Zoom Lens System, Interchangeable Lens Apparatus, and Camera System

TECHNICAL FIELD

The present invention relates to a zoom lens system. More particularly, the present invention relates to a zoom lens system suitable for an imaging lens system of a so-called interchangeable-lens type digital camera system. Further, the present invention relates to an interchangeable lens apparatus and a camera system, each employing the zoom lens system.

BACKGROUND ART

In recent years, the market of interchangeable-lens type camera systems (also referred to simply as “camera systems”, hereinafter) have been spreading rapidly. Such an interchangeable-lens type camera system includes: a camera body having an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide Semiconductor); and an interchangeable lens apparatus having a zoom lens system for forming an optical image on a light receiving surface of the image sensor. An image sensor included in the interchangeable-lens type camera system is larger in scale than that included in a compact digital camera. Accordingly, the interchangeable-lens type camera system can shoot a high-sensitivity and high-quality image. Further, the interchangeable-lens type camera system is advantageous in that a focusing operation and image processing after shooting can be performed at a high speed, and that an interchangeable lens apparatus can be easily replaced in accordance with a scene that a user desires to shoot. An interchangeable lens apparatus having a zoom lens system capable of forming an optical image with variable magnification is popular because such an interchangeable lens apparatus can freely vary the focal length without lens replacement.

CITATION LIST
Patent Literature

[PTL 1] Japanese Laid-Open Patent Publication No. 2006-30582

[PTL 2] Japanese Laid-Open Patent Publication No. 2004-341060

[PTL 3] Japanese Laid-Open Patent Publication No. 2000-221402

[PTL 4] Japanese Laid-Open Patent Publication No. 11-109240

[PTL 5] Japanese Laid-Open Patent Publication No. 8-184756

SUMMARY OF THE INVENTION
Problems to be Solved by the Invention

Although the interchangeable-lens type digital camera system has the above-described advantages, it is larger in size and weight than a compact digital camera. It is preferred that the size and weight of the interchangeable-lens type digital camera system be as small/light as possible in order to improve portability and handleability.

Accordingly, a zoom lens system for the interchangeable-lens type digital camera system is also required to be as compact and lightweight as possible while maintaining imaging performance.

Accordingly, an object of the present invention is to provide a compact and lightweight zoom lens system having excellent imaging performance, which is favorably applicable to an interchangeable-lens type digital camera system.

Another object of the present invention is to provide compact and lightweight interchangeable lens apparatus and camera system.

Solution to the Problems

A zoom lens system according to the present invention includes: in order from an object side to an image side, a first lens unit having positive optical power and composed of not more than two lens elements; a second lens unit having negative optical power; a third lens unit having negative optical power; and a fourth lens unit having positive optical power. In zooming from a wide-angle limit to a telephoto limit, the fourth lens unit moves along an optical axis. Further, the following conditions are satisfied:

1.50<nd₁<1.72 (9)

50<vd₁<75 (10)

where

nd₁is a refractive index to the d line of a positive lens element constituting the first lens unit, and

vd₁is an Abbe number of a positive lens element constituting the first lens unit.

An interchangeable lens barrel according to the present invention includes: the above-described zoom lens system; and a lens mount section which is connectable to a camera body including an image sensor for receiving an optical image formed by the zoom lens system and converting the optical image into an electric image signal.

A camera system according to the present invention includes: an interchangeable lens apparatus including the above-described zoom lens system; and a camera body which is detachably connected to the interchangeable lens apparatus via a camera mount section, and includes an image sensor for receiving an optical image formed by the zoom lens system and converting the optical image into an electric image signal.

Effects of the Invention

According to the present invention, it is possible to realize a compact and lightweight zoom lens system having excellent imaging performance, and an interchangeable lens apparatus and a camera system, each having the zoom lens system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 1 (Example 1).

FIG. 2 is a longitudinal aberration diagram of the zoom lens system according to Example 1 in an infinity in-focus condition.

FIG. 3 is a lateral aberration diagram of the zoom lens system according to Example 1 at a telephoto limit in a basic state where image blur compensation is not performed and in an image blur compensation state.

FIG. 4 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 2 (Example 2).

FIG. 5 is a longitudinal aberration diagram of the zoom lens system according to Example 2 in an infinity in-focus condition.

FIG. 6 is a lateral aberration diagram of the zoom lens system according to Example 2 at a telephoto limit in a basic state where image blur compensation is not performed and in an image blur compensation state.

FIG. 7 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 3 (Example 3).

FIG. 8 is a longitudinal aberration diagram of the zoom lens system according to Example 3 in an infinity in-focus condition.

FIG. 9 is a lateral aberration diagram of the zoom lens system according to Example 3 at a telephoto limit in a basic state where image blur compensation is not performed and in an image blur compensation state.

FIG. 10 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 4 (Example 4).

FIG. 11 is a longitudinal aberration diagram of the zoom lens system according to Example 4 in an infinity in-focus condition.

FIG. 12 is a lateral aberration diagram of the zoom lens system according to Example 4 at a telephoto limit in a basic state where image blur compensation is not performed and in an image blur compensation state.

FIG. 13 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 5 (Example 5).

FIG. 14 is a longitudinal aberration diagram of the zoom lens system according to Example 5 in an infinity in-focus condition.

FIG. 15 is a lateral aberration diagram of the zoom lens system according to Example 5 at a telephoto limit in a basic state where image blur compensation is not performed and in an image blur compensation state.

FIG. 16 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 6 (Example 6).

FIG. 17 is a longitudinal aberration diagram of the zoom lens system according to Example 6 in an infinity in-focus condition.

FIG. 18 is a lateral aberration diagram of the zoom lens system according to Example 6 at a telephoto limit in a basic state where image blur compensation is not performed and in an image blur compensation state.

FIG. 19 is a schematic construction diagram of a camera system according to Embodiment 7.

DESCRIPTION OF EMBODIMENTS

FIGS. 1, 4, 7, 10, 13, and 16 are lens arrangement diagrams of zoom lens systems according to Embodiments 1, 2, 3, 4, 5, and 6, respectively. Each Fig. shows a zoom lens system in an infinity in-focus condition.

In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length f_W), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length f_M=√(f_W*f_T)), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length f_T). Further, in each Fig., each bent arrow located between part (a) and part (b) indicates a line obtained by connecting the positions of each lens unit respectively at a wide-angle limit, a middle position and a telephoto limit. In the part between the wide-angle limit and the middle position and the part between the middle position and the telephoto limit, the positions are connected simply with a straight line, and hence this line does not indicate actual motion of each lens unit. Further, in each Fig. an arrow imparted to a lens element indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates a moving direction during focusing from an infinity in-focus condition to a close-object in-focus condition.

In FIGS. 1, 4, 7, 10, 13, and 16, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., a sign (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. Further, in each Fig., a straight line located on the most right-hand side indicates the position of an image surface S. Further, in each Fig., an aperture diaphragm A is provided in a fourth lens unit G4.

Each of the zoom lens systems according to Embodiments 1 to 6 comprises, in order from the object side to the image side, a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having negative optical power, and a fourth lens unit G4 having positive optical power.

