ZOOM LENS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a compact zoom lens that achieves wide angles, has a high zoom ratio, and is suitable for digital imaging apparatuses such as digital still cameras and digital video cameras.

2. Description of the Related Art

Reductions in the size of digital imaging apparatuses such as digital still cameras, broadcast cameras, and surveillance cameras have advanced. Accordingly, zoom lenses that are compact and, have a high zoom ratio and high imaging performance are demanded as imaging optical systems for use on such digital imaging apparatuses.

To address such demands, several zoom lenses are known that sequentially include from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power that is followed by 1 or more lens groups (see, for example, Japanese Patent Application Laid-Open Publication Nos. 2011-33868, 2012-98699, and 2009-282398).

The zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2011-33868 has a zoom ratio on the order of 9 to 41.2, and an angle of view at the wide angle edge on the order of 68.4 to 79.6 degrees. The zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2012-98699 has a zoom ratio on the order of 33.5 to 44.25, and an angle of view at the wide angle edge on the order of 74 to 84 degrees. The zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2009-282398 has a zoom ratio on the order of 9.7 to 19.4, and an angle of view at the wide angle edge on the order of 74 to 84 degrees.

Although the zoom lenses disclosed in Japanese Patent Application Laid-Open Publication Nos. 2011-33868 and 2012-98699 have a sufficiently large angle of view at the wide angle edge and a sufficiently large zoom ratio, the maximum image height at the wide angle edge cannot be said to be sufficiently large and high imaging performance cannot be achieved. If the image height at the wide angle edge is increased, the diameter of the optical system has to be increased. However, if the diameter of the optical system is increased, the overall length of the optical system accordingly increases. In either case, a compact size for the optical system cannot be maintained, making use on a compact imaging apparatus difficult.

Further, the zoom lens disclosed in Japanese Patent Application Laid-Open Publication No. 2009-282398 corrects image blur by moving the third lens group in a direction orthogonal to the optical axis. Nonetheless, in the zoom lens, the anti-shake coefficient (amount that image shifts/amount that anti-shake group is shifted) of the third lens group at the telephoto edge decreases and therefore, the distance that the third lens group is moved to prevent blurring at the telephoto edge increases. As a result, the imaging performance when blur is corrected deteriorates. Further, a large area for the third lens group to move has to be established, inviting increases in the size of the optical system. In addition, the mechanism for driving the third lens group also has to be of a larger size.

Since the zoom ratio of the zoom lens disclosed in Japanese Patent Application Laid-Open Publication No. 2009-282398 is on the order of 9.7 to 19.4, compared to that of the zoom lenses disclosed in Japanese Patent Application Laid-Open Publication Nos. 2011-33868 and 2012-98699, the zoom ratio is insufficient. However, if the zoom ratio is increased, the distance that the lens group for zooming moves increases and the overall length of the optical system increases, which hinders attempts to reduce the size of the optical system.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least solve the above problems in the conventional technologies.

A zoom lens according to one aspect of the present invention includes sequentially from an object side a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group; and at least one lens group subsequent to the fourth lens group toward an image plane. The zoom lens zooms between a wide angle edge and a telephoto edge by varying intervals between the lens groups, along a direction of an optical axis; and corrects hand-shake that occurs with optical system vibration, by shifting any one among the entire second lens group and a portion of lenses forming the second lens group, in a direction that is substantially orthogonal to the optical axis. The zoom lens satisfies conditional expression (1) 0.5≦D2W×(−F2)/(Ft×tan(ωw))≦2.0 and condition expression (2) 90≦(F1×Ft)/(−F2×F3)≦200, where D2W is an interval between the second lens group and the third lens group at the wide angle edge, F1 is the focal length of the first lens group, F2 is the focal length of the second lens group, F3 is the focal length of the third lens group, Ft is the focal length of the optical system overall at the telephoto edge, and cow is a half-angle at the wide angle edge.

The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view along an optical axis, depicting a configuration of a zoom lens according to a first embodiment;

FIG. 2 is a diagram of various types of aberration in the zoom lens according to the first embodiment;

FIG. 3 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a second embodiment;

FIG. 4 is a diagram of various types of aberration in the zoom lens according to the second embodiment;

FIG. 5 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a third embodiment;

FIG. 6 is a diagram of various types of aberration in the zoom lens according to the third embodiment;

FIG. 7 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fourth embodiment;

FIG. 8 is a diagram of various types of aberration in the zoom lens according to the fourth embodiment;

FIG. 9 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fifth embodiment; and

FIG. 10 is a diagram of various types of aberration in the zoom lens according to the fifth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of a zoom lens according to the present invention will be described in detail with reference to the accompanying drawings.

A zoom lens according to the present invention includes sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group, and 1 or more lens groups subsequent to the fourth lens group, toward an image plane. Zooming from a wide angle edge to a telephoto edge is performed by changing intervals between the lens groups, along a direction of the optical axis. Image blur that occurs with optical system vibration consequent to hand-shake is corrected by shifting (moving) the entire second lens group or a portion of the lenses forming the second lens group, in a direction that is substantially orthogonal to the optical axis. The fourth lens group may have a negative refractive power.

One object of the present invention is to provide a compact zoom lens having a high zoom ratio and a favorable anti-shake correction function. To achieve such an object, the following conditions are set.

In the zoom lens according to the present invention, the following conditional expressions are preferably satisfied, where D2W is the interval between the second lens group and the third lens group at the wide angle edge; F1 is the focal length of the first lens group; F2 is the focal length of the second lens group; F3 is the focal length of the third lens group; Ft is the focal length of the optical system overall at the telephoto edge; and ωw is the half-angle at the wide angle edge.

0.5≦D2W×(−F2)/(Ft×tan(ωw))≦2.0 (1)

90≦(F1×Ft)/(−F2×F3)≦200 (2)

Conditional expression (1) prescribes a condition to improve imaging performance, facilitated by reductions in the diameter and overall length of the optical system.

Below the lower limit of conditional expression (1), the interval between the second lens group and the third lens group at the wide angle edge becomes too narrow, or the power (inverse of the focal length) of the second lens group becomes too strong. In some cases, both may occur. Therefore, although reducing the overall length of the optical system is advantageous, chromatic difference of magnification and coma occurring at the wide angle edge become difficult to correct. Meanwhile, above the upper limit of conditional expression (1), although the correction of various types of aberration becomes favorable, the diameter of the second lens group increases, making the second lens group heaving. In the zoom lens according to the present invention, the entire second lens group or a portion of the lenses forming the second lens group has a function as an anti-shake group, and corrects image blur that occurs with optical system vibrations. Consequently, if the weight of the anti-shake group increases, the power consumption of the driving mechanism that drives the anti-shake group also increases, and therefore, is not desirable.

By satisfying conditional expression (1) within the following range, even more favorable effects can be expected.

0.8≦D2W×(−F2)/(Ft×tan(ωw))≦1.8 (1a)

By satisfying the range prescribed by conditional expression (1a), a smaller diameter and shorter overall length of the optical system can be facilitated while enabling improved imaging performance.

By satisfying conditional expression (1a) within the following range, yet even more favorable effects can be expected.

1.0≦D2W×(−F2)/(Ft×tan(ωw))≦1.75 (1b)

By satisfying the range prescribed by conditional expression (1b), a smaller diameter and a shorter overall length of the optical system can be facilitated while enabling even further improvements in imaging performance.

