
40.10
1.500

5*
−31.7144
0.1000

1.355

6 (Stop)
∞
0.1518

(Variable)

7*
6.6515
0.7500
1.76802
49.24
1.268

8
−4.5000
0.4000
1.84666
23.78
1.185

9*
4.8113
D9

1.058

10
44.8931
0.5000
1.81474
37.03
1.181

11*
3.8464
D11

1.268

12
−32.1035
1.3000
1.82114
24.06
2.886

13*
−4.0000
0.4217

3.000

14
∞
0.3796
1.51633
64.14
2.961

15
∞
0.2900

2.957

Image plane
∞

Aspherical surface data

The first surface

K = −1.000, A4 = −3.19351e−03, A6 = 2.63420e−04, A8 = 1.16363e−05

The third surface

K = −1.000, A4 = −2.77149e−03, A6 = 2.14794e−04, A8 = 5.18982e−05

The fourth surface

K = −1.000, A4 = 1.88539e−03, A6 = 3.55638e−04

The fifth surface

K = −1.000, A4 = 5.68662e−03, A6 = −7.24378e−04

The seventh surface

K = 0.000, A4 = 1.78188e−02, A6 = −8.88828e−04

The ninth surface

K = 11.588, A4 = 2.35797e−02, A6 = −1.00377e−04, A8 = 1.61425e−04

The eleventh surface

K = 0.000, A4 = −1.32598e−03, A6 = 2.94203e−04, A8 = −3.40185e−04

The thirteenth surface

K = −1.000, A4 = 5.47362e−03, A6 = −6.78501e−04, A8 = 2.75097e−05

Various data

Zoom ratio: 2.821

Wide angle

Telephoto

end
Middle
end

Focal length
4.570
7.640
12.890

F No.
3.137
4.383
5.181

Angle of view 2ω
72.832
41.710
24.978

Image height
2.900
2.900
2.900

BF
0.962
0.962
0.962

Lens total length
12.871
12.871
12.871

Distance from an object point
∞
∞
∞

D3
4.231
2.167
0.172

D9
0.758
0.721
1.542

D11
2.057
4.157
5.332

Stop diameter
1.100
1.100
1.300

Entrance pupil position
3.165
2.343
1.167

Exit pupil position
−17.126
44.144
18.147

The position of the front side
6.580
11.335
23.725

principle point

The position of the rear side principle
−4.280
−7.350
−12.600

point

Lens
The first surface of lens
Focal length of lens

L11
1
−6.013

L12
2
36.513

L21
4
3.249

L22
7
3.600

L23
8
−2.693

L3
10
−5.192

L4
12
5.451

Zoom lens group data

The
The

position
position

of the
of the rear

The first

Composition
front side
side

surface of
Focal length
length
principle
principle

Group
lens group
of lens group
of lens group
point
point

G1
1
−7.196
0.750
0.116
−0.345

G2
4
3.400
2.313
−0.522
−1.599

G3
10
−5.192
0.500
0.303
0.026

G4
12
5.451
2.101
0.799
−0.573

Magnification of lens group

Wide angle end
Middle
Telephoto end

G1
0.000
0.000
0.000

G2
−0.433
−0.588
−0.897

G3
1.742
2.147
2.373

G4
0.842
0.842
0.842

Numerical embodiment 9

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
−19.3192
0.4988
1.76802
49.24
2.583

2*
3.7522
0.4683
1.63387
23.38
2.307

3*
11.3663
D3

2.287

4*
2.6413
0.8593
1.69350
53.21
1.473

5*
−9.2555
0.1569

1.381

6 (Stop)
∞
0.1202

(Variable)