Embodiment 1

The first lens unit G1 comprises, in order from the object side to the image side, a negative meniscus first lens element L1 with the convex surface facing the object side, and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

The second lens unit G2 comprises, in order from the object side to the image side, a negative meniscus third lens element L3 with the convex surface facing the object side, a bi-concave fourth lens element L4, and a positive meniscus fifth lens element L5 with the convex surface facing the object side.

The third lens unit G3 comprises a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The fourth lens unit G4 comprises, in order from the object side to the image side, a bi-convex seventh lens element L7, a bi-convex eighth lens element L8, a bi-concave ninth lens element L9, a positive meniscus tenth lens element L10 with the convex surface facing the image side, a bi-convex eleventh lens element L11, and a negative meniscus twelfth lens element L12 with the convex surface facing the image side. The eighth lens element L8 and the ninth lens element are cemented with each other, and the eleventh lens element L11 and the twelfth lens element L12 are cemented with each other. The both surfaces of the tenth lens element L10 are aspheric. The tenth lens element L10 is formed of a resin.

Embodiment 2

The first lens unit G1 comprises, in order from the object side to the image side, a negative meniscus first lens element L1 with the convex surface facing the object side, and a bi-convex second lens element. The first lens element L1 and the second lens element L2 are cemented with each other.

The third lens unit G3 comprises a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The fourth lens unit G4 comprises, in order from the object side to the image side, a bi-convex seventh lens element L7, a bi-convex eighth lens element L8, a bi-concave ninth lens element L9, a negative meniscus tenth lens element L10 with the convex surface facing the object side, a bi-convex eleventh lens element L11, and a negative meniscus twelfth lens element L12 with the convex surface facing the image side. The eighth lens element L8 and the ninth lens element 9 are cemented with each other, and the tenth lens element L10 and the eleventh lens element L11 are cemented with each other. The both surfaces of the twelfth lens element L12 are aspheric. The twelfth lens element L12 is formed of a resin.

Embodiment 3

The third lens unit G3 comprises a negative meniscus sixth lens element L6 with the convex surface facing the image side. The sixth lens element L6 has an aspheric object side surface.

The fourth lens unit G4 comprises, in order from the object side to the image side, a bi-convex seventh lens element L7, a bi-convex eighth lens element L8, a bi-concave ninth lens element L9, a positive meniscus tenth lens element L10 with the convex surface facing the object side, a bi-convex eleventh lens element L11, and a negative meniscus twelfth lens element L12 with the convex surface facing the image side. The eighth lens element L8 and the ninth lens element L9 are cemented with each other. The both surfaces of the tenth lens element L10 are aspheric. The tenth lens element L10 is formed of a resin.

Embodiment 4

The third lens unit G3 comprises a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The fourth lens unit G4 comprises, in order from the object side to the image side, a bi-convex seventh lens element L7, a bi-convex eighth lens element L8, a negative meniscus ninth lens element L9 with the convex surface facing the image side, a bi-convex tenth lens element L10, a bi-convex eleventh lens element L11, and a negative meniscus twelfth lens element L12 with the convex surface facing the image side. The eighth lens element L8 and the ninth lens element are cemented with each other. The object-side surface of the seventh lens element L7 and the both surfaces of the tenth lens element L10 are aspheric. The seventh lens element L7 and the tenth lens element L10 are formed of a resin.

Embodiment 5

The third lens unit G3 comprises a bi-concave sixth lens element L6.

The fourth lens unit G4 comprises, in order from the object side to the image side, a bi-convex seventh lens element L7, a bi-convex eighth lens element L8, a bi-concave ninth lens element L9, a positive meniscus tenth lens element L10 with the convex surface facing the object side, a bi-convex eleventh lens element L11, and a negative meniscus twelfth lens element L12 with the convex surface facing the image side. The eighth lens element L8 and the ninth lens element L9 are cemented with each other, and the eleventh lens element L11 and the twelfth lens element L12 are cemented with each other. The both surfaces of the tenth lens element L10 are aspheric. The tenth lens element L10 is formed of a resin. A vertical line between the ninth lens element L9 and the tenth lens element L10 indicates a flare-cut diaphragm.

Embodiment 6

The third lens unit G3 comprises a negative meniscus sixth lens element L6 with the convex surface facing the image side.

The fourth lens unit G4 comprises, in order from the object side to the image side, a bi-convex seventh lens element L7, a bi-convex eighth lens element L8, a bi-concave ninth lens element L9, a bi-convex tenth lens element L10, a bi-convex eleventh lens element L11, and a negative meniscus eleventh lens element L11 with the convex surface facing the image side. The eighth lens element L8 and the ninth lens element are cemented with each other. The both surfaces of the tenth lens element L10 are aspheric. The tenth lens element L10 is formed of a resin.

In Embodiments 1 to 4 and 6, in zooming from a wide-angle limit to a telephoto limit, the respective lens units move along the optical axis to the object side so that the interval between the first lens unit G1 and the second lens unit G2 becomes longer at the telephoto-limit than at the wide-angle limit, the interval between the second lens unit G2 and the third lens unit G3 becomes longer at the telephoto-limit than at the wide-angle limit, and the interval between the third lens unit G3 and the fourth lens unit G4 becomes shorter at the telephoto-limit than at the wide-angle limit. An aperture diaphragm A moves along the optical axis together with the fourth lens unit G4. Further, in zooming from a wide-angle limit to a telephoto limit, the interval between the first lens unit G1 and the second lens unit G2 monotonically increases, the interval between the second lens unit G2 and the third lens unit G3 decreases and then increases, and the interval between the third lens unit G3 and the fourth lens unit G4 monotonically decreases.

In Embodiment 6, in zooming from a wide-angle limit to a telephoto limit, the respective lens units move along the optical axis to the object side so that the interval between the first lens unit G1 and the second lens unit G2 becomes longer at the telephoto-limit than at the wide-angle limit, the interval between the second lens unit G2 and the third lens unit G3 becomes longer at the telephoto-limit than at the wide-angle limit, and the interval between the third lens unit G3 and the fourth lens unit G4 becomes shorter at the telephoto limit than at the wide-angle limit. An aperture diaphragm A moves along the optical axis together with the fourth lens unit G4. Further, in zooming from a wide-angle limit to a telephoto limit, the interval between the first lens unit G1 and the second lens unit G2 monotonically increases, the interval between the second lens unit G2 and the third lens unit G3 monotonically increases, and the interval between the third lens unit G3 and the fourth lens unit G4 monotonically decreases.

As in the zoom lens systems according to the respective embodiments, it is preferred that, in zooming, the first lens unit G1 moves along the optical axis. By using the first lens unit as a variable magnification unit, the light beam height in the first lens unit G1 can be reduced. As a result, size reduction of the first lens unit G1 is realized. Further, it is preferred that, in zooming, the fourth lens unit G4 moves along the optical axis. By using the fourth lens unit G4 as a variable magnification unit, imaging performance of the zoom lens system is improved while achieving size reduction when the zoom lens system is shrunk.

In the zoom lens systems according to the respective embodiments, in focusing from an infinity in-focus condition to a close-object in-focus condition, the third lens unit G3 moves along the optical axis to the object side. In the case where the third lens unit G3 is given a function as a focusing lens unit and, further, the third lens unit is composed of a single lens element, the weight of the focusing lens unit can be reduced. In this configuration, high-speed focusing is realized.

