Zoom lens and imaging device having the same

Abstract

To provide a compact, high-performance optical zoom lens. [Solution] The zoom lens according to the present invention comprises, in order from the object side to the image side, a positive first lens group, a negative second lens group, and a subsequent group which is positive as a whole and has at least three lens groups, the subsequent group which comprises, in order from the image side to the object side, an image-side positive lens group, an image-side negative lens group, and an intermediate lens group, and when zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves, and the spacing between adjacent lens groups changes, and in the intermediate lens group, the negative lens having a concave shape on the object-side lens surface is positioned furthest towards the image side, and the positive lens is positioned adjacent to the object side of the negative lens, and when the Abbe number with respect to the d line of the negative lens is Vdn and the Abbe number with respect to the d line of the positive lens is Vdp, 1.5 <Vdn / Vdp<5.0 It is characterized by satisfying the following conditional expression.

Description

Technical Field

[0001] The present invention relates to a zoom lens, and particularly to a zoom lens suitably used in imaging devices such as surveillance cameras, network cameras, and video cameras.

Background Art

[0002] In recent years, with the progress of high-definition monitors, there is a demand for high image quality in zoom lenses mounted on imaging devices such as surveillance cameras, network cameras, and video cameras. Specifically, with the progress of high-definition monitors, it is desired that the zoom lens is an optical system having high optical performance with good correction of various aberrations such as chromatic aberration and field curvature.

[0003] Patent Document 1 discloses a zoom lens composed of first, second, third, fourth, and fifth lens groups each having positive, negative, positive, negative, and positive refractive powers.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the zoom lens disclosed in Patent Document 1, the first lens group moves toward the object side during zooming from the wide-angle end to the telephoto end, so it is large-sized. Therefore, an object of the present invention is to provide a zoom lens that is small-sized and has high optical performance.

Means for Solving the Problems

[0006] To achieve the above object, as one aspect of the present invention, a zoom lens includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and including at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power, an image-side negative lens group having a negative refractive power, and an intermediate lens group. During zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves while the interval between adjacent lens groups changes. In the intermediate lens group, a negative lens having a negative refractive power and having a concave lens surface on the object side is disposed closest to the image side, and a positive lens having a positive refractive power is disposed adjacent to the object side of the negative lens. When the Abbe number based on the d-line of the negative lens is Vdn and the Abbe number based on the d-line of the positive lens is Vdp, it satisfies the conditional expression 1.5 < Vdn / Vdp < 5.0. As another aspect of the present invention, a zoom lens includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and including at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power and an image-side negative lens group having a negative refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves while the interval between adjacent lens groups changes. The first lens group includes at least two lenses each having a positive refractive power and a negative lens having a negative refractive power, being disposed closest to the image side, and having a concave lens surface on the image side. When the focal length of the first lens group is f1, the focal length of the negative lens is fr1, and the overall optical length of the zoom lens is TL, it satisfies the conditional expressions -1.2 < fr1 / f1 < -0.5 and 0.85 < f1 / TL < 1.20. As another aspect of the present invention, a zoom lens includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and including at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power and an image-side negative lens group having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves while the interval between adjacent lens groups changes. The image-side negative lens group moves during during focusing focusing, is disposed closest to the object side, has a positive refractive power, and includes a positive lens having a convex shape on the image-side lens surface and at least one lens each having a negative refractive power. When the Abbe number based on the d-line of the negative lens having the smallest absolute value of the focal length among the at least one lens is Vdn, it satisfies the conditional expression 70 < Vdn < 150. As yet another aspect of the present invention, a zoom lens includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and including at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power and an image-side negative lens group having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves while the interval between adjacent lens groups changes. [Effect of the Invention]

[0007] According to the present invention, it is possible to provide a zoom lens that is small and has high optical performance. [Brief Description of the Drawings]

[0008] [Figure 1] Cross-sectional view at the wide-angle end when the zoom lens according to Numerical Example 1 is focused at infinity. [Figure 2]Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 1 is focused at infinity. [Figure 3] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 2. [Figure 4] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 2 is focused at infinity. [Figure 5] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 3. [Figure 6] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 3 is focused at infinity. [Figure 7] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 4. [Figure 8] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 4 is focused at infinity. [Figure 9] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 5. [Figure 10] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 5 is focused at infinity. [Figure 11] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 6. [Figure 12] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 6 is focused at infinity. [Figure 13] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 7. [Figure 14] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 7 is focused at infinity. [Figure 15] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 8. [Figure 16] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 8 is focused at infinity. [Figure 17] Cross-sectional view at the wide-angle end of the zoom lens according to Numerical Example 9 when focused at infinity. [Figure 18] Diagrams of various aberrations at the wide-angle end, zoom intermediate position, and telephoto end of the zoom lens according to Numerical Example 9 when focused at infinity. [Figure 19] Cross-sectional view at the wide-angle end of the zoom lens according to Numerical Example 10 when focused at infinity. [Figure 20] Diagrams of various aberrations at the wide-angle end, zoom intermediate position, and telephoto end of the zoom lens according to Numerical Example 10 when focused at infinity. [Figure 21] Cross-sectional view at the wide-angle end of the zoom lens according to Numerical Example 11 when focused at infinity. [Figure 22] Diagrams of various aberrations at the wide-angle end, zoom intermediate position, and telephoto end of the zoom lens according to Numerical Example 11 when focused at infinity. [Figure 23] Cross-sectional view at the wide-angle end of the zoom lens according to Numerical Example 12 when focused at infinity. [Figure 24] Diagrams of various aberrations at the wide-angle end, zoom intermediate position, and telephoto end of the zoom lens according to Numerical Example 12 when focused at infinity. [Figure 25] Cross-sectional view at the wide-angle end of the zoom lens according to Numerical Example 13 when focused at infinity. [Figure 26] Diagrams of various aberrations at the wide-angle end, zoom intermediate position, and telephoto end of the zoom lens according to Numerical Example 13 when focused at infinity. [Figure 27] Cross-sectional view at the wide-angle end of the zoom lens according to Numerical Example 14 when focused at infinity. [Figure 28] Diagrams of various aberrations at the wide-angle end, zoom intermediate position, and telephoto end of the zoom lens according to Numerical Example 14 when focused at infinity. [Figure 29] Cross-sectional view at the wide-angle end of the zoom lens according to Numerical Example 15 when focused at infinity. [Figure 30] Diagrams of various aberrations at the wide-angle end, zoom intermediate position, and telephoto end of the zoom lens according to Numerical Example 15 when focused at infinity. [Figure 31]Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 16. [Figure 32] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 16 is focused at infinity. [Figure 33] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 17. [Figure 34] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 17 is focused at infinity. [Figure 35] Cross-sectional view of the zoom lens at the wide-angle end when focused at infinity, according to numerical example 18. [Figure 36] Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens according to numerical example 18 is focused at infinity. [Figure 37] A perspective view of an imaging device equipped with a zoom lens according to any of the first to third embodiments. [Modes for carrying out the invention]

[0009] The zoom lens according to this embodiment will be described in detail below with reference to the attached drawings. Note that the drawings shown below may be drawn to a different scale than the actual dimensions in order to facilitate understanding of this embodiment.

[0010] [First Embodiment] In recent years, with the increasing resolution of monitors, there has been a growing demand for higher image quality in zoom lenses used in imaging devices such as surveillance cameras, network cameras, and video cameras.

[0011] Specifically, as monitors become higher resolution, zoom lenses are required to have optical systems with high optical performance, where various aberrations such as chromatic aberration and field curvature are well corrected. At the same time, there is a demand for miniaturization of zoom lenses mounted on imaging devices such as surveillance cameras, in order to reduce the overall size of the imaging device.

[0012] Furthermore, zoom lenses used in imaging devices such as long-range surveillance cameras are required to have a long focal length throughout the entire system. Therefore, conventionally, zoom lenses have been proposed consisting of first, second, third, fourth, and fifth lens groups, each having positive, negative, positive, negative, and positive refractive powers, in order from the object side to the image side.

[0013] As described above, zoom lenses mounted on imaging devices such as surveillance cameras are required to be compact, have a long overall focal length, and possess high optical performance throughout the entire zoom range. However, conventional zoom lenses, while having long focal lengths, do not adequately reduce field curvature and coma aberration, and while being compact, they do not adequately balance increased focal length with overall optical performance.

[0014] Therefore, the objective of this embodiment is to provide a zoom lens that is compact and has a short overall length, yet has a long focal length throughout the entire system, and that provides high optical performance throughout the entire zoom range, as well as an imaging device having the same.

[0015] The zoom lens according to the first embodiment 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, and a subsequent group having positive refractive power as a whole and comprising at least three lens groups. The subsequent group then includes, in order from the image side to the object side, a group of positive image-side lenses having a positive refractive power, a group of negative image-side lenses having a negative refractive power, and an intermediate lens group.

[0016] In this context, a lens group refers to a group that includes at least one lens whose spacing from adjacent lens groups changes during zooming or focusing. In the zoom lens according to this embodiment, the first lens group is fixed (does not move) when zooming from the wide-angle end to the telephoto end.

[0017] Furthermore, since the first lens group is a large lens group in terms of aperture and weight in the zoom lens according to this embodiment, making the first lens group a fixed lens group allows for miniaturization and simplification of the entire zoom lens. Furthermore, in the zoom lens according to this embodiment, at least the second lens group and the negative lens group on the image side are moved during zooming, thereby correcting the image plane shift associated with zooming while zooming is being performed.

[0018] Furthermore, in the zoom lens according to this embodiment, zooming is performed efficiently by changing the distance between each lens group and the adjacent lens group during zooming. In this context, the wide-angle end and telephoto end refer to the state of the zoom lens when the second lens group is positioned at both ends of the range in which it can move along the optical axis due to its mechanism during zooming.

[0019] Furthermore, in the zoom lens according to this embodiment, a negative lens is arranged in the intermediate lens group included in the subsequent group, at the image-side end, which has negative refractive power and a concave shape on the lens surface facing the object. Furthermore, in the intermediate lens group, a positive lens having a positive refractive power is arranged adjacent to the object side of the negative lens.

[0020] In this embodiment, the zoom lens, having the above-described configuration for the intermediate lens group, is of the telephoto type overall, achieving a long focal length for the entire system despite its short overall length. Furthermore, the negative lens and the positive lens described above can suitably correct chromatic aberration, and the object-side lens surface of the negative lens has a concave shape, which allows for suitable correction of field curvature and coma aberration of the entire system.

[0021] In the zoom lens according to this embodiment, when Vdn is the Abbe number with respect to the d line of the negative lens and Vdp is the Abbe number with respect to the d line of the positive lens, the following condition (1) is satisfied. 1.5 <Vdn / Vdp<5.0 ···(1)

[0022] In the zoom lens according to this embodiment, chromatic aberration can be suitably corrected over the entire zoom range if the ratio between the Abbe number of the negative lens and the Abbe number of the positive lens satisfies condition (1). If the value exceeds the upper limit of condition (1), the Abbe number of the positive lens becomes excessively small, meaning the positive lens has excessively high dispersion, making it difficult to correct axial chromatic aberration, which is undesirable. On the other hand, if the value falls below the lower limit of condition (1), the ratio between the Abbe number of the negative lens and the Abbe number of the positive lens becomes excessively small, making it difficult to correct chromatic aberration, which is undesirable.

[0023] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (2) is satisfied. 70 <Vdn<150 ···(2)

[0024] If the value exceeds the upper limit of condition (2), it becomes difficult to correct both aberrations at the design wavelength, such as field curvature, and chromatic aberration, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (2), it becomes difficult to correct chromatic aberration, which is undesirable.