7*
6.3775
0.6959
1.76802
49.24
1.175

8
−17.7460
0.4046
1.84666
23.78
1.035

9*
2.5760
D9

0.900

10*
−2150.7307
0.4011
1.58913
61.14
1.778

11*
8.3413
D11

1.857

12*
−7.5498
0.9821
1.82114
24.06
2.555

13*
−4.0253
D13

2.724

14
∞
0.3796
1.51633
64.14
2.944

15
∞
0.4000

2.966

Image plane
∞

Aspherical surface data

The first surface

K = −55.536, A4 = −9.05980e−03, A6 = 1.14637e−03,

A8 = −5.51750e−05

The second surface

K = −5.943

The third surface

K = 3.375, A4 = −8.51272e−03, A6 = 1.43185e−03, A8 = −6.70214e−05

The fourth surface

K = −2.992, A4 = 1.71186e−02, A6 = −1.00737e−03, A8 = 4.64173e−04

The fifth surface

K = −0.989, A4 = 8.39214e−03, A6 = −8.19252e−04, A8 = 2.03175e−04

The seventh surface

K = 0.788, A4 = 5.33856e−03, A6 = −1.80989e−03, A8 = −4.20069e−04

The ninth surface

K = 1.499, A4 = 6.20768e−03, A6 = −5.64490e−04, A8 = −1.23795e−04

The tenth surface

K = 958794.047, A4 = 1.75804e−03, A6 = 1.99109e−03,

A8 = −4.76253e−04

The eleventh surface

K = −0.095, A4 = 3.52958e−03, A6 = 1.43329e−03, A8 = −3.48716e−04

The twelfth surface

K = −0.216

The thirteenth surface

K = −0.637, A4 = 4.61435e−04, A6 = −1.26973e−04,

A8 = −1.09864e−06

Various data

Zoom ratio: 2.838

Wide angle

Telephoto

end
Middle
end

Focal length
4.538
7.640
12.880

F No.
3.339
4.651
5.209

Angle of view 2ω
72.624
42.356
24.646

Image height
2.900
2.900
2.900

BF
2.364
2.306
2.176

Lens total length
13.369
13.374
13.368

Distance from an object point
∞
∞
∞

D3
4.526
2.251
0.195

D9
0.863
0.766
4.061

D11
1.028
3.465
2.347

D13
1.714
1.655
1.526

Stop diameter
1.000
1.000
1.250

Entrance pupil position
3.512
2.608
1.385

Exit pupil position
−5.255
−15.770
−27.703

The position of the front side
5.348
7.018
8.713

principle point

The position of the rear side principle
−4.136
−7.241
−12.480

point

Lens
The first surface of lens
Focal length of lens

L11
1
−4.053

L12
2
8.631

L21
4
3.053

L22
7
6.186

L23
8
−2.633

L3
10
−14.103

L4
12
9.329

Zoom lens group data

The
The

position
position

of the
of the rear

The first

Composition
front side
side

surface of
Focal length
length
principle
principle

Group
lens group
of lens group
of lens group
point
point

G1
1
−7.490
0.967
0.314
−0.247

G2
4
4.036
2.237
−1.225
−1.943

G3
10
−14.103
0.401
0.251
−0.001

G4
12
9.329
0.982
1.026
0.547

Magnification of lens group

Wide angle end
Middle
Telephoto end

G1
0.000
0.000
0.000

G2
−0.576
−0.854
−1.511

G3
1.306
1.472
1.379

G4
0.805
0.812
0.825

G5
1.000
1.000
1.000

Numerical embodiment 10

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
−23.8081
0.4000
1.90270
31.00
1.764

2*
2.2994
0.3419

1.467

3*
2.8941
0.4964
2.10223
16.77
1.475

4*
5.3026
D4

1.420

5*
2.1625
0.8676
1.76802
49.24
1.201

6*
−6.2445
0.1994

1.091

7 (Stop)
∞
0.0000

(Variable)