In the zoom lens systems according to the respective embodiments, the fourth lens unit G4 comprises, in order from the object side to the image side, a first sub-lens unit and a second sub-lens unit. When a single lens unit is composed of a plurality of lens elements, a sub-lens unit corresponds to any one lens element or a combination of a plurality of adjacent lens elements, which is/are included in the lens unit. In Embodiments 1, 2, 4 to 6, 8, and 9, the seventh lens element L7 constitutes the first sub-lens unit, and the eighth to twelfth lens elements L8 to L12 constitute the second sub-lens unit. In Embodiments 3 and 7, the sixth lens element L6 constitutes the first sub-lens unit, and the seventh to eleventh lens elements L7 to L11 constitute the second sub-lens unit.

In the zoom lens systems according to the respective embodiments, when compensating image blur caused by vibration applied to the zoom lens system, the first sub-lens unit in the fourth lens unit G4 moves in a direction perpendicular to the optical axis to compensate movement of an image point caused by vibration of the entire system.

In this way, when an image blur compensation lens unit is composed of only a part of lens elements constituting the fourth lens unit, weight reduction of the image blur compensation lens unit is achieved. Accordingly, the image blur compensation lens unit can be driven by a simple driving mechanism. Particularly when the image blur compensation lens unit is composed of only a single lens element, the driving mechanism for the image blur compensation lens unit can be more simplified.

It is preferred that the first lens unit be composed of a single or two lens elements. An increase in the number of lens elements constituting the first lens unit causes an increase in the diameter of the first lens unit. When the first lens unit is composed of two lens elements, both the configuration length and the diameter of the first lens unit can be reduced, which is advantageous to size reduction of the entire system. Further, when the number of required lens elements is reduced, cost reduction is also achieved.

It is preferred that the first lens unit be composed of only a cemented lens. In this case, chromatic aberration at a telephoto limit can be favorably compensated.

It is preferred that a resin lens element be included in the fourth lens unit. When at least one lens element constituting the fourth lens unit is formed of a resin, production cost of the zoom lens system can be reduced.

Further, it is preferred that the focusing lens unit, the image blur compensation lens unit, and the aperture diaphragm be arranged adjacent to each other. In this case, since the driving mechanism including an actuator is simplified, size reduction of the interchangeable lens apparatus is achieved. Particularly when the aperture diaphragm is arranged closest to the image side, the driving mechanism can be more simplified.

The following will describe numerical conditions to be satisfied by a zoom lens system according to any of the respective embodiments. A zoom lens system according to any of the respective embodiments is desired to satisfy as many conditions described below as possible However, when an individual condition is satisfied, a zoom lens system having the corresponding effect is obtained.

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (1).

1.0<T₄/f_W<3.5 (1)

where

T₄is a thickness (mm) of the fourth lens unit in the optical axis direction, and

f_Wis a focal length (mm) of the entire system at a wide-angle limit.

The condition (1) sets forth the configuration length of the fourth lens unit in the optical axis direction. When condition (1) is satisfied, size reduction of the zoom lens system and successful compensation for various aberrations such as field curvature can be achieved. If the value exceeds the upper limit of the condition (1), the configuration length of the entire zoom lens system increases, resulting in a disadvantage to size reduction of the zoom lens system. On the other hand, if the value goes below the lower limit of the condition (1), it becomes difficult to compensate the field curvature.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (1′) and (1″) in addition to the condition (1), the above-mentioned advantageous effect is achieved more successfully.

1.4<T₄/f_W (1′)

T
₄
/f
_W<2.0 (1″)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (2).

0.71<|D_4WT/ f_W|<2.5 (2)

where

D_4WTis an amount of movement (mm) of the fourth lens unit in zooming from a wide-angle limit to a telephoto limit, and

f_Wis a focal length (mm) of the entire system at a wide-angle limit.

The condition (2) sets forth an amount of movement of the fourth lens unit in zooming. When the condition (2) is satisfied, size reduction of the zoom lens system and successful aberration compensation are achieved. If the value exceeds the upper limit of the condition (2), the amount of movement of the fourth lens unit at the time of magnification is increased, which makes it difficult to achieve size reduction. On the other hand, if the value goes below the lower limit of the condition (2), contribution of the fourth lens unit to magnification becomes too small, which makes it difficult to achieve aberration compensation.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (2′) and (2″) in addition to the condition (2), the above-mentioned advantageous effect is achieved more successfully.

1.1<|D_4WT/f_W| (2′)

|D_4WT/f_W|<1.9 (2″)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (3).

0.2<|f_W/f_F|<0.6 (3)

where

f_Wis a focal length (mm) of the entire system at a wide-angle limit, and

f_Fis a focal length (mm) of the focusing lens unit.

The condition (3) sets forth a focal length of the focusing lens unit. When the condition (3) is satisfied, suppression of aberration fluctuation in zooming and high-speed focusing are achieved. If the value exceeds the upper limit of the condition (3), aberration fluctuation between an infinity in-focus condition and a close-object in-focus condition, particularly fluctuation of field curvature, becomes considerable, which leads to deterioration of image quality. On the other hand, if the value goes below the lower limit of the condition (3), the amount of focus movement increases, which makes it difficult to realize high-speed focusing.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (3′) and (3″) in addition to the condition (3), the above-mentioned advantageous effect is achieved more successfully.

0.25<|f_W/f_F| (3′)

|f_W/f_F|<0.5 (3″)

A zoom lens system according to each embodiment preferably satisfies the following condition (4).

0.77<|D₁/f_W|<3.5 (4)

where

D₁is an amount of movement (mm) of the first lens unit in zooming from a wide-angle limit to a telephoto limit, and

f_Wis a focal length (mm) of the entire system at a wide-angle limit.

The condition (4) sets forth an amount of movement of the first lens unit. When the condition (4) is satisfied, size reduction of the zoom lens system and successful compensation for various aberrations including field curvature are achieved. When the value exceeds the upper limit of the condition (4), the cam increases in size, which makes it difficult to achieve size reduction of the zoom lens system when it is shrunk. On the other hand, when the value goes below the lower limit of the condition (4), it becomes difficult to compensate various aberration, particularly field curvature at a telephoto limit.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (4′) and (4″) in addition to the condition (4), the above-mentioned advantageous effect is achieved more successfully.

1.7<|D₁/f_W| (4′)

|D₁f_W|<2.3 (⁴″)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (5).

0.3<(D_3WT−D_4WT)/f_W<1.5 (5)

where

D_3WTis an amount of movement (mm) of the third lens unit in zooming from a wide-angle limit to a telephoto limit,

D_4WTis an amount of movement (mm) of the fourth lens unit in zooming from a wide-angle limit to a telephoto limit, and

f_Wis a focal length (mm) of the entire system at a wide-angle limit.