Conditional expression (2) prescribes a condition for achieving both a high zoom ratio and compact size of the zoom lens while improving imaging performance.

Below the lower limit of conditional expression (2), the power of the second lens group and of the third lens group becomes too weak, making both a high zoom ratio and compact size (particularly the second lens group) difficult to achieve. Meanwhile, above the upper limit of conditional expression (2), although both a zoom ratio and a compact size of the zoom lens can be easily achieved, spherical aberration, coma, and chromatic difference of magnification become difficult to correct.

By satisfying conditional expression (2) within the following range, even more favorable effects can be expected.

95≦(F1×Ft)/(−F2×F3)≦170 (2a)

By satisfying the ranges prescribed by conditional expression (2a), both a high zoom ratio and a compact size of the zoom lens can be achieved while enabling imaging performance to be improved further.

By satisfying conditional expression (2a) within the following range, yet even more favorable effects can be expected.

102≦(F1×Ft)/(−F2×F3)≦150 (2b)

By satisfying the range prescribed by conditional expression (2b), both a high zoom ratio and a compact size of the zoom lens can be achieved while enabling even further improvements in imaging performance.

In the zoom lens, the following conditional expression is preferably satisfied, where BXt2 is the anti-shake coefficient (amount of image point shift/amount that anti-shake group is shifted) for the entire second lens group or a portion of the lenses forming the second lens group, at the telephoto edge; and ωw is the half-angle at the wide angle edge.

3.1≦BXt2×tan(ωw)≦10 (3)

Conditional expression (3) prescribes a condition for implementing a zoom lens that maintains a small optical system diameter while having favorable imaging performance at wide angles, by controlling the shift amount that the entire second lens group or a portion of the lenses forming the second lens group is shifted when image blur at the telephoto edge is corrected.

Below the lower limit of conditional expression (3), the anti-shake coefficient for the entire second lens group or a portion of the lenses forming the second lens group, which has a function as the anti-shake group, becomes too small. In particular, the distance that the anti-shake group is shifted when image blur at the telephoto edge is corrected becomes great. Consequently, the optical system diameter increases and as a result, the driving mechanism that drives the anti-shake group also has to be larger, which invites increases in the size of the lens barrel that supports the zoom lens and therefore, is not desirable. On the other hand, above the upper limit of conditional expression (3), the anti-shake coefficient of the anti-shake group becomes large, which enables the distance that the anti-shake group is shifted to correct image blur at the telephoto edge to be suppressed and is advantageous in increasing the wide angle views of the optical system. Nonetheless, since the power of the second lens group becomes too strong, various types of aberration occurring at the wide angle edge become difficult to correct and is therefore, undesirable.

By satisfying conditional expression (3) within the following range, even more favorable effects can be expected.

3.2≦BXt2×tan(ωw)≦8.0 (3a)

By satisfying the range prescribed by conditional expression (3a), a compact zoom lens that has even more favorable imaging performance at wide angles can be implemented.

By satisfying conditional expression (3a) within the following range, yet even more favorable effects can be expected.

3.3≦BXt2×tan(ωw)≦6.0 (3b)

By satisfying the range prescribed by conditional expression (3b), a compact zoom lens having yet even more favorable imaging performance can be implemented.

In the zoom lens, the following conditional expression is preferably satisfied, where Z is the zoom ratio; Ymax is the maximum paraxial image height at the wide angle edge; and F2 is the focal length of the second lens group.

17≦(Z×Ymax)/(−F2)≦35 (4)

Conditional expression (4) prescribes a condition for achieving a wide angle zoom lens with a high zoom ratio while improving imaging performance.

Below the lower limit of conditional expression (4), the power of the second lens group becomes too weak, making both a high zoom ratio and wide angle views difficult to achieve on the zoom lens. Meanwhile, above the upper limit of conditional expression (4), although both a high zoom ratio and wide angles can be achieved for the zoom lens, various types of aberration such as chromatic difference of magnification, spherical aberration, etc. become difficult to correct and is therefore, not desirable.

By satisfying conditional expression (4) within the following range, even more favorable effects can be expected.

18≦(Z×Ymax)/(−F2)≦30 (4a)

By satisfying the range prescribed by conditional expression (4a), wide angles and a high zoom ratio of the zoom lens can be achieved while enabling imaging performance to be improved further.

By satisfying conditional expression (4a) within the following range, yet even more favorable effects can be expected.

19≦(Z×Ymax)/(−F2)≦25 (4b)

By satisfying the range prescribed by conditional expression (4b), wide angles and a high zoom ratio of the zoom lens can be achieved while enabling even further improvements in imaging performance.

Further, in the zoom lens, the following conditional expression is preferably satisfied, where F2 is the focal length of the second lens group; F4 is the focal length of the fourth lens group; D1T is the distance between the first lens group and the second lens group at the telephoto edge; and D3T is the distance between the third lens group and the fourth lens group at the telephoto edge.

0.5≦D3T/−F4≦3.0 (5)

3.5≦(D3T×D1T)/(F2×F4)≦15 (6)

Conditional expression (5) prescribes a condition for reducing the diameter and the overall length of the optical system without hindering the achievement of a high zoom ratio.

Below the lower limit of conditional expression (5), the interval between the third lens group and the fourth lens group at the telephoto edge becomes too wide and the overall length of the optical system increases. Further, the diameter of lens groups subsequent to the fourth lens group toward the image plane increases. Meanwhile, above the upper limit of conditional expression (5), the interval between third lens group and the fourth lens group at the telephoto edge becomes too narrow, hindering the achievement of a high zoom ratio. Further, the power of the fourth lens group becomes too weak and the overall length of the optical system at the telephoto edge increases. In either case, implementation of a compact zoom lens having a high zoom ratio becomes difficult.

By satisfying conditional expression (5) within the following range, even more favorable effects can be expected.

0.65≦D3T/−F4≦2.0 (5a)

By satisfying the range prescribed by conditional expression (5a), reductions in the diameter and overall length of the optical system are facilitated, enabling an even more compact optical system.

By satisfying conditional expression (5a) within the following range, yet even more favorable effects can be expected.

0.80≦D3T/−F4≦1.5 (5b)

By satisfying the range prescribed by conditional expression (5b), further reductions in the diameter and the overall length of the optical system are facilitated, enabling an even more compact optical system to be achieved.

Conditional expression (6) prescribes a condition for achieving a zoom lens that has a high zoom ratio and that is compact. Typically, when a high zoom ratio is attempted for a zoom lens, the distance that the lens group controlling zooming is moved increases and consequently, the overall length of the optical system increases, making a compact size of the optical system difficult. However, by satisfying conditional expression (6), the distance that the lens group controlling zooming is moved can be suppressed while enabling a reduction of the overall length of the optical system and a high zoom ratio.

Below the lower limit of conditional expression (6), the power of the second lens group and of the fourth lens group becomes too weak, and if a high zoom ratio is attempted to be achieved, the second lens group and the fourth lens group have to be moved a large distance when zooming is performed. Consequently, a high zoom ratio and a compact size for the zoom lens become difficult to achieve. Meanwhile, above the upper limit of conditional expression (6), the interval between the first lens group and the second lens group, and the interval between the third lens group and the fourth lens group become too large at the telephoto edge, causing the overall length of the optical system to increase, hindering achievement of a compact size for the optical system.

