JP2019133072A - Zoom lens and image capturing device - Google Patents

Abstract

To provide a zoom lens which is compact and light-weight, has high resolving power, and can be suitably used for video shooting as well.SOLUTION: A zoom lens comprises a first lens group Ghaving negative refractive power, a second lens group Ghaving positive refractive power, a third lens group Ghaving negative refractive power, and a fourth lens group Ghaving positive refractive power arranged in order from the object side. Zooming from the wide-angle end to the telephoto end is done by moving the first lens group G, second lens group G, third lens group G, and fourth lens group Galong an optical axis to change distances among all the lens groups along the optical axis. Focusing is done by moving the third lens group Galong the optical axis. The zoom lens satisfies predetermined conditions. Such an arrangement realizes a compact, light-weight zoom lens with high resolving power.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens and an imaging apparatus, and more particularly to a zoom lens suitable for an imaging apparatus equipped with a solid-state imaging device such as a CCD or CMOS, and an imaging apparatus including the zoom lens.

  Imaging devices equipped with solid-state imaging devices such as CCD and COMS, such as single-lens reflex cameras, digital still cameras, video cameras, surveillance cameras, etc., are rapidly spreading. Along with this, zoom lenses that can be used in an imaging device equipped with a solid-state imaging device such as a CCD or CMOS have been proposed (see, for example, Patent Documents 1 and 2).

  In Patent Document 1, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power including an aperture stop, a third lens group having a positive refractive power, a negative lens group, There is disclosed a zoom lens having a fourth lens unit having a refractive power, in which the distance between adjacent lens units changes during zooming, and the third lens unit moves during focusing.

  Patent Document 2 includes a front group having negative refractive power and a rear group having positive refractive power. The front group includes a first lens having negative refractive power, a second lens having negative refractive power, and a positive lens. The first lens and the second lens are meniscus lenses having a convex surface facing the object side, and the rear group includes two lens units, and in zooming, The distance between the front group and the rear group is narrow, the distance between the two lens units is changed, the first lens unit is composed of two sub lens units and an aperture stop, and the sub lens unit on the image side is There is disclosed a zoom lens having a focus lens group, and the distance between two sub-lens units changes or is constant upon zooming.

JP, 2006-75742, A JP 2017-122744 A

  Since digital cameras can also shoot moving images, high-speed autofocus processing that supports moving image shooting is desired. In autofocus, first, a part of lens groups (focus group) are vibrated at high speed in the optical axis direction (wobbling) to create a non-focus state → a focus state → a non-focus state. Then, a signal component in a specific frequency band in a partial image region is detected from the output signal of the image sensor, the optimum position of the focus group that is in focus is obtained, and the focus group is moved to the optimum position. In particular, in moving image shooting, it is required to repeat such a series of operations continuously at high speed. In order to execute wobbling, the focus group is required to be as small and light as possible so that the focus group can be driven at high speed.

  When wobbling is introduced, the size of the image corresponding to the subject changes during wobbling. This is mainly because the focal length of the entire optical system changes due to the movement of the focus group in the optical axis direction. In addition, since the focus group is always moved during wobbling, when the change in the image magnification due to the change in the angle of view is large, the image always appears to fluctuate, which causes a sense of incongruity. In order to reduce this uncomfortable feeling, it is known that focusing may be performed with a lens group behind the diaphragm.

  On the other hand, when designing a wide-angle zoom lens, if the positive group first type is selected, the front lens becomes large, and it becomes difficult to design a compact and lightweight zoom lens. In general, since the first lens group of a zoom lens is larger than the other lens groups, when a glass material having a high refractive index and a large specific gravity is used for the lenses constituting the first lens group, the lens weight increases and the weight is reduced. Optical system design becomes difficult. In addition, when a lens using a high-dispersion glass material is disposed in the first lens group through which off-axis rays pass at a position far from the optical axis, it becomes difficult to correct lateral chromatic aberration, and an optical system having high resolution is realized. It becomes difficult.

  The zoom lenses disclosed in Patent Documents 1 and 2 are a negative lens group leading type and a small lens suitable for wobbling during moving image shooting because the third lens group behind the stop is a focus group. However, since a high refractive index and high dispersion glass is used for the negative lens disposed in the first lens group, the optical system cannot be expected to have high resolving power.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens that can be suitably applied to moving image shooting and has a small size, light weight, and high resolving power in order to eliminate the above-described problems caused by the prior art. In addition, an object of the present invention is to provide an imaging apparatus including a zoom lens that is small and light and has high resolving power.

In order to solve the above-described problems and achieve the object, a zoom lens according to the present invention includes a first lens group having a negative refractive power and a second lens having a positive refractive power, which are sequentially arranged from the object side. Group, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power, and by changing the interval on the optical axis of each lens group, from the wide-angle end to the telephoto end The third lens group is moved along the optical axis to perform focusing, and the following conditional expression is satisfied.
(1) νd1n ave ≧ 67.5
Here, νd1n ave represents the average value of the Abbe numbers of all the negative lenses included in the first lens group.

  According to the above invention, it is possible to provide a zoom lens that is suitable for moving image shooting and is small and light and has high resolving power.

  An imaging apparatus according to the present invention includes the zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electrical signal.

  According to the above invention, it is possible to provide an imaging apparatus including a zoom lens that is small and light and has high resolving power.

  According to the present invention, there is an effect that it is possible to provide a zoom lens that is suitable for moving image shooting and is small and light and has high resolving power. Furthermore, there is an effect that it is possible to provide an imaging apparatus including a zoom lens that is small and light and has high resolving power.

FIG. 3 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to Example 1; FIG. 3 is a diagram illustrating all aberrations of the zoom lens according to Example 1; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 2; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 2; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 3; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 3; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 4; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 4; FIG. 10 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 5; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 5; It is a figure which shows one application example of the imaging device provided with the zoom lens concerning this invention.

  Hereinafter, preferred embodiments of a zoom lens and an imaging apparatus according to the present invention will be described in detail.

  The zoom lens according to the present invention includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power, which are arranged in order from the object side. And a fourth lens group having a positive refractive power. Then, by moving the first to fourth lens groups along the optical axis and changing the distance between the lens groups on the optical axis, zooming from the wide-angle end to the telephoto end is performed. Further, focusing is performed by moving the third lens group along the optical axis.

  The zoom lens according to the present invention employs a configuration in which four lens groups having negative, positive and negative refractive powers are arranged in order from the object side. In a zoom lens, the aperture of the first lens group tends to be larger than the other lens groups. Therefore, in the present invention, by making the first lens group a negative group, the aperture of the first lens group is kept small, and the optical system is reduced in size and weight. In addition, by setting the first lens group as a negative group, it is easy to secure a wide angle of view.

  In addition, by making the second lens group a positive group, the diameter of the light beam incident on the third lens group can be reduced. Since the third lens group is a focus group, wobbling with a small change in the angle of view is possible with a small-diameter and light-weight lens group, so that it is possible to realize a zoom lens that can be suitably applied to movie shooting. .