The condition (5) sets forth the interval between the third lens unit and the fourth lens unit in zooming from a wide-angle limit to a telephoto limit. When the condition (5) is satisfied, size reduction of the zoom lens system is achieved while maintaining a magnification ratio. If the value exceeds the upper limit of the condition (5), it becomes difficult to achieve size reduction of the zoom lens system. On the other hand, if the value goes below the lower limit of the condition (5), it becomes difficult to ensure a magnification ratio.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (5′) and (5″) in addition to the condition (5), the above-mentioned advantageous effect is achieved more successfully.

0.6<(D_3WT−D_4WT)/f_W (⁵′)

(D_3WT−D_4WT)/f_W<1.1 (5″)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (6).

0.1<(D_3WM−D_4WM)/f_W<1.0 (6)

where

D_3WMis an amount of movement (mm) of the third lens unit in zooming from a wide-angle limit to a middle position,

D_4WMis an amount of movement (mm) of the fourth lens unit in zooming from a wide-angle limit to a middle position, and

f_Wis a focal length (mm) of the entire system at a wide-angle limit.

The condition (6) sets forth an interval between the third lens unit and the fourth lens unit in zooming from a wide-angle unit to a middle position. When the condition (6) is satisfied, size reduction of the zoom lens system is achieved while maintaining a magnification ratio. If the value exceeds the upper limit of the condition (6), it becomes difficult to achieve size reduction of the zoom lens system. On the other hand, if the value goes below the lower limit of the condition (6), it becomes difficult to ensure a magnification ratio.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (6′) and (6″) in addition to the condition (6), the above-mentioned advantageous effect is achieved more successfully.

0.3<(D_3WM−D_4WM)f_W (6′)

(D_3WM−D_4WM)/f_W<0.7 (6″)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (7).

|f_W/f_P|<0.35 (7)

where

f_Wis a focal length (mm) of the entire system at a wide-angle limit, and

f_Pis a focal length (mm) of a resin lens included in the fourth lens unit.

The condition (7) sets forth a focal length of a resin lens included in the fourth lens unit. When the condition (7) is satisfied, image quality can be maintained even when the refractive index of the resin lens varies due to variation in the environmental temperature. If the value is outside the numerical value range of the condition (7), the field curvature increases when the refractive index of the resin lens varies due to variation in the environmental temperature, leading to deterioration of the image quality.

When a zoom lens system according to any of the respective embodiments satisfies the following condition (7′) in addition to the condition (7), the above-mentioned advantageous effect is achieved more successfully.

|f_W/f_P|<0.21 (7′)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (8).

0.7<BF_W|f_W<3.0 (8)

where

BF_Wis a back focus (mm) of the entire system at a wide-angle limit, and

f_Wis a focal length (mm) of the entire system at a wide-angle limit.

The condition (8) sets forth a back focus of the entire system at a wide-angle limit. When the condition (8) is satisfied, size reduction of the zoom lens system is achieved while avoiding deterioration of image quality at a peripheral part of an imaging region. If the value exceeds the upper limit of the condition (8), it becomes difficult to achieve size reduction of the zoom lens system. On the other hand, if the value goes below the lower limit of the condition (8), the incident angle of light beam on the image sensor increases, which makes it difficult to ensure illuminance at the peripheral part of the imaging region.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (8′) and (8″) in addition to the condition (8), the above-mentioned advantageous effect is achieved more successfully.

1.1<BF_W/f_W (8′)

BF
_W
/f
_W<1.8 (8″)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (9).

1.50<nd₁<1.72 (9)

where

nd₁is a refractive index to the d line of a positive lens element constituting the first lens unit.

The condition (9) sets forth a refractive index to the d line of a positive lens element constituting the first lens unit. When the condition (9) is satisfied, size reduction of the zoom lens system is achieved at low cost. If the value exceeds the upper limit of the condition (9), it becomes difficult to achieve cost reduction. On the other hand, if the value goes below the lower limit of the condition (9), the core thickness of the positive lens element constituting the first lens unit increases, resulting in a disadvantage to size reduction of the zoom lens system.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (9′) and (9″) in addition to the condition (9), the above-mentioned advantageous effect is achieved more successfully.

1.55<nd₁ (9′)

nd₁<1.65 (9″)

A zoom lens system according to any of the respective embodiments preferably satisfies the following condition (10).

50<vd₁<75 (10)

where

vd₁is an Abbe number of a positive lens element constituting the first lens unit.

The condition (10) sets forth an Abbe number of a positive lens element constituting the first lens unit. When the condition (10) is satisfied, a zoom lens system having excellent image quality is realized at low cost. If the value exceeds the upper limit of the condition (10), it becomes difficult to achieve cost reduction. On the other hand, if the value goes below the lower limit of the condition (10), it becomes difficult to compensate chromatic aberration at a telephoto limit.

When a zoom lens system according to any of the respective embodiments satisfies at least one of the following conditions (10′) and (10″) in addition to the condition (10), the above-mentioned advantageous effect is achieved more successfully.

55<vd₁ (10′)

vd₁<60 (10″)

Each of the lens units of the zoom lens systems according to the respective embodiments may be constituted exclusively of refractive type lens elements that deflect incident light by refraction (that is, lens elements of a type in which deflection is achieved at the interface between media having different refractive indices). Alternatively, each lens unit may be composed of any one of, or a combination of, diffractive type lens elements that deflect incident light by diffraction; refractive-diffractive hybrid type lens elements that deflect incident light by a combination of diffraction and refraction; and gradient index type lens elements that deflect incident light by distribution of refractive index in the medium.

Embodiment 7

FIG. 19 is a schematic block diagram of an interchangeable-lens type digital camera system according to Embodiment 7.

The interchangeable-lens type digital camera system (hereinafter, referred to simply as “camera system”) 100 according to the present embodiment includes a camera body 101, and an interchangeable lens apparatus 201 which is detachably connected to the camera body 101.

The camera body 101 includes: an image sensor 102 which receives an optical image formed by a zoom lens system 202 of the interchangeable lens apparatus 201, and converts the optical image into an electric image signal; a liquid crystal monitor 103 which displays the image signal obtained by the image sensor 102; and a camera mount 104. On the other hand, the interchangeable lens apparatus 201 includes: a zoom lens system 202 according to any of Embodiments 1 to 6; a lens barrel 203 which holds the zoom lens system 202; and a lens mount 204 connected to the camera mount 104 of the camera body 101. The camera mount 104 and the lens mount 204 are physically connected to each other. Moreover, the camera mount 104 and the lens mount 204 function as interfaces which allow the camera body 101 and the interchangeable lens apparatus 201 to exchange signals, by electrically connecting a controller (not shown) in the camera body 101 and a controller (not shown) in the interchangeable lens apparatus 201.

In the present embodiment, the zoom lens system 202 according to any of Embodiments 1 to 6 is employed. Accordingly, a compact interchangeable lens apparatus having excellent imaging performance can be realized at low cost. Moreover, size reduction and cost reduction of the entire camera system 100 according to the present embodiment can be achieved.

EXAMPLES

Hereinafter, numerical examples are described below in which the zoom lens systems according to the above-described embodiments are implemented. As described later, Numerical Examples 1, 2, 3, 4, 5, and 6 correspond to Embodiments 1, 2, 3, 4, 5, and 6, respectively. In each numerical example, the units of length are all “mm”, and the units of view angle are all “°”. In each numerical example, r is the radius of curvature, d is the axial distance, nd is the refractive index to the d-line, and vd is the Abbe number to the d-line. Further, in each numerical example, the surfaces marked with * are aspheric surfaces, and the aspheric surface configuration is defined by the following expression.

