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

Abstract

To provide a zoom lens which offers high optical performance over an entire zoom range and both a sufficient zoom ratio and reduced size and weight.SOLUTION: A zoom lens L0 is provided, comprising a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, a third lens group L3 having positive refractive power, a fourth lens group L4 having positive refractive power, and a fifth lens group L5 having negative 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 first lens group moves to the object side while a distance between the third lens group and the fourth lens group decreases and a distance between the fourth lens group and the fifth lens group decreases. The first lens group consists of two or less lenses having refractive power. A focal length f1 of the first lens group, a focal length f3 of the third lens group, a change in distance M34 between the third and fourth lens groups while zooming from the wide-angle end to the telephoto end, and a change in distance M45 between the fourth and fifth lens groups satisfy given conditional expressions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens, which is suitable for digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, surveillance cameras, and the like. [Background technology]

[0002] Zoom lenses used in imaging devices are required to have high optical performance, a sufficient zoom ratio, little aberration fluctuation during zooming, and be small and lightweight. A known zoom lens that meets these requirements is one in which the lens group closest to the object (first lens group) is composed of two or less optical elements with refractive power.

[0003] As a zoom lens in which the first lens group is composed of two lenses, Patent Document 1 (Example 7) discloses a zoom lens having first to fifth lens groups arranged in order from the object side to the image side and having positive, negative, positive, positive, negative refractive powers. Patent Document 2 (Example 2) discloses a zoom lens having first to sixth lens groups arranged in order from the object side to the image side and having positive, negative, positive, positive, negative, negative refractive powers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-117351 [Patent Document 2] Patent Publication No. 2021-081660 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the zoom lens described in Patent Document 1, the refractive power of the first lens group is too weak. Therefore, to ensure a sufficient zoom ratio, it is necessary to strengthen the refractive power of the third lens group, which results in an increase in the number of lenses in the third lens group, making it difficult to reduce the weight. Furthermore, in the zoom lens described in Patent Document 2, the amount of change in the distance between the third and fourth lens groups during zooming from the wide-angle end to the telephoto end is too large compared to the amount of change in the distance between the fourth and fifth lens groups. Therefore, in order to suppress aberration fluctuations during zooming, it is necessary to increase the number of lenses in the third and fourth lens groups, making it difficult to reduce the weight.

[0006] Generally, to ensure a sufficient zoom ratio in a zoom lens, it is necessary to increase the amount of change in lateral magnification per unit movement of each lens group when zooming from the wide-angle end to the telephoto end. To achieve this, the refractive power of each lens group must be increased, but this makes it difficult to correct aberrations within the lens group. Therefore, if each lens group is moved too much during zooming, aberration fluctuations become greater, making it impossible to achieve high optical performance across the entire zoom range. To suppress aberration fluctuations during zooming, it is necessary to correct aberrations within each lens group by increasing the number of lenses in each lens group, but increasing the number of lenses in each lens group makes it difficult to reduce the lens weight. Therefore, in a zoom lens with a small number of lenses, it is important to optimize the refractive power of each lens group and the amount of movement of each lens group during zooming.

[0007] The present invention provides a zoom lens that has high optical performance over the entire zoom range and is capable of ensuring a sufficient zoom ratio while being compact and lightweight, as well as an imaging device and imaging system that include the same. [Means for solving the problem]

[0008] A zoom lens according to one aspect of the present invention has, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, and the distance between adjacent lens groups changes during zooming. When zooming from a wide-angle end to a telephoto end, the first lens group moves toward the object side, the distance between the third lens group and the fourth lens group narrows, and the distance between the fourth lens group and the fifth lens group narrows, the first lens group is made up of two or less optical elements having refractive power, and the focal length of the first lens group is f1, the focal length of the third lens group is f3, the amount of change in the distance between the third lens group and the fourth lens group during zooming from the wide-angle end to the telephoto end is M34, and the amount of change in the distance between the fourth lens group and the fifth lens group during zooming from the wide-angle end to the telephoto end is M45. The amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end is M1, and the amount of movement of the third lens group during zooming from the wide-angle end to the telephoto end is M3. When 0.50 <f1 / f3<2.70 0.18<|M34 / M45|<0.70 2.0<|M1 / M3|<4.0 The present invention is characterized in that the following conditional expression is satisfied:

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

[0010] According to the present invention, it is possible to provide a zoom lens that has high optical performance over the entire zoom range, and that is capable of ensuring a sufficient zoom ratio while also being compact and lightweight. [Brief explanation of the drawings]