In addition, in the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied when the average value of Abbe numbers of all the negative lenses included in the first lens group is νd1n ave.
(1) νd1n ave ≧ 67.5

  Conditional expression (1) defines the range of the average value of the Abbe numbers of the negative lenses included in the first lens group. When a lens using a high-dispersion glass material is disposed in the first lens group through which off-axis rays pass at a position far from the optical axis, it becomes difficult to correct chromatic aberration and to realize an optical system having high resolution. Become. Therefore, in the present invention, it is possible to satisfactorily correct lateral chromatic aberration and axial chromatic aberration by adopting a negative lens having a small dispersion that satisfies the conditional expression (1) in the first lens group. An optical system having a high resolving power can be realized.

  The lower limit value of conditional expression (1) is preferably set to 67.7 or more, more preferably 68.0 or more. Moreover, the upper limit value of conditional expression (1) is preferably set to 95.0 or less, more preferably 85.0 or less.

Furthermore, in the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied when the maximum value of the refractive index of the negative lens included in the first lens group is nd1n max.
(2) nd1n max ≦ 1.80

  Conditional expression (2) is an expression that defines the range of the maximum value of the refractive index of the negative lens included in the first lens group. In general, the first lens group of a zoom lens is larger than the other lens groups. Therefore, when a glass material having a high refractive index and a large specific gravity is used for the lenses constituting the first lens group, the lens weight increases and the weight is reduced. Realization of a simple optical system becomes difficult. Therefore, in the present invention, by adopting a negative lens having a small refractive index that satisfies the conditional expression (2) in the first lens group, a glass material having a small specific gravity is used for the largest first lens group in the optical system. Since it will be used, it becomes easy to design a lightweight optical system.

  The lower limit value of conditional expression (2) is preferably set to be 1.44 or more, more preferably 1.49 or more. In addition, the upper limit value of conditional expression (2) is preferably set to 1.75 or less, more preferably 1.72 or less.

Furthermore, in the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied when the focal length of the first lens group is f1 and the focal length of the second lens group is f2.
(3) 0.75 ≦ f2 / | f1 | ≦ 1.70

  Conditional expression (3) is an expression for defining the range of the ratio of the focal length of the second lens group to the absolute value of the focal length of the first lens group. By satisfying conditional expression (3), it is possible to shorten the overall length of the optical system while maintaining a good resolving performance by appropriately adjusting the refractive power of the second lens group with respect to the first lens group. Therefore, it is possible to realize a zoom lens having high resolution.

  If the lower limit of conditional expression (3) is not reached, the refractive power of the second lens group with respect to the first lens group becomes too strong, the correction of spherical aberration becomes excessive, and a zoom lens having high resolution can be realized. It becomes difficult. On the other hand, if the upper limit in conditional expression (3) is exceeded, the refractive power of the second lens group with respect to the first lens group becomes too weak, the overall length of the optical system is extended, and it becomes difficult to realize a compact zoom lens. .

  The lower limit value of conditional expression (3) is preferably set to 0.80 or more, more preferably 0.90 or more. The upper limit value of conditional expression (3) is preferably set to 1.60 or less, more preferably 1.50 or less.

Furthermore, in the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied when the focal length of the first lens unit is f1 and the focal length of the third lens unit is f3.
(4) 1.50 ≦ f3 / f1 ≦ 2.70

  Conditional expression (4) is an expression for defining the range of the ratio of the focal length of the third lens group to the focal length of the first lens group. By satisfying conditional expression (4), it is possible to shorten the overall length of the optical system while maintaining a good resolving performance by appropriately adjusting the refractive power of the third lens group with respect to the first lens group. Therefore, it is possible to realize a zoom lens having high resolution.

  If the lower limit of conditional expression (4) is not reached, the refractive power of the third lens group with respect to the first lens group becomes too strong, the correction of spherical aberration becomes excessive, and a zoom lens having high resolution can be realized. It becomes difficult. On the other hand, if the upper limit in conditional expression (4) is exceeded, the refractive power of the third lens group with respect to the first lens group becomes too weak, and the amount of movement of the third lens group during focusing increases, thereby increasing the total length of the optical system. It becomes difficult to realize a small zoom lens.

  The lower limit value of conditional expression (4) is preferably set to 1.60 or more, more preferably 1.65 or more. Further, the upper limit value of conditional expression (4) is preferably set to 2.60 or less, more preferably 2.45 or less.

Furthermore, in the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied when the focal length of the first lens group is f1 and the focal length of the fourth lens group is f4.
(5) 1.90 ≦ f4 / | f1 | ≦ 4.20

  Conditional expression (5) is an expression for defining the range of the ratio of the focal length of the fourth lens group to the absolute value of the focal length of the first lens group. By satisfying conditional expression (5), it is possible to shorten the overall length of the optical system while maintaining a good resolving performance by appropriately adjusting the refractive power of the fourth lens group with respect to the first lens group. Therefore, it is possible to realize a zoom lens having high resolution.

  If the lower limit of conditional expression (5) is not reached, the refractive power of the fourth lens unit with respect to the first lens unit becomes too strong, the field curvature correction becomes excessive, and a zoom lens having high resolution is realized. Becomes difficult. On the other hand, if the upper limit in conditional expression (5) is exceeded, the refractive power of the fourth lens group with respect to the first lens group becomes too weak, the overall length of the optical system increases, and it becomes difficult to realize a compact zoom lens. .

  Note that the lower limit value of conditional expression (5) is preferably set to be 2.00 or more, more preferably 2.10 or more. Further, the upper limit value of conditional expression (5) is preferably set to 4.00 or less, more preferably 3.90 or less.

  In the zoom lens according to the present invention, it is preferable to move the first lens group so as to draw a convex locus on the image side during zooming. By doing so, it becomes easy to increase the image magnification at the telephoto end, and it becomes easy to realize a zoom lens with a high zoom ratio.

  As described above, the zoom lens according to the present invention can achieve downsizing, weight reduction, and high resolution while securing a high zoom ratio by providing the above-described configuration. Can also be suitably applied. In particular, chromatic aberration can be favorably corrected by satisfying conditional expression (1). By satisfying conditional expression (2), the optical system can be made lighter. By satisfying conditional expression (3), it is possible to further shorten the overall length of the optical system while maintaining good resolution performance (particularly, good correction of spherical aberration becomes possible). By satisfying conditional expression (4), the amount of movement of the third lens unit during focusing is suppressed while maintaining good resolution performance (especially, good correction of spherical aberration becomes possible) The total length of the optical system can be further shortened. By satisfying conditional expression (5), it is possible to further shorten the overall length of the optical system while maintaining good resolution performance (particularly, good correction of field curvature is possible).

  Furthermore, in the present invention, a zoom lens having the above-described configuration and an image pickup device that converts an optical image formed by the zoom lens into an electrical signal are small, lightweight, and have high resolution. An imaging device including a lens can be realized.