$\begin{matrix} Z = \frac{h^{2} / r}{1 + \sqrt{1 - (1 + κ) {(h / r)}^{2}}} + \sum A_{n} h^{n} & [Math . 1] \end{matrix}$

where

Z is a distance from an on-aspheric-surface point at a height of h relative to the optical axis, to a tangential plane at the top of the aspheric surface,

h is a height relative to the optical axis,

r is a radius of curvature at the top,

κ is a conic constant, and

A_nis an n-th order aspheric coefficient.

FIGS. 2, 5, 8, 11, 14, and 17 are longitudinal aberration diagrams of the zoom lens systems according to Numerical Examples 1, 2, 3, 4, 5, and 6 in their infinity in-focus conditions, respectively.

In each longitudinal aberration diagram, part (a), part (b), and part (c) show aberrations at a wide-angle limit, at a middle position, and at a telephoto limit, respectively. Each longitudinal aberration diagram shows, in order from the left-hand side, a spherical aberration (SA (mm)), an astigmatism (AST (mm)), and a distortion (DIS (%)). In each spherical aberration diagram, a vertical axis indicates an F-number (in each Fig., indicated as F), and a solid line, a short dash line, and a long dash line indicate the characteristics to the d-line, the F-line, and the C-line, respectively. In each astigmatism diagram, a vertical axis indicates an image height (in each Fig., indicated as H), and a solid line and a dash line indicate the characteristics to the sagittal plane (in each Fig., indicated as “s”) and the meridional plane (in each Fig., indicated as “m”), respectively. In each distortion diagram, a vertical axis indicates an image height (in each Fig., indicated as H).

FIGS. 3, 6, 9, 12, 15, and 18 are lateral aberration diagrams of the zoom lens systems according to Numerical Examples 1, 2, 3, 4, 5, and 6 in a basic state where image blur compensation is not performed and in an image blur compensation state, respectively.

In each lateral aberration diagram, the aberration diagrams in the upper three parts correspond to a basic state at a telephoto limit, where image blur compensation is not performed at a telephoto limit, and the aberration diagrams in the lower three parts correspond to an image blur compensation state at a telephoto limit, where the image blur compensation sub-lens unit (the first sub-lens unit) included in the fourth lens unit G4 is moved by a predetermined amount in a direction perpendicular to the optical axis. Among the lateral aberration diagrams in the basic state, the upper part shows a lateral aberration at an image point of 70% of the maximum image height, the middle part shows a lateral aberration at an axial image point, and the lower part shows a lateral aberration at an image point of −70% of the maximum image height. Among the lateral aberration diagrams in the image blur compensation state, the upper part shows a lateral aberration at an image point of 70% of the maximum image height, the middle part shows a lateral aberration at an axial image point, and the lower part shows a lateral aberration at an image point of −70% of the maximum image height. In each lateral aberration diagram, a horizontal axis indicates the distance from a principal beam on a pupil surface, and a solid line, a short dash line, and a long dash line indicate the characteristics to the d-line, the F-line and the C-line, respectively. In each lateral aberration diagram, the meridional plane is adopted as a plane containing the optical axis of the first lens unit G1.

Table 1 shows an amount of movement (Y_T(mm)), at a telephoto limit, of the image blur compensation sub-lens unit in the direction perpendicular to the optical axis, in the image blur compensation state of the zoom lens system according to each numerical example. The image blur compensation angle is 0.3°. That is, the amount of movement of the image blur compensation sub-lens unit shown below is equal to an amount of image decentering in a case where the optical axis of the zoom lens system inclines at 0.3°.

TABLE 1

(amount of movement of image blur compensation sub-lens unit)

Amount of

Example
Movement Y_T(mm)

1
0.234

2
0.275

3
0.255

4
0.352

5
0.208

6
0.261

Numerical Example 1

The zoom lens system of Numerical Example 1 corresponds to Embodiment 1 (FIG. 1). The surface data, the aspheric surface data, the various data, the lens element data, the zoom lens unit data, and the zoom lens unit magnification are shown in Tables 2, 3, 4, 5, 6, and 7, respectively.

TABLE 2

(Surface data)

Surface number
r
d
nd
vd

Object surface
∞

1
33.08030
1.20000
1.84666
23.8

2
24.35990
5.63190
1.58913
61.3

3
600.00000
Variable

4
48.85560
0.70000
1.77250
49.6

5
8.67050
4.65400

6
−284.56240
0.70000
1.80420
46.5

7
17.22950
0.53940

8
14.00870
2.96900
1.84666
23.8

9
124.03830
Variable

10
−28.80590
0.70000
1.77250
49.6

11
−96.36410
Variable

12
320.76140
1.47460
1.69680
55.5

13
−49.62440
1.95000

14(Aperture)
∞
0.90000

15
16.64810
3.20120
1.69680
55.5

16
−14.47520
0.70000
1.80610
33.3

17
80.18650
6.24320

18*
−81.87490
1.50000
1.54360
56.0

19*
−32.88020
2.94230

20
21.60610
4.69330
1.51680
64.2

21
−8.33000
0.70000
1.71300
53.9

22
−132.10180
BF

Image surface
∞

TABLE 3

(Aspheric surface data)

Surface

No.
Parameters

18
K = 0.00000E+00, A4 = 1.33886E−04, A6 = 3.24570E−06,

A8 = −7.64286E−08

19
K = 0.00000E+00, A4 = 1.15737E−04, A6 = 3.02082E−06,

A8 = −8.18542E−08

TABLE 4

(Various data)

Zooming ratio 2.81403

Wide
Middle
Telephoto

Focal length
14.4006
24.1581
40.5238

F-number
3.62154
4.64730
5.71166

View angle
39.8141
24.3766
14.7748

Image height
10.8150
10.8150
10.8150

Overall length of lens
82.0609
91.7923
107.6421

system

BF
24.09844
32.83383
44.27395

d3
0.4000
7.7101
15.6769

d9
4.2923
3.6969
4.6923

d11
11.8713
6.1526
1.6000

Entrance pupil position
17.6966
29.5670
47.5893

Exit pupil position
−17.8621
−17.8621
−17.8621

Front principal point
27.1550
42.2130
61.6843

position

Back principal point position
67.6603
67.6342
67.1183

TABLE 5

(Lens element data)

Unit
Initial surface No.
Focal length

1
1
−116.4931

2
2
42.9431

3
4
−13.7501

4
6
−20.1804

5
8
18.4244

6
10
−53.4301

7
12
61.7766

8
15
11.6021

9
16
−15.1611

10
18
99.9998

11
20
12.2898

12
21
−12.4987

TABLE 6

(Zoom lens unit data)

Front
Back

Initial

Length
principal
principal

surface
Focal
of lens
point
point

Unit
No.
length
unit
position
position

1
1
70.00212
6.83190
−0.77084
1.89721

2
4
−15.72872
9.56240
−0.26444
1.33694

3
10
−53.43006
0.70000
−0.16915
0.13413

4
12
19.35651
24.30460
5.05052
8.87194

TABLE 7

(Zoom lens unit magnification)

Initial

surface

Unit
No.
Wide
Middle
Telephoto

1
1
0.00000
0.00000
0.00000

2
4
−0.31967
−0.37545
−0.46362

3
10
0.61744
0.61543
0.59900

4
12
−1.04226
−1.49355
−2.08458

Numerical Example 2

The zoom lens system of Numerical Example 2 corresponds to Embodiment 2 (FIG. 4). The surface data, the aspheric surface data, the various data, the lens element data, the zoom lens unit data, and the zoom lens unit magnification are shown in Tables 8, 9, 10, 11, 12, and 13, respectively.

