JP2016191753A - Zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens system that: has a telephoto side brighter than F2.0; includes a wide angle area; has a zooming ratio of about 3.5 times; has a small front lens diameter; and can be compactly housed in a collapsed state.SOLUTION: A zoom lens includes: a positive first lens group and a negative second lens group, from an object side; and a positive third lens group and its subsequent lens group on an image side. An air interval between the first and second groups is larger than a wide angle end at a telephoto end, and an air interval between the second group and the third group is larger than the telephoto end at the wide angle end. The first group is composed of two lenses of one negative lens and one positive lens. The second group is composed of five lenses including three negative lenses and two positive lenses that are, from the object side, a negative 21 lens, a negative 22 lens, a positive 23 lens, and subsequent lenses. The negative 22 lens and the positive 23 lens are composed of a cemented lens having a cemented surface having a convex surface facing the object side. A predetermined conditional expression is satisfied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a compact zoom lens having a large aperture ratio suitable for a digital still camera or the like, and in particular, ensures a predetermined zoom ratio and reduces the front lens diameter and the total length of the lens in the stored state. It relates to an excellent zoom lens.

  In recent years, in an imaging apparatus such as a video camera or a digital still camera using a solid-state imaging element, the entire apparatus has been downsized together with an increase in functionality. Along with this, as a photographing optical system used for these, a zoom lens having a short overall lens length and a compact size and high performance is required.

  In addition, the need for a lens having an Fno brighter than F2.0 is increasing due to the expansion of the photographing area, and a zoom lens that can be accommodated in a camera having a desired zoom ratio and Fno but having the same portability as before is required. Has been. In particular, there is an increasing expectation for a zoom lens having a bright Fno of less than F2.0 over the entire zoom range while having a zoom ratio of 3 times or more.

  The following lenses are known as zoom lenses that have a positive first group, a negative second group, and a positive third group from the object side and perform zooming by moving each group. That is, Patent Document 1 discloses a lens in which the second lens unit is composed of five lenses that are negative, negative, positive, negative, and positive from the object side. Patent Document 2 discloses a lens in which the second lens unit is composed of five negative, positive, negative, positive, and negative lenses from the object side, and the second positive lens and the third negative lens are cemented together. Has been.

JP 2003-202499 A JP 2006-323212 A

  In recent years, attention has been paid to cameras using a zoom lens that can be compactly accommodated in spite of a compact camera and a high zoom ratio, in spite of a small Fno of F2.0 to F2.5 class. In such a lens, the fluctuation of Fno due to zooming is reduced by using a positive-preceding lens in which a positive lens group is arranged closest to the object side.

  Telephoto side compared to the negative leading type by arranging positive first group, negative second group, positive third group from the object side and increasing the air gap between the first group and the second group on the telephoto side Can be brightened.

  If Fno is reduced on the telephoto side, coma aberration and chromatic coma aberration tend to occur on the telephoto side, so the configuration of the second group is corrected using three negative lenses and two positive lenses. The configuration is effective. In other words, in order to reduce the lens diameter, a plurality of negative lenses are arranged on the object image side of the second group, and the cemented lens is located at a position where the off-axis light beam near the object is high while the most image side is a basic configuration of a positive lens. To correct the chromatic coma aberration.

  In Patent Documents 1 and 2, since the configuration of one group is a negative, positive, and positive three-unit configuration, the first group becomes thick, so that it is far from the stop at the wide angle end, the front lens diameter is increased, and the size is reduced. There was a limit to the compatibility between the large diameter and the large diameter.

  In such a front-end zoom lens, a stop is disposed in the vicinity of the third lens group. However, if the second lens unit has five lenses and the first lens unit also has three or more lens units, an off-axis light beam in a wide-angle range. However, the height passing through the first lens tends to increase and the front lens diameter tends to increase.

  It is an object of the present invention to provide a lens system in which the telephoto side is brighter than F2.0 and includes a wide angle region and has a zoom ratio of about 3.5 times and a small front lens diameter and can be stored compactly when retracted. .