By satisfying conditional expression (6) within the following range, even more favorable effects can be expected.

4.5≦(D3T×D1T)/(F2×F4)≦12 (6a)

By satisfying the range prescribed by conditional expression (6a), the overall length of the optical system can be reduced further while enabling a high zoom ratio.

By satisfying conditional expression (6a) within the following range, yet even more favorable effects can be expected.

5.5≦(D3T×D1T)/(F2×F4)≦10 (6b)

By satisfying the range prescribed by conditional expression (6b), the overall length of the optical system can be reduced even further while enabling a high zoom ratio to be achieved.

As described, the zoom lens according to the present invention has the configuration described above, enabling a compact zoom lens that achieves wide angles and has a high zoom ratio to be implemented while further having a favorable anti-shake correction function. In particular, by satisfying the conditions described above, a compact size, wide angles, and a high zoom ratio are achieved while enabling imaging performance to be improved. Further, the distance that the anti-shake group is shifted at the time of image blur correction is suppressed and imaging performance is maintained during image blur correction.

With reference to the accompanying drawings embodiments of the zoom lens according to the present invention will be described in detail.

FIG. 1 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a first embodiment. The zoom lens includes sequentially from an object side that is nearest an object (not depicted), a first lens group G₁₁having a positive refractive power, a second lens group G₁₂having a negative refractive power, a third lens group G₁₃having a positive refractive power, a fourth lens group G₁₄having a negative refractive power, a fifth lens group G₁₅having a positive refractive power, a sixth lens group G₁₆having a negative refractive power. Further, between the second lens group G₁₂and the third lens group G₁₃, an aperture stop S that prescribes a given diameter is disposed.

The first lens group G₁₁includes sequentially from the object side, a negative lens L₁₁₁, a positive lens L₁₁₂, and a positive lens L₁₁₃. The negative lens L₁₁₁and the positive lens L₁₁₂are cemented.

The second lens group G₁₂includes sequentially from the object side, a negative lens L₁₂₁, a negative lens L₁₂₂, a positive lens L₁₂₃, and a negative lens L₁₂₄. The negative lens L₁₂₂and the positive lens L₁₂₃are cemented. Further, both surfaces of the negative lens L₁₂₄are aspheric.

The third lens group G₁₃includes sequentially from the object side, a positive lens L₁₃₁, a negative lens L₁₃₂, and a positive lens L₁₃₃. The positive lens L₁₃₁and the negative lens L₁₃₂are cemented. Further, both surfaces of the positive lens L₁₃₃are aspheric.

The fourth lens group G₁₄includes sequentially from the object side, a negative lens L₁₄₁and a positive lens L₁₄₂. The negative lens L₁₄₁and positive lens L₁₄₂are cemented.

The fifth lens group G₁₅includes sequentially from the object side, a positive lens L₁₅₁and a negative lens L₁₅₂. On the positive lens L₁₅₁, the surface facing toward the object is aspheric. The positive lens L₁₅₁and the negative lens L₁₅₂are cemented.

The sixth lens group G₁₆is formed by a negative lens L₁₆₁.

The zoom lens moves the first lens group G₁₁along the optical axis, from the image plane side to the object side; moves the second lens group G₁₂along the optical axis, from the object side to the image plane side; moves the third lens group G₁₃along the optical axis, from the image plane side to the object side; moves the fourth lens group G₁₄along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₁₅along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₁₅along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₁₂in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the first embodiment are indicated below.

Focal length of entire zoom lens = 4.7885 (wide angle

edge) to 43.0115 (intermediate position) to 186.8884 (Ft:

telephoto edge)

F number (Fno.) = 2.9 (wide angle edge) to 4.9 (intermediate

position) to 6.4 (telephoto edge)

Half-angle (ω) = 41.39 (ωw: wide angle edge) to

5.09 (intermediate position) to 1.17 (telephoto edge)

Paraxial image height (Y) = 4.22 (Ymax: wide angle edge) to

3.83 (intermediate position) to 3.83 (telephoto edge)

Focal length (F1) of first lens group G₁₁= 76.1290

Focal length (F2) of second lens group G₁₂= −8.0447

Focal length (F3) of third lens group G₁₃= 16.9296

Focal length (F4) of fourth lens group G₁₄= −26.5386

Focal length of fifth lens group G₁₅= 19.5036

Focal length of sixth lens group G₁₆= −60.5779

Zoom ratio (Z) = 39.0244

(Lens Data)

r₁= 104.6796
d₁= 0.9000
nd₁= 1.80610
υd₁= 33.27

r₂= 48.4361
d₂= 4.5000
nd₂= 1.43700
υd₂= 95.10

r₃= −183.2004
d₃= 0.2000

r₄= 43.2099
d₄= 3.0000
nd₃= 1.61800
υd₃= 63.39

r₅= 166.2488
d₅= D(5) (variable)

r₆= 125.5141
d₆= 0.5000
nd₄= 1.69680
υd₄= 55.46

r₇= 8.2265
d₇= 3.9590

r₈= −32.1614
d₈= 0.5000
nd₅= 1.91082
υd₅= 35.25

r₉= 23.1845
d₉= 2.3344
nd₆= 1.94595
υd₆= 17.98

r₁₀= −39.9024
d₁₀= 1.3656

r₁₁= −14.2642
d₁₁= 0.5000
nd₇= 1.83441
υd₇= 37.28

(aspheric surface)

r₁₂= −28.6551
d₁₂= D(12) (variable)

(aspheric surface)

r₁₃= ∞
d₁₃= 0.4000

(aperture stop)

r₁₄= 27.1942
d₁₄= 2.5640
nd₈= 1.61800
υd₈= 63.39

r₁₅= −9.3597
d₁₅= 0.5000
nd₉= 1.74950
υd₉= 35.04

r₁₆= −58.6359
d₁₆= 2.3973

r₁₇= 62.5307
d₁₇= 2.4432
nd₁₀= 1.49710
υd₁₀= 81.56

(aspheric surface)

r₁₈= −14.1291
d₁₈= D(18) (variable)

(aspheric surface)

r₁₉= −36.2539
d₁₉= 0.6000
nd₁₁= 1.74400
υd₁₁= 44.90

r₂₀= 10.2432
d₂₀= 1.7000
nd₁₂= 1.84666
υd₁₂= 23.78

r₂₁= 31.5852
d₂₁= D(21) (variable)

r₂₂= 22.3669
d₂₂= 3.5000
nd₁₃= 1.49710
υd₁₃= 81.56

(aspheric surface)

r₂₃= −8.8079
d₂₃= 0.7000
nd₁₄= 1.84666
υd₁₄= 23.78

r₂₄= −12.1131
d₂₄= D(24) (variable)

r₂₅= −15.0000
d₂₅= 0.7000
nd₁₅= 1.84666
υd₁₅= 23.78

r₂₆= −21.6538
d₂₆= D(26) (variable)

r₂₇= ∞

(image plane)

Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F)

