Zoom lens, and imaging device and imaging system having the same

Abstract

To provide a negative lead-type, wide-angle zoom lens which is compact and light-weight, and yet offers superior optical performance over an entire zoom range.SOLUTION: A zoom lens provided herein comprises a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, and a fourth lens group L4 having positive refractive power. The first lens group consists of three or more lenses. When zooming from the wide-angle end to the telephoto end, the first lens group is stationary relative to the image plane. A focal length f1 of the first lens group, a focal length f2 of the second lens group, a focal length f4 of the fourth lens group, a distance LD1 along an optical axis from an object-side lens surface of a lens located on the most object side in the first lens group to an image-side lens surface of a lens located on the most image side in the first lens group, and a total length TTL of the zoom lens at the wide-angle end satisfy predetermined conditional expressions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens and is suitable for imaging devices such as digital still cameras, digital video cameras, broadcast cameras, surveillance cameras, in-vehicle cameras, and silver halide film cameras. [Background technology]

[0002] In recent years, there has been a demand for imaging optical systems used in imaging devices that are compact zoom lenses with a wide field of view and high optical performance across the entire zoom range.

[0003] Patent Document 1 proposes a negative-lead type wide-angle zoom lens in which the first lens group with negative refractive power is positioned closest to the object, as a zoom lens that is compact overall and easily widens the field of view.

[0004] The negative lead type wide-angle zoom lens proposed in Patent Document 1 achieves a wider angle of view and high optical performance by moving the first lens group with negative refractive power when zooming from the wide-angle end to the telephoto end. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-101750 (Public Relations) [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, a configuration that moves a large and heavy first lens group, such as the wide-angle zoom lens described in Patent Document 1, complicates the movement mechanism and is disadvantageous from the standpoint of miniaturization and weight reduction.

[0007] The present invention provides a negative-lead type wide-angle zoom lens that is compact and lightweight, yet possesses high optical performance across the entire zoom range. [Means for solving the problem]

[0008] A zoom lens as one aspect of the present invention consists of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end, the first lens group and the fourth lens group each consist of three or more lenses, the first lens group has a first negative lens and a second negative lens arranged on the image side of the first negative lens, the first lens group is fixed with respect to the image plane when zooming from the wide-angle end to the telephoto end, the third lens group consists of one negative single lens or two negative single lenses, and the third lens group is - A group of focusing lenses that move during casing, where the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the fourth lens group is f4, the distance along the optical axis from the object-side lens surface of the lens closest to the object in the first lens group to the image-side lens surface of the lens closest to the image in the first lens group is LD1, the air-equivalent length of the distance along the optical axis from the object-side lens surface of the lens closest to the object in the zoom lens at the wide-angle end to the image plane is TTL, the air-equivalent amount of the distance along the optical axis from the image-side lens surface of the lens closest to the image in the zoom lens at the wide-angle end to the image plane is BFw, and the focal length of the second negative lens is fn2. 0.85<(-f1) / f2 ≦1.18 0.00 < (-f1) / f4 < 0.55 0.00 <LD1 / TTL<0.27 0.37 <BFw / (-f1)<1.50 1.34 ≤ fn² / f1 < 10.0 It is characterized by satisfying the following conditional expression.

[0009] Other objects and features of the present invention are described in the following embodiments. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a negative-lead type wide-angle zoom lens that is small and lightweight while having high optical performance over the entire zoom range.

Brief Description of the Drawings

[0011] [Figure 1] It is a lens cross-sectional view at infinity focus at the wide-angle end and the telephoto end of Example 1. [Figure 2] It is a longitudinal aberration diagram at infinity focus at the (a) wide-angle end and (b) telephoto end of Example 1. [Figure 3] It is a lens cross-sectional view at infinity focus at the wide-angle end and the telephoto end of Example 2. [Figure 4] It is a longitudinal aberration diagram at infinity focus at the (a) wide-angle end and (b) telephoto end of Example 2. [Figure 5] It is a lens cross-sectional view at infinity focus at the wide-angle end and the telephoto end of Example 3. [Figure 6] It is a longitudinal aberration diagram at infinity focus at the (a) wide-angle end and (b) telephoto end of Example 3. [[ID=q27]] [Figure 7] It is a lens cross-sectional view at infinity focus at the wide-angle end and the telephoto end of Example 4. [Figure 8] It is a longitudinal aberration diagram at infinity focus at the (a) wide-angle end and (b) telephoto end of Example 4. [Figure 9] It is a lens cross-sectional view at infinity focus at the wide-angle end and the telephoto end of Example 5. [Figure 10] It is a longitudinal aberration diagram at infinity focus at the (a) wide-angle end and (b) telephoto end of Example 5. [Figure 11] It is a lens cross-sectional view at infinity focus at the wide-angle end and the telephoto end of Example 6. [Figure 12] It is a longitudinal aberration diagram at infinity focus at the (a) wide-angle end and (b) telephoto end of Example 6. [Figure 13]It is a lens cross-sectional view when focusing on an infinite object at the wide-angle end and the telephoto end of Example 7. [Figure 14] It is a longitudinal spherical aberration diagram when focusing on an infinite object at the (a) wide-angle end and (b) telephoto end of Example 7. [Figure 15] It is a lens cross-sectional view when focusing on an infinite object at the wide-angle end and the telephoto end of Example 8. [Figure 16] It is a longitudinal spherical aberration diagram when focusing on an infinite object at the (a) wide-angle end and (b) telephoto end of Example 8. [Figure 17] It is a lens cross-sectional view when focusing on an infinite object at the wide-angle end and the telephoto end of Example 9. [Figure 18] It is a longitudinal spherical aberration diagram when focusing on an infinite object at the (a) wide-angle end and (b) telephoto end of Example 9. [Figure 19] It is a lens cross-sectional view when focusing on an infinite object at the wide-angle end and the telephoto end of Example 10. [Figure 20] It is a longitudinal spherical aberration diagram when focusing on an infinite object at the (a) wide-angle end and (b) telephoto end of Example 10. [Figure 21] It is a lens cross-sectional view when focusing on an infinite object at the wide-angle end and the telephoto end of Example 11. [Figure 22] It is a longitudinal spherical aberration diagram when focusing on an infinite object at the (a) wide-angle end and (b) telephoto end of Example 11. [[ID=??]] [Figure 23] It is a lens cross-sectional view when focusing on an infinite object at the wide-angle end and the telephoto end of Example 12. [Figure 24] It is a longitudinal spherical aberration diagram when focusing on an infinite object at the (a) wide-angle end and (b) telephoto end of Example 12. [Figure 25] It is a lens cross-sectional view when focusing on an infinite object at the wide-angle end and the telephoto end of Example 13. [Figure 26] It is a longitudinal spherical aberration diagram when focusing on an infinite object at the (a) wide-angle end and (b) telephoto end of Example 13. [Figure 27] It is a schematic diagram of an imaging device.

Best Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the zoom lens and imaging apparatus and imaging system having the same will be described based on the attached drawings.

[0013] Figures 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, and 25 are cross-sectional views of the zoom lenses of Examples 1 to 13 at the wide-angle (WIDE) and telephoto (TELE) ends when focused at infinity. The zoom lenses of each example are used in imaging devices such as digital still cameras, silver halide film cameras, digital video cameras, surveillance cameras, broadcast cameras, and in-vehicle cameras.

[0014] In each cross-sectional view of the lens, the left side is the object side (front), and the right side is the image side (rear). The zoom lens of each embodiment is composed of multiple lens groups. In this specification, a lens group is a collection of lenses that move or remain stationary as a whole during zooming. That is, in the zoom lens of each embodiment, the distance between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end. A lens group may consist of one lens or multiple lenses. Furthermore, a lens group may include an aperture diaphragm.

[0015] In each lens cross-section diagram, Li represents the i-th lens group (where i is a natural number) from the object side of the zoom lens.

[0016] SP is the aperture diaphragm. The aperture diaphragm SP determines (limits) the light beam at the open F-number (Fno). IP is the image plane, and when the zoom lens of each embodiment is used as the photographic optical system of a digital still camera or video camera, the image plane of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed on it. When the zoom lens of each embodiment is used as the photographic optical system of a silver halide film camera, a photosensitive surface corresponding to the film plane is placed on the image plane IP.

[0017] The arrows along the optical axis indicate the direction of movement of the focusing lens group when focusing from infinity to close range. The solid arrows below each lens group indicate the movement trajectory of each lens group when zooming from the wide-angle end to the telephoto end. The vertical dashed lines below each lens group indicate that each lens group is fixed relative to the image plane when zooming from the wide-angle end to the telephoto end. The double arrows perpendicular to the optical axis indicate the movement of the lens group during image stabilization (image shake correction).