[0011] [Figure 1] 1A and 1B are cross-sectional views of a zoom lens according to a first embodiment at a wide-angle end and a telephoto end, respectively. [Figure 2] 1A and 1B are longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 1. [Figure 3] 4A and 4B are lateral aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 1. [Figure 4] 10A and 10B are cross-sectional views of a zoom lens according to a second embodiment at the wide-angle end and the telephoto end, respectively. [Figure 5] 10A and 10B are longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 2. [Figure 6] 10A and 10B are lateral aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 2. [Figure 7] 10A and 10B are cross-sectional views of a zoom lens according to a third embodiment at the wide-angle end and the telephoto end, respectively. [Figure 8] 10A and 10B are longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 3. [Figure 9] 10A and 10B are lateral aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 3. [Figure 10] 10A and 10B are cross-sectional views of a zoom lens at the wide-angle end and the telephoto end, respectively, in Example 4. [Figure 11] 10A and 10B are longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 4. [Figure 12] 10A and 10B are lateral aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 4. [Figure 13] 10A and 10B are cross-sectional views of a zoom lens at the wide-angle end and the telephoto end, respectively, in Example 5. [Figure 14] 10A and 10B are longitudinal aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 5. [Figure 15] 10A and 10B are lateral aberration diagrams of the zoom lens at the wide-angle end and the telephoto end, respectively, in Example 5. [Figure 16] FIG. 1 is a schematic diagram of an imaging device. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a zoom lens, an imaging device having the same, and an imaging system according to the present invention will be described with reference to the accompanying drawings.

[0013] 1(A), 4(A), 7(A), 10(A), and 13(A) are cross-sectional views of the zoom lens L0 at the wide-angle end of Examples 1 to 5, respectively. 1(B), 4(B), 7(B), 10(B), and 13(B) are cross-sectional views of the zoom lens L0 at the telephoto end of Examples 1 to 5, respectively. The zoom lens L0 of each Example is used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, and surveillance cameras.

[0014] In each lens cross-sectional view, the left side is the object side and the right side is the image side. The zoom lens L0 of each embodiment is configured with multiple lens groups. In each embodiment, a lens group is a group of lenses that either move as a unit or remain stationary during zooming. That is, in the zoom lens L0 of each embodiment, the spacing between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Note that a lens group may be composed of a single lens or multiple lenses. The lens group may also include an aperture stop.

[0015] In each lens cross-sectional view, Li represents the i-th lens group (i is a natural number) counting from the object side among the lens groups included in the zoom lens L0.

[0016] Additionally, SP denotes an aperture stop. IP denotes an image plane, on which the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed when the zoom lens L0 of each embodiment is used as the imaging optical system of a digital still camera or digital video camera. When the zoom lens L0 of each embodiment is used as the imaging optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is placed on the image plane IP.

[0017] In the zoom lens L0 of each embodiment, when zooming from the wide-angle end to the telephoto end, each lens group moves as shown by the solid arrows in each cross-sectional view, and when focusing from infinity to a close distance, each lens group moves as shown by the dotted arrows in each cross-sectional view.

[0018] 2(A), 5(A), 8(A), 11(A), and 14(A) are longitudinal aberration diagrams at the wide-angle end of the zoom lens L0 of Examples 1 to 5, respectively. 2(B), 5(B), 8(B), 11(B), and 14(B) are longitudinal aberration diagrams at the telephoto end of the zoom lens L0 of Examples 1 to 5, respectively.

[0019] In the spherical aberration diagram, Fno is the F-number, and shows the amount of spherical aberration for the d-line (wavelength 587.56 nm) and g-line (wavelength 435.835 nm). In the astigmatism diagram, S shows the amount of astigmatism on the sagittal image plane, and M shows the amount of astigmatism on the meridional image plane. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of lateral chromatic aberration for the g-line is shown. ω is the half angle of view (°) calculated by paraxial calculation.

[0020] Figures 3(A), 6(A), 9(A), 12(A), and 15(A) are lateral aberration diagrams at the wide-angle end of the zoom lens L0 of Examples 1 to 5, respectively. Figures 3(B), 6(B), 9(B), 12(B), and 15(B) are lateral aberration diagrams at the telephoto end of the zoom lens L0 of Examples 1 to 5, respectively. In each diagram, aberration diagrams are shown, from top to bottom, for 100% of the image height, 80% of the image height, 70% of the image height, 50% of the image height, and the d-line and g-line at the center. The dashed line S(d) represents the sagittal image plane for the d-line, the solid line M(d) represents the meridional image plane for the d-line, and the two-dot chain line M(g) represents the meridional image plane for the g-line.

[0021] Next, the characteristic configuration of the zoom lens L0 of each embodiment will be described.