(eleventh plane)

k = 1.0000,

A = 0, B = 1.45339 × 10⁻⁴,

C = −6.22182 × 10⁻⁶, D = 4.06493 × 10⁻⁸,

E = 6.50599 × 10⁻¹⁰, F = −6.52539 × 10⁻¹²

(twelfth plane)

k = 1.0000,

A = 0, B = 8.14642 × 10⁻⁵,

C = −6.44794 × 10⁻⁶, D = 6.78926 × 10⁻⁸,

E = 0, F = 0

(seventeenth plane)

k = 1.0000,

A = 0, B = −1.75747 × 10⁻⁴,

C = 5.53527 × 10⁻⁶, D = −2.97994 × 10⁻⁷,

E = 3.72276 × 10⁻⁹, F = 0

(eighteenth plane)

k = 1.0000,

A = 0, B = −7.65925 × 10⁻⁵,

C = 4.63905 × 10⁻⁶, D = −2.43393 × 10⁻⁷,

E = 2.79005 × 10⁻⁹, F = 0

(twenty-second plane)

k = 1.0000,

A = 0, B = −8.33779 × 10⁻⁵,

C = 7.43779 × 10⁻⁷, D = −3.17595 × 10⁻⁸,

E = 5.00716 × 10⁻¹⁰, F = 0

(Zoom Data)

wide angle
intermediate position
telephoto

D(5)
0.8000
40.5304
55.9335

D(12)
34.7488
8.3490
0.1000

D(18)
2.3744
21.7219
30.8851

D(21)
11.0458
8.8163
10.6225

D(24)
7.1741
4.5967
2.1000

D(26)
7.0917
7.1141
7.1503

Interval (D2W) between second lens group G₁₂and third lens group G₁₃at wide angle edge=35.1488 tan(ωw)=0.8819D2W×(−F2)/(Ft×tan(ωw))=1.7155 (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=104.4660 (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G₁₂overall at telephoto edge=4.8296BXt2×tan(ωw)=4.2594 (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=20.4885 (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G₁₃and fourth lens group G₁₄at telephoto edge=30.8851D3T/−F4=1.1638 (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G₁₁and second lens group G₁₂at telephoto edge=55.9335 (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=8.0916

FIG. 2 is a diagram of various types of aberration in the zoom lens according to the first embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 3 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a second embodiment. The zoom lens includes sequentially from the object side, a first lens group G₂₁having a positive refractive power, a second lens group G₂₂having a negative refractive power, a third lens group G₂₃having a positive refractive power, a fourth lens group G₂₄having a negative refractive power, and a fifth lens group G₂₅having a positive refractive power. Further, between the second lens group G₂₂and the third lens group G₂₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₂₁includes sequentially from the object side, a negative lens L₂₁₁, a positive lens L₂₁₂, and a positive lens L₂₁₃. The negative lens L₂₁₁and the positive lens L₂₁₂are cemented.

The second lens group G₂₂includes sequentially from the object side, a negative lens L₂₂₁, a negative lens L₂₂₂, a positive lens L₂₂₃, and a negative lens L₂₂₄. Both surfaces of the negative lens L₂₂₁and the surface on the negative lens L₂₂₄, facing toward the image plane are aspheric. The negative lens L₂₂₂and the positive lens L₂₂₃are cemented.

The third lens group G₂₃includes sequentially from the object side, a positive lens L₂₃₁, a negative lens L₂₃₂, and a positive lens L₂₃₃. On the positive lens L₂₃₁, the surface facing toward the object is aspheric. The negative lens L₂₃₂and the positive lens L₂₃₃are aspheric.

The fourth lens group G₂₄includes sequentially from the object side, a negative lens L₂₄₁and a positive lens L₂₄₂. Both surfaces of the positive lens L₂₄₂are aspheric.

The fifth lens group G₂₅includes sequentially from the object side, a positive lens L₂₅₁and a negative lens L₂₅₂. On the positive lens L₂₅₁, the surface facing toward the object is aspheric. The positive lens L₂₅₁and the negative lens L₂₅₂are cemented.

The zoom lens moves the first lens group G₂₁along the optical axis, from the image plane side to the object side; moves the second lens group G₂₂along the optical axis, from the object side to the image plane side; moves the third lens group G₂₃along the optical axis, from the image plane side to the object side; moves the fourth lens group G₂₄along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₂₅along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₂₅along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₂₂in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the second embodiment are indicated below.

Focal length of entire zoom lens = 4.6042 (wide angle

edge) to 29.0000 (intermediate position) to 183.6480 (Ft:

telephoto edge)

F number (F no.) = 2.9 (wide angle edge) to 4.1 (intermediate

position) to 6.0 (telephoto edge)

Half-angle (ω) = 42.83 (ωw: wide angle edge) to

3.92 (intermediate position) to 1.20 (telephoto edge)

Paraxial image height (Y) = 4.27 (Ymax: wide angle edge) to

3.92 (intermediate position) to 3.85 (telephoto edge)

Focal length (F1) of first lens group G₂₁= 69.2539

Focal length (F2) of second lens group G₂₂= −7.0524

Focal length (F3) of third lens group G₂₃= 16.4363

Focal length (F4) of fourth lens group G₂₄= −28.2916

Focal length of fifth lens group G₂₅= 19.6612

Zoom ratio (Z) = 39.8870

(Lens Data)

r₁= 86.8572
d₁= 0.7000
nd₁= 1.80610
υd₁= 33.27

r₂= 43.6362
d₂= 6.2000
nd₂= 1.43700
υd₂= 95.10

r₃= −236.7447
d₃= 0.1000

r₄= 40.2773
d₄= 4.6000
nd₃= 1.59282
υd₃= 68.62

r₅= 195.8458
d₅= D(5)

(variable)

r₆= 800.0000
d₆= 0.5000
nd₄= 1.69350
υd₄= 53.20

(aspheric surface)

r₇= 10.0625
d₇= 3.7212

(aspheric surface)

r₈= −61.9805
d₈= 0.5000
nd₅= 1.88100
υd₅= 40.14

r₉= 11.7228
d₉= 2.3603
nd₆= 1.94595
υd₆= 17.98

r₁₀= 102.9725
d₁₀= 0.6542

r₁₁= −76.9383
d₁₁= 0.5000
nd₇= 1.88202
υd₇= 37.22

r₁₂= 37.8481
d₁₂= D(12)

(aspheric surface)
(variable)

r₁₃= ∞
d₁₃= 1.0000

(aperture stop)

r₁₄= 25.1003
d₁₄= 2.1400
nd₈= 1.61881
υd₈= 63.85

(aspheric surface)

r₁₅= −11.2849
d₁₅= 0.3776

r₁₆= −9.0000
d₁₆= 0.5000
nd₉= 1.61293
υd₉= 36.96

r₁₇= −118.8368
d₁₇= 2.3053
nd₁₀= 1.49700
υd₁₀= 81.61

r₁₈= −9.8194
d₁₈= D(18)

(variable)

r₁₉= −28.8403
d₁₉= 0.5000
nd₁₁= 1.80420
υd₁₁= 46.50

r₂₀= 38.6708
d₂₀= 0.1000

r₂₁= 12.1139
d₂₁= 3.2122
nd₁₂= 1.84681
υd₁₂= 23.62

(aspheric surface)

r₂₂= 15.0000
d₂₂= D(22)

(aspheric surface)
(variable)

r₂₃= 13.6781
d₂₃= 5.0000
nd₁₃= 1.49700
υd₁₃= 81.61

(aspheric surface)

r₂₄= −9.6526
d₂₄= 0.8000
nd₁₄= 1.90366
υd₁₄= 31.31

r₂₅= −15.4094
d₂₅= D(25)

(variable)

r₂₆= ∞

(image plane)

Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F)