[0018] In the following embodiments, the wide-angle end and telephoto end refer to the zoom positions when the zoom lens group is located at both ends of the range in which it can move along the optical axis due to the mechanism.

[0019] Figures 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, and 26 are aberration diagrams of the zoom lenses of Examples 1 to 13 at infinity focus, respectively. (a) shows the aberration diagram at the wide-angle end, and (b) shows the aberration diagram at the telephoto end.

[0020] In the spherical aberration diagram, Fno is the F-number and indicates the amount of spherical aberration for the d-line (wavelength 587.56 nm) and the g-line (wavelength 435.84 nm). In the astigmatism diagram, S indicates the amount of astigmatism at the sagittal image plane for the d-line, and M indicates the amount of astigmatism at the meridional image plane for the d-line. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration at the g-line is shown. ω is the half-angle of view (°) (angle of view in paraxial calculation) and indicates the angle of view based on ray tracing values.

[0021] Next, we will describe the characteristic configurations of the zoom lenses in each embodiment.

[0022] The zoom lens in each embodiment consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. In the zoom lens of each embodiment, the spacing between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end.

[0023] The first lens group L1 consists of three or more lenses. When zooming from the wide-angle end to the telephoto end, the first lens group L1 is fixed relative to the image plane IP.

[0024] Furthermore, the zoom lens of each embodiment satisfies the following conditions (1) to (3). Here, the focal length of the first lens group L1 is f1, the focal length of the second lens group L2 is f2, and the focal length of the fourth lens group L4 is f4. LD1 is the distance along the optical axis from the object-side lens surface of the lens closest to the object in the first lens group L1 to the image-side lens surface of the lens closest to the image in the first lens group L1. TTL is the air-equivalent length (total length when parallel plates such as filters are removed) (total lens length) of the distance along the optical axis from the object-side lens surface of the lens closest to the object to the image plane IP in the zoom lens at the wide-angle end.

[0025] 0.85 < (-f1) / f2 < 2.00 ···(1) 0.00 < (-f1) / f4 < 0.55 ... (2) 0.00 <LD1 / TTL<0.27 ···(3) Conditional equation (1) is a conditional equation that defines the ratio of the focal length f1 of the first lens group L1 to the focal length f2 of the second lens group L2. If the refractive power of the second lens group L2 becomes stronger than the upper limit of conditional equation (1), aberration correction becomes difficult. If the refractive power of the second lens group L2 becomes weaker than the lower limit of conditional equation (1), the amount of movement of the second lens group L2 during zooming increases, leading to the need for larger zoom lenses.

[0026] Conditional equation (2) defines the ratio of the focal length f1 of the first lens group L1 to the focal length f4 of the fourth lens group L4. By satisfying the numerical range of conditional equation (2), it is possible to miniaturize the zoom lens while ensuring telecentricity. If the refractive power of the fourth lens group L4 becomes stronger to the extent that it exceeds the upper limit of conditional equation (2), the telecentricity will increase, but it will be disadvantageous for miniaturizing the zoom lens. Note that it will never fall below the lower limit of conditional equation (2).

[0027] Conditional equation (3) defines the ratio of the optical axis distance LD1 from the object-side surface of the lens closest to the object in the first lens group L1 to the image-side surface of the lens closest to the image in the first lens group L1 to the total lens length TTL of the zoom lens at the wide-angle end. Satisfying the numerical range of conditional equation (3) makes it possible to reduce the weight of the zoom lens. If the value exceeds the upper limit of conditional equation (3), the distance LD1 becomes too large, and the first lens group L1 becomes too large. Note that the value will never fall below the lower limit of conditional equation (3).

[0028] Furthermore, it is more preferable that the numerical ranges of conditional expressions (1) to (3) be within the ranges of the following conditional expressions (1a) to (3a).

[0029] 0.88 < (-f1) / f2 < 1.70 ···(1a) 0.09 < (-f1) / f4 < 0.52 ···(2a) 0.07 <LD1 / TTL<0.25 ···(3a) Furthermore, it is even more preferable that the numerical ranges of conditional expressions (1) to (3) be the numerical ranges of the following conditional expressions (1b) to (3b).

[0030] 0.89 < (-f1) / f2 < 1.41 ···(1b) 0.16 < (-f1) / f4 < 0.50 ···(2b) 0.13 <LD1 / TTL<0.24 ···(3b) As described above, the zoom lenses of each embodiment are configured to satisfy conditions (1) to (3). This makes it possible to provide a negative lead type wide-angle zoom lens that is compact and lightweight while having high optical performance across the entire zoom range.

[0031] Next, we will describe the configurations that are preferable to satisfy in each embodiment of the zoom lens.

[0032] In the zoom lens of each embodiment, it is preferable that the first lens group L1 consists only of lenses having refractive power. This makes it possible to correct aberrations occurring in the first lens group L1 to a good level, which is advantageous for miniaturizing the zoom lens.

[0033] In the zoom lens of each embodiment, the second lens group L2 preferably includes an aperture diaphragm SP. Furthermore, the third lens group L3 is preferably a focusing lens group that moves during focusing. This enables high optical performance across focusing from near-range to far-range objects.

[0034] Next, we will describe the conditions that the zoom lenses of each embodiment preferably satisfy. The zoom lenses of each embodiment preferably satisfy one or more of the following conditional formulas (4) to (17).

[0035] Here, when an object at infinity is in focus, the distance along the optical axis from the image-side lens surface to the image plane IP of the lens positioned closest to the image in the zoom lens at the wide-angle end is defined as the air equivalent (distance when parallel plates such as filters are removed) (back focus), which is BFw. The focal length of the zoom lens at the wide-angle end is defined as fw. The focal length of the third lens group L3 is defined as f3. The focal length of the zoom lens at the telephoto end is defined as ft. When an object at infinity is in focus, the lateral magnification of the second lens group L2 at the telephoto end is defined as β2t, and the lateral magnification of the second lens group L2 at the wide-angle end is defined as β2w. The lateral magnification of the third lens group L3 at the telephoto end is defined as β3t, and the lateral magnification of the third lens group L3 at the wide-angle end is defined as β3w. The focal length of the first negative lens in the first lens group L1 is defined as fn1. The focal length of the second negative lens in the first lens group L1 is defined as fn2. Let fp1 be the focal length of the first positive lens in the first lens group L1.

[0036] 0.30 <BFw / (-f1)<1.50 ···(4) 0.07 <BFw / TTL<0.30 ···(5) 2.0 <TTL / (-f1)<6.0 ···(6) 3.0 <TTL / fw<7.5 ···(7) 0.1 <f2 / (-f3)<1.5 ···(8) 0.05 <f2 / f4<0.80 ···(9) 0.1 < (-f3) / f4 < 2.0 ... (10) 0.5 < (-f1) / fw < 2.5 ... (11) 0.2 < (-f1) / ft < 1.4 ···(12) 0.5 < β2t / β2w < 3.0 ···(13) 0.5 < β3t / β3w < 2.0 ···(14) 0.5 <fn1 / f1<2.0 ···(15) 0.5 <fn2 / f1<10.0 ···(16) 0.5 <fp1 / (-f1)<5.0 ···(17) Conditional equation (4) is a conditional equation that defines the ratio of the back focus BFw of the zoom lens at the wide-angle end when an object at infinity is in focus to the focal length f1 of the first lens group L1. If the refractive power of the first lens group L1 becomes too strong, exceeding the upper limit of conditional equation (4), aberration correction becomes difficult, which is undesirable. If the refractive power of the first lens group L1 becomes too weak, falling below the lower limit of conditional equation (4), it leads to an increase in the size of the zoom lens, which is also undesirable.

[0037] Conditional equation (5) is a conditional equation that defines the ratio of the back focus BFw of a zoom lens at the wide-angle end when an object at infinity is in focus to the total lens length TTL of the zoom lens at the wide-angle end. By satisfying the numerical range of conditional equation (5), it is possible to miniaturize the zoom lens while ensuring telecentricity. Exceeding the upper limit of conditional equation (5) is undesirable because it will increase the size of the zoom lens. Exceeding the lower limit of conditional equation (5) is undesirable because the back focus BFw becomes too short, making it difficult to ensure telecentricity.