[0025] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (3) is satisfied when the shape factor of the negative lens is SFn. -5.0 <SFn<0.0 ···(3)

[0026] The shape factor SFn defined in condition (3) is expressed by the following formula, where Rn1 is the radius of curvature of the object-side lens surface of the negative lens and Rn2 is the radius of curvature of the image-side lens surface of the negative lens. SFn = (Rn1 + Rn2) / (Rn1 - Rn2)

[0027] If the value exceeds the upper limit of condition (3), the refractive power of the negative lens becomes excessively strong, making it difficult to correct field curvature and coma aberration, which is undesirable. On the other hand, if the refractive power falls below the lower limit of condition (3), the refractive power of the negative lens becomes excessively weak, which leads to an increase in the overall length of the system, and is therefore undesirable.

[0028] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (4) is satisfied when Rp2 is the radius of curvature of the image-side lens surface of the positive lens. 1.0 <Rp2 / Rn1<5.0 ···(4)

[0029] If the value exceeds the upper limit of condition (4), the radius of curvature of the object-side lens surface of the negative lens becomes excessively small, making it difficult to correct field curvature and coma aberration, which is undesirable. On the other hand, if the value falls below the lower limit of condition (4), the radius of curvature of the image-side lens surface of the positive lens becomes excessively small, making it difficult to correct chromatic aberration, which is undesirable.

[0030] Furthermore, in this embodiment, the negative lens is positioned on the image side of the aperture, resulting in a telephoto-type zoom lens overall, and enabling efficient correction of various aberrations at the design wavelength, such as field curvature and coma aberration, as well as chromatic aberration.

[0031] Furthermore, in the zoom lens according to this embodiment, when Ln1 is the distance on the optical axis between the aperture and the object-side lens surface of the negative lens, it is preferable that the following condition (5) is satisfied. -2.0 <Ln1 / Rn1<-0.5 ···(5)

[0032] If the value exceeds the upper limit of condition (5), the distance on the optical axis between the aperture and the object-side lens surface of the negative lens becomes excessively small, resulting in insufficient correction of various aberrations at the design wavelength, such as field curvature and coma aberration, which is undesirable. On the other hand, if the value falls below the lower limit of condition (5), the distance on the optical axis between the aperture and the object-side lens surface of the negative lens becomes excessively large, which leads to an increase in the overall length of the system and is therefore undesirable.

[0033] Furthermore, let fn be the focal length of the negative lens, and Lr be the distance along the optical axis between the image-side lens surface and the image plane of the negative lens, specifically the air-equivalent length (length excluding the optical block). In this case, it is preferable that the zoom lens according to this embodiment satisfies the following condition (6). -2.0 <fn / Lr<-0.4 ···(6)

[0034] If the value exceeds the upper limit of condition (6), the refractive power of the negative lens becomes excessively strong, making it difficult to correct various aberrations at the design wavelength, such as field curvature and coma aberration, which is undesirable. On the other hand, if the value falls below the lower limit of condition (6), the distance on the optical axis between the lens surface on the image side of the negative lens and the image plane becomes excessively large, which leads to an increase in the overall length of the system and is therefore undesirable.

[0035] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (7) is satisfied when the focal length of the negative lens group on the image side is frn. 0.5 <fn / frn<2.0 ···(7)

[0036] If the value exceeds the upper limit of condition (7), the refractive power of the negative lens becomes excessively weak, leading to an increase in the overall system length, which is undesirable. On the other hand, if the refractive power falls below the lower limit of condition equation (7), the refractive power of the negative lens group on the image side becomes excessively weak, and the amount of movement of the negative lens group on the image side becomes excessively large when correcting for image plane movement associated with zooming, which leads to an increase in the overall length of the system, and is therefore undesirable.

[0037] In the zoom lens according to this embodiment, it is more preferable that the following conditions (1a) to (7a) are satisfied instead of conditions (1) to (7), respectively. 1.5 <Vdn / Vdp<3.0 ···(1a) 75 <Vdn<120 ···(2a) -2.0 <SFn<-1.0 ···(3a) 1.8 <Rp2 / Rn1<4.0 ···(4a) -1.5 <Ln1 / Rn1<-0.8 ···(5a) -1.5 <fn / Lr<-0.6 ···(6a) 0.8 <fn / frn<1.5 ···(7a)

[0038] Furthermore, in the zoom lens according to this embodiment, it is even more preferable that the following conditions (1b) to (7b) are satisfied instead of each of the conditions (1a) to (7a). 1.55 <Vdn / Vdp<2.70 ···(1b) 80 <Vdn<100 ···(2b) -1.850 <SFn<-1.050 ···(3b) 2.0 <Rp2 / Rn1<3.0 ···(4b) -1.35 <Ln1 / Rn1<-1.00 ···(5b) -1.20 <fn / Lr<-0.80 ···(6b) 0.85 <fn / frn<1.40 ···(7b)

[0039] Next, numerical examples 1 to 6 of the zoom lens according to this embodiment will be described in detail based on the attached drawings. Figure 1 is a cross-sectional view of the zoom lens according to numerical embodiment 1 at the wide-angle end when focused at infinity, and Figures 2(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 1 at the wide-angle end, intermediate zoom position, and telephoto end, respectively, when focused at infinity. Figure 3 is a cross-sectional view of the zoom lens according to numerical embodiment 2 at the wide-angle end when focused at infinity, and Figures 4(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 2 at the wide-angle end, intermediate zoom position, and telephoto end, respectively, when focused at infinity.

[0040] Figure 5 is a cross-sectional view of the zoom lens according to numerical embodiment 3 at the wide-angle end when focused at infinity, and Figures 6(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 3 at the wide-angle end, intermediate zoom position, and telephoto end, respectively, when focused at infinity. Figure 7 is a cross-sectional view of the zoom lens according to numerical embodiment 4 at the wide-angle end when focused at infinity, and Figures 8(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 4 at the wide-angle end, intermediate zoom position, and telephoto end, respectively, when focused at infinity.

[0041] Figure 9 is a cross-sectional view of the zoom lens according to numerical embodiment 5 at the wide-angle end when focused at infinity, and Figures 10(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 5 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively. Figure 11 is a cross-sectional view of the zoom lens according to numerical embodiment 6 at the wide-angle end when focused at infinity, and Figures 12(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 6 at the wide-angle end, intermediate zoom position, and telephoto end, respectively, when focused at infinity.

[0042] In each aberration diagram, d and g represent the d-line and g-line, respectively, and M and S represent the meridional image plane and sagittal image plane, respectively. Lateral chromatic aberration is represented by the g-line. In each lens cross-sectional diagram, B1, B2, B3, B4, B5, B6, and B7 represent the first, second, third, fourth, fifth, sixth, and seventh lens groups, respectively. SP represents the aperture, G represents the optical block, and IP represents the image plane.

[0043] The optical block also includes a cover glass for the image sensor's imaging surface, a low-pass filter, an IR cut filter, and dummy glass for correcting the optical path length. Furthermore, in the zoom lens according to this embodiment, a structure may be adopted that allows switching between an IR cut filter and a dummy glass within the optical path in order to correct for changes in optical path length due to the insertion and removal of the IR cut filter.

[0044] Furthermore, in numerical examples 1 to 6, as shown in each lens cross-sectional view, when zooming from the wide-angle end to the telephoto end, each lens group moves as indicated by the arrows. Furthermore, the solid and dashed arrows shown in each lens cross-sectional diagram indicate the movement trajectories of the lens group when focused on an object at infinity and an object at close range, respectively.

[0045] The following shows the numerical data for each of the numerical examples 1 to 6 of the zoom lens according to this embodiment. In each numerical data point, the face number i is shown sequentially from the object side, ri is the radius of curvature of the i-th face, and di is the distance between the i-th face and the (i+1)-th face. Furthermore, in each numerical data, ndi and vdi represent the refractive index and Abbe number, respectively, based on the d-line of the medium (optical material) between the i-th and i+1-th surfaces.

[0046] Furthermore, in each numerical data, the two planes closest to the image correspond to the optical block G, and the angle of view represents the half-angle of view (ω) related to the usable angle of view considering distortion aberration. Furthermore, in each numerical data, the total optical length is expressed as the distance along the optical axis between the lens surface closest to the object and the paraxial image plane, as the air-equivalent length (length excluding the optical block G). In each numerical data, BF represents the back focus, which is the distance along the optical axis between the image-side lens surface and the paraxial image plane, expressed as an air-equivalent length.

[0047] [Numerical Example 1] Unit: mm Surface data Face number ri di ndi vdi 1 57.367 5.62 1.49700 81.5 2 -115.099 0.20 3 57.198 6.04 1.49700 81.5 4 -68.986 1.30 1.69680 55.5 5 -2018.260 5.66 6 -383.719 1.20 1.80400 46.5 7 66.666 (variable) 8 153.212 1.00 1.59522 67.7 9 27.849 3.30 10 -30.500 1.00 1.49700 81.5 11 44.585 1.62 1.95375 32.3 12 293.207 (variable) 13 75.937 2.26 1.49700 81.5 14 -69.226 0.19 15 53.926 4.05 1.49700 81.5 16 -26.528 1.00 1.77250 49.6 17 -3578.392 0.73 18 20.685 3.81 1.49700 81.5 19 -251.102 2.00 20 (aperture) ∞ 4.04 21 44.020 1.00 2.00100 29.1 22 24.778 10.07 23 98.973 1.94 1.56732 42.8 24 -38.655 2.16 25 -15.259 1.00 1.49700 81.5 26 -51.784 (variable) 27 -45.601 1.50 1.54814 45.8 28 -26.441 6.81 29 -21.616 1.00 1.49700 81.5 30 29.304 (Variable) 31 23.642 6.23 1.51742 52.4 32 -117.836 3.00 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.00 147.49 F-number 4.12 4.12 4.12 Field of view: 7.95, 5.60, 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.14 9.14 9.14 d 7 1.66 15.15 26.18 d12 25.52 12.03 0.99 d26 5.03 7.08 2.61 d30 9.53 7.48 11.95 Zoom lens group data Group starting plane focal length 1 1 119.15 2 8 -36.83 3 13 35.39 4 27 -34.27 5 31 38.64

[0048] [Numerical Example 2] Unit: mm Surface data Face number ri di ndi vdi 1 57.620 5.83 1.49700 81.5 2 -101.619 0.20 3 65.517 5.90 1.49700 81.5 4 -62.513 1.30 1.69680 55.5 5 413.465 5.30 6 -305.943 1.20 1.53172 48.8 7 59.808 (variable) 8 153.442 1.00 1.59522 67.7 9 31.220 3.17 10 -33.539 1.00 1.49700 81.5 11 47.540 1.41 2.00100 29.1 12 158.463 (variable) 13 65.656 2.65 1.49700 81.5 14 -58.167 0.20 15 47.644 3.97 1.49700 81.5 16 -30.851 1.00 1.80400 46.5 17 132.162 0.20 18 20.436 3.75 1.49700 81.5 19 -1189.539 3.46 20 (aperture) ∞ 10.93 21 77.825 1.00 2.00069 25.5 22 15.220 1.06 23 16.566 3.85 1.68893 31.1 24 -32.336 1.03 25 -15.687 1.00 1.49700 81.5 26 -628.303 (variable) 27 -48.445 1.41 1.51742 52.4 28 -23.895 5.01 29 -20.253 1.00 1.49700 81.5 30 33.697 (Variable) 31 23.074 4.88 1.51742 52.4 32 -369.459 3.46 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.33 147.49 F-number 4.12 4.12 4.12 Field of view: 7.96 5.59 4.06 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.60 9.60 9.60 d 7 1.79 16.00 27.62 d12 26.82 12.61 0.99 d26 5.14 8.02 3.99 d30 11.54 8.66 12.69 Zoom lens group data Group starting plane focal length 1 1 122.35 2 8 -38.24 3 13 34.67 4 27 -37.87 5 31 42.15