(sixth plane)

k = 1.0000,

A = 0, B = 2.85233 × 10⁻⁴,

C = −3.72392 × 10⁻⁶, D = 3.26691 × 10⁻⁸,

E = −3.17300 × 10⁻¹⁰, F = 1.46784 × 10⁻¹²

(seventh plane)

k = 1.0000,

A = 0, B = 4.54486 × 10⁻⁴,

C = 7.51122 × 10⁻⁷, D = 1.74448 × 10⁻⁷,

E = −3.32774 × 10⁻¹⁰, F = 0

(twelfth plane)

k = 1.0000,

A = 0, B = −1.26158 × 10⁻⁴,

C = −1.22232 × 10⁻⁶, D = −1.48733 × 10⁻¹⁰,

E = −8.83503 × 10⁻¹¹, F = 2.56374 × 10⁻¹¹

(fourteenth plane)

k = 5.9757,

A = 0, B = −1.40409 × 10⁻⁴,

C = −3.45339 × 10⁻⁷, D = 2.12846 × 10⁻⁸,

E = −5.77296 × 10⁻¹⁰, F = 0

(twenty-first plane)

k = 1.0000,

A = 0, B = 1.42918 × 10⁻⁴,

C = 8.28678 × 10⁻⁷, D = 6.90896 × 10⁻⁸,

E = −8.64331 × 10⁻¹⁰, F = 0

(twenty-second plane)

k = 1.0000,

A = 0, B = 2.28550 × 10⁻⁴,

C = 2.57220 × 10⁻⁶, D = 1.07616 × 10⁻⁷,

E = −3.43355 × 10⁻¹¹, F = 0

(twenty-third plane)

k = 1.0000, A = 0, B = −6.57548 × 10⁻⁵,

C = 5.46170 × 10⁻⁸, D = 1.30576 × 10⁻⁸,

E = −1.49895 × 10⁻¹⁰, F = 0

(Zoom Data)

wide angle
intermediate position
telephoto

D(5)
0.8000
33.0675
49.9719

D(12)
31.4258
10.7806
2.1556

D(18)
1.9471
17.5531
31.4720

D(22)
13.3575
9.6265
11.2984

D(25)
7.8285
11.5424
11.5424

Interval (D2W) between second lens group G₂₂and third lens group G₂₃at wide angle edge=32.4258 tan(ωw)=0.9270D2W×(−F2)/(Ft×tan(ωw))=1.3432 (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=109.7209 (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G₂₂overall at telephoto edge=4.8670BXt2×tan(ωw)=4.5119 (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=24.1402 (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G₂₃and fourth lens group G₂₄at telephoto edge=31.4720D3T/−F4=1.1124 (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G₂₁and second lens group G₂₂at telephoto edge=49.9719 (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=7.8824

FIG. 4 is a diagram of various types of aberration in the zoom lens according to the second embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 5 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a third embodiment. The zoom lens includes sequentially from the object side, a first lens group G₃₁having a positive refractive power, a second lens group G₃₂having a negative refractive power, a third lens group G₃₃having a positive refractive power, a fourth lens group G₃₄having a negative refractive power, a fifth lens group G₃₅having a positive refractive power, and a sixth lens group G₃₆having a negative refractive power. Further, between the second lens group G₃₂and the third lens group G₃₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₃₁includes sequentially from the object side, a negative lens L₃₁₁, a positive lens L₃₁₂, and a positive lens L₃₁₃. The negative lens L₃₁₁and the positive lens L₃₁₂are cemented.

The second lens group G₃₂includes sequentially from the object side, a negative lens L₃₂₁, a negative lens L₃₂₂, a positive lens L₃₂₃, and a negative lens L₃₂₄. The negative lens L₃₂₂and the positive lens L₃₂₃are cemented.

The third lens group G₃₃includes sequentially from the object side, a positive lens L₃₃₁, a negative lens L₃₃₂, and a positive lens L₃₃₃. The positive lens L₃₃₁and the negative lens L₃₃₂are cemented. Further, both surfaces of the positive lens L₃₃₃are aspheric.

The fourth lens group G₃₄includes sequentially from the object side, a negative lens L₃₄₁and a positive lens L₃₄₂. The negative lens L₃₄₁and the positive lens L₃₄₂are cemented.

The fifth lens group G₃₅includes sequentially from the object side, a positive lens L₃₅₁and a negative lens L₃₅₂. On the positive lens L₃₅₁, the surface facing toward the object is aspheric. The positive lens L₃₅₁and the negative lens L₃₅₂are cemented.

The sixth lens group G₃₆is formed by a negative lens L₃₆₁.

The zoom lens moves the first lens group G₃₁along the optical axis, from the image plane side to the object side; moves the second lens group G₃₂along the optical axis, from the object side to the image plane side; moves the third lens group G₃₃along the optical axis, from the image plane side to the object side; moves the fourth lens group G₃₄along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₃₅along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₃₅along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₃₂in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the third embodiment are indicated below.

Focal length of entire zoom lens = 4.7887 (wide angle

edge) to 45.032 (intermediate position) to 204.6109 (Ft:

telephoto edge)

F number (F no.) = 2.9 (wide angle edge) to 5.2 (intermediate

position) to 6.5 (telephoto edge)

Half-angle (ω) = 41.70 (ωw: wide angle edge) to

4.81 (intermediate position) to 1.06 (telephoto edge)

Paraxial image height (Y) = 4.27 (Ymax: wide angle edge) to

3.79 (intermediate position) to 3.79 (telephoto edge)

Focal length (F1) of first lens group G₃₁= 80.2143

Focal length (F2) of second lens group G₃₂= −7.4858

Focal length (F3) of third lens group G₃₃= 15.4591

Focal length (F4) of fourth lens group G₃₄= −23.2278

Focal length of fifth lens group G₃₅= 18.7207

Focal length of sixth lens group G₃₆= −41.4617

Zoom ratio (Z) = 42.7252

(Lens Data)

r₁= 118.7286
d₁= 1.0000
nd₁= 1.80610
υd₁= 33.27

r₂= 52.6232
d₂= 5.3000
nd₂= 1.43700
υd₂= 95.10

r₃= −148.5460
d₃= 0.2000

r₄= 45.0241
d₄= 3.6000
nd₃= 1.61800
υd₃= 63.39

r₅= 150.3707
d₅= D(5) (variable)

r₆= 40.5889
d₆= 0.5000
nd₄= 1.69680
υd₄= 55.46

r₇= 10.0218
d₇= 4.4700

r₈= −23.9466
d₈= 0.5000
nd₅= 1.91082
υd₅= 35.25

r₉= 11.0000
d₉= 2.9736
nd₆= 1.94595
υd₆= 17.98

r₁₀= −183.9563
d₁₀= 1.5404

r₁₁= −13.5647
d₁₁= 0.5000
nd₇= 1.90366
υd₇= 31.31

r₁₂= −25.5276
d₁₂= D(12) (variable)

r₁₃= ∞
d₁₃= 0.4000

(aperture stop)

r₁₄= 22.2366
d₁₄= 2.6574
nd₈= 1.61800
υd₈= 63.39

r₁₅= −9.1559
d₁₅= 0.5000
nd₉= 1.74950
υd₉= 35.04

r₁₆= −111.4891
d₁₆= 2.8840

r₁₇= 29.5535
d₁₇= 2.0717
nd₁₀= 1.49710
υd₁₀= 81.56

(aspheric surface)

r₁₈= −14.3273
d₁₈= D(18) (variable)