  Embodiments of the zoom lens according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by the following examples.

FIG. 1 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the first embodiment. The zoom lens includes a first lens group G ₁ having negative refractive power, a second lens group G ₂ having positive refractive power, and a third lens group having negative refractive power in order from the object side (not shown). G ₃ and a fourth lens group G ₄ having a positive refractive power are arranged. A cover glass CG is disposed between the fourth lens group G ₄ and the image plane IMG. Cover glass CG is arrange | positioned as needed.

The first lens group G ₁ includes, in order from the object side, a negative meniscus lens L ₁₁ having a convex surface facing the object side, a negative meniscus lens L ₁₂ having a convex surface facing the object side, a biconcave negative lens L ₁₃ , convex positive lens L _14, is formed are disposed. The both surfaces of the negative meniscus lens L _12, aspheric surface is formed. A biconcave negative lens L ₁₃ of a biconvex positive lens L ₁₄ are cemented.

The second lens group G ₂ includes, in order from the object side, a negative meniscus lens L ₂₁ having a convex surface facing the object side, a positive meniscus lens L ₂₂ having a convex surface facing the object side, and an aperture stop STP that defines a predetermined aperture. When, a biconvex positive lens L _23, a biconcave negative lens L _24, a biconvex positive lens L _25, is formed are disposed. The negative meniscus lens L ₂₁ and the positive meniscus lens L ₂₂ are cemented. A biconvex positive lens L ₂₃ and a biconcave negative lens L ₂₄ are cemented. Aspherical surfaces are formed on both surfaces of the biconvex positive lens L ₂₅ .

The third lens group G ₃ includes, in order from the object side, a biconcave negative lens L ₃₁ and a positive meniscus lens L ₃₂ with a convex surface facing the object side.

The fourth lens group G ₄ includes a biconvex positive lens L ₄₁ and a biconcave negative lens L ₄₂ arranged in order from the object side. The surfaces of the biconcave negative lens L _42, aspheric surface is formed.

In this zoom lens, the second lens group G ₂ and the third lens group are arranged so that the distance between the first lens group G ₁ and the second lens group G ₂ is gradually reduced upon zooming from the wide-angle end to the telephoto end. and the distance between G ₃ widens gradually, as the third lens group G ₃ gradually widened the distance between the fourth lens group G _4, the distance between the fourth lens group G ₄ and the cover glass CG is gradually Each lens group moves so as to spread.

Specifically, when zooming from the wide-angle end to the telephoto end, each lens group moves as follows. The first lens group G ₁ moves so as to draw a convex locus on the image plane IMG side along the optical axis. That is, after moving to the image plane IMG side, it moves to the object side. The second lens group G ₂ monotonously moves from the image plane IMG side to the object side along the optical axis. The third lens group G ₃ monotonously moves from the image plane IMG side to the object side along the optical axis. The fourth lens group G ₄ monotonously moves from the image plane IMG side to the object side along the optical axis.

Further, in this zoom lens, by moving toward the image plane IMG side from the object side along the third lens group G ₃ to the optical axis to perform focusing.

  Various numerical data related to the zoom lens according to Example 1 will be described below.

(Surface data)
r ₁ = 36.1445
d ₁ = 1.2000 nd ₁ = 1.59561 νd ₁ = 67.00
r ₂ = 11.9369
d ₂ = 4.1786
r ₃ = 20.0000 (aspherical surface)
d ₃ = 1.5000 nd ₂ = 1.69979 νd ₂ = 55.46
r ₄ = 9.7567 (aspherical surface)
d ₄ = 6.4499
r ₅ = -29.9941
d ₅ = 0.6500 nd ₃ = 1.49845 νd ₃ = 81.61
r ₆ = 15.5345
d ₆ = 3.7013 nd ₄ = 1.80831 νd ₄ = 46.50
r ₇ = -295.9645
d ₇ = D (7) (variable)
r ₈ = 18.8800
d ₈ = 0.6000 nd ₅ = 1.83945 νd ₅ = 42.72
r ₉ = 8.8369
d ₉ = 2.8000 nd ₆ = 1.61669 νd ₆ = 44.27
r ₁₀ = 47.3804
d ₁₀ = 1.5000
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 3.4702
r ₁₂ = 14.7421
d ₁₂ = 2.7578 nd ₇ = 1.49845 νd ₇ = 81.61
r ₁₃ = -48.4383
d ₁₃ = 0.6000 nd ₈ = 1.80633 νd ₈ = 29.84
r ₁₄ = 28.0242
d ₁₄ = 0.9637
r ₁₅ = 40.3028 (aspherical surface)
d ₁₅ = 2.7732 nd ₉ = 1.49856 νd ₉ = 81.56
r ₁₆ = -16.1149 (aspherical surface)
d ₁₆ = D (16) (variable)
r ₁₇ = -62.3217
d ₁₇ = 0.6500 nd ₁₀ = 1.91695 νd ₁₀ = 35.25
r ₁₈ = 21.7156
d ₁₈ = 0.7068
r ₁₉ = 25.2705
d ₁₉ = 2.0216 nd ₁₁ = 1.93323 νd ₁₁ = 20.88
r ₂₀ = 111.3000
d ₂₀ = D (20) (variable)
r ₂₁ = 27.0257
d ₂₁ = 4.7390 nd ₁₂ = 1.49845 νd ₁₂ = 81.61
r ₂₂ = -23.2392
d ₂₂ = 0.1500
r ₂₃ = -42.3506 (aspherical surface)
d ₂₃ = 1.2000 nd ₁₃ = 1.85639 νd ₁₃ = 40.10
r ₂₄ = 600.0000 (aspherical surface)
d ₂₄ = D (24) (variable)
r ₂₅ = ∞
d ₂₅ = 3.5600 nd ₁₄ = 1.51872 νd ₁₄ = 64.20
r ₂₆ = ∞
d ₂₆ = 3.6260
r ₂₇ = ∞ (image plane)

(Cone coefficient (κ) and aspheric coefficient (A ₄ , A ₆ , A ₈ , A ₁₀ ))
(Third side)
κ = 1.0000,
A ₄ = 4.38991 × 10 ⁻⁵ , A ₆ = −3.54159 × 10 ⁻⁷ ,
A ₈ = 9.26420 × 10 ^-10 , A ₁₀ = -3.29341 × 10 ^-12
(Fourth surface)
κ = -7.69271 × 10 ^-1 ,
A ₄ = 1.07041 × 10 ^-4 , A ₆ = -1.22138 × 10 ^-7 ,
A ₈ = 6.63998 × 10 ^-11 , A ₁₀ = -1.61017 × 10 ^-11
(15th page)
κ = 0,
A ₄ = -1.55206 × 10 ⁻⁴ , A ₆ = 1.89245 × 10 ⁻⁷ ,
A ₈ = -2.43418 × 10 ^-8 , A ₁₀ = 8.84116 × 10 ^-10
(16th page)
κ = 0,
A ₄ = -1.36697 × 10 ⁻⁵ , A ₆ = 1.67240 × 10 ⁻⁷ ,
A ₈ = -1.65197 × 10 ⁻⁸ , A ₁₀ = 6.83693 × 10 ⁻¹⁰
(23rd page)
κ = 0,
A ₄ = 1.64689 × 10 ^-4 , A ₆ = -1.22862 × 10 ^-6 ,
A ₈ = 6.91495 × 10 ⁻⁹ , A ₁₀ = −2.332317 × 10 ⁻¹¹
(24th page)
κ = 0,
A ₄ = 1.99658 × 10 ^-4 , A ₆ = -1.01713 × 10 ^-6 ,
A ₈ = 5.95149 × 10 ^-9 , A ₁₀ = -1.72677 × 10 ^-11