8*
6.5304
0.5563
1.49700
81.54
0.943

9
−11.0440
0.4000
2.10223
16.77
0.864

10*
6.7381
D10

0.803

11*
−4.9986
0.4000
1.53071
55.67
0.915

12*
6.1075
D12

1.016

13*
−4.3703
0.6790
2.10223
16.77
2.225

14*
−2.6586
0.3758

2.242

15
∞
0.3000
1.51633
64.14
2.270

16
∞
0.3500

2.276

Image plane
∞

Aspherical surface data

The first surface

K = −10.000, A4 = 4.48967e−03, A6 = −2.58325e−03,

A8 = 2.70892e−04

The second surface

K = 0.528, A4 = −1.10216e−02, A6 = 6.00177e−03, A8 = −3.60751e−03

The third surface

K = −1.683, A4 = −1.62024e−02, A6 = 1.06888e−02,

A8 = −2.57278e−03

The fourth surface

K = −10.000, A4 = −1.24411e−02, A6 = 6.03283e−03,

A8 = −1.54408e−03

The fifth surface

K = −0.330, A4 = −6.66268e−03, A6 = −7.36472e−04,

A8 = 2.13320e−03

The sixth surface

K = 3.642, A4 = 2.02813e−02, A6 = 5.86325e−03, A8 = −1.69631e−03

The eighth surface

K = −7.584, A4 = 6.35851e−02, A6 = 3.93734e−02, A8 = −1.23472e−02

The tenth surface

K = −10.000, A4 = 5.93583e−02, A6 = 2.28767e−02, A8 = 3.08419e−02

The eleventh surface

K = −9.807, A4 = 2.12775e−02, A6 = −4.53840e−02,

A8 = −2.43365e−03

The twelfth surface

K = −0.858, A4 = 5.63611e−02, A6 = −5.02019e−02, A8 = 8.82711e−03

The thirteenth surface

K = 1.905, A4 = 1.75077e−02, A6 = 1.42222e−03

The fourteenth surface

K = 0.102, A4 = 2.50940e−02, A6 = −3.51630e−04, A8 = 3.23344e−04

Various data

Zoom ratio: 2.800

Wide angle

Telephoto

end
Middle
end

Focal length
2.912
4.629
8.154

F No.
3.500
4.729
4.800

Angle of view 2ω
84.169
52.256
29.967

Image height
2.250
2.250
2.250

BF#
0.924
0.924
0.924

Lens total length#
9.998
9.998
9.998

Distance from an object point
∞
∞
∞

D4
2.912
1.582
0.100

D10
0.297
0.260
1.135

D12
1.525
2.891
3.499

Stop diameter
0.651
0.651
0.954

Entrance pupil position
2.300
1.927
1.315

Exit pupil position
−7.694
−35.857
54.178

The position of the front side
4.231
5.973
10.717

principle point

The position of the rear side principle
−2.532
−4.291
−7.820

point

Lens
The first surface of lens
Focal length of lens

L11
1
−2.306

L12
3
5.217

L21
5
2.190

L22
8
8.345

L23
9
−3.752

L3
11
−5.116

L4
13
5.098

Zoom lens group data

The
The

position
position

of the
of the rear

The first

Composition
front side
side

surface of
Focal length
length
principle
principle

Group
lens group
of lens group
of lens group
point
point

G1
1
−4.287
1.238
0.105
−0.663

G2
5
2.446
2.023
−0.336
−1.340

G3
11
−5.116
0.400
0.116
−0.142

G4
13
5.098
0.679
0.683
0.415

Magnification of lens group

Wide angle end
Middle
Telephoto end

G1
0.000
0.000
0.000

G2
−0.482
−0.652
−1.079

G3
1.577
1.834
1.952

G4
0.894
0.903
0.903

Numerical embodiment 11

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
10.1679
0.4000
1.77377
47.17
1.804

2*
1.8406
0.3689

1.449

3*
2.4091
0.5290
1.70000
15.00
1.449

4*
3.3582
D4

1.400

5*
2.0501
0.7343
1.76802
49.24
1.149

6*
−27.4479
0.1994

1.049

7 (Stop)
∞
0.0000

(Variable)