TABLE 8

(Surface data)

Surface number
r
d
nd
vd

Object surface
∞

1
34.81640
1.20000
1.84666
23.8

2
25.04840
5.76580
1.58913
61.3

3
−4281.80260
Variable

4
36.49200
0.70000
1.77250
49.6

5
11.63370
3.94740

6
−57.69330
0.70000
1.83481
42.7

7
12.31460
1.84990

8
15.66210
3.28110
1.84666
23.8

9
−73.37440
Variable

10
−23.99440
0.70000
1.80610
40.7

11
−303.00270
Variable

12
252.00270
1.45400
1.69680
55.5

13
−50.93810
1.50000

14(Aperture)
∞
0.50000

15
16.36830
3.14470
1.71300
53.9

16
−13.12580
0.70000
1.80610
33.3

17
216.78870
5.15430

18
28.70680
0.70000
1.71300
53.9

19
8.02540
5.91130
1.48749
70.4

20
−18.77270
2.86970

21*
−13.27990
1.50000
1.52996
55.8

22*
−18.41360
BF

Image surface
∞

TABLE 9

(Aspheric surface data)

Surface

No.
Parameters

21
K = 0.00000E+00, A4 = −2.02386E−04, A6 = 1.60650E−06,

A8 = 2.25837E-08

22
K = 0.00000E+00, A4 = −1.85067E−04, A6 = 1.44344E−06,

A8 = 0.00000E+00

TABLE 10

(Various data)

Zooming ratio 2.81399

Wide
Middle
Telephoto

Focal length
14.3988
24.1535
40.5180

F-number
3.61905
4.67350
5.75507

View angle
39.8048
24.2146
14.6513

Image height
10.8150
10.8150
10.8150

Overall length of lens
79.4123
88.7082
104.8128

system

BF
22.41253
31.22306
42.53823

d3
0.4000
7.0992
14.9969

d9
3.6995
3.1356
4.0995

d11
11.3221
5.6721
1.6000

Entrance pupil position
18.6324
29.2744
47.0361

Exit pupil position
−18.5675
−18.5675
−18.5675

Front principal point
27.9720
41.7110
60.6874

position

Back principal point
65.0135
64.5546
64.2948

position

TABLE 11

(Lens element data)

Initial

surface

Unit
No.
Focal length

1
1
−111.7441

2
2
42.2914

3
4
−22.3825

4
6
−12.1015

5
8
15.5066

6
10
−32.3619

7
12
60.9309

8
15
10.6910

9
16
−15.3327

10
18
−15.8469

11
19
12.4312

12
21
−100.0004

TABLE 12

(Zoom lens unit data)

Front
Back

Initial

Length
principal
principal

surface
Focal
of lens
point
point

Unit
No.
length
unit
position
position

1
1
69.79699
6.96580
−0.42501
2.26707

2
4
−21.92420
10.47840
−2.01550
−1.97491

3
10
−32.36192
0.70000
−0.03337
0.27862

4
12
18.53595
23.43400
4.88051
7.72468

TABLE 13

(Zoom lens unit magnification)

Initial

surface

Unit
No.
Wide
Middle
Telephoto

1
1
0.00000
0.00000
0.00000

2
4
−0.48949
−0.57558
−0.72614

3
10
0.39885
0.39245
0.37315

4
12
−1.05664
−1.53197
−2.14241

Numerical Example 3

The zoom lens system of Numerical Example 3 corresponds to Embodiment 3 (FIG. 7). The surface data, the aspheric surface data, the various data, the lens element data, the zoom lens unit data, and the zoom lens unit magnification are shown in Tables 14, 15, 16, 17, 18, and 19, respectively.

TABLE 14

(Surface data)

Surface number
r
d
nd
vd

Object surface
∞

1
37.32260
1.20000
1.84666
23.8

2
26.94840
1.42300

3
27.41330
5.36740
1.58913
61.3

4
−3741.80660
Variable

5
62.26820
0.70000
1.77250
49.6

6
9.19270
5.02000

7
−59.93660
0.70000
1.77250
49.6

8
18.71730
0.15000

9
14.41930
3.72090
1.71736
29.5

10
−33.16660
Variable

11*
−17.14010
0.70000
1.52996
55.8

12
−244.91550
Variable

13
204.25790
1.50000
1.71300
53.9

14
−53.73270
1.50000

15(Aperture)
∞
0.50000

16
15.70190
3.23680
1.62299
58.1

17
−14.70420
0.70000
1.80610
33.3

18
435.01800
6.90350

19*
−236.86850
1.34750
1.52996
55.8

20*
−90.55840
1.61150

21
17.26040
3.61070
1.48749
70.4

22
−13.93540
0.65960

23
−11.01420
0.80000
1.77250
49.6

24
−51.06640
BF

Image surface
∞

TABLE 15

(Aspheric surface data)

Surface

No.
Parameters

11
K = 0.00000E+00, A4 = 1.39196E−05, A6 = −8.50233E−08,

A8 = −2.35288E−09, A10 = 0.00000E+00

19
K = 0.00000E+00, A4 = 5.70926E−04, A6 = −7.94359E−07,

A8 = 4.53692E−08, A10 = −1.69327E−10

20
K = 0.00000E+00, A4 = 5.49448E−04, A6 = 1.12374E−07,

A8 = 3.79362E−08, A10 = 0.00000E+00

TABLE 16

(Various data)

Zooming ratio 3.01496

Wide
Middle
Telephoto

Focal length
14.4002
25.0041
43.4162

F-number
3.62449
4.83510
5.56588

View angle
39.8403
23.6095
13.7447

Image height
10.8150
10.8150
10.8150

Overall length of lens
80.9714
91.0636
109.9580

system

BF
23.48347
33.56829
44.18262

d4
0.4000
7.3024
18.7180

d10
3.4065
3.1847
4.1065

d12
12.3305
5.6573
1.6000

Entrance pupil position
18.3357
28.1745
52.8511

Exit pupil position
−16.0456
−16.0456
−16.0456

Front principal point
27.4900
40.5772
64.9702

position

Back principal point
66.5711
66.0595
66.5418

position

TABLE 17

(Lens element data)

Initial

surface

Unit
No.
Focal length

1
1
−120.9218

2
3
46.2179

3
5
−14.0417

4
7
−18.3923

5
9
14.4828

6
11
−34.8131

7
13
59.8104

8
16
12.7077

9
17
−17.6325

10
19
275.7626

11
21
16.4400

12
23
−18.3384

TABLE 18

(Zoom lens unit data)

Front
Back

Initial

Length
principal
principal

surface
Focal
of lens
point
point

Unit
No.
length
unit
position
position

1
1
75.14899
7.99040
1.92412
4.42746

2
5
−23.94733
10.29090
−3.34002
−3.44835

3
11
−34.81307
0.70000
−0.03447
0.20752

4
13
18.89608
22.36960
3.79459
7.79886

TABLE 19

(Zoom lens unit magnification)

Initial

surface

Unit
No.
Wide
Middle
Telephoto

1
1
0.00000
0.00000
0.00000

2
5
−0.47347
−0.54829
−0.74231

3
11
0.39919
0.39213
0.36899

4
13
−1.01387
−1.54757
−2.10929

Numerical Example 4

The zoom lens system of Numerical Example 4 corresponds to Embodiment 4 (FIG. 10). The surface data, the aspheric surface data, the various data, the lens element data, the zoom lens unit data, and the zoom lens unit magnification are shown in Tables 20, 21, 22, 23, 24, and 25, respectively.