  In order to achieve the above object, the present invention has a positive first lens group and a negative second lens group from the object side, and a positive third lens group and a subsequent lens group on the image side thereof. . In a zoom lens system that performs zooming by changing the air spacing of each lens group, the air spacing between the first and second lens groups is larger than the wide angle end at the telephoto end, and the air spacing between the second lens group and the third lens group at the wide angle end. It is larger than the telephoto end. The first group is composed of two lenses, one negative lens and a positive lens, and the second group is composed of five lenses including three negative lenses and two positive lenses, The second group is composed of a negative 21 lens, a negative 22 lens, a positive 23 lens, and a subsequent lens from the object side, and the negative 22 lens and the positive 23 lens are convex toward the object side. It is composed of a cemented lens having a cemented surface and satisfies the following conditional expression.

2.5 <f22 / f2 <4.0 (1)
−7.0 <f23 / f2 <−3.0 (2)
25 <ν22−ν23 <55 (3)
f2: Focal length of the second lens group
f22: Focal length of the 22nd lens
f23: focal length of the 23rd lens
ν22: Abbe number of the 22nd lens
ν23: Abbe number of the 23rd lens Furthermore, a desirable configuration for approaching the best mode is to satisfy the following conditions.

  In the lens system, the second lens group includes five lenses including a negative 21 lens, a negative 22 lens, a positive 23 lens, a negative 24 lens, and a positive 25 lens from the object side. Satisfies the conditional expression.

9 <f1 / fw <14 (4)
−2.5 <f2 / fw <−1.0 (5)
f1: Focal length of the first lens group
fw: focal length at the wide angle end In the lens system, the positive first lens group, the negative second lens group, the positive third lens group, the negative fourth group, and the positive fifth group from the object side. Is configured.

  In the lens system, from the object side, a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth group, a negative fifth group, and a positive sixth group Is to be configured.

  In the lens system, the first group is constituted by a cemented lens in which a negative eleventh lens and a positive twelfth lens are cemented from the object side.

  In the lens system, the third lens group includes a positive thirty-first lens, a negative thirty-second lens, a positive thirty-third lens, a negative thirty-fourth lens, and a positive thirty-fifth lens, and the thirty-second lens. And the 33rd lens are cemented, and the 34th lens and the 35th lens are respectively cemented.

  Further, in the lens system, the fourth lens group is composed of a positive 41st lens, a negative 42nd lens, and a negative 43rd lens.

  According to the present invention, there is provided a zoom lens that has a zoom ratio that is brighter than F2.0 over the entire zoom range, has a zoom ratio of about 3.5 by the above-described configuration, and is excellent in portability. It can be realized.

Example 1 Lens cross-sectional view (Wide-angle end, middle, telephoto end from above) Example 2 Lens cross-sectional view (wide-angle end, middle, telephoto end from above) Example 3 Lens cross-sectional view (Wide-angle end, middle, telephoto end from above) Longitudinal aberration diagram of Example 1 (in the aberration diagrams, d is the d-line, g is the g-line, and ΔM is the meridional image plane) Intermediate longitudinal aberration diagram of Example 1 Longitudinal aberration diagram of Example 1 at the telephoto end Longitudinal aberration diagram of Example 2 (in the aberration diagrams, d is a d-line, g is a g-line, and ΔM is a meridional image plane) Intermediate longitudinal aberration diagram of Example 2 Longitudinal aberration diagram at telephoto end in Example 2 Longitudinal aberration diagram of Example 3 (in the aberration diagrams, d is the d-line, g is the g-line, and ΔM is the meridional image plane) Intermediate longitudinal aberration diagram of Example 3 Longitudinal aberration diagram at telephoto end in Example 3