[0049] [Numerical Example 3] Unit: mm Surface data Face number ri di ndi vdi 1 55.734 5.77 1.43875 94.7 2 -126.601 0.20 3 66.008 5.81 1.49700 81.5 4 -67.235 1.30 1.65160 58.5 5 -305.292 7.59 6 -166.341 1.20 1.80400 46.5 7 90.551 (variable) 8 270.643 1.00 1.52841 76.5 9 30.096 2.95 10 -33.406 1.00 1.49700 81.5 11 42.727 1.51 1.85025 30.1 12 177.011 (variable) 13 89.945 2.04 1.43875 94.7 14 -73.026 0.20 15 52.911 4.00 1.49700 81.5 16 -26.288 1.00 1.77250 49.6 17 -173.129 0.20 18 17.939 4.14 1.43875 94.7 19 -660.923 2.05 20 (aperture) ∞ 2.00 21 34.417 1.00 1.95375 32.3 22 22.362 10.95 23 130.997 1.80 1.53172 48.8 24 -38.486 1.73 25 -13.935 1.00 1.43875 94.7 26 -53.280 (variable) 27 -36.854 1.50 1.51823 58.9 28 -23.250 6.13 29 -19.800 1.00 1.43875 94.7 30 30.862 (variable) 31 23.827 4.97 1.51742 52.4 32 -199.882 3.86 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.64 107.24 147.50 F-number 4.12 4.12 4.12 Field of view: 7.95 5.59 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.00 10.00 10.00 d 7 1.59 15.03 26.02 d12 25.43 11.99 1.00 d26 5.91 8.45 4.39 d30 10.66 8.11 12.18 Zoom lens group data Group starting plane focal length 1 1 121.44 2 8 -36.33 3 13 34.72 4 27 -37.64 5 31 41.46

[0050] [Numerical Example 4] Unit: mm Surface data Face number ri di ndi vdi 1 59.809 6.59 1.43875 94.7 2 -156.055 0.20 3 85.747 6.59 1.49700 81.5 4 -67.468 1.30 1.60311 60.6 5 314.144 0.20 6 51.409 4.13 1.43875 94.7 7 -3429.709 6.90 8 -307.259 1.20 1.77250 49.6 9 53.138 (variable) 10 -375.427 1.00 1.55343 72.2 11 28.213 2.64 12 -31.759 1.00 1.49700 81.5 13 37.460 1.56 1.85025 30.1 14 188.060 (variable) 15 110.499 1.95 1.43875 94.7 16 -56.832 0.20 17 60.645 3.61 1.49700 81.5 18 -24.313 1.00 1.80400 46.5 19 -98.980 0.20 20 18.165 3.75 1.43875 94.7 21 -350.169 4.88 22 (aperture) ∞ 2.00 23 43.359 1.00 2.00100 29.1 24 25.021 8.80 25 66.399 1.90 1.56732 42.8 26 -39.026 1.30 27 -14.306 1.00 1.43875 94.7 28 -55.125 (variable) 29 -63.298 1.50 1.53172 48.8 30 -25.532 4.42 31 -21.199 1.00 1.52841 76.5 32 25.873 (Variable) 33 22.442 5.60 1.51823 58.9 34 -143.647 4.62 35 ∞ 1.20 1.51633 64.1 36 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.74 147.50 F-number 4.12 4.12 4.12 Field of view: 7.99 5.58 4.08 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.76 10.76 10.76 d 9 2.17 13.71 23.15 d14 21.97 10.44 1.00 d28 3.71 6.34 3.71 d32 11.57 8.94 11.57 Zoom lens group data Group starting plane focal length 1 1 115.34 2 10 -30.83 3 15 31.31 4 29 -32.52 5 33 37.89

[0051] [Numerical Example 5] Unit: mm Surface data Face number ri di ndi vdi 1 56.679 5.46 1.49700 81.5 2 -131.452 0.20 3 51.180 6.12 1.49700 81.5 4 -78.078 1.30 1.69680 55.5 5 -1572.166 5.00 6 -516.735 1.20 1.80400 46.5 7 56.357 (variable) 8 114.547 1.00 1.59522 67.7 9 26.386 3.40 10 -31.503 1.00 1.49700 81.5 11 48.830 1.58 1.95375 32.3 12 436.325 (variable) 13 46.645 2.78 1.49700 81.5 14 -71.734 0.19 15 38.944 4.28 1.49700 81.5 16 -29.019 1.00 1.77250 49.6 17 47.511 0.20 18 20.295 3.87 1.49700 81.5 19 -190.034 2.03 20 (aperture) ∞ (variable) 21 17.178 1.00 1.95906 17.5 22 15.501 (Variable) 23 -586.018 1.63 1.56732 42.8 24 -32.245 1.29 25 -14.230 1.00 1.49700 81.5 26 -48.466 (variable) 27 -47.893 1.50 1.54072 47.2 28 -27.598 6.93 29 -22.216 1.00 1.49700 81.5 30 31.840 (variable) 31 24.526 5.25 1.51823 58.9 32 -111.319 3.49 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.06 147.49 F-number 4.12 4.12 4.12 Field of view: 7.95, 5.60, 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.63 9.63 9.63 d 7 1.70 15.63 27.03 d12 26.32 12.39 0.99 d20 3.30 4.69 6.48 d22 11.24 9.85 8.07 d26 5.92 7.54 2.51 d30 9.26 7.64 12.67 Zoom lens group data Group starting plane focal length 1 1 123.91 2 8 -38.09 3 13 32.52 4 21 -233.83 5 23 -135.09 6 27 -36.01 7 31 39.30

[0052] [Numerical Example 6] Unit: mm Surface data Face number ri di ndi vdi 1 58.222 5.48 1.49700 81.5 2 -121.663 0.20 3 59.251 5.85 1.49700 81.5 4 -72.532 1.30 1.69680 55.5 5 -760.044 5.42 6 -313.544 1.20 1.80400 46.5 7 70.402 (variable) 8 148.686 1.00 1.59522 67.7 9 30.049 3.11 10 -32.585 1.00 1.49700 81.5 11 47.068 1.56 1.90366 31.3 12 306.325 (variable) 13 63.554 2.24 1.49700 81.5 14 -86.780 0.20 15 47.720 4.05 1.49700 81.5 16 -28.017 1.00 1.77250 49.6 17 274.913 0.20 18 19.913 3.88 1.49700 81.5 19 -298.777 2.14 20 (aperture) ∞ 2.00 21 33.929 1.00 1.95375 32.3 22 21.747 11.18 23 45.613 2.23 1.51742 52.4 24 -43.956 1.24 25 -16.488 1.00 1.49700 81.5 26 -75.329 (variable) 27 453.846 1.88 1.51742 52.4 28 -30.718 0.20 29 33.287 1.00 1.49700 81.5 30 19.739 3.05 31 -17.157 1.00 1.49700 81.5 32 37.240 (Variable) 33 23.779 5.14 1.51823 58.9 34 -208.829 4.29 35 ∞ 1.20 1.51633 64.1 36 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.62 108.04 147.50 F-number 4.12 4.12 4.12 Field of view: 8.00 5.58 4.07 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.43 10.43 10.43 d 7 1.61 15.78 27.37 d12 26.75 12.58 0.99 d26 6.13 6.77 2.50 d32 11.95 11.31 15.58 Zoom lens group data Group starting plane focal length 1 1 120.05 2 8 -38.92 3 13 35.51 4 27 -31.29 5 33 41.51

[0053] Furthermore, the values ​​of each conditional expression in each of the numerical examples 1 to 6 of the zoom lens according to this embodiment are shown in Table 1 below.

[0054] [Table 1]

[0055] As described above, according to this embodiment, it is possible to obtain a zoom lens that is compact and has a short overall length, yet has a long focal length throughout the entire system, and that provides high optical performance throughout the entire zoom range, as well as an imaging device having the same.

[0056] [Second Embodiment] In recent years, there has been a demand for miniaturization of zoom lenses used in imaging devices such as surveillance cameras, network cameras, and video cameras, in order to reduce the overall size of the imaging device.

[0057] Furthermore, zoom lenses used in long-range surveillance cameras are required to have a long focal length throughout the entire system. Furthermore, with the increasing resolution of monitors, zoom lenses are required to have various aberrations such as spherical aberration and chromatic aberration adequately corrected.

[0058] Therefore, conventionally, a zoom lens has been proposed consisting of first, second, third, fourth, and fifth lens groups, each having positive, negative, positive, negative, and positive refractive powers, in order from the object side to the image side. As described above, zoom lenses are required to be compact, have a long overall focal length, and possess high optical performance throughout the entire zoom range.

[0059] However, while the conventional zoom lenses mentioned above have long focal lengths as telephoto zoom lenses, they do not adequately correct various aberrations such as spherical aberration and chromatic aberration. Therefore, the objective of this embodiment is to provide a zoom lens that is compact and has a short overall length, yet has a long focal length throughout the entire system, and that can obtain high optical performance in the long focal length range, and an imaging device having the same.

[0060] The zoom lens according to the second embodiment 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, and a subsequent group having positive refractive power as a whole and comprising at least three lens groups. The subsequent group then includes, in order from the image side to the object side, a group of positive image-side lenses having a positive refractive power and a group of negative image-side lenses having a negative refractive power.

[0061] In the zoom lens according to this embodiment, the first lens group is fixed during zooming from the wide-angle end to the telephoto end. Furthermore, since the first lens group is a large lens group in terms of aperture and weight in the zoom lens according to this embodiment, making the first lens group a fixed lens group allows for miniaturization and simplification of the entire zoom lens.

[0062] Furthermore, in the zoom lens according to this embodiment, at least the second lens group and the negative lens group on the image side are moved during zooming, thereby correcting the image plane shift associated with zooming while zooming is being performed. Furthermore, in the zoom lens according to this embodiment, zooming is performed efficiently by changing the distance between each lens group and the adjacent lens group during zooming.

[0063] Furthermore, in the zoom lens according to this embodiment, the first lens group has two or more lenses having positive refractive power. In addition, a negative lens is arranged in the first lens group that has negative refractive power and whose image-side lens surface is concave. By adopting this configuration, the first lens group becomes a telephoto type, making it possible to increase the focal length while maintaining a short overall optical length. Furthermore, spherical aberration and field curvature, particularly at the telephoto end, can be effectively corrected.

[0064] In the zoom lens according to this embodiment, when the focal length of the first lens group is f1, the focal length of the negative lens is fr1, and the total optical length is TL, the following conditions (8) and (9) are satisfied. -1.2 <fr1 / f1<-0.5 ···(8) 0.85 <f1 / TL<1.20 ···(9) Here, the total optical length refers to the distance along the optical axis between the lens surface closest to the object and the paraxial image plane, specifically the air-equivalent length (length excluding the optical block G).

[0065] In the zoom lens according to this embodiment, when condition (8) is satisfied, the first lens group can be set to a telephoto type by the power of the negative lens, thereby achieving both an increase in the overall focal length and suitable correction of various aberrations at the telephoto end. If the value exceeds the upper limit of condition (8), the power of the negative lens becomes excessively strong, making it difficult to correct spherical aberration and field curvature at the telephoto end, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (8), the power of the negative lens becomes excessively weak, making it difficult to increase the focal length of the entire system, which is undesirable.

[0066] Furthermore, in the zoom lens according to this embodiment, when condition (9) is satisfied, the power of the first lens group is appropriately set, and the overall system is miniaturized. If the value exceeds the upper limit of condition (9), the power of the first lens group becomes excessively weak, leading to an increase in overall length, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (9), the power of the first lens group becomes excessively strong, making it difficult to correct spherical aberration and field curvature at the telephoto end, which is undesirable.

[0067] Furthermore, in the zoom lens according to this embodiment, when L1 is the total length of the first lens group, that is, the distance on the optical axis between the object-side surface and the image-side surface of the first lens group, it is preferable that the following condition (10) is satisfied. -6.0 <fr1 / L1<-1.0 ···(10)

[0068] If the value exceeds the upper limit of condition (10), the total length of the first lens group will increase excessively, leading to an undesirable increase in the overall system length. On the other hand, if the value falls below the lower limit of condition equation (10), the power of the negative lens becomes excessively weak, making it difficult to increase the focal length of the entire system, which is undesirable. Furthermore, in the zoom lens according to this embodiment, the positive lens having positive refractive power is positioned on the object side of the first lens group, thereby efficiently setting the first lens group to a telephoto type.