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 12.1603 16.6984 22.9174
F number 3.2996 3.7671 4.3804
Half angle of view (ω) 52.3781 40.9985 31.0120
D (7) 15.3971 7.2134 0.9000
D (16) 1.6387 4.0656 7.9199
D (20) 3.9091 5.3491 5.5896
D (24) 13.7332 15.5738 18.0227

(Zoom lens group data)
Group Start surface Focal length 1 1 -15.96 (f1)
2 8 18.75 (f2)
3 17 -36.40 (f3)
4 21 54.35 (f4)

(Numerical values related to conditional expression (1))
νd1n ave = 68.0
(Νd1n ave: average value of Abbe numbers of all negative lenses included in the first lens group G ₁ )

(Numerical value related to conditional expression (2))
nd1n max = 1.70
(Nd1n max: maximum value of the refractive index of the negative lens included in the first lens group G ₁ )

(Numerical values related to conditional expression (3))
f2 / | f1 | = 1.18

(Numerical values related to conditional expression (4))
f3 / f1 = 2.28

(Numerical values related to conditional expression (5))
f4 / | f1 | = 3.41

  FIG. 2 is a diagram illustrating various aberrations of the zoom lens according to the first example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the long broken line is the F line (486.13 nm), and the short broken line is the C line (656. The wavelength characteristic corresponding to 28 nm) is shown. In the astigmatism diagram, the vertical axis represents the image height (indicated by Y in the figure), the solid line represents the sagittal plane (indicated by S in the figure), and the broken line represents the characteristic of the meridional plane (indicated by M in the figure). Show. In the distortion diagram, the vertical axis represents the image height (indicated by Y in the figure).

  FIG. 3 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the second embodiment. The optical configuration of the zoom lens according to the present embodiment, the movement of each lens group at the time of zooming, and the like are the same as those of the zoom lens shown in Embodiment 1. Therefore, in the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  Various numerical data related to the zoom lens according to Example 2 will be described below.

(Surface data)
r ₁ = 30.9464
d ₁ = 1.2000 nd ₁ = 1.59561 νd ₁ = 67.00
r ₂ = 11.6715
d ₂ = 5.3972
r ₃ = 22.7838 (aspherical surface)
d ₃ = 1.5000 nd ₂ = 1.59412 νd ₂ = 67.02
r ₄ = 9.6000 (aspherical surface)
d ₄ = 6.2598
r ₅ = -31.1490
d ₅ = 0.6500 nd ₃ = 1.49845 νd ₃ = 81.61
r ₆ = 15.6938
d ₆ = 3.4248 nd ₄ = 1.80831 νd ₄ = 46.50
r ₇ = -2108.2925
d ₇ = D (7) (variable)
r ₈ = 12.9644
d ₈ = 0.6000 nd ₅ = 1.88622 νd ₅ = 40.14
r ₉ = 8.5916
d ₉ = 2.8000 nd ₆ = 1.62408 νd ₆ = 36.30
r ₁₀ = 34.8241
d ₁₀ = 1.5000
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 1.4911
r ₁₂ = 14.5432
d ₁₂ = 2.7666 nd ₇ = 1.49845 νd ₇ = 81.61
r ₁₃ = -26.1893
d ₁₃ = 0.6000 nd ₈ = 1.80633 νd ₈ = 29.84
r ₁₄ = 29.3688
d ₁₄ = 1.7308
r ₁₅ = 34.5599 (aspherical surface)
d ₁₅ = 2.6320 nd ₉ = 1.49856 νd ₉ = 81.56
r ₁₆ = -14.9473 (aspherical surface)
d ₁₆ = D (16) (variable)
r ₁₇ = -44.6362
d ₁₇ = 0.6500 nd ₁₀ = 1.91695 νd ₁₀ = 35.25
r ₁₈ = 22.7837
d ₁₈ = 0.3427
r ₁₉ = 24.5498
d ₁₉ = 2.0669 nd ₁₁ = 1.93323 νd ₁₁ = 20.88
r ₂₀ = 96.2460
d ₂₀ = D (20) (variable)
r ₂₁ = 36.4942
d ₂₁ = 4.1829 nd ₁₂ = 1.49845 νd ₁₂ = 81.61
r ₂₂ = -22.3562
d ₂₂ = 1.4093
r ₂₃ = -320.2790 (aspherical surface)
d ₂₃ = 1.2000 nd ₁₃ = 1.85639 νd ₁₃ = 40.10
r ₂₄ = 89.5878 (aspherical surface)
d ₂₄ = D (24) (variable)
r ₂₅ = ∞
d ₂₅ = 3.5600 nd ₁₄ = 1.51872 νd ₁₄ = 64.20
r ₂₆ = ∞
d ₂₆ = 3.6260
r ₂₇ = ∞ (image plane)

(Cone coefficient (κ) and aspheric coefficient (A ₄ , A ₆ , A ₈ , A ₁₀ ))
(Third side)
κ = 1.0000,
A ₄ = 2.89212 × 10 ⁻⁵ , A ₆ = 5.65789 × 10 ⁻⁸ ,
A ₈ = -1.53115 × 10 ⁻⁹ , A ₁₀ = 8.68297 × 10 ⁻¹²
(Fourth surface)
κ = -8.58887 × 10 ⁻¹ ,
A ₄ = 8.66238 × 10 ⁻⁵ , A ₆ = 2.95590 × 10 ⁻⁷ ,
A ₈ = -1.34983 × 10 ^-9 , A ₁₀ = -1.85030 × 10 ^-11
(15th page)
κ = 0,
A ₄ = -1.68755 × 10 ⁻⁴ , A ₆ = 1.20015 × 10 ⁻⁷ ,
A ₈ = -4.15652 × 10 ^-8 , A ₁₀ = 9.29682 × 10 ^-10
(16th page)
κ = 0,
A ₄ = -1.94710 × 10 ⁻⁵ , A ₆ = 8.10568 × 10 ⁻⁸ ,
A ₈ = -3.31981 × 10 ^-8 , A ₁₀ = 7.12003 × 10 ^-10
(23rd page)
κ = 0,
A ₄ = -1.00793 × 10 ^-4 , A ₆ = 1.733333 × 10 ^-6 ,
A ₈ = -9.72346 × 10 ^-9 , A ₁₀ = 2.16596 × 10 ^-11
(24th page)
κ = 0,
A ₄ = -7.04945 × 10 ^-5 , A ₆ = 1.76173 × 10 ^-6 ,
A ₈ = -9.46483 × 10 ^-9 , A ₁₀ = 2.41106 × 10 ^-11