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  In Embodiments 1 and 3 of the present invention, the zoom lens includes a positive first lens unit L1, a negative second lens unit L2, a positive third lens unit L3, a negative fourth lens unit L4, and a positive fifth lens unit from the object side. It consists of group L5. In Embodiment 2 of the present invention, the zoom lens includes a positive first lens unit L1, a negative second lens unit L2, a positive third lens unit L3, a negative fourth lens unit L4, and a negative fifth lens unit L5 from the object side. And consists of a positive sixth group L6. In the first to third embodiments, the first lens unit moves nonlinearly during zooming from the wide-angle end to the telephoto end, and at the telephoto end is positioned closer to the object side than the wide-angle end. The second group moves nonlinearly, and is located closer to the image side than the wide-angle end at the telephoto end. The third group moves toward the object side, and a flare cut stop that moves independently is arranged between the second group and the third group. The fourth group moves nonlinearly. The fifth group is fixed with respect to the image plane during zooming.

  In the embodiment of the present invention, the zoom ratio is about 3.5 times. While having such a high zoom ratio, a large aperture is realized with Fno at the wide-angle end of about F1.4 and Fno at the telephoto end of about F1.8.

  In the embodiment of the present invention, three negative pieces including a cemented lens with a coma flare in the wide-angle peripheral portion, a coma aberration in the peripheral portion of the telephoto region, and a chromatic coma aberration close to the second group as the aperture is increased. The correction is satisfactorily corrected by adopting a five-sheet configuration of two positive sheets.

  When the second group is composed of five elements and the stop is arranged in the vicinity of the third group, which is the main zooming group, the position of the first group is separated from the stop, so that the beam height of the peripheral luminous flux is increased in the vicinity of the first group. The front lens diameter tends to increase.

  When three or more lenses are used in the first group, the thickness of the first group increases, and therefore the diameter of the lens disposed on the most object side tends to be further increased.

  In the embodiment of the present invention, the increase in the front lens diameter is suppressed with the first group having two negative and positive configurations. If the first group consists of two lenses, the chromatic coma generated in the first group cannot be corrected in the telephoto range. Therefore, the second and third lenses of the second group are used as cemented lenses to correct this chromatic coma. Yes.

  The second group preferably has a configuration in which the principal point position is closer to the object in order to reduce the lens diameter. From the object side, a five-lens configuration including a negative 21 lens, a negative 22 lens, a positive 23 lens, and a subsequent lens It is said.

  In the embodiment of the present invention, since the first lens group is composed of two lenses, when the lens is brighter than F2.0 on the telephoto side, a large amount of chromatic coma aberration is generated at the periphery of the telephoto area in order to secure a peripheral light amount. The chromatic coma generated in the first group can be improved by cementing the negative 22 lens and the positive 23 lens and setting each focal length, and by appropriately setting the Abbe number difference between the two lenses. It is corrected.

  That is, the negative 22 lens and the positive 23 lens are configured by a cemented lens having a cemented surface with a convex surface facing the object side, and satisfy the following conditional expression.

2.5 <f22 / f2 <4.0 (1)
−7.0 <f23 / f2 <−3.0 (2)
25 <ν22−ν23 <55 (3)
f2: Focal length of the second lens group
f22: Focal length of the 22nd lens
f23: focal length of the 23rd lens
ν22: Abbe number of the 22nd lens
f23: Abbe number of the 23rd lens In the embodiment of the present invention, as described above, it is possible to appropriately set the lens configuration power distribution in the second group and appropriately set the powers of the first group and the second group. desirable. Since the first group in this case has two negative and positive elements, if the power is too strong, the occurrence of chromatic coma aberration generated in the first group becomes large and cannot be corrected in the second group. In the second group, a relatively strong power is set in the above-described lens configuration to reduce the size, but if the power is too strong, it is difficult to correct chromatic coma. That is, the following conditional expression should be satisfied.

9 <f1 / fw <14 (4)
−2.5 <f2 / fw <−1.0 (5)
f1: Focal length of the first lens group
fw: Focal length at the wide-angle end In the embodiment of the present invention, since Fno is bright in the entire region from the wide-angle end to the telephoto range, the third group as the main imaging group includes two sets of cemented lenses. The zoom variation of the upper chromatic aberration and the axial chromatic aberration is corrected. That is, in the lens system, the third lens group includes a positive 31st lens, a negative 32nd lens, a positive 33rd lens, a negative 34th lens, and a positive 35th lens, and the 32nd lens. And the 33rd lens are joined, and the 34th lens and the 35th lens are joined together.