[0069] Furthermore, in the zoom lens according to this embodiment, when the focal length of the positive lens located closest to the object in the first lens group is f11, it is preferable that the following condition (11) is satisfied. -2.0 <fr1 / f11<-0.4 ···(11)

[0070] If the value exceeds the upper limit of condition (11), the power of the positive lens becomes excessively weak, which leads to an increase in the overall length of the system, and is therefore undesirable. On the other hand, if the value falls below the lower limit of condition equation (11), the power of the positive lens becomes excessively strong, making it difficult to correct spherical aberration at the telephoto end, which is undesirable.

[0071] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (12) is satisfied when the focal length at the telephoto end of the entire system is fT. 0.6 <TL / fT<1.0 ···(12)

[0072] If the value exceeds the upper limit of condition (12), the optical length becomes excessively long, which leads to an increase in the overall size of the device, and is therefore undesirable. On the other hand, if the value falls below the lower limit of condition (12), the overall optical length becomes excessively short, making it difficult to correct aberrations across the entire zoom range, which is undesirable.

[0073] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (13) is satisfied when the Abbe number Vdr1 is taken as the reference line d of the negative lens. 40 <Vdr1<80 ···(13)

[0074] If the value exceeds the upper limit of condition (13), axial chromatic aberration at the telephoto end will be insufficiently corrected, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (13), the dispersion of the negative lens that corrects chromatic aberration within the first lens group becomes excessively high, making it difficult to reduce chromatic aberration across the entire visible light range, which is undesirable.

[0075] Furthermore, in the zoom lens according to this embodiment, when Vdnave1 is the average value of the Abbe numbers with respect to the d line of each of the negative lenses included in the first lens group, it is preferable that the following condition (14) is satisfied. 40 <Vdnave1<80 ···(14)

[0076] If the value exceeds the upper limit of condition (14), axial chromatic aberration at the telephoto end will be insufficiently corrected, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (14), the dispersion of the lenses for color correction within the first lens group becomes excessively high, making it difficult to reduce chromatic aberration across the entire visible light range, which is undesirable.

[0077] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (15) is satisfied when the Abbe number with respect to the d line of the positive lens is Vd11. 1.2 <Vd11 / Vdr1<3.0 ···(15)

[0078] If the value exceeds the upper limit of condition (15), the ratio between the dispersion of the positive lens and the dispersion of the negative lens becomes excessively large, making it difficult to achieve both appropriate correction of axial chromatic aberration and appropriate correction of various aberrations at the design wavelength, such as spherical aberration, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (15), the Abbe number of the negative lens becomes excessively large, resulting in insufficient correction of axial chromatic aberration at the telephoto end, which is undesirable.

[0079] In the zoom lens according to this embodiment, it is more preferable that the following conditions (8a) to (15a) are satisfied instead of conditions (8) to (15), respectively. -1.0 <fr1 / f1<-0.5 ···(8a) 0.9 <f1 / TL<1.0 ···(9a) -5.0 <fr1 / L1<-2.0 ···(10a) -1.5 <fr1 / f11<-0.5 ···(11a) 0.8 <TL / fT<0.9 ···(12a) 45 <Vdr1<60 ···(13a) 45 <Vdnave1<60 ···(14a) 1.5 <Vd11 / Vdr1<2.5 ···(15a)

[0080] Furthermore, in the zoom lens according to this embodiment, it is even more preferable that the following conditions (8b) to (15b) are satisfied instead of each of the conditions (8a) to (15a). -0.80 <fr1 / f1<-0.50 ···(8b) 0.900 <f1 / TL<0.980 ···(9b) -4.80 <fr1 / L1<-2.10 ···(10b) -1.260 <fr1 / f11<-0.580 ···(11b) 0.860 <TL / fT<0.870 ···(12b) 46.0 <Vdr1<50.0 ···(13b) 51.0 <Vdnave1<56.0 ···(14b) 1.65 <Vd11 / Vdr1<2.05 ···(15b)

[0081] Next, numerical examples 7 to 12 of the zoom lens according to this embodiment will be described in detail based on the attached drawings. Figure 13 is a cross-sectional view of the zoom lens according to numerical embodiment 7 at the wide-angle end when focused at infinity, and Figures 14(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 7 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively. Figure 15 is a cross-sectional view of the zoom lens according to numerical embodiment 8 at the wide-angle end when focused at infinity, and Figures 16(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 8 at the wide-angle end, intermediate zoom position, and telephoto end, respectively, when focused at infinity.

[0082] Figure 17 is a cross-sectional view of the zoom lens according to numerical embodiment 9 at the wide-angle end when focused at infinity, and Figures 18(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 9 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively. Figure 19 is a cross-sectional view of the zoom lens according to numerical example 10 at the wide-angle end when focused at infinity, and Figures 20(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical example 10 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively.

[0083] Figure 21 is a cross-sectional view of the zoom lens according to numerical embodiment 11 at the wide-angle end when focused at infinity, and Figures 22(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 11 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively. Figure 23 is a cross-sectional view of the zoom lens according to numerical example 12 at the wide-angle end when focused at infinity, and Figures 24(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical example 12 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively.

[0084] In each aberration diagram, d and g represent the d-line and g-line, respectively, and M and S represent the meridional image plane and sagittal image plane, respectively. Lateral chromatic aberration is represented by the g-line. In each lens cross-sectional diagram, B1, B2, B3, B4, B5, B6, and B7 represent the first, second, third, fourth, fifth, sixth, and seventh lens groups, respectively. SP represents the aperture, G represents the optical block, and IP represents the image plane.

[0085] The optical block also includes a cover glass for the image sensor's imaging surface, a low-pass filter, an IR cut filter, and dummy glass for correcting the optical path length. Furthermore, in the zoom lens according to this embodiment, a structure may be adopted that allows switching between an IR cut filter and a dummy glass within the optical path in order to correct for changes in optical path length due to the insertion and removal of the IR cut filter.

[0086] Furthermore, in numerical examples 7 to 12, as shown in each lens cross-sectional view, when zooming from the wide-angle end to the telephoto end, each lens group moves as indicated by the arrows. Furthermore, the solid and dashed arrows shown in each lens cross-sectional diagram indicate the movement trajectories of the lens group when focused on an object at infinity and an object at close range, respectively.

[0087] The following shows the numerical data for each of the numerical examples 7 to 12 of the zoom lens according to this embodiment. In each numerical data point, the face number i is shown sequentially from the object side, ri is the radius of curvature of the i-th face, and di is the distance between the i-th face and the (i+1)-th face. Furthermore, in each numerical data, ndi and vdi represent the refractive index and Abbe number, respectively, based on the d-line of the medium (optical material) between the i-th and i+1-th surfaces.

[0088] Furthermore, in each numerical data, the two planes closest to the image correspond to the optical block G, and the angle of view represents the half-angle of view (ω) related to the usable angle of view considering distortion aberration. Furthermore, in each numerical data, the total optical length is expressed as the distance along the optical axis between the lens surface closest to the object and the paraxial image plane, as the air-equivalent length (length excluding the optical block G). In each numerical data, BF represents the back focus, which is the distance along the optical axis between the image-side lens surface and the paraxial image plane, expressed as an air-equivalent length.

[0089] [Numerical Example 7] Unit: mm Surface data Face number ri di ndi vdi 1 57.367 5.62 1.49700 81.5 2 -115.099 0.20 3 57.198 6.04 1.49700 81.5 4 -68.986 1.30 1.69680 55.5 5 -2018.260 5.66 6 -383.719 1.20 1.80400 46.5 7 66.666 (variable) 8 153.212 1.00 1.59522 67.7 9 27.849 3.30 10 -30.500 1.00 1.49700 81.5 11 44.585 1.62 1.95375 32.3 12 293.207 (variable) 13 75.937 2.26 1.49700 81.5 14 -69.226 0.19 15 53.926 4.05 1.49700 81.5 16 -26.528 1.00 1.77250 49.6 17 -3578.392 0.73 18 20.685 3.81 1.49700 81.5 19 -251.102 2.00 [[ID=,32]]20 (aperture) ∞ 4.04 21 44.020 1.00 2.00100 29.1 22 24.778 10.07 23 98.973 1.94 1.56732 42.8 24 -38.655 2.16 ) 25 -15.259 1.00 1.49700 81.5 26 -51.784 (variable) 27 -45.601 1.50 1.54814 45.8 28 -26.441 6.81 29 -21.616 1.00 1.49700 81.5 30 29.304 (variable) 31 23.642 6.23 1.51742 52.4 32 -117.836 3.00 Note: There seems to be a formatting issue in the original text where "32 (絞り) ∞ 4.04" might be better written as "32 (aperture) ∞ 4.04" for clarity in the English translation. Also, the translation of "可変" as "variable" is a common way to represent "variable" in this context.33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide angle Middle Telephoto Focal length 75.63 107.00 147.49 F-number 4.12 4.12 4.12 Angle of view 7.95 5.60 4.05 Image height 10.72 10.72 10.72 Overall optical length 127.60 127.60 127.60 BF 9.14 9.14 9.14 d 7 1.66 15.15 26.18 d12 25.52 12.03 0.99 d26 5.03 7.08 2.61 d30 9.53 7.48 11.95 Zoom lens group data Group Starting surface Focal length 1 1 119.15 2 8 -36.83 3 13 35.39 4 27 -34.27 5 31 38.64

[0090] [Numerical Example 8] Unit mm Surface data Surface number ri di ndi vdi 1 57.620 5.83 1.49700 81.5 2 -101.619 0.20 3 65.517 5.90 1.49700 81.5 4 -62.513 1.30 1.69680 55.5 5 413.465 5.30 6 -305.943 1.20 1.53172 48.8 7 59.808 (variable) 8 153.442 1.00 1.59522 67.7 9 31.220 3.17 10 -33.539 1.00 1.49700 81.5 11 47.540 1.41 2.00100 29.1 12 158.463 (variable) 13 65.656 2.65 1.49700 81.5 14 -58.167 0.20 15 47.644 3.97 1.49700 81.5 16 -30.851 1.00 1.80400 46.5 17 132.162 0.20 18 20.436 3.75 1.49700 81.5 19 -1189.539 3.46 20 (aperture) ∞ 10.93 21 77.825 1.00 2.00069 25.5 22 15.220 1.06 23 16.566 3.85 1.68893 31.1 24 -32.336 1.03 25 -15.687 1.00 1.49700 81.5 26 -628.303 (variable) 27 -48.445 1.41 1.51742 52.4 28 -23.895 5.01 29 -20.253 1.00 1.49700 81.5 30 33.697 (variable) 31 23.074 4.88 1.51742 52.4 32 -369.459 3.46 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.33 147.49 F-number 4.12 4.12 4.12 Field of view: 7.96 5.59 4.06 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.60 9.60 9.60 d 7 1.79 16.00 27.62 d12 26.82 12.61 0.99 d26 5.14 8.02 3.99 d30 11.54 8.66 12.69 Zoom lens group data Group starting plane focal length 1 1 122.35 2 8 -38.24 3 13 34.67 4 27 -37.87 5 31 42.15

