Zoom lens and imaging device having the same

Abstract

To provide a compact, high-zoom-ratio zoom lens which is well corrected for chromatic aberration, and to provide an image capturing device equipped with the same.SOLUTION: A zoom lens provided herein comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and at least one succeeding lens group, and is configured such that distances between adjacent lens groups change when zooming. The second lens group has two positive lenses. A minimum Abbe number of a material of a negative lens included in the first lens group, a minimum Abbe number of a material of the positive lenses included in the second lens group, a focal length of the first lens group, and a focal length of the second lens group are appropriately set.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a zoom lens and an imaging device having the same. [Background technology]

[0002] In recent years, monitors have become increasingly high-definition, and the image quality of zoom lenses mounted on digital cameras, video cameras, and TV cameras has also improved. Aspherical lenses are known as a means of improving image quality, but they are not effective in correcting chromatic aberration, and the selection of materials and lens configuration are important for correcting chromatic aberration.

[0003] 2. Description of the Related Art Conventionally, zoom lenses having lens groups having, from the object side, positive, negative and positive refractive powers in that order have been known as small-sized zoom lenses capable of efficiently ensuring a desired zoom ratio.

[0004] Patent Document 1 discloses a zoom lens having lens groups with positive, negative, positive, positive, negative refractive powers arranged in that order from the object side, all of which move when varying magnification, and a zoom ratio of about 5. Patent Document 2 discloses a zoom lens having lens groups with positive, negative, positive, positive, positive refractive powers arranged in that order from the object side, the first lens group, the third lens group, and the fifth lens group are fixed when varying magnification, and a zoom ratio of about 36. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-168933 A [Patent Document 2] JP 2018-155818 A Summary of the Invention [Problem to be solved by the invention]

[0006] The lens disclosed in Patent Document 1 is a telephoto zoom lens with a small zoom ratio, and therefore has good optical performance despite the simple configuration of the first and second lens groups. However, there are problems when attempting to achieve a wider angle or higher magnification.

[0007] In Patent Document 2, the axial chromatic aberration at the telephoto end of a zoom lens having a large zoom ratio is corrected satisfactorily, but there is a problem with the correction of lateral chromatic aberration.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a small-sized, high-magnification zoom lens in which chromatic aberration is well corrected, and an image pickup apparatus having the same. [Means for solving the problem]

[0009] In order to achieve the above object, the zoom lens of the present invention comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and at least one subsequent lens group. It is a zoom lens that , the distance between the adjacent lens groups changes during magnification change, the second lens group has two positive lenses, the minimum Abbe number of the material constituting the negative lens included in the first lens group is ν1nmin, the minimum Abbe number of the material constituting the positive lens included in the second lens group is ν2pmin, the focal length of the first lens group is f1, and the focal length of the second lens group is f2 , the focal length of the wide-angle end of the zoom lens is fw When 34<ν1nmin 30<ν2pmin -6.0 <f1 / f2<-3.0 -4.0 <f2 / fw<-1.0 The present invention is characterized in that the following conditional expression is satisfied: Effect of the Invention

[0010] According to the present invention, it is possible to provide a small-sized, high-magnification zoom lens in which chromatic aberration is well corrected, and an imaging apparatus having the same. [Brief description of the drawings]