  In the embodiment of the present invention, as a configuration for correcting an intermediate curvature of field between the wide-angle range and the telephoto range, the fourth lens configuration is a positive 41st lens, a negative 42nd lens, and a negative 43rd lens. It consists of three pieces.

  The first and third embodiments have a five-group configuration of positive, negative, positive, negative, and positive, and the second embodiment has a six-group configuration of positive, negative, positive, negative, negative, and positive. The six-group configuration facilitates correction of image plane fluctuations in the intermediate area, but has a demerit that the mechanical mechanism is complicated.

  Next, the meaning of each conditional expression will be described.

  Equation (1) is obtained by standardizing the focal length of the 22nd lens with the focal length of the entire second lens group. If the power of the f22 lens becomes too loose beyond the upper limit of Equation (1), the color in the telephoto range is obtained. It becomes difficult to correct coma. If the power of the f22 lens becomes too strong beyond the lower limit of the expression (1), it is difficult to correct distortion aberration in the wide angle region.

  Formula (2) is obtained by standardizing the focal length of the 23rd lens with the focal length of the entire second lens group. If the power of the f23 lens becomes too strong beyond the upper limit of Formula (2), the edge is secured. Therefore, since the entire second group becomes thick, the front lens diameter increases, which is not good. If the power of the f223 lens becomes too loose beyond the lower limit of the expression (2), it is not good because it becomes difficult to correct chromatic coma in the telephoto range.

  Equation (3) relates to the difference between the Abbe numbers of the 22nd lens and the 23rd lens, and the Abbe number difference between the two lenses becomes too large or too small beyond the upper limit value or lower limit value of Equation (3). If it becomes too much, it becomes difficult to correct chromatic coma in the telephoto range.

  Equation (4) is obtained by normalizing the focal length of the first lens unit with the focal length at the wide-angle end. If the power of the first lens unit becomes too weak beyond the upper limit of equation (4), the spherical aberration is corrected in the telephoto range. It becomes difficult. When the power of the first group becomes too strong exceeding the lower limit of the equation (4). It becomes difficult to correct coma and chromatic coma in the telephoto range.

  Equation (5) is obtained by standardizing the focal length of the second group with the focal length at the wide-angle end, and correcting the coma flare in the telephoto range when the power of the second group becomes too strong beyond the upper limit of equation (5). It becomes difficult. If the power of the second group becomes too loose beyond the lower limit of the expression (5), the zoom stroke of the second group will increase and the whole system will become large, which is not good.

  In order to bring the object of the present invention closer to the best, it is better to satisfy the following conditions.

2.8 <f22 / f2 <3.5 (1d)
−6.0 <f23 / f2 <−4.0 (2d)
32 <ν22−ν23 <50 (3d)
10 <f1 / fw <12 (4d)
−2.0 <f2 / fw <−1.3 (5d)


(Numerical example 1)
Unit mm

Surface data surface number rd nd vd
1 31.362 1.00 1.85478 24.8
2 24.309 5.88 1.69680 55.5
3 92.408 (variable)
4 41.195 0.80 1.88300 40.8
5 12.501 5.12
6 162.439 0.60 1.54247 54.2
7 14.961 1.80 1.92286 18.9
8 22.080 3.43
9 -26.598 0.60 1.76802 49.2
10 * 35.448 0.30
11 23.320 1.84 1.95906 17.5
12 75.125 (variable)
13 (Aperture) ∞ (Variable)
14 * 18.632 3.29 1.76802 49.2
15 * -38.407 1.29
16 -15.703 0.70 1.62806 36.0
17 104.827 2.68 1.83481 42.7
18 -18.298 1.02
19 14.655 0.70 1.95906 17.5
20 8.608 4.61 1.49700 81.5
21 -40.708 (variable)
22 11.081 1.20 2.00272 19.3
23 11.576 0.07
24 10.083 0.60 1.55332 71.7
25 * 5.906 1.38
26 -27.904 0.50 1.48749 70.2
27 11.750 (variable)
28 * 14.549 2.82 1.85135 40.1
29 -25.987 (variable)
30 ∞ 0.60 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Aspheric data 10th surface
K = 0.00000e + 000 A 4 = 2.38235e-005 A 6 = 1.07351e-007