(aspheric surface)

r₁₉= −44.1928
d₁₉= 0.6000
nd₁₁= 1.74400
υd₁₁= 44.90

r₂₀= 8.2752
d₂₀= 1.7000
nd₁₂= 1.84666
υd₁₂= 23.78

r₂₁= 22.0953
d₂₁= D(21) (variable)

r₂₂= 18.4314
d₂₂= 3.5000
nd₁₃= 1.49710
υd₁₃= 81.56

(aspheric surface)

r₂₃= −8.8357
d₂₃= 0.7000
nd₁₄= 1.84666
υd₁₄= 23.78

r₂₄= −12.5408
d₂₄= D(24) (variable)

r₂₅= −15.0000
d₂₅= 0.7000
nd₁₅= 1.84666
υd₁₅= 23.78

r₂₆= −26.7521
d₂₆= D(26) (variable)

r₂₇= ∞

(image plane)

Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F)

(seventeenth plane)

k = 1.0000,

A = 0, B = −1.01511 × 10⁻⁴,

C = 3.78727 × 10⁻⁶, D = −1.96610 × 10⁻⁷,

E = 4.41959 × 10⁻⁹, F = 0

(eighteenth plane)

k = 1.0000,

A = 0, B = 2.11066 × 10⁻⁵,

C = 2.99520 × 10⁻⁶, D = −1.57582 × 10⁻⁷,

E = 3.61863 × 10⁻⁹, F = 0

(twenty-second plane)

k = 1.0000,

A = 0, B = −8.11343 × 10⁻⁵,

C = 4.92638 × 10⁻⁷, D = −1.99687 × 10⁻⁸,

E = 3.40661 × 10⁻¹⁰, F = 0

(Zoom Data)

wide angle
intermediate position
telephoto

D(5)
0.8000
42.9524
59.3239

D(12)
33.0122
7.7431
0.1000

D(18)
2.4917
19.5447
25.5895

D(21)
11.0485
9.4848
11.5894

D(24)
7.1712
4.1811
2.1000

D(26)
5.0039
5.0246
5.0366

Interval (D2W) between second lens group G₃₂and third lens group G₃₃at wide angle edge=33.4122 tan(ωw)=0.8909D2W×(−F2)/(Ft×tan(ωw))=1.3722 (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=141.8268 (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G₃₂overall at telephoto edge=4.9762BXt2×tan(ωw)=4.4331 (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=24.3503 (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G₃₃and fourth lens group G₃₄at telephoto edge=25.5895D3T/−F4=1.1017 (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G₃₁and second lens group G₃₂at telephoto edge=59.3239 (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=8.7306

FIG. 6 is a diagram of various types of aberration in the zoom lens according to the third embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 7 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fourth embodiment. The zoom lens includes sequentially from the object side, a first lens group G₄₁having a positive refractive power, a second lens group G₄₂having a negative refractive power, a third lens group G₄₃having a positive refractive power, a fourth lens group G₄₄having a negative refractive power, a fifth lens group G₄₅having a positive refractive power, and a sixth lens group G₄₆having a negative refractive power. Further, between the second lens group G₄₂and the third lens group G₄₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₄₁includes sequentially from the object side, a negative lens L₄₁₁, a positive lens L₄₁₂, and a positive lens L₄₁₃. The negative lens L₄₁₁and the positive lens L₄₁₂are cemented.

The second lens group G₄₂includes sequentially from the object side, front group G_42Fhaving positive refractive power and a rear group G_42Rhaving negative refractive power. The front group G_42Fincludes sequentially from the object side, a negative lens L₄₂₁, a negative lens L₄₂₂, and a positive lens L₄₂₃. Both surfaces of the negative lens L₄₂₁and the surface on the negative lens L₄₂₂, facing toward the object are aspheric. The negative lens L₄₂₂and the positive lens L₄₂₃are cemented. The rear group G_42Ris formed by a negative lens L₄₂₄. Both surfaces of the negative lens L₄₂₄are aspheric.

The third lens group G₄₃includes sequentially from the object side, a positive lens L₄₃₁, a negative lens L₄₃₂, and a positive lens L₄₃₃. The positive lens L₄₃₁and the negative lens L₄₃₂are cemented. Further, both surfaces of the positive lens L₄₃₃are aspheric.

The fourth lens group G₄₄includes sequentially from the object side, a negative lens L₄₄₁and a positive lens L₄₄₂. The negative lens L₄₄₁and the positive lens L₄₄₂are cemented.

The fifth lens group G₄₅includes sequentially from the object side, a positive lens L₄₅₁and a negative lens L₄₅₂. On the positive lens L₄₅₁, the surface facing toward the object is aspheric. The positive lens L₄₅₁and the negative lens L₄₅₂are cemented.

The sixth lens group G₄₆is formed by a negative lens L₄₆₁.

The zoom lens moves the first lens group G₄₁along the optical axis, from the image plane side to the object side; moves the second lens group G₄₂along the optical axis, from the object side to the image plane side; moves the third lens group G₄₃along the optical axis, from the image plane side to the object side; moves the fourth lens group G₄₄along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₄₅along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₄₅along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens moves the front group G_42Fof the second lens group G₄₂in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the fourth embodiment are indicated below.

Focal length of entire zoom lens = 4.7549 (wide angle

edge) to 29.0164 (intermediate position) to 198.539 (Ft:

telephoto edge)

F number (F no.) = 2.9 (wide angle edge) to 4.5 (intermediate

position) to 6.1 (telephoto edge)

Half-angle (ω) = 41.91 (ωw: wide angle edge) to

7.51 (intermediate position) to 1.10 (telephoto edge)

Paraxial image height (Y) = 4.268 (Ymax: wide angle edge) to

3.825 (intermediate position) to 3.802 (telephoto edge

Focal length (F1) of first lens group G₄₁= 80.8922

Focal length (F2) of second lens group G₄₂= −8.1514

Focal length (F3) of third lens group G₄₃= 15.9264

Focal length (F4) of fourth lens group G₄₄= −22.5499

Focal length of fifth lens group G₄₅= 18.8794

Focal length of sixth lens group G₄₆= −47.9414

Zoom ratio (Z) = 41.7537

(Lens Data)

r₁= 99.5194
d₁= 1.0000
nd₁= 1.80610
υd₁= 33.27

r₂= 50.4174
d₂= 5.6000
nd₂= 1.43700
υd₂= 95.10

r₃= −283.2720
d₃= 0.2000

r₄= 46.0953
d₄= 4.1000
nd₃= 1.59282
υd₃= 68.62

r₅= 206.4139
d₅= D(5) (variable)

r₆= 28.4100
d₆= 0.5000
nd₄= 1.80139
υd₄= 45.45

(aspheric surface)

r₇= 9.4498
d₇= 4.5520

(aspheric surface)

r₈= −17.2432
d₈= 0.5000
nd₅= 1.85135
υd₅= 40.10

(aspheric surface)

r₉= 20.0002
d₉= 2.2937
nd₆= 1.94595
υd₆= 17.98

r₁₀= −74.9586
d₁₀= 1.3235

r₁₁= −32.1740
d₁₁= 0.5000
nd₇= 1.72903
υd₇= 54.04

(aspheric surface)

r₁₂= −200.0000
d₁₂= D(12) (variable)