[0022] The zoom lens L0 of each embodiment has, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power. In the zoom lens L0 of each embodiment, the spacing between adjacent lens groups changes during zooming. This configuration makes it easy to reduce the size of the zoom lens L0. Note that the same effect can be achieved by arranging one or more lens groups on the image side of the fifth lens group L5.

[0023] Furthermore, in the zoom lens L0 of each embodiment, the first lens unit L1 moves toward the object side when zooming from the wide-angle end to the telephoto end. This shortens the overall lens length at the wide-angle end, facilitating compactness. Also, when zooming from the wide-angle end to the telephoto end, the distance between the third lens unit L3 and the fourth lens unit L4 narrows, and when zooming from the wide-angle end to the telephoto end, the distance between the fourth lens unit L4 and the fifth lens unit L5 narrows. This means that the zoom lens L0 of each embodiment has a telephoto-type power arrangement at the telephoto end, which facilitates shortening the overall lens length. Also, the first lens unit L1 is composed of two or fewer optical elements having refractive power. This facilitates reducing the weight of the zoom lens L0.

[0024] Furthermore, the zoom lens L0 of each embodiment satisfies the following conditional expression (1).

[0025] 0.50 <f1 / f3<2.70 ···(1) Here, f1 is the focal length of the first lens group L1, and f3 is the focal length of the third lens group L3.

[0026] Conditional expression (1) defines the ratio of the focal length f1 of the first lens group L1 to the focal length f3 of the third lens group L3. By appropriately setting the focal length f1 of the first lens group L1 relative to the focal length f3 of the third lens group L3, it is possible to ensure a large ratio of the absolute value |β2wt| of the magnification variable contribution ratio of the second lens group L2 to the zoom ratio. This allows a sufficient zoom ratio to be achieved without increasing the number of lenses in each lens group. If the focal length f1 of the first lens group L1 becomes too long, exceeding the upper limit of conditional expression (1), the ratio of the absolute value |β2wt| of the magnification variable contribution ratio of the second lens group L2 to the zoom ratio becomes small, making it difficult to achieve both a sufficient zoom ratio and lightweight design. It also makes it difficult to shorten the overall lens length at the wide-angle end. Furthermore, if the upper limit of conditional expression (1) is exceeded and the focal length f3 of the third lens group L3 becomes too short, the number of lenses in the third lens group L3 must be increased to suppress aberration fluctuations during zooming, making it difficult to reduce the weight of the zoom lens L0. If the lower limit of conditional expression (1) is exceeded and the focal length f1 of the first lens group L1 becomes too short, it becomes difficult to correct various aberrations, such as spherical aberration, that occur in the first lens group L1. Increasing the number of lenses in the first lens group L1 to correct this makes it difficult to reduce the weight of the zoom lens L0. If the lower limit of conditional expression (1) is exceeded and the focal length f3 of the third lens group L3 becomes too long, the overall lens length increases, making the zoom lens L0 larger.

[0027] Furthermore, the zoom lens L0 of each embodiment satisfies the following conditional expression (2).

[0028] 0.18<|M34 / M45|<0.70 (2) Here, M34 is the amount of change in the distance between the third lens unit L3 and the fourth lens unit L4 when zooming from the wide-angle end to the telephoto end. M45 is the amount of change in the distance between the fourth lens unit L4 and the fifth lens unit L5 when zooming from the wide-angle end to the telephoto end. These M34 and M45 are amounts defined as follows, where M3, M4, and M5 are the amounts of movement of the third lens unit L3, the fourth lens unit L4, and the fifth lens unit L5 when zooming from the wide-angle end to the telephoto end, respectively.

[0029] M34=M4-M3 M45=M5-M4 Here, the movement amounts M3, M4, and M5 are based on the vertex positions of the surfaces of the third lens group L3, the fourth lens group L4, and the fifth lens group L5 closest to the object at the wide-angle end, respectively, and the signs of the movement amounts M3, M4, and M5 are negative when each lens group is closer to the object than the reference.