[0011] [Figure 1]FIG. 2 is a lens cross-sectional view of an optical system according to a first numerical example. [Diagram 2] 6A to 6C are aberration diagrams at the wide-angle end in Numerical Example 1. [Diagram 3] 11A to 11C are aberration diagrams at an intermediate focal length in Numerical Example 1. [Figure 4] 6A to 6C are aberration diagrams at the telephoto end in Numerical Example 1. [Diagram 5] FIG. 11 is a lens cross-sectional view of an optical system according to a second numerical example. [Figure 6] 11A to 11C are aberration diagrams at the wide-angle end in Numerical Example 2. [Figure 7] 11A to 11C are aberration diagrams at an intermediate focal length in Numerical Example 2. [Figure 8] 11A to 11C are aberration diagrams at the telephoto end in Numerical Example 2. [Figure 9] FIG. 11 is a lens cross-sectional view of an optical system according to a numerical example 3. [Figure 10] 13A to 13C are aberration diagrams at the wide-angle end in Numerical Example 3. [Figure 11] 13A to 13C are aberration diagrams at an intermediate focal length in Numerical Example 3. [Figure 12] 13A to 13C are aberration diagrams at the telephoto end in Numerical Example 3. [Figure 13] FIG. 11 is a lens cross-sectional view of an optical system according to a fourth numerical example. [Figure 14] 13A to 13C are aberration diagrams at the wide-angle end in Numerical Example 4. [Figure 15] 13A to 13C are aberration diagrams at an intermediate focal length in Numerical Example 4. [Figure 16] 13A to 13C are aberration diagrams at the telephoto end in Numerical Example 4. [Figure 17] 1 is a diagram for explaining an embodiment of an imaging device of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In order to obtain the effects of the invention, the present invention has, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and at least one subsequent lens group, which is a configuration suitable for high-magnification zoom. The spacing between adjacent lens groups changes during magnification.

[0013] In the second lens group having negative refractive power, chromatic aberration occurring in the negative lens is corrected by a positive lens. Materials with close Abbe numbers often have a close refractive index ratio at any wavelength, so chromatic aberration can be easily corrected well from short wavelengths to long wavelengths. However, when chromatic aberration is corrected between materials with close Abbe numbers, the refractive power of the lens becomes strong, so high-order aberrations are likely to occur. In many cases, a lens group having negative refractive power has only one positive lens for correcting chromatic aberration, but when the refractive power of the lens becomes strong, it is difficult to correct high-order aberrations with only one positive lens. Therefore, in the present invention, the second lens group having negative refractive power is configured to have two positive lenses, so that high-order aberrations can be corrected even when chromatic aberration is corrected between materials with close Abbe numbers. Furthermore, the following condition is satisfied: 34<ν1nmin…(1) 30<ν2pmin…(2) -6.0 <f1 / f2<-3.0 …(3) Here, ν1nmin is the minimum Abbe number of the negative lens in the first lens group, ν2pmin is the minimum Abbe number of the positive lens in the second lens group, f1 is the focal length of the first lens group, and f2 is the focal length of the second lens group. The refractive index and Abbe number shown in the present invention are values ​​based on the d line.

[0014] Conditional formula (1) defines the minimum Abbe number of the negative lens in the first lens group. If the lower limit of conditional formula (1) is exceeded, it becomes difficult to correct axial chromatic aberration at the telephoto end.

[0015] Condition (2) defines the minimum Abbe number of the positive lens in the second lens group. If the lower limit of condition (2) is exceeded, it becomes difficult to correct fluctuations in lateral chromatic aberration during zooming.

[0016] Conditional formula (3) defines the ratio of the focal length of the first lens group to the focal length of the second lens group. If the upper limit of conditional formula (3) is exceeded, it becomes difficult to obtain a desired zoom ratio. Conversely, if the lower limit of conditional formula (3) is exceeded, it becomes difficult to correct the fluctuation of the field curvature during zooming.

[0017] Although the object of the present invention is achieved as described above, it is preferable that the following conditional expression be satisfied in the present invention. -4.0 <f2 / fw<-1.0 …(4) Here, fw is the focal length at the wide-angle end.

[0018] Conditional formula (4) defines the ratio of the focal length of the second lens group to the focal length at the wide-angle end. If the upper limit of conditional formula (4) is exceeded, it becomes difficult to correct the fluctuation of the field curvature during zooming. Conversely, if the lower limit of conditional formula (4) is exceeded, the overall length becomes too long to achieve the desired zoom ratio, which is undesirable. In the present invention, it is preferable to satisfy the following condition: 6.5 <z<100.0 …(5) Here, z is the zoom ratio.

[0019] Condition (5) defines the zoom ratio. If the upper limit of condition (5) is exceeded, it becomes difficult to correct axial chromatic aberration at the telephoto end. Conversely, if the lower limit of condition (5) is exceeded, the effect of the present invention becomes less noticeable. In the present invention, it is preferable that the first lens group includes only one negative lens.