[0038] Conditional equation (6) is a conditional equation that defines the ratio of the total lens length TTL of the zoom lens at the wide-angle end to the focal length f1 of the first lens group L1. If the refractive power of the first lens group L1 becomes too strong, exceeding the upper limit of conditional equation (6), aberration correction becomes difficult, which is undesirable. If the refractive power of the first lens group L1 becomes too weak, falling below the lower limit of conditional equation (6), it leads to an increase in the size of the zoom lens, which is also undesirable.

[0039] Conditional equation (7) is a conditional equation that defines the ratio of the total lens length TTL of the zoom lens at the wide-angle end to the focal length fw of the zoom lens at the wide-angle end. Exceeding the upper limit of conditional equation (7) is undesirable because it leads to an increase in the size of the zoom lens. Exceeding the lower limit of conditional equation (7) is also undesirable because it makes aberration correction difficult.

[0040] Conditional equation (8) is a conditional equation that defines the ratio of the focal length f2 of the second lens group L2 to the focal length f3 of the third lens group L3. If the refractive power of the second lens group L2 becomes too weak to exceed the upper limit of conditional equation (8), it will lead to an increase in the size of the zoom lens, which is undesirable. If the refractive power of the second lens group L2 becomes too strong to exceed the lower limit of conditional equation (8), aberration correction will become difficult, which is also undesirable.

[0041] Conditional equation (9) is a conditional equation that defines the ratio of the focal length f2 of the second lens group L2 to the focal length f4 of the fourth lens group L4. If the refractive power of the second lens group L2 becomes too weak to exceed the upper limit of conditional equation (9), it will lead to an increase in the size of the zoom lens, which is undesirable. If the refractive power of the second lens group L2 becomes too strong to exceed the lower limit of conditional equation (9), it will become difficult to correct aberrations, which is also undesirable.

[0042] Conditional equation (10) is a conditional equation that defines the ratio of the focal length f3 of the third lens group L3 to the focal length f4 of the fourth lens group L4. If the refractive power of the third lens group L3 becomes too weak to exceed the upper limit of conditional equation (10), it will lead to an increase in the size of the zoom lens, which is undesirable. If the refractive power of the third lens group L3 becomes too strong to exceed the lower limit of conditional equation (10), aberration correction will become difficult, which is also undesirable.

[0043] Conditional equation (11) is a conditional equation that defines the ratio of the focal length f1 of the first lens group L1 to the focal length fw of the zoom lens at the wide-angle end. If the refractive power of the first lens group L1 becomes too weak to exceed the upper limit of conditional equation (11), it will lead to an increase in the size of the zoom lens, which is undesirable. If the refractive power of the first lens group L1 becomes too strong to exceed the lower limit of conditional equation (11), aberration correction will become difficult, which is also undesirable.

[0044] Conditional equation (12) is a conditional equation that defines the ratio of the focal length f1 of the first lens group L1 to the focal length ft of the zoom lens at the telephoto end. If the refractive power of the first lens group L1 becomes too weak to exceed the upper limit of conditional equation (12), it leads to an increase in the size of the zoom lens, which is undesirable. If the refractive power of the first lens group L1 becomes too strong to exceed the lower limit of conditional equation (12), aberration correction becomes difficult, which is also undesirable.

[0045] Conditional equation (13) is a conditional equation that defines the ratio of the lateral magnification β2t of the second lens group L2 at the telephoto end when an object at infinity is in focus to the lateral magnification β2w of the second lens group L2 at the wide-angle end when an object at infinity is in focus. If the numerical value falls outside the range of conditional equation (13), aberration correction becomes difficult across the entire zoom range, which is undesirable.

[0046] Conditional equation (14) is a conditional equation that defines the ratio of the lateral magnification β3t of the third lens group L3 at the telephoto end when an object at infinity is in focus to the lateral magnification β3w of the third lens group L3 at the wide-angle end when an object at infinity is in focus. If the numerical value falls outside the range of conditional equation (14), aberration correction becomes difficult across the entire zoom range, which is undesirable.

[0047] Conditional equation (15) is a conditional equation that defines the ratio between the focal length fn1 of the first negative lens, which is one of the lenses constituting the first lens group L1, and the focal length f1 of the first lens group L1. If the value falls outside the numerical range of conditional equation (15), aberration correction becomes difficult across the entire zoom range, which is undesirable.

[0048] Conditional equation (16) is a conditional equation that defines the ratio between the focal length fn2 of the second negative lens, which is one of the lenses constituting the first lens group L1, and the focal length f1 of the first lens group L1. If the numerical value falls outside the range of conditional equation (16), aberration correction becomes difficult across the entire zoom range, which is undesirable.

[0049] Conditional equation (17) is a conditional equation that defines the ratio between the focal length fp1 of the first positive lens, which is one of the lenses constituting the first lens group L1, and the focal length f1 of the first lens group L1. If the numerical value falls outside the range of conditional equation (17), aberration correction becomes difficult across the entire zoom range, which is undesirable.

[0050] Furthermore, it is preferable that the numerical range of conditional expressions (4) to (17) be within the range of the following conditional expressions (4a) to (17a).

[0051] 0.33 <BFw / (-f1)<1.11 ···(4a) 0.10 <BFw / TTL<0.27 ···(5a) 2.3 <TTL / (-f1)<5.3 ···(6a) 3.6 <TTL / fw<7.1 ···(7a) 0.17 <f2 / (-f3)<1.12 ···(8a) 0.09 <f2 / f4<0.62 ···(9a) 0.15<(-f3) / f4<1.68 (10a) 0.89<(-f1) / fw<2.11 (11a) 0.39<(-f1) / ft<1.13 (12a) 1.0<β2t / β2w<2.45 (13a) 0.8<β3t / β3w<1.63 (14a) 0.60 <fn1 / f1<1.82 ···(15a) 0.76 <fn2 / f1<8.22 ···(16a) 0.72 <fp1 / (-f1)<4.16 ···(17a) Furthermore, it is even more preferable to set the numerical range of conditional expressions (4) to (17) to the range of (4b) to (17b).

[0052] 0.37 <BFw / (-f1)<0.75 ···(4b) 0.12 <BFw / TTL<0.24 ···(5b) 2.7 <TTL / (-f1)<4.7 ···(6b) 4.3 <TTL / fw<6.8 ···(7b) 0.23 <f2 / (-f3)<0.76 ···(8b) 0.11 <f2 / f4<0.45 ···(9b) 0.17<(-f3) / f4<1.37 (10b) 1.2 < (-f1) / fw < 1.9 ···(11b) 0.58<(-f1) / ft<0.90 (12b) 1.5 < β2t / β2w < 2.0 ···(13b) 1.09<β3t / β3w<1.26 (14b) 0.68 <fn1 / f1<1.65 ···(15b) 1.0 <fn2 / f1<6.5 ···(16b) 0.9 <fp1 / (-f1)<3.4 ···(17b) Next, we will describe the zoom lenses of each embodiment in detail.

[0053] The zoom lens of Example 1 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the first lens group L1 in a direction that includes a component perpendicular to the optical axis.

[0054] The zoom lens of Example 2 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the second lens group L2 in a direction that includes a component perpendicular to the optical axis.

[0055] The zoom lens of Example 3 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the second lens group L2 in a direction that includes a component perpendicular to the optical axis.

[0056] The zoom lens of Example 4 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the first lens group L1 in a direction that includes a component perpendicular to the optical axis.

[0057] The zoom lens of Example 5 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the second lens group L2 in a direction that includes a component perpendicular to the optical axis.

[0058] The zoom lens of Example 6 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the fourth lens group L4 in a direction that includes a component perpendicular to the optical axis.

[0059] The zoom lens of Example 7 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the second lens group L2 in a direction that includes a component perpendicular to the optical axis.

[0060] The zoom lens of Example 8 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the second lens group L2 in a direction that includes a component perpendicular to the optical axis.

[0061] The zoom lens of Example 9 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the first lens group L1 in a direction that includes a component perpendicular to the optical axis.

[0062] The zoom lens of Example 10 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the second lens group L2 in a direction that includes a component perpendicular to the optical axis.

[0063] The zoom lens of Example 11 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the first lens group L1 in a direction that includes a component perpendicular to the optical axis.

[0064] The zoom lens of Example 12 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the first lens group L1 in a direction that includes a component perpendicular to the optical axis.

[0065] The zoom lens of Example 13 consists of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes, and the first lens group L1 and the fourth lens group L4 are fixed with respect to the image plane IP. During focusing, the third lens group L3 moves. Image blur correction may be performed by moving a part of the first lens group L1 in a direction that includes a component perpendicular to the optical axis.