[0091] [Numerical Example 9] Unit: mm Surface data Face number ri di ndi vdi 1 55.734 5.77 1.43875 94.7 2 -126.601 0.20 3 66.008 5.81 1.49700 81.5 4 -67.235 1.30 1.65160 58.5 5 -305.292 7.59 6 -166.341 1.20 1.80400 46.5 7 90.551 (variable) 8 270.643 1.00 1.52841 76.5 9 30.096 2.95 10 -33.406 1.00 1.49700 81.5 11 42.727 1.51 1.85025 30.1 12 177.011 (variable) 13 89.945 2.04 1.43875 94.7 14 -73.026 0.20 15 52.911 4.00 1.49700 81.5 16 -26.288 1.00 1.77250 49.6 17 -173.129 0.20 18 17.939 4.14 1.43875 94.7 19 -660.923 2.05 20 (aperture) ∞ 2.00 21 34.417 1.00 1.95375 32.3 22 22.362 10.95 23 130.997 1.80 1.53172 48.8 24 -38.486 1.73 25 -13.935 1.00 1.43875 94.7 26 -53.280 (variable) 27 -36.854 1.50 1.51823 58.9 28 -23.250 6.13 29 -19.800 1.00 1.43875 94.7 30 30.862 (variable) 31 23.827 4.97 1.51742 52.4 32 -199.882 3.86 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.64 107.24 147.50 F-number 4.12 4.12 4.12 Field of view: 7.95 5.59 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.00 10.00 10.00 d 7 1.59 15.03 26.02 d12 25.43 11.99 1.00 d26 5.91 8.45 4.39 d30 10.66 8.11 12.18 Zoom lens group data Group starting plane focal length 1 1 121.44 2 8 -36.33 3 13 34.72 4 27 -37.64 5 31 41.46

[0092] [Numerical Example 10] Unit: mm Surface data Face number ri di ndi vdi 1 59.809 6.59 1.43875 94.7 2 -156.055 0.20 3 85.747 6.59 1.49700 81.5 4 -67.468 1.30 1.60311 60.6 5 314.144 0.20 6 51.409 4.13 1.43875 94.7 7 -3429.709 6.90 8 -307.259 1.20 1.77250 49.6 9 53.138 (variable) 10 -375.427 1.00 1.55343 72.2 11 28.213 2.64 12 -31.759 1.00 1.49700 81.5 13 37.460 1.56 1.85025 30.1 14 188.060 (variable) 15 110.499 1.95 1.43875 94.7 16 -56.832 0.20 17 60.645 3.61 1.49700 81.5 18 -24.313 1.00 1.80400 46.5 19 -98.980 0.20 20 18.165 3.75 1.43875 94.7 21 -350.169 4.88 22 (aperture) ∞ 2.00 23 43.359 1.00 2.00100 29.1 24 25.021 8.80 25 66.399 1.90 1.56732 42.8 26 -39.026 1.30 27 -14.306 1.00 1.43875 94.7 28 -55.125 (variable) 29 -63.298 1.50 1.53172 48.8 30 -25.532 4.42 31 -21.199 1.00 1.52841 76.5 32 25.873 (Variable) 33 22.442 5.60 1.51823 58.9 34 -143.647 4.62 35 ∞ 1.20 1.51633 64.1 36 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.74 147.50 F-number 4.12 4.12 4.12 Field of view: 7.99 5.58 4.08 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.76 10.76 10.76 d 9 2.17 13.71 23.15 d14 21.97 10.44 1.00 d28 3.71 6.34 3.71 d32 11.57 8.94 11.57 Zoom lens group data Group starting plane focal length 1 1 115.34 2 10 -30.83 3 15 31.31 4 29 -32.52 5 33 37.89

[0093] [Numerical Example 11] Unit: mm Surface data Face number ri di ndi vdi 1 56.679 5.46 1.49700 81.5 2 -131.452 0.20 3 51.180 6.12 1.49700 81.5 4 -78.078 1.30 1.69680 55.5 5 -1572.166 5.00 6 -516.735 1.20 1.80400 46.5 7 56.357 (variable) 8 114.547 1.00 1.59522 67.7 9 26.386 3.40 10 -31.503 1.00 1.49700 81.5 11 48.830 1.58 1.95375 32.3 12 436.325 (variable) 13 46.645 2.78 1.49700 81.5 14 -71.734 0.19 15 38.944 4.28 1.49700 81.5 16 -29.019 1.00 1.77250 49.6 17 47.511 0.20 18 20.295 3.87 1.49700 81.5 19 -190.034 2.03 20 (aperture) ∞ (variable) 21 17.178 1.00 1.95906 17.5 22 15.501 (Variable) 23 -586.018 1.63 1.56732 42.8 24 -32.245 1.29 25 -14.230 1.00 1.49700 81.5 26 -48.466 (variable) 27 -47.893 1.50 1.54072 47.2 28 -27.598 6.93 29 -22.216 1.00 1.49700 81.5 30 31.840 (variable) 31 24.526 5.25 1.51823 58.9 32 -111.319 3.49 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.06 147.49 F-number 4.12 4.12 4.12 Field of view: 7.95, 5.60, 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.63 9.63 9.63 d 7 1.70 15.63 27.03 d12 26.32 12.39 0.99 d20 3.30 4.69 6.48 d22 11.24 9.85 8.07 d26 5.92 7.54 2.51 d30 9.26 7.64 12.67 Zoom lens group data Group starting plane focal length 1 1 123.91 2 8 -38.09 3 13 32.52 4 21 -233.83 5 23 -135.09 6 27 -36.01 7 31 39.30

[0094] [Numerical Example 12] Unit: mm Surface data Face number ri di ndi vdi 1 58.222 5.48 1.49700 81.5 2 -121.663 0.20 3 59.251 5.85 1.49700 81.5 4 -72.532 1.30 1.69680 55.5 5 -760.044 5.42 6 -313.544 1.20 1.80400 46.5 7 70.402 (variable) 8 148.686 1.00 1.59522 67.7 9 30.049 3.11 10 -32.585 1.00 1.49700 81.5 11 47.068 1.56 1.90366 31.3 12 306.325 (variable) 13 63.554 2.24 1.49700 81.5 14 -86.780 0.20 15 47.720 4.05 1.49700 81.5 16 -28.017 1.00 1.77250 49.6 17 274.913 0.20 18 19.913 3.88 1.49700 81.5 19 -298.777 2.14 20 (aperture) ∞ 2.00 21 33.929 1.00 1.95375 32.3 22 21.747 11.18 23 45.613 2.23 1.51742 52.4 24 -43.956 1.24 25 -16.488 1.00 1.49700 81.5 26 -75.329 (variable) 27 453.846 1.88 1.51742 52.4 28 -30.718 0.20 29 33.287 1.00 1.49700 81.5 30 19.739 3.05 31 -17.157 1.00 1.49700 81.5 32 37.240 (Variable) 33 23.779 5.14 1.51823 58.9 34 -208.829 4.29 35 ∞ 1.20 1.51633 64.1 36 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.62 108.04 147.50 F-number 4.12 4.12 4.12 Field of view: 8.00 5.58 4.07 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.43 10.43 10.43 d 7 1.61 15.78 27.37 d12 26.75 12.58 0.99 d26 6.13 6.77 2.50 d32 11.95 11.31 15.58 Zoom lens group data Group starting plane focal length 1 1 120.05 2 8 -38.92 3 13 35.51 4 27 -31.29 5 33 41.51

[0095] Furthermore, the values ​​of each conditional expression in each of the numerical examples 7 to 12 of the zoom lens according to this embodiment are shown in Table 2 below.

[0096] [Table 2]

[0097] As described above, according to this embodiment, it is possible to obtain a zoom lens that is compact and has a short overall length, yet has a long focal length throughout the entire system, and that can obtain high optical performance in the long focal length range, as well as an imaging device having the same.

[0098] [Third Embodiment] In recent years, with the increasing resolution of monitors, there has been a growing demand for higher image quality in zoom lenses used in imaging devices such as surveillance cameras, network cameras, and video cameras.

[0099] Specifically, as monitors become higher resolution, zoom lenses are required to have optical systems with high optical performance, where various aberrations such as chromatic aberration and field curvature are well corrected. In particular, with telephoto zoom lenses that have long focal lengths, it is desired that even when focusing is performed to accommodate changes in the subject distance, various aberrations such as chromatic aberration and field curvature are maintained in a well-corrected state.

[0100] Therefore, in order to maintain high optical performance during focusing, an inner-focus type zoom lens has been proposed, consisting of first to fifth lens groups, each having positive, negative, positive, negative, and positive refractive powers, with focusing performed by the fourth lens group. Furthermore, an inner-focus type zoom lens has been proposed that consists of a first to sixth lens group, each having positive, negative, positive, positive, negative, and positive refractive powers, with focusing performed by the fifth lens group.

[0101] In an inner focusing system, where focusing is performed by a lens group positioned closer to the image than the first lens group to accommodate changes in subject distance, focusing can be done with a relatively small and lightweight lens group, making it easy to miniaturize the entire zoom lens. On the other hand, compared to focusing methods that generally move the first lens group or the entire optical system, the inner focusing method results in larger aberration fluctuations when the focusing lens group is moved, making it difficult to perform good aberration correction across the entire range of object distances.

[0102] Furthermore, with telephoto zoom lenses that have long focal lengths, the amount of movement required for focusing the focus lens tends to be longer, making it even more difficult to suppress aberration fluctuations. Therefore, in order to obtain high optical performance across the entire range of object distances using an inner focusing system in a telephoto zoom lens, it is important to appropriately set the optical arrangement, refractive power, and lens configuration of each lens group that makes up the zoom lens.

[0103] From this perspective, while the conventional zoom lenses mentioned above offer good optical performance as telephoto zoom lenses, they do not adequately suppress the fluctuations in chromatic aberration that occur during focusing. Furthermore, while other conventional zoom lenses mentioned above offer compact and lightweight focusing lenses, they do not adequately suppress fluctuations such as spherical aberration and field curvature that occur during focusing.

[0104] Therefore, the objective of this embodiment is to provide a zoom lens that is small and lightweight while achieving high optical performance across the entire range of object distances, and an imaging device having the same.

[0105] The zoom lens according to the third embodiment 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, and a subsequent group having positive refractive power as a whole and comprising at least three lens groups. The subsequent group then includes, in order from the image side to the object side, a group of positive image-side lenses having a positive refractive power and a group of negative image-side lenses having a negative refractive power. In the zoom lens according to this embodiment, the first lens group is fixed during zooming from the wide-angle end to the telephoto end.

[0106] Furthermore, since the first lens group is a large lens group in terms of aperture and weight in the zoom lens according to this embodiment, making the first lens group a fixed lens group allows for miniaturization and simplification of the entire zoom lens. Furthermore, in the zoom lens according to this embodiment, at least the second lens group and the negative lens group on the image side are moved during zooming, thereby correcting the image plane shift associated with zooming while zooming is being performed.

[0107] Furthermore, in the zoom lens according to this embodiment, zooming is performed efficiently by changing the distance between each lens group and the adjacent lens group during zooming. Furthermore, in the zoom lens according to this embodiment, when focusing from infinity to a close-range object, the negative lens group on the image side moves toward the image side.

[0108] In the zoom lens according to this embodiment, the negative lens group on the image side has a relatively small aperture and is a compact and lightweight lens group, making it suitable for use as the focusing group. In the image-side negative lens group, a positive lens is arranged that has a positive refractive power closest to the object and whose image-side lens surface is convex (has a convex shape). In addition, each member of the image-side negative lens group has at least one negative lens, each having a negative refractive power. As described above, by making the image-side lens surface of the positive lens convex, it is possible to suitably correct spherical aberration while suitably suppressing fluctuations in field curvature that occur during focusing.

[0109] In the zoom lens according to this embodiment, when Vdn is the Abbe number with respect to the d line of the negative lens with the smallest absolute value of focal length among at least one negative lens included in the image-side negative lens group, the following condition (16) is satisfied. 70 <Vdn<150 ···(16)

[0110] Among the negative lenses included in the image-side negative lens group, the negative lens with the smallest absolute focal length is the negative lens with the greatest power, and therefore the negative lens that has the greatest influence on the various aberrations generated by the image-side negative lens group. Furthermore, by satisfying the Abbe number of such a negative lens with condition (16), fluctuations in chromatic aberration during focusing can be effectively suppressed.