TABLE 20

(Surface data)

Surface number
r
d
nd
vd

Object surface
∞

1
34.58860
1.20000
1.84666
23.8

2
24.73020
1.68270

3
24.90680
5.60520
1.58913
61.3

4
647.45250
Variable

5
38.78230
0.70000
1.77250
49.6

6
8.59640
5.02000

7
−70.88560
0.70000
1.77250
49.6

8
20.17810
0.15000

9
14.52510
2.92050
1.84666
23.8

10
−363.32930
Variable

11
−24.35070
0.70000
1.80610
40.7

12
−108.62990
Variable

13*
111.70590
1.50000
1.52996
55.8

14
−60.47860
1.50000

15(Aperture)
∞
0.50000

16
17.81270
3.21810
1.62041
60.3

17
−12.71740
0.70000
1.80610
33.3

18
−103.52570
6.48300

19*
97.52070
1.90600
1.52996
55.8

20*
−130.55850
2.90870

21
16.81410
3.29850
1.48749
70.4

22
−21.38630
0.91360

23
−13.42820
0.80000
1.77250
49.6

24
−77.41170
BF

Image surface
∞

TABLE 21

(Aspheric surface data)

Surface

No.
Parameters

13
K = 0.00000E+00, A4 = −1.13941E−05, A6 = 1.53340E−07,

A8 = −2.82359E−10, A10 = 0.00000E+00

19
K = 0.00000E+00, A4 = 4.63655E−04, A6 = −1.84239E−07,

A8 = 5.83649E−08, A10 = −3.63492E−10

20
K = 0.00000E+00, A4 = 4.46471E−04, A6 = 8.56266E−07,

A8 = 5.42542E−08, A10 = 0.00000E+00

TABLE 22

(Various data)

Zooming ratio 3.01501

Wide
Middle
Telephoto

Focal length
14.3994
25.0028
43.4142

F-number
3.61279
4.82536
5.52388

View angle
39.8262
23.8400
13.8944

Image height
10.8150
10.8150
10.8150

Overall length of lens
80.9632
91.1399
109.9409

system

BF
22.77225
32.98361
43.35881

d4
0.4000
6.9522
18.4058

d10
3.4700
3.2891
4.1700

d12
11.9146
5.5087
1.6000

Entrance pupil position
18.9921
28.4261
53.6396

Exit pupil position
−16.9442
−16.9442
−16.9442

Front principal point
28.1709
40.9080
65.7984

position

Back principal point
66.5638
66.1371
66.5267

position

TABLE 23

(Lens element data)

Initial

surface

Unit
No.
Focal length

1
1
−108.5383

2
3
43.8225

3
5
−14.4431

4
7
−20.2648

5
9
16.5549

6
11
−39.0807

7
13
74.2597

8
16
12.4627

9
17
−18.0480

10
19
105.6409

11
21
19.8721

12
23
−21.1461

TABLE 24

(Zoom lens unit data)

Front
Back

Initial

Length
principal
principal

surface
Focal
of lens
point
point

Unit
No.
length
unit
position
position

1
1
73.70704
8.48790
2.10453
4.70655

2
5
−19.33088
9.49050
−1.03958
0.20119

3
11
−39.08066
0.70000
−0.11240
0.19859

4
13
18.50764
23.72790
4.33235
8.77998

TABLE 25

(Zoom lens unit magnification)

Initial

surface

Unit
No.
Wide
Middle
Telephoto

1
1
0.00000
0.00000
0.00000

2
5
−0.37730
−0.43263
−0.58175

3
11
0.49878
0.49319
0.47083

4
13
−1.03809
−1.58982
−2.15041

Numerical Example 5

The zoom lens system of Numerical Example 5 corresponds to Embodiment 5 (FIG. 13). The surface data, the aspheric surface data, the various data, the lens element data, the zoom lens unit data, and the zoom lens unit magnification are shown in Tables 26, 27, 28, 29, 30, and 31, respectively.

TABLE 26

(Surface data)

Surface number
r
d
nd
vd

Object surface
∞

1
47.65040
1.20000
1.84666
23.8

2
31.61190
7.01310
1.71300
53.9

3
397.39840
Variable

4
43.46490
0.70000
1.71300
53.9

5
9.00310
6.16270

6
−29.86210
0.70000
1.71300
53.9

7
41.45870
0.15000

8
18.69810
3.51650
1.80518
25.5

9
−46.64210
Variable

10
−28.97190
0.70000
1.83400
37.3

11
169.53010
Variable

12
79.92270
1.62240
1.61800
63.4

13
−38.83920
1.30000

14(Aperture)
∞
0.80000

15
17.89240
2.11780
1.71300
53.9

16
−27.84220
0.70000
1.80518
25.5

17
60.13520
7.20000

18
∞
6.03890

19*
22.18890
1.20000
1.52996
55.9

20*
22.30780
0.80000

21
17.03250
4.91090
1.51823
59.0

22
−12.23210
0.70000
1.71300
53.9

23
271.51730
BF

Image surface
∞

TABLE 27

(Aspheric surface data)

Surface

No.
Parameters

19
K = 0.00000E+00, A4 = 3.31973E−05, A6 = −2.45043E−06,

A8 = 5.51240E−08, A10 = −2.25928E−10

20
K = 0.00000E+00, A4 = 8.10984E−05, A6 = −2.10215E−06,

A8 = 3.77361E−08, A10 = −3.90270E−12

TABLE 28

(Various data)

Zooming ratio 3.02696

Wide
Middle
Telephoto

Focal length
14.4217
25.0911
43.6540

F-number
3.62324
4.49954
5.88048

View angle
39.7747
23.7186
13.6860

Image height
10.8150
10.8150
10.8150

Overall length of lens
80.9602
91.1806
110.7909

system

BF
17.02390
26.35686
34.37962

d3
0.4000
8.4039
22.9412

d9
3.1446
3.1955
4.1494

d11
12.8594
5.6920
1.7884

Entrance pupil position
19.6432
31.7755
67.0815

Exit pupil position
−22.4207
−22.4207
−22.4207

Front principal point
28.7920
43.9598
77.1851

position

Back principal point
66.5385
66.0895
67.1369

position

TABLE 29

(Lens element data)