[0066] The numerical values ​​corresponding to each of Examples 1 to 13 are shown below.

[0067] In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axial spacing (distance along the optical axis) between the m-th surface and the (m+1)-th surface. Here, m is the surface number counted from the light incident side. Also, nd represents the refractive index of each optical element with respect to the d line, and νd represents the Abbe number of the optical element with respect to the d line. Note that the Abbe number νd of a certain material with respect to the d line is expressed as νd = (Nd-1) / (NF-NC), where Nd, NF, and NC are the refractive indices at the Fraunhofer lines d line (587.6 nm), F line (486.1 nm), and C line (656.3 nm).

[0068] In each numerical example, d, focal length (mm), F-number, and half-angle of view (°) are all values ​​when the zoom lens of each example is focused on an object at infinity. Back focus BF is the distance along the optical axis from the final lens surface (the surface closest to the image) of the zoom lens to the paraxial image plane, expressed in terms of air-equivalent length. The total length of the zoom lens is the distance along the optical axis from the first lens surface (the lens surface closest to the object) to the final lens surface plus the back focus. A lens group includes not only cases where it is composed of multiple lenses, but also cases where it is composed of a single lens.

[0069] When the optical surface is an aspherical surface, an asterisk (*) is attached to the right side of the surface number. The aspherical shape is defined as follows, where X is the displacement from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial curvature radius, k is the conic constant, and A4, A6, A8, A10, and A12 are the aspherical coefficients of each order: x=(h , , , , , , , , / R) / [1+{1-(1+k)(h / R) 2} 1 / 2 +A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 It is expressed as such. Note that "e±XX" in each aspherical coefficient means "×10± XX ".