(Various data)
Wide angle end Intermediate focal position Telephoto end focal length 12.1595 16.6985 22.9197
F number 3.2677 3.7396 4.3658
Half angle of view (ω) 52.3678 41.1105 31.0052
D (7) 14.4779 6.7237 0.9000
D (16) 2.8706 6.1328 10.6621
D (20) 2.6987 3.7214 4.0198
D (24) 13.6268 14.8321 16.8281

(Zoom lens group data)
Group Start surface Focal length 1 1 -15.42 (f1)
2 8 18.66 (f2)
3 17 -31.07 (f3)
4 21 41.42 (f4)

(Numerical values related to conditional expression (1))
νd1n ave = 71.9
(Νd1n ave: average value of Abbe numbers of all negative lenses included in the first lens group G ₁ )

(Numerical value related to conditional expression (2))
nd1n max = 1.60
(Nd1n max: maximum value of the refractive index of the negative lens included in the first lens group G ₁ )

(Numerical values related to conditional expression (3))
f2 / | f1 | = 1.21

(Numerical values related to conditional expression (4))
f3 / f1 = 2.01

(Numerical values related to conditional expression (5))
f4 / | f1 | = 2.69

  FIG. 4 is a diagram illustrating various aberrations of the zoom lens according to the second example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the long broken line is the F line (486.13 nm), and the short broken line is the C line (656. The wavelength characteristic corresponding to 28 nm) is shown. In the astigmatism diagram, the vertical axis represents the image height (indicated by Y in the figure), the solid line represents the sagittal plane (indicated by S in the figure), and the broken line represents the characteristic of the meridional plane (indicated by M in the figure). Show. In the distortion diagram, the vertical axis represents the image height (indicated by Y in the figure).

FIG. 5 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the third embodiment. In the zoom lens according to the present embodiment, optical other than the positive meniscus lens L ₃₁₄ with a convex surface on the object side in place of the first biconvex positive lens L ₁₄ of the lens group G ₁ is arranged in the first embodiment The configuration and movement of each lens group during zooming are the same as those of the zoom lens shown in the first embodiment. Therefore, in the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  Various numerical data relating to the zoom lens according to Example 3 will be described below.

(Surface data)
r ₁ = 33.9498
d ₁ = 1.2000 nd ₁ = 1.59561 νd ₁ = 67.00
r ₂ = 12.5148
d ₂ = 5.4644
r ₃ = 20.5583 (aspherical surface)
d ₃ = 1.5000 nd ₂ = 1.59412 νd ₂ = 67.02
r ₄ = 9.6000 (aspherical surface)
d ₄ = 7.5127
r ₅ = -33.0572
d ₅ = 0.6500 nd ₃ = 1.43810 νd ₃ = 95.10
r ₆ = 17.4533
d ₆ = 3.1978 nd ₄ = 1.80831 νd ₄ = 46.50
r ₇ = 198.7410
d ₇ = D (7) (variable)
r ₈ = 12.1269
d ₈ = 0.6000 nd ₅ = 1.88622 νd ₅ = 40.14
r ₉ = 8.7861
d ₉ = 2.8000 nd ₆ = 1.61669 νd ₆ = 44.27
r ₁₀ = 29.1110
d ₁₀ = 2.2471
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 2.7420
r ₁₂ = 10.5006
d ₁₂ = 2.7823 nd ₇ = 1.49845 νd ₇ = 81.61
r ₁₃ = -128.4436
d ₁₃ = 0.6000 nd ₈ = 1.80633 νd ₈ = 29.84
r ₁₄ = 19.4029
d ₁₄ = 0.3867
r ₁₅ = 30.7206 (aspherical surface)
d ₁₅ = 2.1368 nd ₉ = 1.49856 νd ₉ = 81.56
r ₁₆ = -24.3421 (aspherical surface)
d ₁₆ = D (16) (variable)
r ₁₇ = -77.3626
d ₁₇ = 0.6500 nd ₁₀ = 1.91695 νd ₁₀ = 35.25
r ₁₈ = 19.7771
d ₁₈ = 0.2119
r ₁₉ = 20.4747
d ₁₉ = 1.8487 nd ₁₁ = 1.93323 νd ₁₁ = 20.88
r ₂₀ = 42.3042
d ₂₀ = D (20) (variable)
r ₂₁ = 30.9906
d ₂₁ = 5.5489 nd ₁₂ = 1.49845 νd ₁₂ = 81.61
r ₂₂ = -23.6498
d ₂₂ = 0.1500
r ₂₃ = -320.2790 (aspherical surface)
d ₂₃ = 1.2000 nd ₁₃ = 1.58547 νd ₁₃ = 59.46
r ₂₄ = 74.7284 (Aspherical surface)
d ₂₄ = D (24) (variable)
r ₂₅ = ∞
d ₂₅ = 3.5600 nd ₁₄ = 1.51872 νd ₁₄ = 64.20
r ₂₆ = ∞
d ₂₆ = 3.6260
r ₂₇ = ∞ (image plane)

(Cone coefficient (κ) and aspheric coefficient (A ₄ , A ₆ , A ₈ , A ₁₀ ))
(Third side)
κ = 1.0000,
A ₄ = -7.18752 × 10 ^-6 , A ₆ = 1.73362 × 10 ^-8 ,
A ₈ = -4.11962 × 10 ^-10 , A ₁₀ = -2.58725 × 10 ^-13
(Fourth surface)
κ = -8.77947 × 10 ⁻¹ ,
A ₄ = 5.04440 × 10 ⁻⁵ , A ₆ = 3.32103 × 10 ⁻⁸ ,
A ₈ = 1.91678 × 10 ⁻⁹ , A ₁₀ = −2.669349 × 10 ⁻¹¹
(15th page)
κ = 0,
A ₄ = -7.70822 × 10 ⁻⁵ , A ₆ = 2.89943 × 10 ⁻⁶ ,
A ₈ = 1.39540 × 10 ⁻⁷ , A ₁₀ = 7.49915 × 10 ⁻¹⁰
(16th surface)
κ = 0,
A ₄ = 1.51955 × 10 ^-4 , A ₆ = 4.774831 × 10 ^-6 ,
A ₈ = 7.25441 × 10 ⁻⁸ , A ₁₀ = 3.27423 × 10 ⁻⁹
(23rd page)
κ = 0,
A ₄ = -1.29885 × 10 ⁻⁴ , A ₆ = 1.98555 × 10 ⁻⁶ ,
A ₈ = -1.11022 × 10 ^-8 , A ₁₀ = 2.25963 × 10 ^-11
(24th page)
κ = 0,
A ₄ = -9.59295 × 10 ^-5 , A ₆ = 1.997820 × 10 ^-6 ,
A ₈ = -1.02422 × 10 ^-8 , A ₁₀ = 2.19156 × 10 ^-11