[0020] The first lens group has a large diameter, and the negative lens, which is thicker at the periphery, has a large impact on the mass. In order to keep the mass down, it is desirable to limit the number of negative lenses in the first lens group to one, at the very least. In the present invention, it is preferable that the positive lens located closest to the object side in the second lens group has a concave surface facing the object side.

[0021] If the positive lens closest to the object side in the second lens group has a convex surface on the object side, it becomes difficult to satisfactorily correct spherical aberration and coma aberration from short wavelengths to long wavelengths at the telephoto end.

[0022] In the present invention, it is preferable that a lens group disposed closer to the image side than the second lens group has at least one positive lens satisfying the following conditional expression: 1.9 <n …(6) ν<33 …(7) Here, n is the refractive index and ν is the Abbe number.

[0023] Condition (6) defines the refractive index of at least one positive lens in the lens group located closer to the image side than the second lens group. If the lower limit of condition (6) is exceeded, it becomes difficult to correct fluctuations in coma aberration during zooming.

[0024] Condition (7) defines the Abbe number of at least one positive lens in the lens group located closer to the image than the second lens group. If the upper limit of condition (7) is exceeded, it becomes difficult to correct axial chromatic aberration at the telephoto end.

[0025] In the present invention, it is desirable that at least the first lens group is fixed during magnification variation. The first lens group has a large mass and requires a large thrust to move it, which is not preferable.

[0026] In the present invention, it is preferable that at least three lens groups move during zooming. If the number of lens groups that move during magnification is two or less, the diameter of the front lens becomes large when the angle of view is widened, which is not preferable.

[0027] In the present invention, it is preferable that the second lens group has, in order from the image side, a positive lens, a negative lens, and a positive lens.

[0028] By disposing a positive lens closest to the image side of the second lens group, the principal point position of the second lens group is moved closer to the object side, and the diameter of the front lens is reduced. In addition, by disposing a negative lens between two positive lenses, a difference occurs in the height of light rays passing through the two positive lenses, making it possible to correct spherical aberration and coma aberration from short wavelengths to long wavelengths and to correct lateral chromatic aberration. In the disclosed embodiment, the second lens group has two positive lenses, but the present invention is not limited to this. Although the effect of the present invention can be obtained by the second lens group having two positive lenses, the effect of the present invention can also be obtained by the second lens group having three or more positive lenses. In addition, in the present invention, it is preferable that the second lens group has a negative lens and a negative lens in this order from the object side.

[0029] If the second lens group is composed of a negative lens and a negative lens in that order from the object side, the principal point position of the second lens group moves closer to the object side, so that an increase in the diameter of the front lens can be suppressed when the angle is widened. In the present invention, it is preferable that the second lens group has at least five lenses.

[0030] Since two positive lenses are arranged in the second lens group having negative refractive power, it becomes easier to correct various aberrations if the number of negative lenses is greater than the number of positive lenses. It is more desirable to specify the numerical ranges of the conditional expressions (1) to (7) as follows: 34<ν1nmin<60 …(1a) 30<ν2pmin<60 …(2a) -5.7 <f1 / f2<-3.05 …(3a) -3.5 <f2 / fw<-1.05 …(4a) 6.6 <z<50.0 …(5a) 1.9 <n<2.2 …(6a) 15<ν<33 …(7a)

[0031] If the upper limit value of conditional expression (1a) is exceeded, it becomes difficult to correct axial chromatic aberration at the telephoto end, so an upper limit value like that of conditional expression (1a) may be set. If the upper limit of conditional expression (2a) is exceeded, it becomes difficult to correct axial chromatic aberration at the telephoto end, and therefore an upper limit like that of conditional expression (2a) may be set. If the upper limit of conditional formula (6a) is exceeded, it becomes difficult to manufacture a glass material with high transmittance, and therefore an upper limit like that of conditional formula (6a) may be set. If the lower limit of conditional formula (7a) is exceeded, it becomes difficult to manufacture a glass material with high transmittance, and therefore the lower limit of conditional formula (7a) may be set.