14th page
K = -3.39109e + 000 A 4 = 2.76454e-005 A 6 = -1.14902e-007

15th page
K = -6.19722e + 000 A 4 = 2.27365e-005

25th page
K = 0.00000e + 000 A 4 = 1.29021e-004 A 6 = 3.96537e-006

28th page
K = 0.00000e + 000 A 4 = -2.04973e-005 A 6 = 5.87820e-007

Various data summ ratio 3.43
Wide angle Medium telephoto focal length 6.15 20.03 21.08
F number 1.44 1.85 1.85
Angle of view 37.08 13.06 12.43
Image height 4.65 4.65 4.65
Lens total length 74.93 77.34 76.67
BF 3.98 3.98 3.98

d 3 0.35 16.18 15.90
d12 21.52 2.30 1.36
d13 2.20 2.03 2.02
d21 0.60 5.86 6.55
d27 4.04 4.75 4.62
d29 1.82 1.82 1.82
d31 1.76 1.76 1.76

Smoothness group Data group Start surface Focal length
1 1 71.60
2 4 -10.20
3 13 ∞
4 14 12.48
5 22 -12.05
6 28 11.32
7 30 ∞


(Numerical example 2)
Unit mm

Surface data surface number rd nd vd
1 28.779 1.00 1.85478 24.8
2 22.146 6.70 1.69680 55.5
3 87.181 (variable)
4 42.286 0.80 1.88300 40.8
5 12.515 4.66
6 82.187 0.60 1.53356 63.8
7 12.583 1.80 1.92286 18.9
8 16.080 3.88
9 -25.264 0.60 1.76802 49.2
10 * 32.685 0.30
11 20.785 1.88 1.95906 17.5
12 64.334 (variable)
13 (Aperture) ∞ (Variable)
14 * 19.911 3.23 1.76802 49.2
15 * -34.685 1.22
16 -15.733 0.70 1.64829 34.2
17 72.101 2.68 1.83481 42.7
18 -18.079 1.21
19 14.582 0.70 1.95906 17.5
20 8.869 4.60 1.49700 81.5
21 -40.654 (variable)
22 10.857 1.20 2.00272 19.3
23 10.547 0.30
24 12.679 0.60 1.55332 71.7
25 * 6.679 (variable)
26 -33.130 0.50 1.48749 70.2
27 11.960 (variable)
28 * 12.535 3.22 1.85135 40.1
29 -28.254 (variable)
30 ∞ 0.60 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Aspheric data 10th surface
K = 0.00000e + 000 A 4 = 3.89489e-005 A 6 = 8.64543e-008

14th page
K = -3.79440e + 000 A 4 = 2.65918e-005 A 6 = -1.63388e-007

15th page
K = -5.56894e + 000 A 4 = 2.28537e-005

25th page
K = 0.00000e + 000 A 4 = 1.34041e-004 A 6 = 3.55767e-006

28th page
K = 0.00000e + 000 A 4 = -3.18864e-005 A 6 = -1.86067e-007

Various data summ ratio 3.43
Wide angle Medium Telephoto focal length 6.15 19.94 21.08
F number 1.44 1.85 1.85
Angle of view 37.08 13.12 12.43
Image height 4.65 4.65 4.65
Lens total length 74.86 78.07 77.96
BF 3.99 3.99 3.99

d 3 0.35 15.14 15.03
d12 19.99 1.98 2.00
d13 2.12 2.74 2.02
d21 0.64 5.39 5.73
d25 1.35 1.92 2.12
d27 4.04 4.53 4.70
d29 1.82 1.82 1.82
d31 1.77 1.77 1.77