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 12.1600 16.6991 22.9204
F number 3.1883 3.6745 4.3338
Half angle of view (ω) 52.3872 41.0321 31.0136
D (7) 15.1586 7.0723 0.9000
D (16) 1.6003 4.3537 7.9411
D (20) 4.4626 6.1158 7.1560
D (24) 11.6194 12.8430 15.3877

(Zoom lens group data)
Group Start surface Focal length 1 1 -16.57 (f1)
2 8 18.29 (f2)
3 17 -28.77 (f3)
4 21 36.94 (f4)

(Numerical values related to conditional expression (1))
νd1n ave = 76.4
(Νd1n ave: average value of Abbe numbers of all negative lenses included in the first lens group G ₁ )

(Numerical value related to conditional expression (2))
nd1n max = 1.60
(Nd1n max: maximum value of the refractive index of the negative lens included in the first lens group G ₁ )

(Numerical values related to conditional expression (3))
f2 / | f1 | = 1.10

(Numerical values related to conditional expression (4))
f3 / f1 = 1.74

(Numerical values related to conditional expression (5))
f4 / | f1 | = 2.23

  FIG. 6 is a diagram illustrating all aberrations of the zoom lens according to the third example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the long broken line is the F line (486.13 nm), and the short broken line is the C line (656. The wavelength characteristic corresponding to 28 nm) is shown. In the astigmatism diagram, the vertical axis represents the image height (indicated by Y in the figure), the solid line represents the sagittal plane (indicated by S in the figure), and the broken line represents the characteristic of the meridional plane (indicated by M in the figure). Show. In the distortion diagram, the vertical axis represents the image height (indicated by Y in the figure).

FIG. 7 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the fourth example. In the zoom lens according to the present embodiment, optical elements other than the biconvex positive lens L ₄₂₂ disposed in place of the positive meniscus lens L ₂₂ having a convex surface facing the object side of the second lens group G ₂ in the third embodiment. The configuration and movement of each lens group during zooming are the same as those of the zoom lens shown in the third embodiment. Therefore, in the present embodiment, the same members as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Various numerical data relating to the zoom lens according to Example 4 will be described below.

(Surface data)
r ₁ = 30.2479
d ₁ = 1.2000 nd ₁ = 1.59561 νd ₁ = 67.00
r ₂ = 11.2071
d ₂ = 4.8485
r ₃ = 20.1731 (aspherical surface)
d ₃ = 1.5000 nd ₂ = 1.69979 νd ₂ = 55.46
r ₄ = 9.6000 (aspherical surface)
d ₄ = 5.8933
r ₅ = -34.8702
d ₅ = 0.6500 nd ₃ = 1.49845 νd ₃ = 81.61
r ₆ = 14.1654
d ₆ = 3.3705 nd ₄ = 1.80831 νd ₄ = 46.50
r ₇ = 186.7264
d ₇ = D (7) (variable)
r ₈ = 15.5490
d ₈ = 0.6000 nd ₅ = 1.83945 νd ₅ = 42.72
r ₉ = 10.7089
d ₉ = 2.8000 nd ₆ = 1.61669 νd ₆ = 44.27
r ₁₀ = -341.2266
d ₁₀ = 1.5000
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 3.0722
r ₁₂ = 24.0280
d ₁₂ = 2.3343 nd ₇ = 1.49845 νd ₇ = 81.61
r ₁₃ = -20.8607
d ₁₃ = 0.6000 nd ₈ = 1.80633 νd ₈ = 29.84
r ₁₄ = 57.4121
d ₁₄ = 4.2744
r ₁₅ = 26.4365 (aspherical surface)
d ₁₅ = 2.9956 nd ₉ = 1.49856 νd ₉ = 81.56
r ₁₆ = -21.3386 (aspherical surface)
d ₁₆ = D (16) (variable)
r ₁₇ = -49.9700
d ₁₇ = 0.6500 nd ₁₀ = 1.91695 νd ₁₀ = 35.25
r ₁₈ = 21.7156
d ₁₈ = 0.2640
r ₁₉ = 23.7819
d ₁₉ = 2.2712 nd ₁₁ = 1.93323 νd ₁₁ = 20.88
r ₂₀ = 111.3000
d ₂₀ = D (20) (variable)
r ₂₁ = 23.5605
d ₂₁ = 5.3175 nd ₁₂ = 1.49845 νd ₁₂ = 81.61
r ₂₂ = -22.8051
d ₂₂ = 0.1500
r ₂₃ = -36.6347 (aspherical surface)
d ₂₃ = 1.2000 nd ₁₃ = 1.85639 νd ₁₃ = 40.10
r ₂₄ = 600.0000 (aspherical surface)
d ₂₄ = D (24) (variable)
r ₂₅ = ∞
d ₂₅ = 3.5600 nd ₁₄ = 1.51872 νd ₁₄ = 64.20
r ₂₆ = ∞
d ₂₆ = 3.6260
r ₂₇ = ∞ (image plane)

(Cone coefficient (κ) and aspheric coefficient (A ₄ , A ₆ , A ₈ , A ₁₀ ))
(Third side)
κ = 1.0000,
A ₄ = 8.45594 × 10 ⁻⁵ , A ₆ = −6.91666 × 10 ⁻⁷ ,
A ₈ = 1.64015 × 10 ^-9 , A ₁₀ = 1.14453 × 10 ^-12
(Fourth surface)
κ = -7.95393 × 10 ^-1 ,
A ₄ = 1.69360 × 10 ⁻⁴ , A ₆ = −3.114226 × 10 ⁻⁷ ,
A ₈ = -4.10529 × 10 ^-9 , A ₁₀ = 6.34240 × 10 ^-12
(15th page)
κ = 0,
A ₄ = -4.70292 × 10 ^-5 , A ₆ = -8.70626 × 10 ^-7 ,
A ₈ = 1.70316 × 10 ⁻⁸ , A ₁₀ = −4.554818 × 10 ⁻¹⁰
(16th surface)
κ = 0,
A ₄ = 3.88403 × 10 ⁻⁵ , A ₆ = −9.41698 × 10 ⁻⁷ ,
A ₈ = 2.19223 × 10 ⁻⁸ , A ₁₀ = −4.78310 × 10 ⁻¹⁰
(23rd page)
κ = 0,
A ₄ = 9.25515 × 10 ⁻⁵ , A ₆ = −3.558687 × 10 ⁻⁷ ,
A ₈ = -6.60108 × 10 ^-10 , A ₁₀ = 9.65178 × 10 ^-12
(24th page)
κ = 0,
A ₄ = 1.27317 × 10 ^-4 , A ₆ = -1.46689 × 10 ^-7 ,
A ₈ = -1.87811 × 10 ⁻⁹ , A ₁₀ = 1.71430 × 10 ⁻¹¹