[0111] If the value exceeds the upper limit of condition (16), the fluctuations in lateral chromatic aberration that occur during focusing can be effectively suppressed. On the other hand, the correction of axial chromatic aberration and lateral chromatic aberration at infinity by achromatic aberration between the positive lens included in the negative lens group on the image side becomes excessive, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (16), it becomes difficult to suppress the fluctuations in chromatic aberration that occur during focusing, which is undesirable.

[0112] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (17) is satisfied when the focal length of the negative lens with the smallest absolute value of focal length among at least one negative lens included in the image-side negative lens group is fFn, and the total length of the image-side negative lens group is LF. -5.0 <fFn / LF<-2.0 ···(17)

[0113] If the value exceeds the upper limit of condition (17), the refractive power of the negative lenses included in the negative lens group on the image side becomes excessively strong, making it difficult to suppress fluctuations in field curvature that occur during focusing, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (17), the refractive power of the negative lens included in the image-side negative lens group becomes insufficient, and the amount of movement required for focusing becomes excessively large, which is undesirable.

[0114] Furthermore, R2p is defined as the radius of curvature of the image-side lens surface of the positive lens located furthest towards the object in the image-side negative lens group, and R1n is defined as the radius of curvature of the object-side lens surface of the negative lens with the smallest absolute focal length among the at least one negative lens included in the image-side negative lens group. In this embodiment, it is preferable that the following condition (18) is satisfied in the zoom lens. 1.0 <R2p / R1n<2.0 ···(18)

[0115] If the value exceeds the upper limit of condition (18), the radius of curvature of the object-side lens surface of the negative lens with the smallest absolute focal length becomes excessively small, making it difficult to suppress the fluctuations in coma aberration that occur during focusing, which is undesirable. On the other hand, if the value falls below the lower limit of condition (18), the radius of curvature of the image-side lens surface of the positive lens located closest to the object in the image-side negative lens group becomes excessively small, making it difficult to suppress fluctuations in spherical aberration that occur during focusing, which is undesirable.

[0116] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (19) is satisfied when the focal length of the positive lens located closest to the object in the image-side negative lens group is fFp. -8.0 <fFp / fFn<-1.5 ···(19)

[0117] If the value exceeds the upper limit of condition (19), the refractive power of the negative lens in the image-side negative lens group becomes excessively strong, making it difficult to suppress the fluctuations in field curvature that occur during focusing, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (19), the refractive power of the positive lens located closest to the object in the negative lens group on the image side becomes excessively strong, making it difficult to suppress fluctuations in spherical aberration that occur during focusing, which is undesirable.

[0118] Furthermore, in the zoom lens according to this embodiment, when Vdp is the Abbe number with respect to the d line of the positive lens located furthest towards the object in the negative lens group on the image side, it is preferable that the following condition (20) is satisfied. 1.2 <Vdn / Vdp<3.0 ···(20)

[0119] If the value exceeds the upper limit of condition (20), the color correction effect in the negative lens group on the image side becomes excessively strong, resulting in excessive correction of axial chromatic aberration and lateral chromatic aberration at infinity, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (20), the effect of color correction in the negative lens group on the image side becomes excessively weak, making it difficult to suppress fluctuations in chromatic aberration during focusing, which is undesirable.

[0120] Furthermore, in the zoom lens according to this embodiment, it is preferable that the following condition (21) is satisfied when the focal length of the negative lens group on the image side is fn and the focal length of the positive lens group on the image side is fp. -2.0 <fp / fn<-1.0 ···(21)

[0121] If the value exceeds the upper limit of condition (21), the refractive power of the negative lens group on the image side becomes excessively strong, making it difficult to correct field curvature and coma aberration, which is undesirable. On the other hand, if the value falls below the lower limit of condition equation (21), the refractive power of the negative lens group on the image side becomes excessively weak, and the amount of movement required for focusing becomes excessively large, which is undesirable.

[0122] In the zoom lens according to this embodiment, it is more preferable that the following conditions (16a) to (21a) are satisfied instead of conditions (16) to (21), respectively. 75 <Vdn<120 ···(16a) -4.0 <fFn / LF<-2.5 ···(17a) 1.0 <R2p / R1n<1.9 ···(18a) -5.0 <fFp / fFn<-2.0 ···(19a) 1.5 <Vdn / Vdp<2.0 ···(20a) -1.50 <fp / fn<-1.05 ···(21a)

[0123] Furthermore, in the zoom lens according to this embodiment, it is even more preferable that the following conditions (16b) to (21b) are satisfied instead of conditions (16a) to (21a), respectively. 76.0 <Vdn<100.0 ···(16b) -3.5 <fFn / LF<-2.6 ···(17b) 1.10 <R2p / R1n<1.80 ···(18b) -4.50 <fFp / fFn<-2.30 ···(19b) 1.55 <Vdn / Vdp<1.80 ···(20b) -1.400 <fp / fn<-1.090 ···(21b)

[0124] Next, numerical examples 13 to 18 of the zoom lens according to this embodiment will be described in detail based on the attached drawings. Figure 25 is a cross-sectional view of the zoom lens according to numerical embodiment 13 at the wide-angle end when focused at infinity, and Figures 26(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 13 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively. Figure 27 is a cross-sectional view of the zoom lens according to numerical embodiment 14 at the wide-angle end when focused at infinity, and Figures 28(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 14 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively.

[0125] Figure 29 is a cross-sectional view of the zoom lens according to numerical example 15 at the wide-angle end when focused at infinity, and Figures 30(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical example 15 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively. Figure 31 is a cross-sectional view of the zoom lens according to numerical embodiment 16 at the wide-angle end when focused at infinity, and Figures 32(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 16 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively.

[0126] Figure 33 is a cross-sectional view of the zoom lens according to numerical embodiment 17 at the wide-angle end when focused at infinity, and Figures 34(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 17 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively. Figure 35 is a cross-sectional view of the zoom lens according to numerical embodiment 18 at the wide-angle end when focused at infinity, and Figures 36(a), (b), and (c) show aberration diagrams of the zoom lens according to numerical embodiment 18 at the wide-angle end, intermediate zoom position, and telephoto end when focused at infinity, respectively.

[0127] In each aberration diagram, d and g represent the d-line and g-line, respectively, and M and S represent the meridional image plane and sagittal image plane, respectively. Lateral chromatic aberration is represented by the g-line. In each lens cross-sectional diagram, B1, B2, B3, B4, B5, B6, and B7 represent the first, second, third, fourth, fifth, sixth, and seventh lens groups, respectively. SP represents the aperture, G represents the optical block, and IP represents the image plane.

[0128] The optical block also includes a cover glass for the image sensor's imaging surface, a low-pass filter, an IR cut filter, and dummy glass for correcting the optical path length. Furthermore, in the zoom lens according to this embodiment, a structure may be adopted that allows switching between an IR cut filter and a dummy glass within the optical path in order to correct for changes in optical path length due to the insertion and removal of the IR cut filter.

[0129] Furthermore, in numerical examples 13 to 18, as shown in each lens cross-sectional view, when zooming from the wide-angle end to the telephoto end, each lens group moves as indicated by the arrows. Furthermore, the solid and dashed arrows shown in each lens cross-sectional diagram indicate the movement trajectories of the lens group when focused on an object at infinity and an object at close range, respectively.

[0130] The numerical data for each of the numerical examples 13 to 18 of the zoom lens according to this embodiment are shown below. In each numerical data point, the face number i is shown sequentially from the object side, ri is the radius of curvature of the i-th face, and di is the distance between the i-th face and the (i+1)-th face. Furthermore, in each numerical data, ndi and vdi represent the refractive index and Abbe number, respectively, based on the d-line of the medium (optical material) between the i-th and i+1-th surfaces.

[0131] Furthermore, in each numerical data, the two planes closest to the image correspond to the optical block G, and the angle of view represents the half-angle of view (ω) related to the usable angle of view considering distortion aberration. Furthermore, in each numerical data, the total optical length is expressed as the distance along the optical axis between the lens surface closest to the object and the paraxial image plane, as the air-equivalent length (length excluding the optical block G). In each numerical data, BF represents the back focus, which is the distance along the optical axis between the image-side lens surface and the paraxial image plane, expressed as an air-equivalent length.

[0132] [Numerical Example 13] Unit: mm Surface data Face number ri di ndi vdi 1 57.367 5.62 1.49700 81.5 2 -115.099 0.20 3 57.198 6.04 1.49700 81.5 4 -68.986 1.30 1.69680 55.5 5 -2018.260 5.66 6 -383.719 1.20 1.80400 46.5 7 66.666 (variable) 8 153.212 1.00 1.59522 67.7 9 27.849 3.30 10 -30.500 1.00 1.49700 81.5 11 44.585 1.62 1.95375 32.3 12 293.207 (variable) 13 75.937 2.26 1.49700 81.5 14 -69.226 0.19 15 53.926 4.05 1.49700 81.5 16 -26.528 1.00 1.77250 49.6 17 -3578.392 0.73 18 20.685 3.81 1.49700 81.5 19 -251.102 2.00 20 (aperture) ∞ 4.04 21 44.020 1.00 2.00100 29.1 22 24.778 10.07 23 98.973 1.94 1.56732 42.8 24 -38.655 2.16 25 -15.259 1.00 1.49700 81.5 26 -51.784 (variable) 27 -45.601 1.50 1.54814 45.8 28 -26.441 6.81 29 -21.616 1.00 1.49700 81.5 30 29.304 (Variable) 31 23.642 6.23 1.51742 52.4 32 -117.836 3.00 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.00 147.49 F-number 4.12 4.12 4.12 Field of view: 7.95, 5.60, 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.14 9.14 9.14 d 7 1.66 15.15 26.18 d12 25.52 12.03 0.99 d26 5.03 7.08 2.61 d30 9.53 7.48 11.95 Zoom lens group data Group starting plane focal length 1 1 119.15 2 8 -36.83 3 13 35.39 4 27 -34.27 5 31 38.64

[0133] [Numerical Example 14] Unit: mm Surface data Face number ri di ndi vdi 1 57.620 5.83 1.49700 81.5 2 -101.619 0.20 3 65.517 5.90 1.49700 81.5 4 -62.513 1.30 1.69680 55.5 5 413.465 5.30 6 -305.943 1.20 1.53172 48.8 7 59.808 (variable) 8 153.442 1.00 1.59522 67.7 9 31.220 3.17 10 -33.539 1.00 1.49700 81.5 11 47.540 1.41 2.00100 29.1 12 158.463 (variable) 13 65.656 2.65 1.49700 81.5 14 -58.167 0.20 15 47.644 3.97 1.49700 81.5 16 -30.851 1.00 1.80400 46.5 17 132.162 0.20 18 20.436 3.75 1.49700 81.5 19 -1189.539 3.46 20 (aperture) ∞ 10.93 21 77.825 1.00 2.00069 25.5 22 15.220 1.06 23 16.566 3.85 1.68893 31.1 24 -32.336 1.03 25 -15.687 1.00 1.49700 81.5 26 -628.303 (variable) 27 -48.445 1.41 1.51742 52.4 28 -23.895 5.01 29 -20.253 1.00 1.49700 81.5 30 33.697 (Variable) 31 23.074 4.88 1.51742 52.4 32 -369.459 3.46 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.33 147.49 F-number 4.12 4.12 4.12 Field of view: 7.96 5.59 4.06 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.60 9.60 9.60 d 7 1.79 16.00 27.62 d12 26.82 12.61 0.99 d26 5.14 8.02 3.99 d30 11.54 8.66 12.69 Zoom lens group data Group starting plane focal length 1 1 122.35 2 8 -38.24 3 13 34.67 4 27 -37.87 5 31 42.15