8*
4.4431
0.5434
1.49700
81.54
0.931

9
−4.9922
0.4000
1.70000
15.00
0.888

10*
27.3397
D10

0.846

11*
−2.0238
0.4000
1.53071
55.67
0.868

12*
−24.7934
D12

0.946

13*
−4.1717
0.8192
1.70000
15.00
2.139

14*
−2.5605
0.5342

2.223

15
∞
0.3000
1.51633
64.14
2.258

16
∞
0.3500

2.263

Image plane
∞

Aspherical surface data

The first surface

K = −2.968, A4 = 1.54293e−02, A6 = −8.65844e−03, A8 = 8.28284e−04

The second surface

K = 0.002, A4 = 8.96390e−03, A6 = −1.08004e−03, A8 = −5.17338e−03

The third surface

K = −0.982, A4 = −4.16429e−02, A6 = 1.42120e−03

The fourth surface

K = −4.286, A4 = −4.16742e−02, A6 = −2.66315e−03,

A8 = 1.91253e−03

The fifth surface

K = −0.227, A4 = 1.02517e−03, A6 = 8.62020e−04, A8 = 2.01632e−03

The sixth surface

K = −9.886, A4 = −7.92533e−03, A6 = 1.68283e−02,

A8 = −4.56115e−03

The eighth surface

K = −3.826, A4 = −2.05536e−02, A6 = 3.91404e−02,

A8 = −1.54510e−02

The tenth surface

K = −9.474, A4 = 4.13517e−02, A6 = 1.51235e−02, A8 = 2.94491e−02

The eleventh surface

K = −9.859, A4 = 6.25595e−02, A6 = −1.76258e−02,

A8 = −5.16373e−02

The twelfth surface

K = −10.000, A4 = 2.13359e−01, A6 = −9.44745e−02,

A8 = 9.69920e−04

The thirteenth surface

K = 2.062, A4 = 1.88493e−02, A6 = 1.42105e−03

The fourteenth surface

K = 0.080, A4 = 2.24501e−02, A6 = −5.53882e−04, A8 = 3.18452e−04

Various data

Zoom ratio: 2.795

Wide angle

Telephoto

end
Middle
end

Focal length
2.917
4.633
8.154

F No.
3.500
4.662
4.800

Angle of view 2ω
84.108
52.711
30.750

Image height
2.250
2.250
2.250

BF#
1.082
1.082
1.082

Lens total length#
9.998
9.998
9.998

Distance from an object point
∞
∞
∞

D4
2.873
1.548
0.100

D10
0.240
0.227
0.840

D12
1.408
2.746
3.581

Stop diameter
0.665
0.665
0.937

Entrance pupil position
2.457
2.069
1.428

Exit pupil position
−5.371
−11.293
−24.106

The position of the front side
4.062
4.966
6.940

principle point

The position of the rear side principle
−2.533
−4.299
−7.825

point

Lens
The first surface of lens
Focal length of lens

L11
1
−2.967

L12
3
9.905

L21
5
2.511

L22
8
4.822

L23
9
−6.000

L3
11
−4.178

L4
13
7.831

Zoom lens group data

The
The

position
position

of the
of the rear

The first

Composition
front side
side

surface of
Focal length
length
principle
principle

Group
lens group
of lens group
of lens group
point
point

G1
1
−4.046
1.298
0.414
−0.453

G2
5
2.234
1.877
0.026
−1.159

G3
11
−4.178
0.400
−0.023
−0.286

G4
13
7.831
0.819
1.032
0.633

Magnification of lens group

Wide angle end
Middle
Telephoto end

G1
0.000
0.000
0.000

G2
−0.433
−0.582
−0.935

G3
1.776
2.083
2.281

G4
0.938
0.945
0.945

Numerical embodiment 12

Surface data

Unit: mm

Effective

Surface No.
r
d
nd
vd
diameter

Object plane
∞
∞

1*
−20.6604
0.6681
1.69350
53.21
2.556

2*
6.2554
D2

2.275

3*
2.8735
1.2776
1.77377
47.17
1.550

4
−41.3684
0.5180
1.79491
25.63
1.357

5*
10.6571
0.5000

1.208

6 (Stop)
∞
0.1965

(Variable)