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 12.1605 16.7002 22.9175
F number 3.3102 3.7520 4.3804
Half angle of view (ω) 52.3732 41.0349 31.0022
D (7) 14.2367 6.5795 0.9000
D (16) 1.5982 5.3054 10.4972
D (20) 2.2118 2.6212 2.6047
D (24) 12.7392 13.8556 15.5580

(Zoom lens group data)
Group Start surface Focal length 1 1 -14.18 (f1)
2 8 19.15 (f2)
3 17 -33.90 (f3)
4 21 53.76 (f4)

(Numerical values related to conditional expression (1))
νd1n ave = 68.0
(Νd1n ave: average value of Abbe numbers of all negative lenses included in the first lens group G ₁ )

(Numerical value related to conditional expression (2))
nd1n max = 1.70
(Nd1n max: maximum value of the refractive index of the negative lens included in the first lens group G ₁ )

(Numerical values related to conditional expression (3))
f2 / | f1 | = 1.35

(Numerical values related to conditional expression (4))
f3 / f1 = 2.39

(Numerical values related to conditional expression (5))
f4 / | f1 | = 3.79

  FIG. 8 is a diagram illustrating various aberrations of the zoom lens according to the fourth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the long broken line is the F line (486.13 nm), and the short broken line is the C line (656. The wavelength characteristic corresponding to 28 nm) is shown. In the astigmatism diagram, the vertical axis represents the image height (indicated by Y in the figure), the solid line represents the sagittal plane (indicated by S in the figure), and the broken line represents the characteristic of the meridional plane (indicated by M in the figure). Show. In the distortion diagram, the vertical axis represents the image height (indicated by Y in the figure).

FIG. 9 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the fifth example. In the zoom lens according to the present embodiment, optics except that the negative meniscus lens L ₅₄₂ with a convex surface on the object side in place of the biconcave negative lens L ₄₂ in the fourth lens group G ₄ of Example 3 is placed The configuration and movement of each lens group during zooming are the same as those of the zoom lens shown in the third embodiment. Note that an aspheric surface is formed on both surfaces of the negative meniscus lens _L542 . In the present embodiment, the same members as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Various numerical data relating to the zoom lens according to Example 5 will be described below.

(Surface data)
r ₁ = 34.3699
d ₁ = 1.2000 nd ₁ = 1.62032 νd ₁ = 63.39
r ₂ = 12.8489
d ₂ = 5.4326
r ₃ = 20.1046 (aspherical surface)
d ₃ = 1.5000 nd ₂ = 1.59412 νd ₂ = 67.02
r ₄ = 9.7698 (aspherical surface)
d ₄ = 7.1083
r ₅ = -37.0135
d ₅ = 0.6500 nd ₃ = 1.49845 νd ₃ = 81.61
r ₆ = 16.4695
d ₆ = 3.9966 nd ₄ = 1.80831 νd ₄ = 46.50
r ₇ = 20023.1523
d ₇ = D (7) (variable)
r ₈ = 12.6227
d ₈ = 0.6000 nd ₅ = 1.80633 νd ₅ = 29.84
r ₉ = 9.7010
d ₉ = 2.4915 nd ₆ = 1.62408 νd ₆ = 36.30
r ₁₀ = 30.0925
d ₁₀ = 2.5572
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 2.7742
r ₁₂ = 10.5901
d ₁₂ = 2.8267 nd ₇ = 1.49845 νd ₇ = 81.61
r ₁₃ = -52.0180
d ₁₃ = 0.6000 nd ₈ = 1.80633 νd ₈ = 29.84
r ₁₄ = 20.5123
d ₁₄ = 0.2592
r ₁₅ = 25.0330 (aspherical surface)
d ₁₅ = 2.0670 nd ₉ = 1.49856 νd ₉ = 81.56
r ₁₆ = -29.3332 (aspherical surface)
d ₁₆ = D (16) (variable)
r ₁₇ = -45.0377
d ₁₇ = 0.6500 nd ₁₀ = 1.91695 νd ₁₀ = 35.25
r ₁₈ = 28.2018
d ₁₈ = 2.9179
r ₁₉ = 40.1365
d ₁₉ = 2.0151 nd ₁₁ = 1.93323 νd ₁₁ = 20.88
r ₂₀ = 383.0135
d ₂₀ = D (20) (variable)
r ₂₁ = 77.2896
d ₂₁ = 4.6070 nd ₁₂ = 1.49845 νd ₁₂ = 81.61
r ₂₂ = -21.4598
d ₂₂ = 0.1500
r ₂₃ = 34.0442 (aspherical surface)
d ₂₃ = 1.2000 nd ₁₃ = 1.85639 νd ₁₃ = 40.10
r ₂₄ = 24.7568 (Aspherical surface)
d ₂₄ = D (24) (variable)
r ₂₅ = ∞
d ₂₅ = 3.5600 nd ₁₄ = 1.51872 νd ₁₄ = 64.20
r ₂₆ = ∞
d ₂₆ = 3.6260
r ₂₇ = ∞ (image plane)

(Cone coefficient (κ) and aspheric coefficient (A ₄ , A ₆ , A ₈ , A ₁₀ ))
(Third side)
κ = 1.0000,
A ₄ = −2.61092 × 10 ⁻⁵ , A ₆ = 3.18825 × 10 ⁻⁸ ,
A ₈ = 2.12005 × 10 ⁻¹⁰ , A ₁₀ = −4.115154 × 10 ⁻¹²
(Fourth surface)
κ = -9.32256 × 10 ⁻¹ ,
A ₄ = 3.57757 × 10 ⁻⁵ , A ₆ = −2.02911 × 10 ⁻⁸ ,
A ₈ = 3.92053 × 10 ⁻⁹ , A ₁₀ = −3.08281 × 10 ⁻¹¹
(15th page)
κ = 0,
A ₄ = -2.58945 × 10 ⁻⁵ , A ₆ = 4.46462 × 10 ⁻⁶ ,
A ₈ = 1.00161 × 10 ⁻⁷ , A ₁₀ = 1.00288 × 10 ⁻⁹
(16th surface)
κ = 0,
A ₄ = 2.21120 × 10 ⁻⁴ , A ₆ = 6.14546 × 10 ⁻⁶ ,
A ₈ = 6.05775 × 10 ^-8 , A ₁₀ = 3.18262 × 10 ^-9
(23rd page)
κ = 0,
A ₄ = -1.73227 × 10 ⁻⁴ , A ₆ = 7.98530 × 10 ⁻⁷ ,
A ₈ = 9.71295 × 10 ^-11 , A ₁₀ = -9.24158 × 10 ^-12
(24th page)
κ = 0,
A ₄ = -1.67122 × 10 ⁻⁴ , A ₆ = 9.58443 × 10 ⁻⁷ ,
A ₈ = -7.73126 × 10 ^-10 , A ₁₀ = -5.90203 × 10 ^-12