[0134] [Numerical Example 15] Unit: mm Surface data Face number ri di ndi vdi 1 55.734 5.77 1.43875 94.7 2 -126.601 0.20 3 66.008 5.81 1.49700 81.5 4 -67.235 1.30 1.65160 58.5 5 -305.292 7.59 6 -166.341 1.20 1.80400 46.5 7 90.551 (variable) 8 270.643 1.00 1.52841 76.5 9 30.096 2.95 10 -33.406 1.00 1.49700 81.5 11 42.727 1.51 1.85025 30.1 12 177.011 (variable) 13 89.945 2.04 1.43875 94.7 14 -73.026 0.20 15 52.911 4.00 1.49700 81.5 16 -26.288 1.00 1.77250 49.6 17 -173.129 0.20 18 17.939 4.14 1.43875 94.7 19 -660.923 2.05 20 (aperture) ∞ 2.00 21 34.417 1.00 1.95375 32.3 22 22.362 10.95 23 130.997 1.80 1.53172 48.8 24 -38.486 1.73 25 -13.935 1.00 1.43875 94.7 26 -53.280 (variable) 27 -36.854 1.50 1.51823 58.9 28 -23.250 6.13 29 -19.800 1.00 1.43875 94.7 30 30.862 (variable) 31 23.827 4.97 1.51742 52.4 32 -199.882 3.86 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.64 107.24 147.50 F-number 4.12 4.12 4.12 Field of view: 7.95 5.59 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.00 10.00 10.00 d 7 1.59 15.03 26.02 d12 25.43 11.99 1.00 d26 5.91 8.45 4.39 d30 10.66 8.11 12.18 Zoom lens group data Group starting plane focal length 1 1 121.44 2 8 -36.33 3 13 34.72 4 27 -37.64 5 31 41.46

[0135] [Numerical Example 16] Unit: mm Surface data Face number ri di ndi vdi 1 59.809 6.59 1.43875 94.7 2 -156.055 0.20 3 85.747 6.59 1.49700 81.5 4 -67.468 1.30 1.60311 60.6 5 314.144 0.20 6 51.409 4.13 1.43875 94.7 7 -3429.709 6.90 8 -307.259 1.20 1.77250 49.6 9 53.138 (variable) 10 -375.427 1.00 1.55343 72.2 11 28.213 2.64 12 -31.759 1.00 1.49700 81.5 13 37.460 1.56 1.85025 30.1 14 188.060 (variable) 15 110.499 1.95 1.43875 94.7 16 -56.832 0.20 17 60.645 3.61 1.49700 81.5 18 -24.313 1.00 1.80400 46.5 19 -98.980 0.20 20 18.165 3.75 1.43875 94.7 21 -350.169 4.88 22 (aperture) ∞ 2.00 23 43.359 1.00 2.00100 29.1 24 25.021 8.80 25 66.399 1.90 1.56732 42.8 26 -39.026 1.30 27 -14.306 1.00 1.43875 94.7 28 -55.125 (variable) 29 -63.298 1.50 1.53172 48.8 30 -25.532 4.42 31 -21.199 1.00 1.52841 76.5 32 25.873 (Variable) 33 22.442 5.60 1.51823 58.9 34 -143.647 4.62 35 ∞ 1.20 1.51633 64.1 36 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.74 147.50 F-number 4.12 4.12 4.12 Field of view: 7.99 5.58 4.08 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.76 10.76 10.76 d 9 2.17 13.71 23.15 d14 21.97 10.44 1.00 d28 3.71 6.34 3.71 d32 11.57 8.94 11.57 Zoom lens group data Group starting plane focal length 1 1 115.34 2 10 -30.83 3 15 31.31 4 29 -32.52 5 33 37.89

[0136] [Numerical Example 17] Unit: mm Surface data Face number ri di ndi vdi 1 56.679 5.46 1.49700 81.5 2 -131.452 0.20 3 51.180 6.12 1.49700 81.5 4 -78.078 1.30 1.69680 55.5 5 -1572.166 5.00 6 -516.735 1.20 1.80400 46.5 7 56.357 (variable) 8 114.547 1.00 1.59522 67.7 9 26.386 3.40 10 -31.503 1.00 1.49700 81.5 11 48.830 1.58 1.95375 32.3 12 436.325 (variable) 13 46.645 2.78 1.49700 81.5 14 -71.734 0.19 15 38.944 4.28 1.49700 81.5 16 -29.019 1.00 1.77250 49.6 17 47.511 0.20 18 20.295 3.87 1.49700 81.5 19 -190.034 2.03 20 (aperture) ∞ (variable) 21 17.178 1.00 1.95906 17.5 22 15.501 (Variable) 23 -586.018 1.63 1.56732 42.8 24 -32.245 1.29 25 -14.230 1.00 1.49700 81.5 26 -48.466 (variable) 27 -47.893 1.50 1.54072 47.2 28 -27.598 6.93 29 -22.216 1.00 1.49700 81.5 30 31.840 (variable) 31 24.526 5.25 1.51823 58.9 32 -111.319 3.49 33 ∞ 1.20 1.51633 64.1 34 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.63 107.06 147.49 F-number 4.12 4.12 4.12 Field of view: 7.95, 5.60, 4.05 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 9.63 9.63 9.63 d 7 1.70 15.63 27.03 d12 26.32 12.39 0.99 d20 3.30 4.69 6.48 d22 11.24 9.85 8.07 d26 5.92 7.54 2.51 d30 9.26 7.64 12.67 Zoom lens group data Group starting plane focal length 1 1 123.91 2 8 -38.09 3 13 32.52 4 21 -233.83 5 23 -135.09 6 27 -36.01 7 31 39.30

[0137] [Numerical Example 18] Unit: mm Surface data Face number ri di ndi vdi 1 58.222 5.48 1.49700 81.5 2 -121.663 0.20 3 59.251 5.85 1.49700 81.5 4 -72.532 1.30 1.69680 55.5 5 -760.044 5.42 6 -313.544 1.20 1.80400 46.5 7 70.402 (variable) 8 148.686 1.00 1.59522 67.7 9 30.049 3.11 10 -32.585 1.00 1.49700 81.5 11 47.068 1.56 1.90366 31.3 12 306.325 (variable) 13 63.554 2.24 1.49700 81.5 14 -86.780 0.20 15 47.720 4.05 1.49700 81.5 16 -28.017 1.00 1.77250 49.6 17 274.913 0.20 18 19.913 3.88 1.49700 81.5 19 -298.777 2.14 20 (aperture) ∞ 2.00 21 33.929 1.00 1.95375 32.3 22 21.747 11.18 23 45.613 2.23 1.51742 52.4 24 -43.956 1.24 25 -16.488 1.00 1.49700 81.5 26 -75.329 (variable) 27 453.846 1.88 1.51742 52.4 28 -30.718 0.20 29 33.287 1.00 1.49700 81.5 30 19.739 3.05 31 -17.157 1.00 1.49700 81.5 32 37.240 (Variable) 33 23.779 5.14 1.51823 58.9 34 -208.829 4.29 35 ∞ 1.20 1.51633 64.1 36 ∞ 5.35 Image plane ∞ Various data Zoom ratio 1.95 Wide-angle, Medium, Telephoto Focal length 75.62 108.04 147.50 F-number 4.12 4.12 4.12 Field of view: 8.00 5.58 4.07 Image height 10.72 10.72 10.72 Optical total length 127.60 127.60 127.60 BF 10.43 10.43 10.43 d 7 1.61 15.78 27.37 d12 26.75 12.58 0.99 d26 6.13 6.77 2.50 d32 11.95 11.31 15.58 Zoom lens group data Group starting plane focal length 1 1 120.05 2 8 -38.92 3 13 35.51 4 27 -31.29 5 33 41.51

[0138] Furthermore, the values ​​of each conditional expression in each of the numerical examples 13 to 18 of the zoom lens according to this embodiment are shown in Table 3 below. [Table 3]

[0139] As described above, according to this embodiment, it is possible to obtain a zoom lens that is small and lightweight, yet provides high optical performance across the entire range of object distances, and an imaging device having the same.

[0140] Next, an imaging device having a solid-state image sensor that receives an image formed by a zoom lens according to any of the first to third embodiments will be described. Specifically, the imaging device has a solid-state image sensor such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor for digitally processing images.

[0141] Figure 37 shows a perspective view of an imaging device 50 using a zoom lens according to any of the first to third embodiments as the imaging optical system 15. As shown in Figure 37, the imaging device 50 comprises a main body 11, an image sensor 12 such as a CCD sensor or a CMOS sensor, and a memory unit 13 that records information corresponding to the subject image converted photoelectrically by the image sensor 12.

[0142] The imaging device 50 also includes a network cable 14 for transmitting the subject image converted photoelectrically by the image sensor 12, and an imaging optical system 15 formed by a zoom lens according to any of the first to third embodiments. Furthermore, when the imaging device 50 is used, for example, as a surveillance camera, a protective cover may be attached to the object side of the imaging optical system 15, or a hemispherical dome cover may be attached.

[0143] Furthermore, the imaging device 50 can be used not only as a surveillance camera, but also as a video camera, digital camera, etc. Furthermore, by using an electronic image sensor such as a CCD sensor as the image sensor 12 in the imaging device 50, aberration correction can be performed electronically, thereby further improving the image quality of the output image.

[0144] Furthermore, the shape of each lens and the number of lenses in the zoom lens according to any of the first to third embodiments may be changed as appropriate. Furthermore, in a zoom lens according to any of the first to third embodiments, image blur caused by vibrations such as camera shake may be corrected by moving some of the lenses or lens groups in a direction having a component perpendicular to the optical axis, that is, in a direction non-parallel to the optical axis. Furthermore, distortion, chromatic aberration, and the like may be corrected by providing an electrical correction means in the zoom lens according to any of the first to third embodiments.

[0145] Although preferred embodiments have been described above, the invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence.