7*
7.5874
0.8263
1.76802
49.24
1.136

8*
−21.6754
D8

1.217

9*
279.5342
0.3790
1.82114
24.06
1.225

10*
3.4792
D10

1.229

11*
−7.1348
0.9360
1.79491
25.63
2.746

12*
−3.7927
1.3721

2.868

13
∞
0.4000
1.51633
64.14
2.972

14
∞
0.4000

2.983

Image plane
∞

Aspherical surface data

The first surface

K = −28.194, A4 = −9.53942e−03, A6 = 1.14164e−03,

A8 = −5.01129e−05

The second surface

K = −0.224, A4 = −9.75476e−03, A6 = 1.35826e−03,

A8 = −4.78131e−05

The third surface

K = 0.624, A4 = −1.58057e−03, A6 = −1.23052e−04, A8 = 7.62687e−06

The fifth surface

K = 44.632, A4 = 5.76135e−04, A6 = 1.26800e−03, A8 = −7.09871e−05

The seventh surface

K = −1.283, A4 = −2.54498e−02, A6 = −2.93083e−03,

A8 = −1.21006e−03

The eighth surface

K = 44.767, A4 = −2.16942e−02, A6 = −2.05558e−03,

A8 = −1.25759e−05

The ninth surface

K = −560206.977

The tenth surface

K = −0.582, A4 = 7.46329e−03, A6 = 1.55863e−03, A8 = −8.04564e−04

The eleventh surface

K = −4.214

The twelfth surface

K = −0.006, A4 = 4.15000e−03, A6 = −2.49039e−05,

A8 = −2.17406e−05, A10 = 2.21954e−06

Various data

Zoom ratio: 2.816

Wide angle

Telephoto

end
Middle
end

Focal length
4.574
7.639
12.879

F No.
3.228
3.726
5.123

Angle of view 2ω
70.712
41.233
24.715

Image height
2.900
2.900
2.900

BF
2.036
2.036
2.036

Lens total length
13.864
13.864
13.864

Distance from an object point
∞
∞
∞

D2
4.476
2.312
0.201

D8
0.611
0.650
1.363

D10
1.439
3.564
4.963

Stop diameter
0.900
1.100
1.100

Entrance pupil position
3.777
3.155
2.278

Exit pupil position
−5.287
−14.748
−40.735

The position of the front side
5.494
7.317
11.279

principle point

The position of the rear side principle
−4.174
−7.239
−12.479

point

Lens
The first surface of lens
Focal length of lens

L1
1
−6.854

L21
3
3.517

L22
4
−10.614

L23
7
7.409

L3
9
−4.293

L4
11
9.062

Zoom lens group data

The
The

position
position

of the
of the rear

The first

Composition
front side
side

surface of
Focal length
length
principle
principle

Group
lens group
of lens group
of lens group
point
point

G1
1
−6.854
0.668
0.300
−0.091

G2
3
3.459
3.318
0.621
−1.898

G3
9
−4.293
0.379
0.211
0.003

G4
11
9.062
2.708
0.990
−1.109

Magnification of lens group

Wide angle end
Middle
Telephoto end

G1
0.000
0.000
0.000

G2
−0.403
−0.539
−0.803

G3
1.987
2.482
2.808

G4
0.833
0.833
0.833

Next, parameter values which the embodiment 1 (the numeral embodiment 1) to the embodiment 12 (the numeral embodiment 12) have in the conditions (1) to (22) are given.

Parameter values which the embodiments 1 to 12 have in the respective conditions

Condition (1)
Condition (2)
Condition (3)
Condition (4)
Condition (5)
Condition (6)

Embodiment 1
24.06
0.08
0.90
0.50
0.48
1.98

Embodiment 2
24.06
0.10
0.92
0.50
0.50
2.01

Embodiment 3
23.89
0.87
0.96
0.87
−3.63
2.34

Embodiment 4
31.00
0.08
0.90
0.50
0.46
1.97

Embodiment 5
30.25
0.04
0.88
0.50
0.56
1.91

Embodiment 6
24.06
0.42
0.96
0.53
0.23
2.53

Embodiment 7
20.88
0.43
0.91
0.50
0.29
2.41

Embodiment 8
24.06
0.16
0.94
0.44
0.78
2.48

Embodiment 9
24.06
0.42
0.98
0.53
0.30
2.58

Embodiment 10
16.77
−0.02
0.88
0.50
0.24
1.91

Embodiment 11
15.00
−0.72
0.83
0.46
0.24
1.80

Embodiment 12
25.63
0.31
0.89
0.45
0.31
2.36

Condition (7)
Condition (8)
Condition (9)
Condition (10)
Condition (11)

Embodiment 1
1.10
24.06
2.47
42.96
0.50

Embodiment 2
1.10
24.06
2.46
42.96
0.50

Embodiment 3
2.10
23.89
—
—
0.87

Embodiment 4
1.10
31.00
2.29
42.96
0.50

Embodiment 5
1.10
30.25
2.34
42.96
0.50

Embodiment 6
1.40
24.06
2.30
29.43
0.53

Embodiment 7
1.32
20.88
2.55
29.43
0.50

Embodiment 8
1.17
24.06
2.70
25.46
0.44

Embodiment 9
1.39
24.06
2.29
29.43
0.53

Embodiment 10
1.09
16.77
2.69
64.77
0.50

Embodiment 11
0.99
15.00
3.00
66.54
0.46

Embodiment 12
1.19
25.63
2.67
23.61
0.45

Condition (12)
Condition (13)
Condition (14

Embodiment 1
0.48
0.21
1.10

Embodiment 2
0.50
0.21
1.10

Embodiment 3
−3.63
—
2.10

Embodiment 4
0.46
−0.13
1.10

Embodiment 5
0.56
−0.08
1.10

Embodiment 6
0.23
−0.09
1.40

Embodiment 7
0.29
0.13
1.32

Embodiment 8
0.78
0.05
1.17

Embodiment 9
0.30
−0.10
1.39

Embodiment 10
0.24
0.61
1.09

Embodiment 11
0.24
0.81
0.99

Embodiment 12
0.31
−0.02
1.19

Condition (15)
Condition (16)