[0070] (Numerical Example 1) Unit: mm Surface Data Surface Number r d nd νd 1 31.510 1.00 1.80400 46.5 2 13.253 5.81 3 384.169 1.00 1.59282 68.6 [[ID=4y]]4 16.237 2.57 5 20.027 2.35 1.85478 24.8<00​​​​​​​​​​​​​​​​​​15 20.752 0.90 1.80400 46.5 16 8.522 3.98 1.49700 81.5 17 -23.714 (variable) 18 -19.766 0.80 1.56732 42.8 19 209.263 2.07 20* -13.721 2.00 1.53110 55.9 21* -19.057 (variable) 22 -129.610 4.47 1.85150 40.8 23 -26.924 12.29 Image plane ∞ Aspherical data Page 20 K = 0.00000e+00 A 4= 3.64281e-04 A 6= 2.03779e-06 A 8=-1.61378e-08 Page 21 K = 0.00000e+00 A 4= 3.50063e-04 A 6= 1.61923e-06 A 8=-1.64849e-08 Various data Zoom ratio 2.34 Wide-angle, Medium, Telephoto Focal length 12.42 18.65 29.07 F-numbers: 4.10, 5.13, 6.40 Half-angle (°): 47.72, 36.22, 25.17 Image height 11.37 12.86 13.66 Lens length 82.97 82.97 82.97 BF 12.29 12.29 12.29 d 8 18.70 10.05 1.39 d17 1.69 2.74 6.86 d21 3.20 10.80 15.34 Zoom lens group data Group starting plane focal length 1 1 -17.76 2 9 17.38 3 18 -24.70 4 22 39.13 (Numerical Example 2) Unit: mm Surface data Face number rd nd νd 1 34.396 1.00 1.77250 49.6 2 13.292 5.69 3 -323.606 1.00 1.59282 68.6 4 16.748 2.92 5 20.652 2.29 1.84666 23.8 6 36.566 (variable) 7 -301.068 3.73 1.48749 70.2 8 -30.039 4.78 9 (aperture) ∞ 0.50 10 19.485 3.34 1.83481 42.7 11 -14.251 1.90 1.90366 31.3 12 ∞ 4.14 13 25.728 1.00 1.83481 42.7 14 9.171 3.79 1.49700 81.5 15 -26.368 (variable) 16 -23.072 0.80 1.51742 52.4 17 82.694 2.02 18* -15.829 2.00 1.53110 55.9 19* -21.570 (variable) 20 -120.000 4.42 1.77250 49.6 21 -27.671 12.13 Image plane ∞ Aspherical data Side 18 K = 0.00000e+00 A 4= 3.32711e-04 A 6= 1.73403e-06 A 8=-1.45204e-08 Page 19 K = 0.00000e+00 A 4= 3.39522e-04 A 6= 1.63472e-06 A 8=-1.61755e-08 Various data Zoom ratio 2.35 Wide-angle, Medium, Telephoto Focal length 12.40 18.66 29.10 F-numbers: 4.10, 5.10, 6.40 Half-angle (°): 47.76, 36.21, 25.15 Image height 11.37 12.86 13.66 Lens length 83.44 83.44 83.44 BF 12.13 12.13 12.13 d 6 19.82 10.85 1.88 d15 1.77 2.36 6.01 d19 4.41 12.78 18.10 d21 12.13 12.13 12.13 Zoom lens group data Group starting plane focal length 1 1 -18.26 2 7 17.57 3 16 -27.60 4 20 45.60 (Numerical Example 3) Unit: mm Surface data Face number rd nd νd 1 35.706 1.00 1.77250 49.6 2 14.414 5.20 3 -441.444 1.00 1.59282 68.6 4 16.131 3.30 5 21.292 3.27 1.84666 23.8 6 38.733 (variable) 7 -260.840 2.46 1.48749 70.2 8 -33.213 2.00 9 (aperture) ∞ 2.00 10 20.926 4.64 1.85150 40.8 11 -18.671 0.22 12 -17.428 0.80 1.85478 24.8 13 218.347 4.07 14 28.492 1.00 1.72916 54.7 15 9.356 5.18 1.49700 81.5 16 -24.952 (variable) 17 -22.720 0.80 1.57099 50.8 18 148.402 1.72 19* -23.196 2.00 1.53110 55.9 20* -30.564 (variable) 21 -120.000 4.34 1.77250 49.6 22 -27.692 (variable) Image plane ∞ Aspherical data Page 19 K = 0.00000e+00 A 4= 2.94393e-04 A 6= 7.13003e-07 A 8=-1.72892e-08 Page 20 K = 0.00000e+00 A 4= 3.24911e-04 A 6= 1.01599e-06 A 8=-1.72183e-08 Various data Zoom ratio 2.35 Wide-angle, Medium, Telephoto Focal length 12.40 18.69 29.10 F-number 4.10 4.10 4.10 Half-angle (°): 47.76, 36.16, 25.15 Image height 11.37 12.86 13.66 Lens length 82.02 82.02 82.02 BF 12.79 12.79 12.79 d 6 19.99 10.92 1.84 d16 1.66 2.03 5.63 d20 2.58 11.29 16.76 d22 12.79 12.79 12.79 Zoom lens group data Group starting plane focal length 1 1 -19.53 2 7 17.94 3 17 -29.69 4 21 45.67 (Numerical Example 4) Unit: mm Surface data Face number rd nd νd 1 114.124 1.00 1.77250 49.6 2 12.042 4.29 3* 43.105 2.50 1.53110 55.9 4* 20.966 1.99 5 35.204 2.90 1.77047 29.7 6 -114.527 1.97 7 -32.492 1.00 1.49700 81.5 8 -70.456 (variable) 9 18.171 1.94 1.77250 49.6 10 -529.066 2.48 11 (aperture) ∞ 1.38 12 12.421 1.79 1.59282 68.6 13 44.069 0.36 14 -46.037 1.00 1.68893 31.1 15 10.684 0.48 16 25.111 3.36 1.59282 68.6 17 -21.982 (variable) 18* -18.435 2.00 1.53110 55.9 19* -32.813 (variable) 20 -120.000 4.59 1.63854 55.4 21 -29.908 11.78 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-8.94309e-05 A 6= 7.11824e-07 A 8=-3.52027e-09 Side 4 K = 0.00000e+00 A 4=-1.48535e-04 A 6= 6.59805e-07 A 8=-5.15433e-09 Side 18 K = 0.00000e+00 A 4= 2.68346e-04 A 6= 2.81044e-06 A 8=-9.40023e-08 Page 19 K = 0.00000e+00 A 4= 2.67097e-04 A 6= 1.59679e-06 A 8=-5.11740e-08 Various data Zoom ratio 2.02 Wide-angle, Medium, Telephoto Focal length 14.40 20.07 29.10 F-number 4.10 5.02 6.29 Half-angle (°): 43.40, 34.24, 25.14 Image height 11.46 12.40 13.17 Lens length 75.06 75.06 75.06 BF 11.78 11.78 11.78 d 8 16.11 8.43 0.74 d17 1.84 1.00 6.15 d19 10.29 18.81 21.35 d21 11.78 11.78 11.78 Zoom lens group data Group starting plane focal length 1 1 -21.90 2 9 19.73 3 18 -83.23 4 20 61.17 (Numerical Example 5) Unit: mm Surface data Face number rd nd νd 1 235.833 1.00 1.77250 49.6 2 10.085 4.16 3* -895.559 2.50 1.53110 55.9 4* 44.647 1.74 5 64.099 1.78 2.05090 26.9 6 -162.178 (variable) 7 -459.615 2.29 1.48749 70.2 8 -33.943 4.00 9 18.560 3.57 1.69680 55.5 10 -16.150 1.00 1.90043 37.4 11 -62.644 1.84 12 (aperture) ∞ 4.68 13 25.922 1.00 1.83481 42.7 14 8.456 4.21 1.49700 81.5 15 -26.343 (variable) 16 -34.878 0.80 1.61772 49.8 17 139.823 4.14 18* -9.417 2.00 1.53110 55.9 19* -12.991 (variable) 20 -120.000 4.63 1.63854 55.4 21 -24.348 11.50 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-8.12193e-05 A 6= 8.99724e-07 A 8=-1.19209e-08 Side 4 K = 0.00000e+00 A 4=-1.28410e-04 A 6= 3.69150e-07 A 8=-1.09948e-08 Side 18 K = 0.00000e+00 A 4= 2.77887e-04 A 6= 6.15575e-06 A 8=-2.56537e-08 Page 19 K = 0.00000e+00 A 4= 2.14784e-04 A 6= 3.85389e-06 A 8=-2.47687e-08 Various data Zoom ratio 2.02 Wide-angle, Medium, Telephoto Focal length 14.40 20.23 29.10 F-numbers: 4.10, 5.04, 6.40 Half-angle (°): 43.30, 34.02, 25.14 Image height 11.42 12.56 13.22 Lens length 78.52 78.52 78.52 BF 11.50 11.50 11.50 d 6 16.23 8.82 1.41 d15 1.45 2.48 6.02 d19 3.98 10.37 14.24 d21 11.50 11.50 11.50 Zoom lens group data Group starting plane focal length 1 1 -18.40 2 7 18.55 3 16 -28.78 4 20 46.95 (Numerical Example 6) Unit: mm Surface data Face number rd nd νd 1 93.086 1.00 1.77250 49.6 2 11.534 5.04 3* 35.096 2.50 1.53110 55.9 4* 18.745 1.76 5 34.034 2.40 1.84666 23.8 6 247.520 (variable) 7 21.135 3.07 1.77250 49.6 8 -83.384 2.42 9 (aperture) ∞ 1.42 10 11.906 1.79 1.60311 60.6 11 24.109 0.36 12 -32.365 1.05 1.72151 29.2 13 11.247 0.46 14 18.005 2.74 1.60311 60.6 15 -16.851 (variable) 16* -20.785 2.00 1.53110 55.9 17* -46.785 (variable) 18 227.811 1.00 1.65844 50.9 19 39.504 5.98 20 41.856 6.15 1.72916 54.7 21 -63.192 13.08 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-1.05255e-04 A 6= 6.96967e-07 A 8=-3.20460e-09 Side 4 K = 0.00000e+00 A 4=-1.71621e-04 A 6= 6.71606e-07 A 8=-5.21171e-09 Page 16 K = 0.00000e+00 A 4= 2.57526e-04 A 6= 2.11426e-06 A 8=-6.79744e-08 Page 17 K = 0.00000e+00 A 4= 2.59203e-04 A 6= 1.45831e-06 A 8=-4.89468e-08 Various data Zoom ratio 1.97 Wide-angle, Medium, Telephoto Focal length 14.47 19.96 28.47 F-number 4.10 5.01 6.22 Half-angle (°): 43.35, 34.39, 25.63 Image height 11.42 12.56 13.22 Lens length 72.82 72.82 72.82 BF 13.08 13.08 13.08 d 6 15.12 7.96 0.79 d15 1.64 0.67 4.33 d17 1.83 9.96 13.47 d21 13.08 13.08 13.08 Zoom lens group data Group starting plane focal length 1 1 -22.02 2 7 18.72 3 16 -72.35 4 18 57.69 (Numerical Example 7) Unit: mm Surface data Face number rd nd νd 1 ∞ 1.50 2 49.839 1.40 1.77250 49.6 3 17.865 9.70 4 -74.024 1.10 1.59282 68.6 5 26.453 2.18 6 28.144 5.42 1.80610 33.3 7 155.531 (variable) 8 24.363 3.01 1.72916 54.7 9 133.320 2.61 10 (aperture) ∞ 2.00 11 42.759 1.00 1.76634 35.8 12 11.137 5.77 1.72916 54.7 13 -107.618 2.85 14 -20.935 1.00 1.53172 48.8 15 38.508 0.15 16* 29.415 7.00 1.49700 81.5 17* -16.643 (variable) 18 26.091 0.80 1.60342 38.0 19 16.431 9.30 20* -50.394 2.40 1.53110 55.9 21* -1001.831 (variable) 22 -200.000 3.26 1.90065 31.6 23 -61.168 12.68 Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-5.16959e-05 A 6=-1.53463e-07 A 8=-3.31876e-09 Page 17 K = 0.00000e+00 A 4= 3.33206e-05 A 6=-2.05294e-07 A 8=-1.88875e-09 Page 20 K = 0.00000e+00 A 4=-3.57991e-05 A 6=-1.41049e-07 A 8=-1.54522e-09 Page 21 K = 0.00000e+00 A 4=-4.36025e-05 A 6=-1.02183e-07 A 8=-4.60803e-10 Various data Zoom ratio 1.89 Wide-angle, Medium, Telephoto Focal