[0032] It is more desirable to specify the numerical ranges of the conditional expressions (1a) to (7a) as follows: 34.5<ν1nmin<53 …(1b) 30.5<ν2pmin<51 …(2b) -5.5 <f1 / f2<-3.1 …(3b) -3.2 <f2 / fw<-1.1 …(4b) 6.7 <z<30.0 …(5b) 1.9 <n<2.1 …(6b) 16<ν<32 …(7b)

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figures 1, 5, 9, and 13 are lens cross-sectional views of Numerical Examples 1 to 4 described later, and Figures 2 to 4, 6 to 8, 10 to 12, and 14 to 16 are aberration diagrams of each Numerical Example. In Figures 2 to 4, 6 to 8, 10 to 12, and 14 to 16, Figures 2, 6, 10, and 14 are aberration diagrams at the wide-angle end, Figures 3, 7, 11, and 15 are aberration diagrams at intermediate focal lengths, and Figures 4, 8, 12, and 16 are aberration diagrams at the telephoto end. In the aberration diagrams, d and g indicate the d-line and g-line, respectively, and M and S indicate the meridional image plane and the sagittal image plane, respectively. Magnification chromatic aberration is represented by the g-line.

[0034] In the lens cross-sectional views of Figures 1, 5, 9 and 13, L1 to L5 respectively indicate the first, second, third, fourth and fifth lens groups, SP indicates an aperture, P indicates a glass block such as a CCD face plate or a low-pass filter, and I indicates an image surface. In this embodiment, when changing magnification from the wide-angle end to the telephoto end, each group is moved as indicated by the arrows in Figures 1, 5, 9 and 13. The solid and dotted arrows indicate the movement locus when focusing on an object at infinity and a close distance, respectively.

[0035] Numerical examples of the present invention will be described below. In the numerical examples, ri is the radius of curvature of the i-th surface from the object side, di is the distance between the i-th surface and the (i+1)-th surface (lens thickness or air distance), and ndi and νdi are the refractive index and Abbe number of the medium (optical material) between the i-th surface and the (i+1)-th surface, respectively. An * mark to the right of the surface number indicates that the surface is aspheric.

[0036] The aspheric shape is defined as follows: X-axis is in the direction of the optical axis, h-axis is perpendicular to the optical axis, the direction of light travel is positive, R is the paraxial radius of curvature, k is the conic constant, and A4, A6, and A8 are aspheric coefficients.

number

[0037] [Numerical Example 1] Unit: mm Surface Data Surface number rd nd vd 1 160.188 1.60 1.83481 42.7 2 43.002 6.36 1.49700 81.5 3 -1052.033 0.17 4 46.280 3.90 1.49700 81.5 5 226.727 0.17 6 48.944 3.38 1.49700 81.5 7 438.851 (variable) 8 -466.054 0.88 1.77250 49.6 9 14.076 3.89 10 1412.073 0.70 1.60311 60.6 11 27.979 4.19 12 -17.687 1.39 1.90366 31.3 13 -15.206 0.70 1.48749 70.2 14 -301.949 0.43 15 52.960 2.12 1.90366 31.3 16 -106.588 (variable) 17 (Aperture) ∞ (Variable) 18* 15.733 5.36 1.55332 71.7 19* -100.082 3.99 20 17.643 0.60 1.91650 31.6 21 12.241 5.06 22 26.441 3.10 1.62299 58.2 23 -16.246 0.60 1.85478 24.8 24 -35.572 (variable) 25 127.000 1.77 1.95906 17.5 26 -21.895 0.60 2.00100 29.1 27 22.288 (variable) 28 -16.858 0.66 1.96300 24.1 29 -27.974 0.17 30 -120.284 3.83 1.49700 81.5 31 -16.799 0.92 32 21.006 2.99 1.59522 67.7 33 77.417 (variable) 34 ∞ 0.66 1.51633 64.1 35∞1.00 Image plane ∞ Aspheric Data Side 18 K =-6.60943e-001 A 4= 5.94018e-007 A 6= 3.05523e-008 A 8= 1.65647e-011 Page 19 K = 0.00000e+000 A 4= 1.44837e-005 Various data Zoom ratio 9.75 Wide Angle Mid-Telephoto Focal length 9.89 46.56 96.41 F-number 2.88 3.75 4.12 Half angle of view 36.80 9.31 4.43 Image height 6.45 7.41 7.41 Lens length 139.24 139.24 139.24 BF 14.09 18.13 14.02 d 7 1.13 24.67 34.72 d16 34.87 11.33 1.28 d17 19.66 1.34 1.34 d24 2.22 7.04 8.96 d27 7.72 17.19 19.38 d33 12.65 16.69 12.59 Zoom lens group data Group starting plane focal length 1 1 64.79 2 8 -14.85 3 18 23.11 4 25 -25.72 5 28 34.58