[0030] Conditional expression (2) defines the absolute value of the ratio of the spacing change amount M34 between the third lens group L3 and the fourth lens group L4 to the spacing change amount M45 between the fourth lens group L4 and the fifth lens group L5. By appropriately setting the spacing change amount M34 relative to the spacing change amount M45, it becomes easy to simultaneously suppress aberration fluctuations during zooming and reduce the number of lenses in the third lens group L3. If the absolute value of the spacing change amount M34 between the third lens group L3 and the fourth lens group L4 becomes too large, exceeding the upper limit of conditional expression (2), aberration fluctuations during zooming become significant. Furthermore, if the spacing change amount M45 between the fourth lens group L4 and the fifth lens group L5 becomes too small, exceeding the upper limit of conditional expression (2), it becomes difficult to achieve the desired zoom ratio. Therefore, it becomes necessary to increase the number of lenses in the fourth lens group L4 and the fifth lens group L5 to strengthen their refractive power. This makes it difficult to reduce the weight of the zoom lens L0. Furthermore, if the absolute value of the change in the distance M34 between the third lens group L3 and the fourth lens group L4 becomes too small, falling below the lower limit of conditional expression (2), it becomes difficult to correct aberration fluctuations that occur during zooming by changing the distance between the third lens group L3 and the fourth lens group L4. Also, if the change in the distance M45 between the fourth lens group L4 and the fifth lens group L5 becomes too large, falling below the lower limit of conditional expression (2), the position of the fifth lens group L5 at the wide-angle end becomes too far from the aperture stop SP. This increases the effective diameter of the fifth lens group L5, making it difficult to reduce the weight of the zoom lens L0.

[0031] Furthermore, it is preferable that the numerical ranges of the conditional expressions (1) and (2) satisfy the ranges of the following conditional expressions (1a) and (2a).

[0032] 0.80 <f1 / f3<2.65 ···(1a) 0.19<|M34 / M45|<0.68 (2a) It is more preferable that the numerical ranges of the conditional expressions (1) and (2) satisfy the ranges of the following conditional expressions (1b) and (2b).

[0033] 0.90 <f1 / f3<2.60 ···(1b) 0.20<|M34 / M45|<0.67 (2b) With the above configuration, it is possible to realize a zoom lens that has high optical performance over the entire zoom range, and that is capable of ensuring a sufficient zoom ratio while also being compact and lightweight.

[0034] Next, the configuration that is preferably satisfied in the zoom lens L0 of each embodiment will be described.

[0035] It is preferable that an optical element with positive refractive power be disposed closest to the image side of the first lens group L1, which facilitates the miniaturization and weight reduction of the zoom lens L0 and makes it easy to realize a zoom lens in which various aberrations, including chromatic aberration, are well corrected.

[0036] It is preferable to place an aperture stop SP between the second lens unit L2 and the third lens unit L3, which allows the effective diameter of the lens unit located closer to the image side than the aperture stop SP to be kept small, making it easier to reduce the weight of the zoom lens L0.

[0037] During zooming from the wide-angle end to the telephoto end, it is preferable that the second lens unit L2 is stationary relative to the image plane IP, which simplifies the mechanism for holding the second lens unit L2 and makes it easier to reduce the size of the second lens unit L2 and the zoom lens L0.

[0038] It is preferable that the third lens group L3 or the fourth lens group L4 is composed of two or less lenses, which allows the weight of the third lens group L3 or the fourth lens group L4 to be reduced, making it easier to reduce the weight of the zoom lens L0.

[0039] It is preferable that at least one of the lens surfaces of the third lens group L3 and the fourth lens group L4 be aspherical, which allows the number of lens elements in the third lens group L3 or the fourth lens group L4 to be reduced, thereby reducing the weight of the zoom lens L0 and suppressing aberration fluctuations during zooming.

[0040] Furthermore, it is preferable that the fifth lens group L5 moves when focusing from infinity to a close distance. That is, focusing from infinity to a close distance is preferably performed by the fifth lens group L5. The lens group closer to the image side than the aperture stop SP tends to have a small effective diameter of the light beam. Therefore, if the lens group closer to the image side than the aperture stop SP is used as the focus lens group, the holding mechanism and drive mechanism can be simplified and the effective diameter of the entire lens system can be reduced, making it easier to reduce the weight of the zoom lens L0. Furthermore, since the magnification change is relatively small on the image side than the aperture stop SP, the change in image magnification when focusing from infinity to a close distance can be reduced. In this regard, the change in angle of view when the focus lens group is moved from infinity to a close distance, known as breathing, can be reduced, making this ideal for video shooting. In particular, using the fifth lens group L5 as the focus lens group can sufficiently increase focus sensitivity and reduce the amount of movement of the fifth lens group L5 during focusing, making it easier to reduce the size of the zoom lens L0.

[0041] By driving all or part of any of the lens groups in a direction that includes a component perpendicular to the optical axis, it is possible to reduce image quality degradation due to image shake (camera shake). In particular, it is preferable to drive the second lens group L2 in a direction that includes a component perpendicular to the optical axis during image shake correction. Using the second lens group L2 as an image shake correction lens group simplifies the image shake correction mechanism while reducing the amount of movement of the lens group during image shake correction, which is preferable because it facilitates the miniaturization of the zoom lens L0. Note that, because the second lens group L2 performs image shake correction by including a component that moves perpendicular to the optical axis, the same effect can be achieved even when image shake correction is performed using a rotational component around a certain point, i.e., image shake correction by rotation.