length 20.60 28.40 39.00 F-number 4.10 4.10 4.10 Half-angle (°): 46.40, 37.29, 29.01 Image height 17.94 19.62 20.74 Lens length 97.01 97.01 97.01 BF 12.68 12.68 12.68 d 7 18.11 9.58 1.05 d17 1.79 1.00 2.86 d21 2.00 11.32 18.00 d23 12.68 12.68 12.68 Zoom lens group data Group starting plane focal length 1 1 -30.37 2 8 24.27 3 18 -41.20 4 22 96.76 (Numerical Example 8) Unit: mm Surface data Face number rd nd νd 1 42.299 1.50 1.75500 52.3 2 18.914 8.16 3 -142.144 1.20 1.59282 68.6 4 30.217 5.54 5 33.034 2.03 1.96300 24.1 6 50.217 (variable) 7 3588.151 3.04 1.53775 74.7 8 -40.853 1.62 9 23.007 4.07 1.79952 42.2 10 -26.519 1.01 1.95375 32.3 11 79.436 3.46 12 (aperture) ∞ 5.69 13 28.102 1.00 1.85150 40.8 14 11.348 4.25 1.59522 67.7 15 -45.381 (variable) 16 41.052 0.80 1.51742 52.4 17 15.294 6.27 18* -51.838 2.10 1.53110 55.9 19* -1006.304 (variable) 20 -200.000 5.59 1.77250 49.6 21 -45.565 (variable) Image plane ∞ Aspherical data Side 18 K = 0.00000e+00 A 4=-2.18376e-04 A 6= 8.06571e-07 A 8=-7.88304e-09 Page 19 K = 0.00000e+00 A 4=-1.88281e-04 A 6= 7.88400e-07 A 8=-4.74781e-09 Various data Zoom ratio 2.35 Wide-angle, Medium, Telephoto Focal length 20.60 31.11 48.50 F-numbers: 4.10, 5.20, 5.88 Half-angle (°): 46.40, 34.81, 24.04 Image height 18.22 20.32 21.64 Lens length: 106.52 106.52 106.52 BF 19.41 19.41 19.41 d 6 26.05 13.88 1.70 d15 1.00 2.05 6.67 d19 2.72 13.84 21.40 d21 19.41 19.41 19.41 Zoom lens group data Group starting plane focal length 1 1 -28.51 2 7 23.49 3 16 -31.34 4 20 75.20 (Numerical Example 9) Unit: mm Surface data Face number rd nd νd 1 60.703 1.30 1.95375 32.3 2 10.568 5.26 3* -158.794 2.00 1.53110 55.9 4* 35.904 0.68 5 69.552 2.59 1.85478 24.8 6 -37.356 0.90 7 -41.573 1.00 1.43875 94.7 8 -114.793 (variable) 9 19.470 2.27 1.65160 58.5 10 -126.753 6.20 11 (aperture) ∞ 0.80 12 13.509 2.32 1.49700 81.5 13 -29.196 0.23 14 -18.502 2.50 1.59551 39.2 15 10.390 1.45 16 16.003 2.95 1.43875 94.7 17 -17.071 (variable) 18* -18.646 1.50 1.53110 55.9 19* -46.212 (variable) 20 -40.654 3.48 1.43875 94.7 21 -20.238 13.34 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-1.84708e-04 A 6= 1.47430e-06 A 8=-1.09499e-08 Side 4 K = 0.00000e+00 A 4=-2.31582e-04 A 6= 1.38450e-06 A 8=-1.10945e-08 Side 18 K = 0.00000e+00 A 4= 4.14762e-04 A 6=-1.81540e-06 A 8=-1.40506e-09 Page 19 K = 0.00000e+00 A 4= 4.21395e-04 A 6=-2.16529e-06 A 8= 8.23735e-09 Various data Zoom ratio 2.01 Wide-angle, Medium, Telephoto Focal length 14.45 20.17 29.09 F-number 4.10 5.05 6.40 Half angle of view (°) 43.39 34.10 25.15 Image height 11.46 12.41 13.18 Overall length of lens 77.99 77.99 77.99 BF 13.34 13.34 13.34 d 8 16.17 8.48 0.80 d17 0.80 1.51 7.58 d19 10.26 17.23 18.84 d21 13.34 13.34 13.34 Zoom lens group data Group Starting surface Focal length 1 1 -18.40 2 9 20.41 3 18 -59.99 4 20 87.31 (Numerical Example 10) Unit: mm Surface data Surface number r d nd νd 1 42.644 1.30 1.72916 54.7 2 17.764 8.77 3 -70.406 1.20 1.53775 74.7 4 25.301 2.36 5 25.884 4.26 1.62588 35.7 6 209.726 (Variable) 7 25.792 2.12 1.59522 67.7 8 539.599 5.57 9 (Aperture) ∞ 0.88 10 59.108 1.00 1.69895 30.1 11 19.640 2.76 1.72916 54.7 12 -88.410 2.69 13 -18.122 1.01 1.54072 47.2 14 71.719 2.69 15* 23.626 4.90 1.43875 94.7 16* -14.207 (variable) 17 24.461 1.00 1.51633 64.1 18 15.091 9.99 19* -51.360 2.00 1.53110 55.9 20 * 199.736 (variable) 21 -991.849 2.03 2.05090 26.9 22 -167.475 12.67 Image plane ∞ Aspherical data Page 15 K = 0.00000e+00 A 4=-2.76672e-05 A 6=-3.81028e-08 A 8= 1.77147e-09 Page 16 K = 0.00000e+00 A 4= 8.66431e-05 A 6=-1.50654e-07 A 8= 3.16848e-09 Page 19 K = 0.00000e+00 A 4=-2.50400e-05 A 6=-1.73349e-07 A 8=-1.30647e-09 Page 20 K = 0.00000e+00 A 4=-4.36025e-05 A 6=-1.02183e-07 A 8=-4.60803e-10 Various data Zoom ratio 1.88 Wide-angle, Medium, Telephoto Focal length 20.92 28.94 39.31 F-number 4.10 4.10 4.10 Half drawing angle (°) 45.96 36.78 28.82 Image height 18.00 19.62 20.76 Overall lens length 91.22 91.22 91.22 BF 12.67 12.67 12.67 d 6 17.87 9.33 0.80 d16 2.47 0.80 1.28 d20 1.69 11.90 19.95 d22 12.67 12.67 12.67 Zoom lens group data Group Starting surface Focal length 1 1 -33.47 2 7 23.91 3 17 -36.80 4 21 191.50 (Numerical Example 11) Unit: mm Surface data Surface number r d nd νd 1 620.156 1.00 1.80610 40.9 2 13.951 3.20 3* 31.386 1.77 1.53110 55.9 4* 16.340 2.55 5 -2188.375 1.00 1.43875 94.7 6 22.775 3.74 1.90043 37.4 7 -107.410 1.34 8 -53.431 1.00 1.43875 94.7 9 -351.116 (Variable) 10 18.205 2.17 1.69680 55.5 11 -182.560 2.82 12 (Aperture) ∞ 0.80 13 11.712 2.38 1.43875 94.7 14 -80.486 0.31 15 -25.729 2.00 1.60342 38.0 16 10.136 1.04 17 20.451 2.17 1.43875 94.7 18 -17.817 (variable) 19* -40.343 1.50 1.53110 55.9 20 * 106.642 (variable) 21 -547.596 5.61 1.49700 81.5 22 -21.883 (variable) Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-1.92346e-04 A 6= 1.46585e-06 A 8=-5.19278e-09 Side 4 K = 0.00000e+00 A 4=-2.49552e-04 A 6= 1.56459e-06 A 8=-7.02285e-09 Page 19 K = 0.00000e+00 A 4= 2.25885e-04 A 6=-7.11818e-07 A 8=-1.70513e-08 Page 20 K = 0.00000e+00 A 4= 2.83610e-04 A 6=-1.54983e-06 A 8=-2.79368e-09 Various data Zoom ratio 2.01 Wide-angle, Medium, Telephoto Focal length 14.44 20.17 29.09 F-number 4.10 5.07 6.40 Half-angle (°): 43.41, 34.11, 25.15 Image height 11.46 12.41 13.18 Lens length 74.83 74.83 74.83 BF 13.10 13.10 13.10 d 9 16.17 8.48 0.80 d18 2.41 3.08 8.46 d20 6.75 13.76 16.06 d22 13.10 13.10 13.10 Zoom lens group data Group starting plane focal length 1 1 -22.35 2 10 20.11 3 19 -54.92 4 21 45.70 (Numerical Example 12) Unit: mm Surface data Face number rd nd νd 1 333.322 1.00 1.59145 68.4 2 14.457 2.17 3* 16.664 1.75 1.53110 55.9 4* 13.429 3.12 5 72.731 0.99 1.43830 95.0 6 15.506 1.36 7 18.208 3.08 1.80652 46.7 8 82.353 2.05 9 -59.712 1.00 1.43846 94.8 10 1265.032 (variable) 11 16.222 1.79 1.69462 57.7 12 -120.338 0.80 13 (aperture) ∞ 0.80 14 8.920 1.59 1.51616 79.3 15 24.467 0.35 16 -291.423 1.00 1.60753 37.9 17 7.730 2.37 18 15.894 1.71 1.43787 95.3 19 -25.062 (variable) 20* -20.249 1.28 1.53110 55.9 21* -67.405 (variable) 22 1468.914 4.86 1.49667 81.9 23 -26.178 13.10 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-1.53281e-04 A 6= 1.08426e-06 A 8=-4.18904e-09 Side 4 K = 0.00000e+00 A 4=-2.14777e-04 A 6= 1.34839e-06 A 8=-7.81236e-09 Page 20 K = 0.00000e+00 A 4= 6.82662e-04 A 6=-2.35509e-06 A 8=-8.17593e-08 Page 21 K = 0.00000e+00 A 4= 7.14470e-04 A 6=-3.68516e-06 A 8=-2.76365e-08 Various data Zoom ratio 2.02 Wide-angle, Medium, Telephoto Focal length 14.43 20.17 29.10 F-number 4.10 5.00 6.16 Half-angle (°): 43.42, 34.11, 25.14 Image height 11.46 12.41 13.18 Lens length 70.63 70.63 70.63 BF 13.10 13.10 13.10 d10 16.17 8.49 0.80 d19 1.57 0.80 3.54 d21 6.72 15.18 20.12 d23 13.10 13.10 13.10 Zoom lens group data Group starting plane focal length 1 1 -24.90 2 11 18.46 3 20 -55.02 4 22 51.84 (Numerical Example 13) Unit: mm Surface data Face number rd nd νd 1 206.545 1.30 1.72916 54.7 2 11.330 4.19 3* 62.888 1.81 1.53110 55.9 4* 20.219 0.80 5 24.916 2.72 1.90043 37.4 6 -390.408 2.23 7 -25.898 1.02 1.43875 94.7 8 -47.695 (variable) 9 18.212 1.40 1.69680 55.5 10 63.288 2.25 11 (aperture) ∞ 0.80 12 11.731 2.68 1.53775 74.7 13 -13.536 0.17 14 -12.668 1.50 1.57099 50.8 15 6.966 0.63 16 8.050 3.16 1.43875 94.7 17 -26.152 (variable) 18* -12.552 1.50 1.53110 55.9 19* -21.575 (variable) 20 -28.270 2.55 1.49700 81.5 21 -19.416 16.10 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-1.14002e-04 A 6= 1.79201e-06 A 8=-9.57523e-09 Side 4 K = 0.00000e+00 A 4=-1.76654e-04 A 6= 1.89620e-06 A 8=-1.42839e-08 Side 18 K = 0.00000e+00 A 4= 9.49757e-04 A 6= 5.59399e-06 A 8=-2.76077e-07 Page 19 K = 0.00000e+00 A 4= 8.99649e-04 A 6= 3.06165e-06 A 8=-1.04329e-07 Various data Zoom ratio 2.02 Wide-angle, Medium, Telephoto Focal length 14.42 20.24 29.10 F-number 4.10 5.06 6.28 Half-angle (°): 43.44, 34.01, 25.15 Image height 11.46 12.41 13.18 Lens length 69.58 69.58 69.58 BF 16.10 16.10 16.10 d 8 16.17 8.48 0.80 d17 2.79 0.79 2.42 d19 3.84 13.52 19.58 d21 16.10 16.10 16.10 Zoom lens group data Group starting plane focal length 1 1 -23.46 2 9 18.06 3 18 -59.97 4 20 113.86 The various values ​​in each numerical example are summarized in Tables 1 and 2 below.