[0038] [Numerical Example 2] Unit: mm Surface Data Surface number rd nd vd 1 -204.968 4.15 1.80400 46.5 2 177.947 10.71 1.49700 81.5 3 -244.936 0.17 4 312.263 8.62 1.43875 94.9 5 -157.827 0.17 6 135.300 4.67 1.49700 81.5 7 614.853 0.17 8 89.751 4.94 1.49700 81.5 9 227.532 (variable) 10 642.099 1.31 1.75500 52.3 11 20.804 7.39 12 -140.145 1.08 1.69680 55.5 13 80.309 3.01 14 -69.270 8.74 1.51742 52.4 15 -17.297 1.14 1.49700 81.5 16 37.244 4.94 1.83481 42.7 17 -413.494 (variable) 18 (Aperture) ∞ (Variable) 19 -27.814 1.01 1.96300 24.1 20 -32.615 0.17 21 75.553 3.13 1.67270 32.1 22 -119.096 18.99 23 66.057 3.20 1.95906 17.5 24 -176.186 1.84 1.96300 24.1 25 27.464 4.62 1.49700 81.5 26 -103.901 (variable) 27 -25.233 0.88 1.96300 24.1 28 -35.047 0.97 29 -334.625 3.20 1.49700 81.5 30 -30.861 0.17 31 68.338 2.31 1.49700 81.5 32 -162.032 (variable) 33∞ 33.00 1.60859 46.4 34 ∞ 13.20 1.51633 64.1 35∞7.00 Image plane ∞ Various data Zoom ratio 19.55 Wide Angle Mid-Telephoto Focal length 8.24 54.69 161.14 F-number 1.85 2.70 2.99 Half angle of view 37.50 5.75 1.96 Image height 5.50 5.50 5.50 Lens total length 278.06 278.06 278.06 BF 40.67 53.49 47.73 d 9 1.30 75.64 100.46 d17 100.87 26.53 1.71 d18 27.59 3.74 3.74 d26 5.94 16.97 22.74 d32 4.45 17.27 11.50 Zoom lens group data Group starting plane focal length 1 1 132.79 2 10 -24.79 3 19 79.07 4 27 62.46