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 12.1593 16.6983 22.9197
F number 3.1215 3.5937 4.2742
Half angle of view (ω) 52.3842 41.1375 31.0037
D (7) 16.0593 7.4453 0.9000
D (16) 1.6042 3.2763 5.7054
D (20) 1.9278 4.2823 6.6782
D (24) 11.4118 13.2069 15.9272

(Zoom lens group data)
Group Start surface Focal length 1 1 -17.87 (f1)
2 8 17.87 (f2)
3 17 -34.51 (f3)
4 21 47.15 (f4)

(Numerical values related to conditional expression (1))
νd1n ave = 70.7
(Νd1n ave: average value of Abbe numbers of all negative lenses included in the first lens group G ₁ )

(Numerical value related to conditional expression (2))
nd1n max = 1.62
(Nd1n max: maximum value of the refractive index of the negative lens included in the first lens group G ₁ )

(Numerical values related to conditional expression (3))
f2 / | f1 | = 1.00

(Numerical values related to conditional expression (4))
f3 / f1 = 1.93

(Numerical values related to conditional expression (5))
f4 / | f1 | = 2.64

  FIG. 10 is a diagram illustrating various aberrations of the zoom lens according to the fifth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the long broken line is the F line (486.13 nm), and the short broken line is the C line (656. The wavelength characteristic corresponding to 28 nm) is shown. In the astigmatism diagram, the vertical axis represents the image height (indicated by Y in the figure), the solid line represents the sagittal plane (indicated by S in the figure), and the broken line represents the characteristic of the meridional plane (indicated by M in the figure). Show. In the distortion diagram, the vertical axis represents the image height (indicated by Y in the figure).

  The correspondence table of the conditional expressions in the above embodiments is shown below.

In the numerical data in each of the above embodiments, r ₁ , r ₂ ,... Are the radii of curvature of the lens and aperture stop surface, and d ₁ , d ₂ ,. Thickness or spacing between them, nd ₁ , nd ₂ ,... Is a refractive index with respect to d-line (587.56 nm) such as a lens, and νd ₁ , νd ₂ ,. Indicates the Abbe number. The unit of length is all “mm”, and the unit of angle is “°”.

Each of the aspherical shapes has a height in the direction perpendicular to the optical axis as h, a displacement amount in the optical axis direction at a height h when the top of the lens surface is the origin, Z, a paraxial curvature radius as r, When the conic coefficient is κ, the nth-order aspheric coefficient is _An , and the image plane direction is positive, it is expressed by the following equation.

As described above, the zoom lens according to each of the embodiments can achieve miniaturization, weight reduction, and high resolution while ensuring a high zoom ratio by satisfying each conditional expression. It is also suitable for moving image shooting. In particular, chromatic aberration can be favorably corrected by satisfying conditional expression (1). By satisfying conditional expression (2), the optical system can be made lighter. By satisfying conditional expression (3), it is possible to further shorten the overall length of the optical system while maintaining good resolution performance (particularly, good correction of spherical aberration becomes possible). Satisfying conditional expression (4) suppresses the amount of movement of the third lens group G ₃ during focusing while maintaining good resolution performance (especially enabling good correction of spherical aberration). Thus, the overall length of the optical system can be further reduced. By satisfying conditional expression (5), it is possible to further shorten the overall length of the optical system while maintaining good resolution performance (particularly, good correction of field curvature is possible).

  In addition, the zoom lens of each of the above embodiments can further improve the aberration correction capability by arranging a lens having a suitable aspherical surface and a cemented lens.

<Application example>
Hereinafter, an example in which the zoom lens described in Embodiments 1 to 5 of the present invention is applied to an imaging apparatus will be described. FIG. 11 is a diagram illustrating an application example of an imaging apparatus including the zoom lens according to the present invention. FIG. 11 shows a state in which the lens barrel 110 that houses the zoom lens 100 is attached to the imaging apparatus 200.

  The zoom lens 100 is shown in Examples 1-5. The lens barrel 110 can be attached to and detached from the imaging apparatus 200 via the mount unit 111. As the mount portion 111, a screw type or bayonet type mount is used. In this example, a bayonet type mount is used.

  An image picked up by the zoom lens 100 is formed on an image pickup surface of an image pickup element 201 (CCD, CMOS, etc.) mounted on the image pickup apparatus 200, and an output signal from the image pickup element 201 relating to the image is a signal processing circuit (not shown). And the image is displayed on the display unit 202.

  FIG. 11 shows an example in which the zoom lens according to the present invention is used in a mirrorless single-lens camera. However, the zoom lens according to the present invention can be used not only in a mirrorless single-lens camera, but also in other interchangeable lens cameras, digital still cameras, surveillance cameras, video cameras, and the like.

  As described above, the zoom lens according to the present invention is useful for a small-sized imaging device that requires a high zoom ratio and high resolution performance, and a lens interchangeable camera such as a mirrorless single-lens camera or a single-lens reflex camera, Suitable for surveillance cameras, video cameras, digital still cameras and the like.

G ₁ first lens group G ₂ the second lens group G ₃ third lens group G ₄ fourth lens group _{L 11, L 12, L 21} , L 32, L 542 negative meniscus lens _{L 13, L 24, L 31} , L ₄₂ biconcave negative lens L _14, L ₂₃ , L ₂₅ , L ₄₁ , L ₄₂₂ biconvex positive lens L ₂₂ , L ₃₂ , L ₃₁₄ positive meniscus lens STP Aperture stop CG Cover glass IMG Image surface 100 Zoom lens 110 Lens mirror Tube 111 Mount unit 200 Imaging device 201 Imaging element 202 Display unit

Claims (7)

A first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. A fourth lens group,
By changing the distance on the optical axis of each lens group, zooming from the wide-angle end to the telephoto end is performed.
Focusing is performed by moving the third lens group along the optical axis,
A zoom lens that satisfies the following conditional expression:
(1) νd1n ave ≧ 67.5
Here, νd1n ave represents the average value of the Abbe numbers of all the negative lenses included in the first lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(2) nd1n max ≦ 1.80
Here, nd1n max represents the maximum value of the refractive index of the negative lens included in the first lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(3) 0.75 ≦ f2 / | f1 | ≦ 1.70
Here, f1 represents the focal length of the first lens group, and f2 represents the focal length of the second lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(4) 1.50 ≦ f3 / f1 ≦ 2.70
Here, f1 represents the focal length of the first lens group, and f3 represents the focal length of the third lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(5) 1.90 ≦ f4 / | f1 | ≦ 4.20
Here, f1 represents the focal length of the first lens group, and f4 represents the focal length of the fourth lens group.   The zoom lens according to any one of claims 1 to 5, wherein the zoom lens moves the first lens group so as to draw a convex locus on the image side.   An image pickup apparatus comprising: the zoom lens according to claim 1; and an image pickup element that converts an optical image formed by the zoom lens into an electrical signal.

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