[0071] [Table 1]

[0072] [Table 2]

[0073] [Imaging device] Next, an example of a digital still camera (imaging device) using the zoom lens of each embodiment as the imaging optical system will be described with reference to Figure 27. Figure 27 is a diagram showing the configuration of the imaging device 10. The imaging device 10 comprises a camera body 13, a lens device 11 including any of the zoom lenses of embodiments 1 to 13 described above, and an image sensor (light-receiving element) 12 that converts the image formed by the zoom lens into photoelectricity. As the image sensor 12, an image sensor such as a CCD sensor or a CMOS sensor can be used. The lens device 11 and the camera body 13 may be configured as an integral unit or may be configured to be detachable. The camera body 13 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror. The imaging device 10 of this embodiment is small and lightweight and can obtain high optical performance.

[0074] Furthermore, the imaging device 10 in this embodiment is not limited to the digital still camera shown in Figure 27, but can be applied to various imaging devices such as broadcast cameras, silver halide film cameras, and surveillance cameras.

[0075] [Imaging System] Furthermore, an imaging system (surveillance camera system) may be configured that includes the zoom lens of each embodiment and a control unit that controls the zoom lens. In this case, the control unit can control the zoom lens so that each lens group moves as described above during zooming, focusing, and image shake correction. At this time, the control unit does not need to be integrated with the zoom lens; the control unit may be configured separately from the zoom lens. For example, a control unit (control device) located far away from the drive unit that drives each lens of the zoom lens may be configured to include a transmission unit that sends control signals (commands) for controlling the zoom lens. With such a control unit, the zoom lens can be remotely operated.

[0076] Alternatively, the control unit may be equipped with an operating section such as a controller or buttons for remotely operating the zoom lens, thereby enabling the zoom lens to be controlled in response to user input to the operating section. For example, the operating section may include a zoom-in button and a zoom-out button. The control unit can then be configured to send a signal to the drive unit of the zoom lens L0 so that when the user presses the zoom-in button, the magnification of the zoom lens increases, and when the user presses the zoom-out button, the magnification of the zoom lens decreases.

[0077] Furthermore, the imaging system may have a display unit, such as an LCD panel, that displays information (movement status) related to the zoom of the zoom lens. This information could include, for example, the zoom magnification (zoom status) or the amount of movement of each lens group (movement status). In this case, the user can remotely operate the zoom lens via the control unit while viewing the zoom information displayed on the display unit. The display unit and the control unit may be integrated by, for example, using a touch panel.

[0078] Each of the above embodiments includes the following configurations.

[0079] (Composition 1) This zoom lens consists of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged sequentially from the object side to the image side, and the spacing between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end. The first lens group consists of three or more lenses, When zooming from the wide-angle end to the telephoto end, the first lens group is fixed to the image plane. When the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the fourth lens group is f4, the distance along the optical axis from the object-side lens surface of the lens closest to the object in the first lens group to the image-side lens surface of the lens closest to the image in the first lens group is LD1, and the air-equivalent length of the distance along the optical axis from the object-side lens surface of the lens closest to the object in the zoom lens at the wide-angle end to the image plane is TTL, 0.85 < (-f1) / f2 < 2.00 0.00 < (-f1) / f4 < 0.55 0.00 <LD1 / TTL<0.27 A zoom lens characterized by satisfying the following conditional equation. (Configuration 2) When BFw is the air equivalent of the distance along the optical axis from the image-side lens surface to the image plane of the lens positioned closest to the image in the zoom lens at the wide-angle end, 0.30 <BFw / (-f1)<1.50 A zoom lens according to configuration 1, characterized in that it satisfies the following condition. (Composition 3) When BFw is the air equivalent of the distance along the optical axis from the image-side lens surface to the image plane of the lens positioned closest to the image in the zoom lens at the wide-angle end, 0.07 <BFw / TTL<0.30 A zoom lens according to configuration 1 or 2, characterized by satisfying the following conditional expression. (Composition 4) 2.0 <TTL / (-f1)<6.0 A zoom lens according to any one of configurations 1 to 3, characterized by satisfying the following conditional expression. (Composition 5) When the focal length of the zoom lens at the wide-angle end is fw, 3.0 <TTL / fw<7.5 A zoom lens according to any one of configurations 1 to 4, characterized by satisfying the following conditional expression. (Composition 6) When the focal length of the third lens group is f3, 0.1 <f2 / (-f3)<1.5 A zoom lens according to any one of configurations 1 to 5, characterized by satisfying the following conditional expression. (Composition 7) 0.05 <f2 / f4<0.80 A zoom lens according to any one of configurations 1 to 6, characterized by satisfying the following conditional expression. (Composition 8) When the focal length of the third lens group is f3, 0.1 < (-f3) / f4 < 2.0 A zoom lens according to any one of configurations 1 to 7, characterized by satisfying the following conditional expression. (Composition 9) When the focal length of the zoom lens at the wide-angle end is fw, 0.5 < (-f1) / fw < 2.5 A zoom lens according to any one of configurations 1 to 8, characterized by satisfying the following conditional expression. (Composition 10) When the focal length of the zoom lens at the telephoto end is ft, 0.2 < (-f1) / ft < 1.4 A zoom lens according to any one of configurations 1 to 9, characterized by satisfying the following conditional expression. (Composition 11) When the lateral magnification of the second lens group at the telephoto end is β2t and the lateral magnification of the second lens group at the wide-angle end is β2w, 0.5 < β2t / β2w < 3.0 A zoom lens according to any one of configurations 1 to 10, characterized by satisfying the following conditional expression. (Composition 12) When the lateral magnification of the third lens group at the telephoto end is β3t and the lateral magnification of the third lens group at the wide-angle end is β3w, 0.5 < β3t / β3w < 2.0 A zoom lens according to any one of configurations 1 to 11, characterized by satisfying the following conditional expression. (Composition 13) The first lens group includes a first negative lens, When the focal length of the first negative lens is fn1, 0.5 <fn1 / f1<2.0 A zoom lens according to any one of configurations 1 to 12, characterized by satisfying the following conditional expression. (Composition 14) The first lens group includes a second negative lens, When the focal length of the second negative lens is fn2, 0.5 <fn2 / f1<10.0 A zoom lens according to any one of configurations 1 to 13, characterized by satisfying the following conditional expression. (Composition 15) The first lens group includes a first positive lens, When the focal length of the first positive lens is fp1, 0.5 <fp1 / (-f1)<5.0 A zoom lens according to any one of configurations 1 to 14, characterized by satisfying the following conditional expression. (Composition 16) The zoom lens according to any one of configurations 1 to 15, characterized in that the first lens group L1 is composed only of lenses having refractive power. (Composition 17) A zoom lens according to any one of configurations 1 to 16, characterized in that the fourth lens group is fixed to the image plane when zooming from the wide-angle end to the telephoto end. (Composition 18) The zoom lens according to any one of configurations 1 to 17, characterized in that the second lens group includes an aperture diaphragm. (Composition 19) The zoom lens according to any one of configurations 1 to 18, characterized in that the fourth lens group consists of a single positive lens. (Composition 20) The zoom lens according to any one of configurations 1 to 19, characterized in that the first lens group consists of a negative lens, a negative lens, and a positive lens arranged in order from the object side to the image side. (Composition 21) The zoom lens according to any one of configurations 1 to 19, characterized in that the first lens group consists of a negative lens, a negative lens, a positive lens, and a negative lens arranged in order from the object side to the image side. (Composition 22) The zoom lens according to any one of configurations 1 to 19, characterized in that the first lens group consists of a negative lens, a negative lens, a negative lens, a positive lens, and a negative lens arranged in order from the object side to the image side. (Composition 23) The zoom lens according to any one of configurations 1 to 22, characterized in that the third lens group is a focus lens group that moves during focusing. (Composition 24) The zoom lens according to configuration 23, characterized in that the third lens group is composed of a single negative lens. (Composition 25) The zoom lens according to configuration 23, characterized in that the third lens group is composed of two negative single lenses. (Composition 26) An imaging device characterized by having a zoom lens according to any one of configurations 1 to 25, and an image sensor that receives an image formed by the zoom lens. (Composition 27) An imaging system characterized by having a zoom lens as described in any one of configurations 1 to 25, and a control unit that controls the zoom lens during zooming. (Composition 28) The imaging system according to configuration 27, characterized in that the control unit is configured separately from the zoom lens and has a transmitting unit that transmits control signals for controlling the zoom lens. (Composition 29) The imaging system according to configuration 27 or 28, characterized in that the control unit is configured separately from the zoom lens and has an operating section for operating the zoom lens. (Composition 30) The imaging system according to any one of configurations 27 to 29, characterized in that it has a display unit that displays information regarding the zoom of the zoom lens.