Smoothness group Data group Start surface Focal length
1 1 64.38
2 4 -9.26
3 13 ∞
4 14 12.33
5 22 -30.25
6 26 -17.96
7 28 10.58
8 30 ∞


(Numerical Example 3)
Unit mm

Surface data surface number rd nd vd
1 31.344 1.00 1.85478 24.8
2 24.138 5.97 1.69680 55.5
3 93.446 (variable)
4 41.527 0.80 1.88300 40.8
5 12.503 5.20
6 167.437 0.60 1.51633 64.1
7 15.443 1.80 1.94595 18.0
8 21.559 3.47
9 -26.404 0.60 1.76802 49.2
10 * 35.338 0.30
11 23.319 1.79 1.95906 17.5
12 72.964 (variable)
13 (Aperture) ∞ (Variable)
14 * 18.594 3.30 1.76802 49.2
15 * -38.393 1.28
16 -15.707 0.70 1.62852 35.8
17 100.108 2.70 1.83481 42.7
18 -18.277 0.99
19 14.658 0.70 1.95906 17.5
20 8.609 4.62 1.49700 81.5
21 -41.078 (variable)
22 11.062 1.20 2.00272 19.3
23 11.534 0.07
24 10.015 0.60 1.55332 71.7
25 * 5.893 1.41
26 -27.899 0.50 1.48749 70.2
27 11.644 (variable)
28 * 14.462 2.83 1.85135 40.1
29 -25.974 (variable)
30 ∞ 0.60 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Aspheric data 10th surface
K = 0.00000e + 000 A 4 = 2.31782e-005 A 6 = 1.04555e-007

14th page
K = -3.36639e + 000 A 4 = 2.76754e-005 A 6 = -1.16149e-007

15th page
K = -6.08197e + 000 A 4 = 2.34966e-005

25th page
K = 0.00000e + 000 A 4 = 1.22155e-004 A 6 = 4.40076e-006

28th page
K = 0.00000e + 000 A 4 = -2.06565e-005 A 6 = 6.17290e-007

Various data summ ratio 3.43
Wide angle Medium telephoto focal length 6.15 20.20 21.08
F number 1.44 1.85 1.85
Angle of view 37.08 12.96 12.43
Image height 4.65 4.65 4.65
Lens total length 74.93 77.69 76.99
BF 4.00 4.00 4.00

d 3 0.35 16.40 16.01
d12 21.39 2.33 1.39
d13 2.10 1.92 2.02
d21 0.59 5.98 6.61
d27 4.05 4.63 4.52
d29 1.82 1.82 1.82
d31 1.78 1.78 1.78

Smoothness group Data group Start surface Focal length
1 1 71.32
2 4 -10.07
3 13 ∞
4 14 12.46
5 22 -12.00
6 28 11.28
7 30 ∞

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view of Example 1 according to the embodiment of the present invention.

(Examples 1 and 3)
Hereinafter, the configuration of the first embodiment of the present invention will be described with reference to FIG. The wide-angle end, the middle, and the telephoto end are shown in order from the top of the figure. At the three zoom positions, the first and second groups increase, the second and third group intervals decrease, the third and fourth group intervals increase, and the fourth and fifth groups change.

  In the first embodiment, the first lens group is composed of two negative lenses, and the second lens group is composed of a negative meniscus, a negative meniscus, a biconvex positive lens, a biconcave negative lens, and a positive five lens lens. The lens is joined to the third positive lens. The third group consists of five lenses: a biconvex positive lens, an object-side concave negative lens, a positive lens, an object-side negative meniscus, and a biconvex lens from the object side. The second, third, fourth, and fifth lenses Join each eye.

The fourth group is composed of a positive lens, a negative lens, and a negative lens. The fifth group is composed of a positive single lens.
A diaphragm is provided near the object side of the third group. An anti-vibration mechanism that corrects camera shake by shifting the entire third group in a direction perpendicular to the optical axis is provided. Focusing is performed by moving the fourth group or the entire fifth group on the optical axis.