[0146] This embodiment includes the following configuration. (Configuration 1) A zoom lens comprising, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and comprising at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power, an image-side negative lens group having a negative refractive power, and an intermediate lens group. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves while the interval between adjacent lens groups changes. In the intermediate lens group, a negative lens having a negative refractive power and having a concave lens surface on the object side is disposed closest to the image side, and a positive lens having a positive refractive power is disposed adjacent to the object side of the negative lens. When the Abbe number based on the d-line of the negative lens is Vdn and the Abbe number based on the d-line of the positive lens is Vdp, the zoom lens is characterized by satisfying the conditional expression 1.5 < Vdn / Vdp < 5.0. (Configuration 2) The zoom lens according to Configuration 1, characterized by satisfying the conditional expression 70 < Vdn < 150. (Configuration 3) The zoom lens according to Configuration 1 or 2, characterized by satisfying the conditional expression -5.0 < (Rn1 + Rn2) / (Rn1 - Rn2) < 0.0 when the radius of curvature of the lens surface on the object side of the negative lens is Rn1 and the radius of curvature of the lens surface on the image side of the negative lens is Rn2. (Configuration 4) The zoom lens according to any one of Configurations 1 to 3, characterized by satisfying the conditional expression 1.0 < Rp2 / Rn1 < 5.0 when the radius of curvature of the lens surface on the object side of the negative lens is Rn1 and the radius of curvature of the lens surface on the image side of the positive lens is Rp2. (Configuration 5) The zoom lens according to any one of Configurations 1 to 4, characterized by comprising an aperture disposed on the object side of the negative lens and satisfying the conditional expression -2.0 < Ln1 / Rn1 < -0.5 when the radius of curvature of the lens surface on the object side of the negative lens is Rn1 and the distance on the optical axis between the aperture and the lens surface on the object side of the negative lens is Ln1. When the focal length of the negative lens is fn and the air equivalent length between the lens surface on the image side of the negative lens and the image plane is Lr, the zoom lens according to any one of Configurations 1 to 5, characterized in that it satisfies the conditional expression -2.0 < fn / Lr < -0.4. When the focal length of the negative lens is fn and the focal length of the image-side negative lens group is frn, the zoom lens according to any one of Configurations 1 to 6, characterized in that it satisfies the conditional expression 0.5 < fn / frn < 2.0. A zoom lens comprising, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and comprising at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power and an image-side negative lens group having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves while the interval between adjacent lens groups changes. The first lens group includes at least two lenses each having a positive refractive power and a negative lens having a negative refractive power, being disposed closest to the image side, and having a concave lens surface on the image side. When the focal length of the first lens group is f1, the focal length of the negative lens is fr1, and the overall optical length of the zoom lens is TL, the zoom lens is characterized in that it satisfies the conditional expressions -1.2 < fr1 / f1 < -0.5 and 0.85 < f1 / TL < 1.20. When the overall length of the first lens group is L1, the zoom lens according to Configuration 8, characterized in that it satisfies the conditional expression -6.0 < fr1 / L1 < -1.0. When at least two lenses include the positive lens disposed closest to the object side in the first lens group and the focal length of the positive lens is f11, the zoom lens according to Configuration 8 or 9, characterized in that it satisfies the conditional expression -2.0 < fr1 / f11 < -0.4. When the focal length at the telephoto end of the zoom lens is fT, the zoom lens according to any one of Configurations 8 to 10, characterized in that it satisfies the conditional expression 0.6 < TL / fT < 1.0. The zoom lens according to any one of Configurations 8 to 11, characterized in that when the Abbe number based on the d-line of the negative lens is Vdr1, the conditional expression 40 < Vdr1 < 80 is satisfied. The zoom lens according to any one of Configurations 8 to 12, characterized in that when the average value of the Abbe numbers based on the d-line of each lens having a negative refractive power included in the first lens group is Vdnave1, the conditional expression 40 < Vdnave1 < 80 is satisfied. The zoom lens according to any one of Configurations 8 to 13, characterized in that at least two lenses include the positive lens disposed closest to the object side in the first lens group, and when the Abbe number based on the d-line of the positive lens is Vd11 and the Abbe number based on the d-line of the negative lens is Vdr1, the conditional expression 1.2 < Vd11 / Vdr1 < 3.0 is satisfied. A zoom lens comprising, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and having at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power and an image-side negative lens group having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves, and the interval between adjacent lens groups changes. The image-side negative lens group moves during focusing, is disposed closest to the object side, has a positive refractive power, and has a convex lens surface on the image side. When the Abbe number based on the d-line of the negative lens having the smallest absolute value of the focal length among at least one lens is Vdn, the zoom lens is characterized in that the conditional expression 70 < Vdn < 150 is satisfied. The zoom lens according to Configuration 15, characterized in that when the focal length of the negative lens is fFn and the total length of the image-side negative lens group is LF, the conditional expression -5.0 < fFn / LF < -2.0 is satisfied. When the radius of curvature of the lens surface on the image side of the positive lens is R2p and the radius of curvature of the lens surface on the object side of the negative lens is R1n, the zoom lens according to Configuration 15 or 16, characterized in that it satisfies the conditional expression 1.0 < R2p / R1n < 2.0. When the focal length of the negative lens is fFn and the focal length of the positive lens is fFp, the zoom lens according to any one of Configurations 15 to 17, characterized in that it satisfies the conditional expression -8.0 < fFp / fFn < -1.5. When the Abbe number of the positive lens based on the d-line is Vdp, the zoom lens according to any one of Configurations 15 to 18, characterized in that it satisfies the conditional expression 1.2 < Vdn / Vdp < 3.0. When the focal length of the image-side negative lens group is fn and the focal length of the image-side positive lens group is fp, the zoom lens according to any one of Configurations 15 to 19, characterized in that it satisfies the conditional expression -2.0 < fp / fn < -1.0. A zoom lens comprising, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group having a positive refractive power as a whole and having at least three lens groups. The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power and an image-side negative lens group having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the image-side negative lens group moves, and the interval between adjacent lens groups changes. The subsequent group includes an intermediate lens group. In the intermediate lens group, a negative lens having a negative refractive power and having a concave lens surface on the object side is disposed closest to the image side, and a positive lens having a positive refractive power is disposed adjacent to the object side of the negative lens. The zoom lens according to Configuration 21. When the Abbe number of the negative lens based on the d-line is Vdn and the Abbe number of the positive lens based on the d-line is Vdp, the zoom lens according to Configuration 22, characterized in that it satisfies the conditional expression 1.5 < Vdn / Vdp < 5.0. (Configuration 24) The first lens group includes at least two lenses each having a positive refractive power, and a negative lens having a negative refractive power, being disposed on the most image side, and having a concave shape on the image-side lens surface. The zoom lens according to Configuration 21, characterized in that it includes these components. (Configuration 25) When the focal length of the first lens group is f1, the focal length of the negative lens is fr1, and the overall optical length of the zoom lens is TL, the zoom lens according to Configuration 24, characterized in that it satisfies the conditional expression: -1.2 < fr1 / f1 < -0.5, 0.85 < f1 / TL < 1.20. (Configuration 26) The image-side negative lens group includes a positive lens that moves during focusing, is disposed on the most object side, has a positive refractive power, and has a convex shape on the image-side lens surface, and at least one lens each having a negative refractive power. The zoom lens according to Configuration 21, characterized in that it includes these components. (Configuration 27) When the Abbe number based on the d-line of the negative lens having the smallest absolute value of the focal length among at least one lens is Vdn, the zoom lens according to Configuration 26, characterized in that it satisfies the conditional expression: 70 < Vdn < 150. (Configuration 28) An imaging device comprising the zoom lens according to any one of Configurations 1 to 27, and an imaging element that receives an image formed by the zoom lens.

Explanation of Reference Numerals

[0147] B1 First lens group B2 Second lens group B3 Third lens group (subsequent group) B4 Fourth lens group (subsequent group) B5 Fifth lens group (subsequent group) B6 Sixth lens group (subsequent group, image-side negative lens group) B7 Seventh lens group (subsequent group, image-side positive lens group)

Claims

1. 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, and a subsequent group having positive refractive power as a whole and having at least three lens groups, The subsequent group includes, in order from the image side to the object side, an image-side positive lens group having a positive refractive power, an image-side negative lens group having a negative refractive power, and an intermediate lens group. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the negative lens group on the image side moves, and the spacing between adjacent lens groups changes. In the aforementioned intermediate lens group, a negative lens having negative refractive power and a concave lens surface on the object side is positioned closest to the image, and a positive lens having positive refractive power is positioned adjacent to the object side of the negative lens. When Vdn is the Abbe number with respect to the d line of the negative lens, and Vdp is the Abbe number with respect to the d line of the positive lens, 1.5<Vdn / Vdp<5.0 A zoom lens characterized by satisfying the following condition.

2. 70<Vdn<150 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. When the radius of curvature of the object-side lens surface of the negative lens is Rn1, and the radius of curvature of the image-side lens surface of the negative lens is Rn2, -5.0<(Rn1+Rn2) / (Rn1-Rn2)<0.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

4. When the radius of curvature of the object-side lens surface of the negative lens is Rn1, and the radius of curvature of the image-side lens surface of the positive lens is Rp2, 1.0<Rp2 / Rn1<5.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

5. The negative lens is provided with an aperture located on the object side, When Rn1 is the radius of curvature of the object-side lens surface of the negative lens, and Ln1 is the distance on the optical axis between the aperture and the object-side lens surface of the negative lens, -2.0<Ln1 / Rn1<-0.5 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

6. When the focal length of the negative lens is fn and the air-equivalent length between the image-side lens surface and the image plane of the negative lens is Lr, -2.0<fn / Lr<-0.4 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

7. When the focal length of the negative lens is fn and the focal length of the image-side negative lens group is frn, 0.5<fn / frn<2.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

8. 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, and a subsequent group having positive refractive power as a whole and having at least three lens groups, The subsequent group includes, in order from the image side to the object side, a group of positive image-side lenses having a positive refractive power and a group of negative image-side lenses having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the negative lens group on the image side moves, and the spacing between adjacent lens groups changes. The first lens group includes at least two lenses, each having a positive refractive power, and a negative lens having a negative refractive power, positioned closest to the image, and having a concave shape on the image-side lens surface. When the focal length of the first lens group is f1, the focal length of the negative lens is fr1, and the total optical length of the zoom lens is TL, -1.2<fr1 / f1<-0.5 0.85<f1 / TL<1.20 A zoom lens characterized by satisfying the following condition.

9. When the total length of the first lens group is L1, -6.0<fr1 / L1<-1.0 The zoom lens according to claim 8, characterized in that it satisfies the following condition.

10. The at least two lenses include a positive lens positioned closest to the object in the first lens group, When the focal length of the positive lens is set to f11, -2.0<fr1 / f11<-0.4 The zoom lens according to claim 8, characterized in that it satisfies the following condition.

11. When the focal length at the telephoto end of the zoom lens is denoted as fT, 0.6<TL / fT<1.0 The zoom lens according to claim 8, characterized in that it satisfies the following condition.

12. When the Abbe number with respect to the d line of the negative lens is Vdr1, 40<Vdr1<80 The zoom lens according to claim 8, characterized in that it satisfies the following condition.

13. When Vdnave1 is the average value of the Abbe numbers with respect to the d line of each of the negative refractive power lenses included in the first lens group, 40<Vdnave1<80 The zoom lens according to claim 8, characterized in that it satisfies the following condition.

14. The at least two lenses include a positive lens positioned closest to the object in the first lens group, When the Abbe number with respect to the d line of the positive lens is Vd11 and the Abbe number with respect to the d line of the negative lens is Vdr1, 1.2<Vd11 / Vdr1<3.0 The zoom lens according to claim 8, characterized in that it satisfies the following condition.

15. 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, and a subsequent group having positive refractive power as a whole and having at least three lens groups, The subsequent group includes, in order from the image side to the object side, a group of positive image-side lenses having a positive refractive power and a group of negative image-side lenses having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the negative lens group on the image side moves, and the spacing between adjacent lens groups changes. The aforementioned image-side negative lens group moves during focusing and includes a positive lens that is positioned closest to the object, has positive refractive power, and has a convex shape on the image-side lens surface, and at least one lens, each having negative refractive power. When Vdn is the Abbe number with respect to the d line of the negative lens with the smallest absolute value of focal length among the at least one of the lenses, 70<Vdn<150 A zoom lens characterized by satisfying the following condition.

16. When the focal length of the negative lens is fFn and the total length of the image-side negative lens group is LF, -5.0<fFn / LF<-2.0 The zoom lens according to claim 15, characterized in that it satisfies the following condition.

17. When the radius of curvature of the image-side lens surface of the positive lens is R2p, and the radius of curvature of the object-side lens surface of the negative lens is R1n, 1.0<R2p / R1n<2.0 The zoom lens according to claim 15, characterized in that it satisfies the following condition.

18. When the focal length of the negative lens is fFn and the focal length of the positive lens is fFp, -8.0<fFp / fFn<-1.5 The zoom lens according to claim 15, characterized in that it satisfies the following condition.

19. When Vdp is the Abbe number with respect to the d line of the positive lens, 1.2<Vdn / Vdp<3.0 The zoom lens according to claim 15, characterized in that it satisfies the following condition.

20. When the focal length of the negative lens group on the image side is fn and the focal length of the positive lens group on the image side is fp, -2.0<fp / fn<-1.0 The zoom lens according to claim 15, characterized in that it satisfies the following condition.

21. 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, and a subsequent group having positive refractive power as a whole and having at least three lens groups, The subsequent group includes, in order from the image side to the object side, a group of positive image-side lenses having a positive refractive power and a group of negative image-side lenses having a negative refractive power. A zoom lens characterized in that, when zooming from the wide-angle end to the telephoto end, the first lens group does not move, the second lens group moves, and the negative lens group on the image side moves, while the spacing between adjacent lens groups changes.

22. A zoom lens according to any one of claims 1 to 21, An image sensor that receives the image formed by the zoom lens, An imaging device characterized by comprising:

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