[0080] Although preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various combinations, modifications, and changes are possible within the scope of its gist. [Explanation of Symbols]

[0081] L1 First lens group L2 Second lens group L3 Third lens group L4 4th lens group

Claims

1. This zoom lens consists of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged sequentially from the object side to the image side, and the spacing between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end. The first lens group consists of three or more lenses, The first lens group comprises a first negative lens and a second negative lens positioned on the image side of the first negative lens. When zooming from the wide-angle end to the telephoto end, the first lens group and the fourth lens group are fixed with respect to the image plane. The third lens group consists of one negative single lens or two negative single lenses. The third lens group is a focusing lens group that moves during focusing. When the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the fourth lens group is f4, the distance along the optical axis from the object-side lens surface of the lens closest to the object in the first lens group to the image-side lens surface of the lens closest to the image in the first lens group is LD1, the air-equivalent length of the distance along the optical axis from the object-side lens surface of the lens closest to the object in the zoom lens at the wide-angle end to the image plane is TTL, the air-equivalent amount of the distance along the optical axis from the image-side lens surface of the lens closest to the image in the zoom lens at the wide-angle end to the image plane is BFw, and the focal length of the second negative lens is fn2, 0.85<(-f1) / f2≦1.18 0.21≦(-f1) / f4<0.55 0.00<LD1 / TTL<0.27 0.37<BFw / (-f1)<1.50 1.61≦fn2 / f1<10.0 A zoom lens characterized by satisfying the following conditional equation.

2. When BFw is the air equivalent of the distance along the optical axis from the image-side lens surface to the image plane of the lens positioned closest to the image in the zoom lens at the wide-angle end, 0.07<BFw / TTL<0.30 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. 2.0<TTL / (-f1)<6.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

4. When the focal length of the zoom lens at the wide-angle end is fw, 3.0<TTL / fw<7.5 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

5. When the focal length of the third lens group is f3, 0.1<f2 / (-f3)<1.5 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

6. 0.05<f2 / f4<0.80 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

7. When the focal length of the third lens group is f3, 0.1<(-f3) / f4<2.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

8. When the focal length of the zoom lens at the wide-angle end is fw, 0.5<(-f1) / fw<2.5 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

9. When the focal length of the zoom lens at the telephoto end is ft, 0.2<(-f1) / ft<1.4 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

10. When the lateral magnification of the second lens group at the telephoto end is β2t and the lateral magnification of the second lens group at the wide-angle end is β2w, 0.5<β2t / β2w<3.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

11. When the lateral magnification of the third lens group at the telephoto end is β3t and the lateral magnification of the third lens group at the wide-angle end is β3w, 0.5<β3t / β3w<2.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

12. The first lens group includes a first negative lens, When the focal length of the first negative lens is fn1, 0.5<fn1 / f1<2.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

13. The first lens group includes a first positive lens, When the focal length of the first positive lens is fp1, 0.5<fp1 / (-f1)<5.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

14. The zoom lens according to claim 1, characterized in that the first lens group consists only of lenses having refractive power.

15. The zoom lens according to claim 1, characterized in that the second lens group includes an aperture diaphragm.

16. The zoom lens according to claim 1, characterized in that the fourth lens group consists of a single positive lens.

17. The zoom lens according to claim 1, characterized in that the first lens group is composed of a negative lens, a negative lens, and a positive lens arranged in order from the object side to the image side.

18. The zoom lens according to claim 1, characterized in that the first lens group is composed of a negative lens, a negative lens, a positive lens, and a negative lens arranged in order from the object side to the image side.

19. This zoom lens consists of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged sequentially from the object side to the image side, and the spacing between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end. The first lens group consists of three or more lenses, The first lens group consists of a first negative lens, a second negative lens, a positive lens, and a negative lens, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the first lens group is fixed with respect to the image plane. The third lens group consists of one negative single lens or two negative single lenses. The third lens group is a focusing lens group that moves during focusing. When the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the fourth lens group is f4, the distance along the optical axis from the object-side lens surface of the lens closest to the object in the first lens group to the image-side lens surface of the lens closest to the image in the first lens group is LD1, the air-equivalent length of the distance along the optical axis from the object-side lens surface of the lens closest to the object in the zoom lens at the wide-angle end to the image plane is TTL, the air-equivalent amount of the distance along the optical axis from the image-side lens surface of the lens closest to the image in the zoom lens at the wide-angle end to the image plane is BFw, and the focal length of the second negative lens is fn2, 0.85<(-f1) / f2<2.00 0.00<(-f1) / f4<0.55 0.00<LD1 / TTL<0.27 0.37<BFw / (-f1)<1.50 1.34≦fn2 / f1<10.0 A zoom lens characterized by satisfying the following conditional equation.

20. The zoom lens according to claim 1, characterized in that the first lens group is composed of a negative lens, a negative lens, a negative lens, a positive lens, and a negative lens arranged in order from the object side to the image side.

21. This zoom lens consists of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged sequentially from the object side to the image side, and the spacing between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end. The first lens group consists of three or more lenses, The first lens group consists of a first negative lens, a second negative lens, a negative lens, a positive lens, and a negative lens, arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the first lens group is fixed with respect to the image plane. The third lens group consists of one negative single lens or two negative single lenses. The third lens group is a focusing lens group that moves during focusing. When the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the fourth lens group is f4, the distance along the optical axis from the object-side lens surface of the lens closest to the object in the first lens group to the image-side lens surface of the lens closest to the image in the first lens group is LD1, the air-equivalent length of the distance along the optical axis from the object-side lens surface of the lens closest to the object in the zoom lens at the wide-angle end to the image plane is TTL, the air-equivalent amount of the distance along the optical axis from the image-side lens surface of the lens closest to the image in the zoom lens at the wide-angle end to the image plane is BFw, and the focal length of the second negative lens is fn2, 0.85<(-f1) / f2<2.00 0.00<(-f1) / f4<0.55 0.00<LD1 / TTL<0.27 0.37<BFw / (-f1)<1.50 1.34≦fn2 / f1<10.0 A zoom lens characterized by satisfying the following conditional equation.

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

23. An imaging system characterized by having a zoom lens according to any one of claims 1 to 21 and a control unit that controls the zoom lens during zooming.

24. The imaging system according to claim 23, characterized in that the control unit is configured separately from the zoom lens and has a transmitting unit that transmits control signals for controlling the zoom lens.

25. The imaging system according to claim 23, characterized in that the control unit is configured separately from the zoom lens and has an operating section for operating the zoom lens.

26. The imaging system according to claim 23, characterized in that it has a display unit that displays information regarding the zoom of the zoom lens.

Images