[0042] Next, conditions that the zoom lens L0 of each embodiment should preferably satisfy will be described. The zoom lens L0 of each embodiment should preferably satisfy one or more of the following conditional expressions (3) to (9).

[0043] 0.50 <TTLt / ft<1.00 ···(3) 0.90<|β2wt / βRwt|<10.00 ···(4) 2.0<|M1 / M3|<4.0 (5) 0.3 <f1 / ft<0.7 ···(6) 0.18 <f3 / ft<0.70 ···(7) 0.10 <f4 / ft<0.30 ···(8) -0.22 <f5 / ft<-0.10 ···(9) Here, TTLt is the distance on the optical axis from the surface of the zoom lens L0 closest to the object to the image plane IP at the telephoto end (total lens length). ft is the focal length of the zoom lens L0 at the telephoto end. β2wt is the magnification sharing ratio of the second lens unit L2 when zooming from the wide-angle end to the telephoto end. βRwt is the magnification sharing ratio of the composite lens unit from the fourth lens unit L4 to the lens unit located closest to the image when zooming from the wide-angle end to the telephoto end. M1 is the movement amount of the first lens unit L1 when zooming from the wide-angle end to the telephoto end. M3 is the movement amount of the third lens unit L3 when zooming from the wide-angle end to the telephoto end. f4 is the focal length of the fourth lens unit L4. f5 is the focal length of the fifth lens unit L5.

[0044] Note that the movement amount M1 is based on the vertex position of the surface of the first lens group L1 closest to the object at the wide-angle end, and the sign of the movement amount M1 is negative when the first lens group L1 is closer to the object than the reference. The movement amount M3 is based on the vertex position of the surface of the third lens group L3 closest to the object at the wide-angle end, and the sign of the movement amount M3 is negative when the third lens group L3 is closer to the object than the reference. Furthermore, the magnification variation contribution ratios β2wt and βRwt are amounts defined as follows:

[0045] β2wt=β2t / β2w βRwt=βRt / βRw Here, β2w is the lateral magnification of the second lens unit L2 at the wide-angle end. β2t is the lateral magnification of the second lens unit L2 at the telephoto end. βRw is the combined lateral magnification of the combined lens units from the fourth lens unit to the lens unit located closest to the image at the wide-angle end. βRt is the combined lateral magnification of the combined lens units from the fourth lens unit to the lens unit located closest to the image at the telephoto end.

[0046] The composite lateral magnification βRw is a quantity expressed by the total product of the lateral magnifications of each lens group from the fourth lens group L4 to the lens group closest to the image at the wide-angle end, and the composite lateral magnification βRt is a quantity expressed by the total product of the lateral magnifications of each lens group from the fourth lens group L4 to the lens group closest to the image at the telephoto end.

[0047] Conditional expression (3) defines the ratio of the distance TTLt on the optical axis from the surface closest to the object of the zoom lens L0 at the telephoto end to the image plane IP to the focal length ft of the zoom lens L0 at the telephoto end. Setting the distance TTLt appropriately facilitates the miniaturization and weight reduction of the zoom lens L0. If the value of the distance TTLt relative to the focal length ft of the zoom lens L0 falls below the lower limit of conditional expression (3), the refractive power of each lens group constituting the zoom lens L0 becomes too strong. Therefore, the number of lenses in each lens group must be increased to correct aberrations generated within each lens group, which is undesirable as it makes it difficult to reduce the weight of the zoom lens L0. If the value of the distance TTLt relative to the focal length ft exceeds the upper limit of conditional expression (3), the diameter of the first lens group L1 at the telephoto end becomes large, which is undesirable as it makes it difficult to reduce the weight of the zoom lens L0. Furthermore, the overall length of the zoom lens L0 at the wide-angle end becomes long, which is undesirable as well.

[0048] Conditional expression (4) defines the absolute value of the ratio between the magnification sharing ratio β2wt of the second lens group L2 and the magnification sharing ratio βRwt of the composite lens group from the fourth lens group L4 to the lens group closest to the image. By appropriately setting the value of the magnification sharing ratio β2wt relative to the magnification sharing ratio βRwt, it becomes easy to ensure a sufficient zoom ratio while shortening the overall length. If the absolute value of the magnification sharing ratio β2wt relative to the absolute value of the magnification sharing ratio βRwt falls below the lower limit of conditional expression (4) and becomes too small, it becomes necessary to ensure the zoom ratio with the lens groups after the fourth lens group L4, which move less during zooming. Therefore, to ensure a sufficient zoom ratio, it is necessary to strengthen the refractive power of the lens groups after the fourth lens group L4. As a result, the number of lenses after the fourth lens group L4 increases, making it difficult to reduce the weight of the zoom lens L0, which is undesirable. Furthermore, if the absolute value of the magnification variation sharing ratio β2wt relative to the absolute value of the magnification variation sharing ratio βRwt exceeds the upper limit of conditional expression (4) and becomes too large, the refractive power of the first lens unit L1 becomes too strong, and the number of lenses in the first lens unit L1 increases, which is undesirable because it becomes difficult to reduce the weight of the zoom lens L0.