L11
L12
L11
L12
Condition (17)
Condition (18)
Condition (19)

Embodiment 1
1.901
2.102
31.00
16.77
14.23
0.09
−0.152

Embodiment 2
1.851
1.821
40.10
24.06
16.04
0.08
−0.101

Embodiment 10
1.903
2.102
31.00
16.77
14.23
0.07
−0.115

Condition (20)
Condition (21)
Condition (22)

Embodiment 1
−0.43
0.84
24.06

Embodiment 2
−0.44
0.85
24.06

Embodiment 10
−0.44
1.21
16.77

The variable power optical systems according to the embodiments of the present invention as described above can be used for image pickup apparatuses, such as digital camera and video camera, in which shooting is performed by forming on an imaging sensor like CCD an object image that is formed by the variable power optical systems. A concrete example for the image pickup apparatuses is given below.

FIGS. 43, 44, and 45 are conceptual views showing the constitution of a digital camera including a variable power optical system of one of the embodiments of the present invention, FIG. 43 is a front perspective view showing the appearance of a digital camera, FIG. 44 is a rear perspective view showing the appearance of the digital camera which is shown in FIG. 43, and FIG. 45 is a perspective view schematically showing the constitution of the digital camera.

The digital camera is provided with an opening section 1 for shooting, a finder opening section 2, and a flash-firing section 3 on the front side of the digital camera. Also, the digital camera is provided with a shutter button 4 on the top of the digital camera. Also, the digital camera is provided with a liquid crystal display monitor 5 and an information input section 6 on the rear side of the digital camera. In addition, the digital camera is provided with a variable power optical system 7 that is formed in the same manner as in the embodiment 1, 12, or 23 for example, a processing means 8, a recording means 9, and a finder optical system 10 inside the digital camera. Also, cover members 12 are arranged in the finder opening section 2 and in an opening section 11, the opening section 11 being located on the exit side of the finder optical system 10 and being provided on the rear side of the digital camera. In addition, a cover member 13 is also arranged in the opening section 1 for shooting.

When the shutter button 4 which is arranged on the top of the digital camera is pressed, shooting is performed through the variable power optical system 7 in response to the pressing of the shutter button 4. An object image is formed on the image forming plane of a CCD 7a that is a solid-state imaging sensor, through the variable power optical system 7 and the cover glass CG. The image information on the object image which is formed on the image forming plane of the CCD 7a is recorded on the recording means 9 through the processing means 8. Also, recorded image information can be taken through the processing means 8, and the image information can be also displayed as an electronic image on the liquid crystal display monitor 5 which is provided on the rear side of the camera.

Also, the finder optical system 10 is composed of a finder objective optical system 10a, an erecting prism 10b, and an eyepiece optical system 10c. Light from an object which enters through the finder opening section 2 is led to the erecting prism 10b that is a member for erecting an image, by the finder objective optical system 10a, and an object image is formed as an erect image in the view finder frame 10b₁, and, afterward, the object image is led to an eye E of an observer by the eyepiece optical system 10c.

Digital cameras which are formed in such a manner secure good performances while it is possible to achieve downsizing of the digital cameras, because the variable power optical system 7 has a high magnification ratio and is small.

Number	Date	Country	Kind
2009-212134	Sep 2009	JP	national
2009-212135	Sep 2009	JP	national
2009-212136	Sep 2009	JP	national

	Number	Date	Country
Parent	PCT/JP2010/065751	Sep 2010	US
Child	13418430		US

VARIABLE POWER OPTICAL SYSTEM AND IMAGE PICKUP APPARATUS HAVING THE SAME

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CPC

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Abstract

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Priority Claims (3)

Continuations (1)