(Example 2)
At the three zoom positions, the first and second groups increase, the second and third group intervals decrease, the third and fourth group intervals increase, the fourth and fifth groups change, and the fifth and sixth groups change. . In Example 2, the first group is composed of two negative positive lenses, and the second group is composed of a negative menis, negative menis, biconvex positive, biconcave negative, and positive five lenses. The lens is joined to the third positive lens.

The third group consists of five elements: positive biconvex, negative concave, positive lens, negative convex meniscus on the object side, and biconvex lens from the object side. Second, third, fourth, and fifth lenses Join each one. The fourth group is composed of two lenses, a positive lens and a negative lens. The fifth group is composed of one negative lens. The sixth group is composed of a positive single lens. A diaphragm is provided near the object side of the third group. An anti-vibration mechanism that corrects camera shake by shifting the entire third group in a direction perpendicular to the optical axis is provided.
Focusing is performed by moving the fifth group or the entire sixth group on the optical axis.

  As described above, the present invention has a predetermined zoom ratio suitable for a digital still camera and the like, and has an aperture ratio brighter than F2.0 over the entire zoom range, shortens the overall lens length, and is compact and excellent in portability. A small zoom lens with a wide angle of view can be provided.

  In addition, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

d d line, g g line, ΔM meridional image plane

Claims (8)

By having a positive first lens group and a negative second lens group from the object side, a positive third lens group and a succeeding lens group on the image side, and changing the air spacing of each lens group In zoom lenses that perform zooming,
The air gap between the first lens group and the second lens group is larger at the telephoto end than at the wide angle end,
The air gap between the second lens group and the third lens group is larger at the wide angle end than at the telephoto end,
The first lens group is composed of two lenses, one negative lens and one positive lens.
The second lens group includes five lenses including three negative lenses and two positive lenses, and the second lens group includes 21 negative lenses, 22 negative lenses, and positive lenses from the object side. 23 lenses and the following lens, and the negative 22 lenses and the positive 23 lenses are composed of cemented lenses having a cemented surface with the convex side facing the object side, and satisfy the following conditional expression: A zoom lens characterized by that.
2.5 <f22 / f2 <4.0
−7.0 <f23 / f2 <−3.0
25 <ν22−ν23 <55
f2: focal length of the second lens group f22: focal length of the 22nd lens f23: focal length of the 23rd lens ν22: Abbe number of the 22nd lens ν23: Abbe number of the 23rd lens The negative second lens group includes five lenses including a negative 21 lens, a negative 22 lens, a positive 23 lens, a negative 24 lens, and a positive 25 lens from the object side, and the following conditions are satisfied. The zoom lens according to claim 1, wherein the zoom lens satisfies the expression.
9 <f1 / fw <14
−2.5 <f2 / fw <−1.0
f1: Focal length of the first lens group fw: Focal length at the wide angle end   The positive first lens group, the negative second lens group, the positive third lens group, the negative fourth lens group, and the positive fifth lens group are configured from the object side. The zoom lens according to claim 1 or 2.   The positive first lens group, the negative second lens group, the positive third lens group, the negative fourth lens group, the negative fifth lens group, and the positive sixth lens group are configured from the object side. The zoom lens according to claim 1, wherein the zoom lens is a zoom lens.   5. The positive first lens group includes a cemented lens in which a negative eleventh lens and a positive twelfth lens are cemented from the object side. Zoom lens described in 1.   The positive third lens group includes a positive 31st lens, a negative 32nd lens, a positive 33rd lens, a negative 34th lens, and a positive 35th lens, and the 32nd lens and the 33rd lens. The zoom lens according to any one of claims 1 to 5, wherein a lens is cemented and a 34th lens and a 35th lens are respectively cemented.   5. The zoom lens according to claim 3, wherein the fourth negative lens group includes a positive forty-first lens, a negative forty-second lens, and a negative forty-third lens. .   An imaging apparatus comprising the zoom lens according to any one of claims 1 to 7.