(aspheric surface)

r₁₃= ∞
d₁₃= 0.4000

(aperture stop)

r₁₄= 26.7974
d₁₄= 2.6066
nd₈= 1.61800
υd₈= 63.39

r₁₅= −9.7147
d₁₅= 0.5000
nd₉= 1.74950
υd₉= 35.04

r₁₆= −47.5489
d₁₆= 2.5000

r₁₇= 36.1276
d₁₇= 1.9301
nd₁₀= 1.49710
υd₁₀= 81.56

(aspheric surface)

r₁₈= −16.6859
d₁₈= D(18) (variable)

(aspheric surface)

r₁₉= −35.9822
d₁₉= 0.5000
nd₁₁= 1.74330
υd₁₁= 49.22

r₂₀= 8.1860
d₂₀= 1.6953
nd₁₂= 1.90366
υd₁₂= 31.31

r₂₁= 20.9654
d₂₁= D(21) (variable)

r₂₂= 17.4717
d₂₂= 4.3000
nd₁₃= 1.49710
υd₁₃= 81.56

(aspheric surface)

r₂₃= −8.3849
d₂₃= 0.7000
nd₁₄= 1.90366
υd₁₄= 31.31

r₂₄= −12.0966
d₂₄= D(24) (variable)

r₂₅= −17.3657
d₂₅= 0.7000
nd₁₅= 1.84666
υd₁₅= 23.78

r₂₆= −30.9116
d₂₆= D(26) (variable)

r₂₇= ∞

(image plane)

Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F)

(sixth plane)

k = −72.6590,

A = 0, B = 1.39938 × 10⁻⁴,

C = −2.54371 × 10⁻⁶, D = 4.33966 × 10⁻⁸,

E = −4.15406 × 10⁻¹⁰, F = 1.88610 × 10⁻¹²

(seventh plane)

k = −0.5118,

A = 0, B = 3.06961 × 10⁻⁵,

C = 1.41245 × 10⁻⁵, D = −4.25273 × 10⁻⁷,

E = 1.05745 × 10⁻⁸, F = −7.85149 × 10⁻¹¹

(eighth plane)

k = 1.0000,

A = 0, B = 1.14758 × 10⁻⁴,

C = −1.42956 × 10⁻⁶, D = 1.95709 × 10⁻⁷,

E = −4.50142 × 10⁻⁹, F = 1.15154 × 10⁻¹¹

(eleventh plane)

k = 1.0000,

A = 0, B = 2.45048 × 10⁻⁴,

C = −1.43869 × 10⁻⁵, D = 4.58757 × 10⁻⁸,

E = 7.75921 × 10⁻⁹, F = −9.21631 × 10⁻¹¹

(twelfth plane)

k = 1.0000,

A = 0, B = 2.54443 × 10⁻⁴,

C = −1.71144 × 10⁻⁵, D = 3.38852 × 10⁻⁷,

E = −2.04437 × 10⁻⁹, F = 0

(seventeenth plane)

k = 3.6599,

A = 0, B = −1.42745 × 10⁻⁴,

C = 8.50625 × 10⁻⁶, D = −4.56478 × 10⁻⁷,

E = 8.64884 × 10⁻⁹, F = 0

(eighteenth plane)

k = 1.0000,

A = 0, B = −5.92382 × 10⁻⁵,

C = 8.20070 × 10⁻⁶, D = −4.29042 × 10⁻⁷,

E = 7.95619 × 10⁻⁹, F = 0

(twenty-second plane)

k = 1.0000,

A = 0, B = −7.99966 × 10⁻⁵,

C = 9.05381 × 10⁻⁷, D = −3.22230 × 10⁻⁸,

E = 5.49078 × 10⁻¹⁰, F = 0

(Zoom Data)

wide angle
intermediate position
telephoto

D(5)
0.8000
36.5962
58.6343

D(12)
37.8121
13.3712
0.1000

D(18)
2.2579
13.5450
25.9125

D(21)
11.0481
12.7909
11.3729

D(24)
7.0717
3.8218
2.0000

D(26)
5.5710
5.6120
5.5867

Interval (D2W) between second lens group G₄₂and third lens group G₄₃at wide angle edge=38.2121 tan(ωw)=0.8974D2W×(−F2)/(Ft×tan(ωw))=1.7483 (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=123.7094 (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for front group G_42Fof second lens group G₄₂at telephoto edge=3.8616BXt2×tan(ωw)=3.4652 (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=21.8563 (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G₄₃and fourth lens group G₄₄at telephoto edge=25.9125D3T/−F4=1.1491 (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G₄₁and second lens group G₄₂at telephoto edge=58.6343 (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=8.2658

FIG. 8 is a diagram of various types of aberration in the zoom lens according to the fourth embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 9 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fifth embodiment. The zoom lens includes sequentially from the object side, a first lens group G₅₁having a positive refractive power, a second lens group G₅₂having a negative refractive power, a third lens group G₅₃having a positive refractive power, a fourth lens group G₅₄having a negative refractive power, a fifth lens group G₅₅having a positive refractive power, and a sixth lens group G₅₆having a negative refractive power. Further, between the second lens group G₅₂and the third lens group G₅₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₅₁includes sequentially from the object side, a negative lens L₅₁₁, a positive lens L₅₁₂, and a positive lens L₅₁₃. The negative lens L₅₁₁and the positive lens L₅₁₂are cemented.

The second lens group G₅₂includes sequentially from the object side, a negative lens L₅₂₁, a negative lens L₅₂₂, a positive lens L₅₂₃, and a negative lens L₅₂₄. The negative lens L₅₂₂and the positive lens L₅₂₃are cemented. Furthermore, both sides of the negative lens L₅₂₄are aspheric.

The third lens group G₅₃includes sequentially from the object side, a positive lens L₅₃₁, a negative lens L₅₃₂, and a positive lens L₅₃₃. The positive lens L₅₃₁and the negative lens L₅₃₂are cemented. Furthermore, both surfaces of the positive lens L₅₃₃are cemented.

The fourth lens group G₅₄includes sequentially from the object side, a negative lens L₅₄₁and a positive lens L₅₄₂. The negative lens L₅₄₁and the positive lens L₅₄₂are cemented.

The fifth lens group G₅₅includes sequentially from the object side, a positive lens L₅₅₁and a negative lens L₅₅₂. On the positive lens L₅₅₁, the surface facing toward the object is aspheric. The positive lens L₅₅₁and the negative lens L₅₅₂are cemented.

The sixth lens group G₅₆is formed by a negative lens L₅₆₁.

The zoom lens moves the first lens group G₅₁along the optical axis, from the image plane side to the object side; moves the second lens group G₅₂along the optical axis, from the object side to the image plane side; moves the third lens group G₅₃along the optical axis, from the image plane side to the object side; moves the fourth lens group G₅₄along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₅₅along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₅₅along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₅₂in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according the fifth embodiment are indicated below.