[0049] Conditional expression (5) defines the absolute value of the ratio between the movement amount M1 of the first lens group L1 and the movement amount M3 of the third lens group L3 during zooming from the wide-angle end to the telephoto end. By appropriately setting the value of the movement amount M1 relative to the movement amount M3, it becomes easy to achieve a compact and lightweight zoom lens L0 while maintaining a sufficient zoom ratio. If the absolute value of the movement amount M1 of the first lens group L1 becomes too small, falling below the lower limit of conditional expression (5), the overall lens length at the wide-angle end becomes long, making it difficult to reduce the size of the zoom lens L0, which is undesirable. Also, if the absolute value of the movement amount M3 of the third lens group L3 becomes too large, falling below the lower limit of conditional expression (5), aberration fluctuations during zooming become large, and the number of lenses in the third lens group L3 must be increased to correct this. As a result, it becomes difficult to reduce the weight of the zoom lens L0, which is undesirable. If the absolute value of the movement amount M1 of the first lens group L1 becomes too large, exceeding the upper limit of conditional expression (5), aberration fluctuations during zooming will increase. Therefore, to suppress this, it is necessary to increase the number of lenses in the first lens group L1, which is undesirable as it makes it difficult to reduce the weight of the zoom lens L0. Furthermore, if the absolute value of the movement amount M3 of the third lens group L3 becomes too small, exceeding the upper limit of conditional expression (5), it is undesirable as it makes it difficult to ensure a sufficient zoom ratio.

[0050] Conditional expression (6) defines the ratio of the focal length f1 of the first lens group L1 to the focal length ft of the zoom lens L0 at the telephoto end. By appropriately setting the focal length f1 of the first lens group L1 relative to the focal length ft at the telephoto end, it becomes easy to shorten the overall length of the zoom lens L0 while maintaining high optical performance. If the focal length f1 of the first lens group L1 becomes too short relative to the focal length ft at the telephoto end, falling below the lower limit of conditional expression (6), the number of lenses in the first lens group L1 will increase in order to correct various aberrations, such as spherical aberration. This makes it difficult to reduce the weight of the zoom lens L0, which is undesirable. If the focal length f1 of the first lens group L1 becomes too long, exceeding the upper limit of conditional expression (6), the overall lens length will increase, making it difficult to reduce the size of the zoom lens L0, which is undesirable.

[0051] Conditional expression (7) defines the ratio of the focal length f3 of the third lens group L3 to the focal length ft of the zoom lens L0 at the telephoto end. By appropriately setting the focal length f3 of the third lens group L3 relative to the focal length ft at the telephoto end, it becomes easy to achieve both a reduced number of lenses and a sufficient zoom ratio. If the focal length f3 of the third lens group L3 falls below the lower limit of conditional expression (7) and becomes too short relative to the focal length ft at the telephoto end, the number of lenses in the third lens group L3 must be increased to suppress zoom fluctuations of various aberrations, such as coma. This makes it difficult to reduce the weight of the zoom lens L0, which is undesirable. If the focal length f3 of the third lens group L3 exceeds the upper limit of conditional expression (7), making it difficult to achieve the desired zoom ratio, which is undesirable.

[0052] Conditional expression (8) defines the ratio of the focal length f4 of the fourth lens group L4 to the focal length ft of the zoom lens L0 at the telephoto end. By appropriately setting the focal length f4 of the fourth lens group L4 relative to the focal length ft at the telephoto end, it becomes easy to achieve both a reduced number of lenses and a sufficient zoom ratio. If the focal length f4 of the fourth lens group L4 falls below the lower limit of conditional expression (8) and becomes too short relative to the focal length ft at the telephoto end, the number of lenses in the fourth lens group L4 must be increased to suppress zoom fluctuations of various aberrations, such as coma. This makes it difficult to reduce the weight of the zoom lens L0, which is undesirable. If the focal length f4 of the fourth lens group L4 exceeds the upper limit of conditional expression (8), making it difficult to achieve the desired zoom ratio, which is undesirable.