[0039] [Numerical Example 3] Unit: mm Surface Data Surface number rd nd vd 1 62.778 1.59 1.91082 35.3 2 40.453 7.12 1.43875 94.9 3 -552.783 0.17 4 40.669 4.67 1.49700 81.5 5 538.415 (variable) 6 -239.200 0.89 1.77250 49.6 7 15.440 3.57 8 514.203 0.72 1.60311 60.6 9 44.747 3.14 10 -22.620 0.87 1.90366 31.3 11 -20.381 0.69 1.48749 70.2 12 25.772 0.17 13 26.706 2.72 1.90366 31.3 14 -294.397 (variable) 15 (Aperture) ∞ (Variable) 16* 14.986 4.78 1.69350 53.2 17* 77.242 2.93 18 39.701 6.67 1.49700 81.5 19 -10.101 0.60 1.88300 40.8 20 19.240 0.55 21 25.133 6.56 1.49700 81.5 22 -10.522 0.62 1.56732 42.8 23 -17.622 0.17 24 26.207 2.41 1.76200 40.1 25 -894.382 (variable) 26 -42.065 1.83 1.95906 17.5 27 -19.555 0.62 1.67300 38.3 28 18.862 (variable) 29 26.190 6.12 1.77250 49.6 30 -25.691 1.55 1.92286 18.9 31 -63.070 (variable) 32∞2.15 1.51633 64.1 33∞1.00 Image plane ∞ Aspheric Data Page 16 K = 5.74864e-001 A 4=-9.23993e-006 A 6=-3.28590e-008 A 8=-1.66866e-010 Page 17 K = 0.00000e+000 A 4= 1.73435e-005 Various data Zoom ratio 9.75 Wide Angle Mid-Telephoto Focal length 9.89 48.76 96.42 F-number 2.88 3.75 4.12 Half angle of view 36.80 8.70 4.41 Image height 6.45 7.41 7.41 Lens total length 139.16 139.16 139.16 BF 14.22 14.22 14.22 d 5 1.27 26.03 36.65 d14 27.11 3.61 1.27 d15 27.25 8.78 1.03 d25 2.98 11.84 11.09 d28 4.62 12.96 13.19 d31 11.80 11.80 11.80 Zoom lens group data Group starting plane focal length 1 1 67.64 2 6 -15.05 3 16 25.56 4 26 -22.52 5 29 26.96

[0040] [Numerical Example 4] Unit: mm Surface Data Surface number rd nd vd 1 77.583 1.87 1.90525 35.0 2 43.532 9.16 1.49700 81.5 3 -740.409 0.17 4 40.763 5.76 1.59522 67.7 5 284.606 (variable) 6 458.138 1.10 1.90366 31.3 7 16.199 8.09 8 -31.733 3.49 1.90366 31.3 9 -21.797 0.88 1.60311 60.6 10 23.356 4.52 1.90366 31.3 11 -505.085 (variable) 12 29.922 1.80 1.90366 31.3 13 87.160 4.83 14 (Aperture) ∞ (Variable) 15 26.579 4.70 1.48749 70.2 16 -51.678 1.46 1.76182 26.5 17 22.753 1.73 18 70.681 2.18 1.74400 44.8 19 -83.367 (variable) 20 -16.706 1.06 1.67270 32.1 21 -30.478 0.17 22 -180.188 4.72 1.48749 70.2 23 -23.841 0.17 24 44.776 4.31 1.48749 70.2 25 -102.730 (variable) 26 ∞ 2.00 1.51633 64.1 27∞1.00 Image plane ∞ Various data Zoom ratio 6.85 Wide Angle Mid-Telephoto Focal length 17.51 ​​68.37 119.94 F-number 2.47 3.71 4.12 Half angle of view 34.40 9.05 5.04 Image height 10.82 10.82 10.82 Lens length 149.37 149.37 149.37 BF 31.80 36.83 18.29 d 5 0.97 25.71 33.96 d11 42.60 3.96 0.50 d14 4.12 5.70 0.96 d19 7.73 15.01 33.51 d25 29.48 34.51 15.97 Zoom lens group data Group starting plane focal length 1 1 65.11 2 6 -20.81 3 12 49.68 4 15 1037.88 5 20 53.08 Table 1 shows the relationship between the above-mentioned conditional expressions and various numerical values ​​in the numerical examples. [Table 1]

[0041] As described above, according to each embodiment, it is possible to realize a small-sized, high-magnification zoom lens in which chromatic aberration is well corrected.

[0042] In the examples, zoom lenses having four or five lens groups as a whole have been illustrated, but the present invention is not limited to this. It should be noted that as long as the configurations of the first, second and third lens groups satisfy the above-mentioned conditions of the present invention, the effects of the present invention can be obtained regardless of the lens configuration of the fourth lens group and subsequent groups.