Focal length of entire zoom lens = 4.7395 (wide angle

edge) to 43.0117 (intermediate position) to 203.3847 (Ft:

telephoto edge)

F number (F no.) = 2.9 (wide angle edge) to 5.0 (intermediate

position) to 6.5(telephoto edge)

Half-angle (ω) = 41.99 (ωw: wide angle edge) to

4.93 (intermediate position) to 1.07 (telephoto edge)

Paraxial image height(Y) = 4.27 (Ymax: wide angle edge) to

3.71 (intermediate position) to 3.80 (telephoto edge)

Focal length (F1) of first lens group G₅₁= 75.1144

Focal length (F2) of second lens group G₅₂= −7.8437

Focal length (F3) of third lens group G₅₃= 17.1792

Focal length (F4) of fourth lens group G₅₄= −31.5511

Focal length of fifth lens group G₅₅= 20.9376

Focal length of sixth lens group G₅₆= −60.5410

Zoom ratio (Z) = 42.9173

(Lens Data)

r₁= 97.6858
d₁= 1.0000
nd₁= 1.80610
υd₁= 33.27

r₂= 46.5191
d₂= 5.2000
nd₂= 1.43700
υd₂= 95.10

r₃= −238.2465
d₃= 0.2000

r₄= 43.4953
d₄= 3.7000
nd₃= 1.61800
υd₃= 63.39

r₅= 198.1204
d₅= D(5) (variable)

r₆= 72.3886
d₆= 0.5000
nd₄= 1.69680
υd₄= 55.46

r₇= 8.6209
d₇= 4.3094

r₈= −21.7879
d₈= 0.5000
nd₅= 1.91082
υd₅= 35.25

r₉= −21.7879
d₉= 2.4000
nd₆= 1.94595
υd₆= 17.98

r₁₀= −36.7935
d₁₀= 1.4363

r₁₁= −13.5739
d₁₁= 0.5000
nd₇= 1.83441
υd₇= 37.28

(aspheric surface)

r₁₂= −24.5104
d₁₂= D(12) (variable)

(aspheric surface)

r₁₃= ∞
d₁₃= 0.4000

(aperture stop)

r₁₄= 22.7781
d₁₄= 2.5000
nd₈= 1.59349
υd₈= 67.00

r₁₅= −10.8005
d₁₅= 0.5000
nd₉= 1.80610
υd₉= 33.27

r₁₆= −40.9889
d₁₆= 2.7295

r₁₇= 108.2255
d₁₇= 2.3500
nd₁₀= 1.49710
υd₁₀= 81.56

(aspheric surface)

r₁₈= −14.8586
d₁₈= D(18) (variable)

(aspheric surface)

r₁₉= −40.8236
d₁₉= 0.6000
nd₁₁= 1.72342
υd₁₁= 37.99

r₂₀= 9.2151
d₂₀= 2.0000
nd₁₂= 1.84666
υd₁₂= 23.78

r₂₁= 31.1982
d₂₁= D(21) (variable)

r₂₂= 19.8859
d₂₂= 3.6000
nd₁₃= 1.49710
υd₁₃= 81.56

(aspheric surface)

r₂₃= −9.5445
d₂₃= 0.7000
nd₁₄= 1.84666
υd₁₄= 23.78

r₂₄= −13.9684
d₂₄= D(24) (variable)

r₂₅= −15.0000
d₂₅= 0.7000
nd₁₅= 1.80518
υd₁₅= 25.46

r₂₆= −22.1184
d₂₆= D(26) (variable)

r₂₇= ∞

(image plane)

Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F)

(eleventh plane)

k = 1.0000,

A = 0, B = 9.22813 × 10⁻⁵,

C = −5.19243 × 10⁻⁶, D = 1.61167 × 10⁻⁸,

E = 1.38709 × 10⁻⁹, F = −1.11770 × 10⁻¹¹

(twelfth plane)

k = 1.0000,

A = 0, B = 5.80683 × 10⁻⁵,

C = −5.76820 × 10⁻⁶, D = 7.48974 × 10⁻⁸,

E = 0, F = 0

(seventeenth plane)

k = 1.0000,

A = 0, B = −8.93615 × 10⁻⁵,

C = 2.81304 × 10⁻⁶, D = −1.77829 × 10⁻⁷,

E = 3.99999 × 10⁻⁹, F = 0

(eighteenth plane)

k = 1.0000,

A = 0, B = 2.29650 × 10⁻⁶,

C = 2.11271 × 10⁻⁶, D = −1.30186 × 10⁻⁷,

E = 2.86026 × 10⁻⁹, F = 0

(twenty-second plane)

k = 1.0000,

A = 0, B = −7.25054 × 10⁻⁵,

C = 1.47968 × 10⁻⁶, D = −6.55813 × 10⁻⁸,

E = 1.06529 × 10⁻⁹, F = 0

(Zoom Data)

wide angle
intermediate position
telephoto

D(5)
0.9000
40.5237
55.5639

D(12)
35.1240
9.4972
0.1000

D(18)
2.3271
20.9398
28.5219

D(21)
11.0524
10.3393
12.7390

D(24)
7.1674
4.0999
2.1000

D(26)
4.9956
5.0139
5.0476

Interval (D2W) between second lens group G₅₂and third lens group G₅₃at wide angle edge=35.5240 tan(ωw)=0.9000D2W×(−F2)/(Ft×tan(ωw))=1.5223 (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=113.3752 (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G₅₂overall at telephoto edge=4.9546BXt2×tan(ωw)=4.4589 (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=23.3356 (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G₅₃and fourth lens group G₅₄at telephoto edge=28.5219D3T/−F4=0.9040 (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G₅₁and second lens group G₅₂at telephoto edge=55.5639 (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=6.4038

FIG. 10 is a diagram of various types of aberration in the zoom lens according to the fifth embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

Among the values for each of the examples above, r₁, r₂, . . . indicate radii of curvature for each lens, diaphragm surface, etc.; d₁, d₂, . . . indicate the thickness of the lenses, diaphragm, etc. or the distance between surfaces thereof; nd₁, nd₂, . . . indicate the refraction index of each lens with respect to the d-line (λ=587.56 nm), and υd₁, υd₂, . . . indicate the Abbe number with respect to the d-line (λ=587.56 nm). Lengths are indicated in units of [mm] and angles are indicated in [degrees].

Each of the aspheric surfaces described above is expressed by equation [1], where X represents a direction of the optical axis; h represents a height from the optical axis; k is the constant of the cone, and A, B, C, D, E, and F are second, fourth, sixth, eighth, tenth, and twelfth order aspheric coefficients. The direction of light is assumed to be positive.

$\begin{matrix} X = \frac{h^{2} / R}{1 + \sqrt{1 - (1 + k) {(h / R)}^{2}}} + {Ah}^{2} + {Bh}^{4} + {Ch}^{6} + {Dh}^{8} + {Eh}^{10} + {Fh}^{12} & [1] \end{matrix}$

As described, by satisfying each of the conditional expression above, the zoom lens according to each of the embodiments achieves a compact size, wide angle views (in particular, the angle of view at the wide angle edge is 75 degrees or more), and a high zoom ratio (on the order of 40 times) while enabling imaging performance to be improved. Further, with the zoom lens, the amount that the anti-shake group is shifted when image blur is corrected can be suppressed and the imaging performance when image blur is corrected can be maintained. Moreover, in the zoom lens, aspheric lenses and cemented lenses are disposed as necessary, enabling imaging performance to be further improved.

As described, the zoom lens according to the present invention is useful in digital imaging apparatuses such as digital still cameras and digital video cameras; and is particularly suitable for digital imaging apparatuses of which a compact size and high zoom ratio are demanded.

Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.

The present document incorporates by reference the entire contents of Japanese priority document, 2013-020888 filed in Japan on Feb. 5, 2013.

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