[0053] Conditional expression (9) defines the ratio of the focal length f5 of the fifth lens group L5 to the focal length ft of the zoom lens L0 at the telephoto end. By appropriately setting the focal length f5 of the fifth lens group L5 relative to the focal length ft at the telephoto end, it becomes easy to achieve both a small number of lenses and a sufficient zoom ratio. Furthermore, when the zoom lens L0 satisfies conditional expression (9), it becomes easy to achieve both a lightweight focus lens group and sufficient focus sensitivity when focusing from infinity to a close distance using the fifth lens group L5. If the focal length f5 of the fifth lens group L5 falls below the lower limit of conditional expression (9) and becomes too short relative to the focal length ft at the telephoto end, the number of lenses in the fifth lens group L5 must be increased to suppress zoom fluctuations of various aberrations such as field curvature. This makes it difficult to reduce the weight of the zoom lens L0, which is undesirable. Furthermore, if the lower limit of conditional expression (9) is exceeded, when the fifth lens group L5 is used as a focus lens group, the focus sensitivity becomes too high, making it difficult to control the focus lens group using an actuator, which is undesirable. If the upper limit of conditional expression (9) is exceeded and the focal length f5 of the fifth lens group L5 becomes too long, it becomes difficult to ensure a desired zoom ratio, which is undesirable. If the upper limit of conditional expression (9) is exceeded, when the fifth lens group is used as a focus lens group, the amount of movement of the focus lens group during focusing becomes too large, making it difficult to reduce the size of the zoom lens L0, which is undesirable.

[0054] It is more preferable that the numerical ranges of the conditional expressions (3) to (9) be within the ranges of the following conditional expressions (3a) to (9a).

[0055] 0.70 <TTLt / ft<0.80 ···(3a) 0.92<|β2wt / βRwt|<9.00 ···(4a) 2.1<|M1 / M3|<3.8 (5a) 0.4 <f1 / ft<0.6 ···(6a) 0.20 <f3 / ft<0.60 ···(7a) 0.11 <f4 / ft<0.25 ···(8a) -0.20 <f5 / ft<-0.11 ···(9a) It is more preferable that the numerical ranges of the conditional expressions (3) to (9) be within the ranges of the following conditional expressions (3b) to (9b).

[0056] 0.74 <TTLt / ft<0.77 ···(3b) 0.93<|β2wt / βRwt|<8.40 ···(4b) 2.2<|M1 / M3|<3.5 (5b) 0.50 <f1 / ft<0.58 ···(6b) 0.22 <f3 / ft<0.52 ···(7b) 0.12 <f4 / ft<0.21 ···(8b) -0.19 <f5 / ft<-0.12 ···(9b) Next, the zoom lens L0 of each embodiment will be described in detail.

[0057] The lens configuration of the zoom lens L0 of Examples 1 to 3 will be described. FIGS. 1, 4, and 7 are cross-sectional views of the zoom lens L0 of Examples 1 to 3, respectively. The zoom lens L0 of Examples 1 to 3 is composed of first to fifth lens groups. L1 is a first lens group with positive refractive power, L2 is a second lens group with negative refractive power, L3 is a third lens group with positive refractive power, L4 is a fourth lens group with positive refractive power, and L5 is a fifth lens group with negative refractive power. Furthermore, focusing from infinity to a close distance can be performed by moving the fifth lens group L5 toward the image side. Furthermore, driving the second lens group L2 in a direction including a component perpendicular to the optical axis can reduce image quality degradation due to image shake (camera shake).

[0058] The lens configuration of the zoom lens L0 of Example 4 will be described. FIG. 10 is a lens cross-section of the zoom lens L0 of Example 4. The zoom lens L0 of Example 4 is composed of first to sixth lens groups. L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with positive refractive power, L4 is the fourth lens group with positive refractive power, L5 is the fifth lens group with negative refractive power, and L6 is the sixth lens group with negative refractive power. Furthermore, focusing from infinity to a close distance can be performed by moving the fifth lens group L5 toward the image side. Furthermore, driving the second lens group L2 in a direction including a component perpendicular to the optical axis can reduce image quality degradation due to image shake (camera shake).

[0059] The lens configuration of the zoom lens L0 of Example 5 will be described. FIG. 13 is a lens cross-section of the zoom lens L0 of Example 5. The zoom lens L0 of Example 5 is composed of first to sixth lens groups. L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with positive refractive power, L4 is the fourth lens group with positive refractive power, L5 is the fifth lens group with negative refractive power, and L6 is the sixth lens group with positive refractive power. Furthermore, focusing from infinity to a close distance can be performed by moving the fifth lens group L5 toward the image side. Furthermore, driving the second lens group L2 in a direction including a component perpendicular to the optical axis can reduce image quality degradation due to image shake (camera shake).