[0043] Next, an embodiment of a video camera using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

[0044] In Fig. 17, reference numeral 10 denotes a video camera body, 11 denotes a photographing optical system constituted by the zoom lens of the present invention, 12 denotes an image pickup element such as a CCD that receives a subject image through the photographing optical system 11, 13 denotes a recording means that records the subject image received by the image pickup element 12, and 14 denotes a finder for observing the subject image displayed on a display element (not shown). The display element is constituted by a liquid crystal panel or the like, and displays the subject image formed on the image pickup element 12.

[0045] In this way, by applying the imaging device of the present invention to optical equipment such as a video camera, it is possible to realize an optical equipment that is small in size and has high optical performance.

[0046] If an electronic imaging element such as a CCD is used as the imaging element, the image quality of the output image can be further improved by electronically correcting aberrations.

[0047] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0048] L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group L5 Fifth lens group SP Aperture P Filters I image plane

Claims

1. A zoom lens having, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and at least one subsequent lens group, The spacing between adjacent lens groups changes during magnification. the second lens group has two positive lenses, Let v1nmin be the minimum Abbe number of a material constituting the negative lens included in the first lens group, v2pmin be the minimum Abbe number of a material constituting the positive lens included in the second lens group, f1 be the focal length of the first lens group, f2 be the focal length of the second lens group, and fw be the focal length of the wide-angle end of the zoom lens. 34<ν1 nmin 30<ν2p min -6.0<f1 / f2<-3.0 -4.0<f2 / fw<-1.0 A zoom lens characterized by satisfying the following conditional expressions:

2. When z is the zoom ratio, 6.5<z<100.0 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. 3. The zoom lens according to claim 1, wherein the first lens group includes one negative lens.

4. 4. The zoom lens according to claim 1, wherein the positive lens arranged closest to the object side in the second lens group has a concave surface facing the object side.

5. When n is a refractive index and ν is an Abbe number, the lens group disposed on the image side of the second lens group is 1.9<n ν<33 5. The zoom lens according to claim 1, further comprising at least one positive lens which satisfies the following condition:

6. 6. The zoom lens according to claim 1, wherein the first lens group does not move for varying magnification.

7. 7. The zoom lens according to claim 1, wherein three or more lens groups move during zooming.

8. 8. The zoom lens according to claim 1, wherein the second lens group comprises, in order from the image side to the object side, a positive lens, a negative lens, and a positive lens.

9. 9. The zoom lens according to claim 1, wherein the second lens group comprises, in order from the object side to the image side, a negative lens and a negative lens.

10. 10. The zoom lens according to claim 1, wherein the second lens group has five lenses.

11. 11. The zoom lens according to claim 1, comprising, in order from the object side to the image side, the first lens group, the second lens group, the third lens group, and a fourth lens group having positive refractive power.

12. 11. The zoom lens according to claim 1, comprising, in order from the object side to the image side, the first lens group, the second lens group, the third lens group, a fourth lens group, and a fifth lens group having positive refractive power.

13. A zoom lens having, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and at least one subsequent lens group; The spacing between adjacent lens groups changes during magnification. the second lens group includes, in order from the image side to the object side, a positive lens, a negative lens, and a positive lens, Let the minimum Abbe number of the material constituting the negative lens included in the first lens group be ν1nmin, the minimum Abbe number of the material constituting the positive lens included in the second lens group be ν2pmin, the focal length of the first lens group be f1, and the focal length of the second lens group be f2. 34<ν1 nmin 30<ν2p min -6.0<f1 / f2<-3.0 A zoom lens characterized by satisfying the following conditional expressions:

14. A zoom lens comprising, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group, and a fifth lens group having positive refractive power; The spacing between adjacent lens groups changes during magnification. the second lens group has two positive lenses, Let the minimum Abbe number of the material constituting the negative lens included in the first lens group be ν1nmin, the minimum Abbe number of the material constituting the positive lens included in the second lens group be ν2pmin, the focal length of the first lens group be f1, and the focal length of the second lens group be f2. 34<ν1 nmin 30<ν2p min -6.0<f1 / f2<-3.0 A zoom lens characterized by satisfying the following conditional expressions:

15. 15. An imaging device comprising: the zoom lens according to claim 1; and an imaging element that receives an image formed by the zoom lens.

Images