Initial

surface

Unit
No.
Focal length

1
1
−114.8688

2
2
47.7868

3
4
−16.0617

4
6
−24.2471

5
8
16.9845

6
10
−29.6208

7
12
42.5156

8
15
15.5772

9
16
−23.5521

10
19
1747.2128

11
21
14.5724

12
22
−16.3994

TABLE 30

(Zoom lens unit data)

Front
Back

Initial

Length
principal
principal

surface
Focal
of lens
point
point

Unit
No.
length
unit
position
position

1
1
83.92677
8.21310
−0.94662
2.57496

2
4
−32.20400
11.22920
−5.29793
−6.36303

3
10
−29.62079
0.70000
0.05562
0.37455

4
12
18.93137
27.39000
4.66837
7.58142

TABLE 31

(Zoom lens unit magnification)

Initial

surface

Unit
No.
Wide
Middle
Telephoto

1
1
0.00000
0.00000
0.00000

2
4
−0.63167
−0.74930
−1.13229

3
10
0.28769
0.27735
0.24666

4
12
−0.94558
−1.43857
−1.86235

Numerical Example 6

The zoom lens system of Numerical Example 6 corresponds to Embodiment 6 (FIG. 16). The surface data, the aspheric surface data, the various data, the lens element data, the zoom lens unit data, and the zoom lens unit magnification are shown in Tables 32, 33, 34, 35, 36, and 37, respectively.

TABLE 32

(Surface data)

Surface number
r
d
nd
vd

Object surface
∞

1
34.98850
1.20000
1.84666
23.8

2
24.95140
0.70000

3
25.32570
5.27390
1.58913
61.3

4
−1117.09550
Variable

5
36.59270
0.70000
1.77250
49.6

6
9.88930
5.02000

7
−49.58200
0.70000
1.77250
49.6

8
15.19140
0.20000

9
13.74870
2.70190
1.84666
23.8

10
289.98460
Variable

11
−11.94400
0.70000
1.71300
53.9

12
−20.16380
Variable

13
597.66450
1.50000
1.71300
53.9

14
−44.15500
1.50000

15(Aperture)
∞
0.50000

16
16.10220
3.18650
1.62299
58.1

17
−14.80840
0.70000
1.80610
33.3

18
392.17240
8.75800

19*
103.72930
1.56040
1.52996
55.8

20*
−107.79100
0.18790

21
16.64420
4.00000
1.48749
70.4

22
−12.74810
0.68280

23
−11.13690
0.80000
1.77250
49.6

24
−133.84180
BF

Image surface
∞

TABLE 33

(Aspheric surface data)

Surface

No.
Parameters

19
K = 0.00000E+00, A4 = 3.66811E−04, A6 = 1.81869E−06,

A8 = −6.63412E−09, A10 = 7.91954E−11

20
K = 0.00000E+00, A4 = 3.72321E−04, A6 = 2.25209E−06,

A8 = 4.28346E−09, A10 = 0.00000E+00

TABLE 34

(Various data)

Zooming ratio 3.01502

Wide
Middle
Telephoto

Focal length
14.3998
25.0031
43.4155

F-number
3.62556
4.79091
5.70944

View angle
39.7851
23.4171
13.7449

Image height
10.8150
10.8150
10.8150

Overall length of lens
79.4628
91.0730
108.4496

system

BF
23.46462
33.24994
46.04101

d4
0.4000
7.9148
16.0673

d10
3.4700
3.3706
3.6362

d12
11.5568
5.9663
2.1337

Entrance pupil position
18.3202
30.4335
48.5024

Exit pupil position
−16.7621
−16.7621
−16.7621

Front principal point
27.5653
42.9365
61.9049

position

Back principal point
65.0631
66.0699
65.0341

position

TABLE 35

(Lens element data)

Initial

surface

Unit
No.
Focal length

1
1
−108.6886

2
3
42.1075

3
5
−17.7454

4
7
−14.9826

5
9
16.9708

6
11
−42.6035

7
13
57.7242

8
16
12.8925

9
17
−17.6884

10
19
100.0000

11
21
15.4997

12
23
−15.7700

TABLE 36

(Zoom lens unit data)

Front
Back

Initial

Length
principal
principal

surface
Focal
of lens
point
point

Unit
No.
length
unit
position
position

1
1
69.71664
7.17390
0.84789
3.32318

2
5
−15.47835
9.32190
0.90398
2.79598

3
11
−42.60347
0.70000
−0.61561
−0.33926

4
13
18.08709
23.37560
4.23950
8.63666

TABLE 37

(Zoom lens unit magnification)

Initial

surface

Unit
No.
Wide
Middle
Telephoto

1
1
0.00000
0.00000
0.00000

2
5
−0.31535
−0.37236
−0.46320

3
11
0.58891
0.58260
0.56958

4
13
−1.11220
−1.65321
−2.36041

Values corresponding to the individual conditions in the zoom lens systems of the respective numerical examples are shown below.

TABLE 38

(Values corresponding to the individual conditions)

Example

Condition
1
2
3
4

(1)
T₄/f_W
1.69
1.63
1.55
1.65

(2)
|D_4WT/f_W|
1.40
1.40
1.44
1.43

(3)
|f_W/f₃|
0.27
0.44
0.41
0.37

(4)
|D₁/f_W|
1.78
1.76
2.01
2.01

(5)
(D_3WT− D_4WT)/f_W
0.71
0.68
0.75
0.72

(6)
(D_3WN− D_4WN)/f_W
0.40
0.39
0.46
0.44

0.19

(L7)

(7)
|f_W/f_P|
0.14
0.01
0.41
0.14

(L10)

(8)
BF_W/f_W
1.67
1.56
1.63
1.58

(9)
nd₁
1.59
1.59
1.59
1.59

(10)
vd₁
61
61
61
61

Example

Condition
5
6

(1)
T₄/f_W
1.90
1.62

(2)
|D_4WT/f_W|
1.20
1.57

(3)
|f_W/f₃|
0.49
0.34

(4)
|D₁/f_W|
2.07
2.01

(5)
(D_3WT− D_4WT)/f_W
0.77
0.65

(6)
(D_3WN− D_4WN)/f_W
0.50
0.39

(7)
|f_W/f_P|
0.01
0.14

(8)
BF_W/f_W
1.18
1.63

(9)
nd₁
1.59
1.59

(10)
vd₁
61
61

INDUSTRIAL APPLICABILITY

A zoom lens system according to the present invention is applicable to a digital still camera, a digital video camera, a camera of a mobile telephone, a camera of a PDA (Personal Digital Assistance), a monitor camera in a monitor system, a Web camera, an in-vehicle camera, and the like. In particular, the zoom lens system is suitable for an imaging optical system such as a digital still camera system or a digital video camera system, which requires high image quality

DESCRIPTION OF THE REFERENCE CHARACTERS

100 interchangeable-lens type digital camera system

101 camera body

102 image sensor

104 camera mount

201 interchangeable lens apparatus

202 zoom lens system

Zoom Lens System, Interchangeable Lens Apparatus, and Camera System

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CPC

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PCT Information