[0060] Numerical examples 1 to 5 corresponding to the first to fifth embodiments, respectively, are shown below.

[0061] In the surface data of each numerical example, r (mm) represents the radius of curvature of each optical surface, and d (mm) represents the axial spacing (distance on the optical axis) between the mth 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 at the d-line, and vd represents the Abbe number of the optical element. Note that the Abbe number vd of a certain material is given by the following when the refractive indices at the d-line (587.56 nm), F-line (486.13 nm), and C-line (656.27 nm) of the Fraunhofer lines are Nd, NF, and NC, respectively: νd=(Nd-1) / (NF-NC) It is expressed as:

[0062] In each numerical example, d (mm), focal length (mm), F-number, and half angle of view (°) calculated by paraxial calculation are all values ​​when the zoom lens L0 of each example is focused on an object at infinity. The back focus BF is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. The total lens length is the distance on the optical axis from the first lens surface (the lens surface closest to the object) to the final lens surface plus the back focus. The lens group is not limited to being composed of multiple lenses, and may also be composed of a single lens. If the optical surface is aspherical, an asterisk (*) is added to the right of the surface number. The aspherical shape is expressed as follows: 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 radius of curvature, K is the conic constant, and A4, A6, A8, A10, and A12 are the aspherical coefficients of each order. x=(h 2 / 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 In addition, "e±XX" in each aspherical coefficient is "×10± XX " means.

[0063] [Numerical Example 1] Unit: mm Surface Data Surface number rd nd νd 1 45.825 1.50 1.91082 35.2 2 33.201 5.15 1.49700 81.5 3 -334.892 (variable) 4 -49.993 0.80 1.77250 49.6 5 14.423 2.23 2.05090 26.9 6 27.415 (variable) 7 (Aperture) ∞ 0.38 8 20.369 3.30 1.48749 70.2 9 -47.315 4.76 10 -17.892 1.00 1.84666 23.9 11 -33.732 (variable) 12 32.322 3.39 1.49700 81.5 13 -19.312 0.82 14 -26.496 1.90 1.53110 55.9 15* -34.445 (variable) 16 -218.570 1.50 1.89286 20.4 17 -34.943 0.70 1.77250 49.6 18 23.223 (variable) Image plane ∞ Aspheric data Page 15 K = 0.00000e+00 A 4= 5.54876e-05 A 6= 1.06102e-07 A 8=-1.28230e-09 A10=2.87863e-11 A12=-3.23250e-14 Various data Zoom ratio 3.64 Wide-angle Mid-range Telephoto Focal length 55.72 131.14 202.99 F-number 5.19 6.53 7.28 Half angle of view (°) 13.77 5.95 3.85 Image height 13.66 13.66 13.66 Lens length 110.95 140.56 154.01 BF 33.31 50.77 60.84 d 3 14.77 44.38 57.83 d 6 21.16 10.97 4.47 d11 4.61 1.01 1.00 d15 9.68 6.01 2.44 d18 33.31 50.77 60.84 Zoom lens group data Group starting plane focal length 1 1 110.76 2 4 -29.03 3 7 61.52 4 12 28.18 5 16 -29.40 [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 45.531 1.50 1.91082 35.2 2 33.042 5.15 1.49700 81.5 3 -301.422 (variable) 4 -53.807 0.80 1.77250 49.6 5 15.485 2.23 2.05090 26.9 6 28.905 (variable) 7 (Aperture) ∞ 0.38 8 21.214 3.30 1.48749 70.2 9 -217.922 6.03 10 -19.999 1.00 1.84666 23.9 11 -37.377 (variable) 12 24.246 3.39 1.49700 81.5 13 -24.401 2.49 14 -39.700 1.90 1.53110 55.9 15* -45.150 (variable) 16 -642.141 1.50 1.89286 20.4 17 -40.848 0.70 1.77250 49.6 18 22.945 (variable) Image plane ∞ Aspheric data Page 15 K = 0.00000e+00 A 4= 6.52836e-05 A 6= 1.80332e-07 A 8=-2.40292e-09 A10= 3.90789e-11 A12=-1.26282e-13 Various data Zoom ratio 3.66 Wide-angle Mid-range Telephoto Focal length 55.70 89.31 203.70 F-number 5.10 6.05 7.24 Half angle of view (°) 13.78 8.70 3.84 Image height 13.66 13.66 13.66 Lens length 112.15 126.46 152.60 BF 29.61 39.68 58.93 d 3 16.02 30.32 56.47 d 6 22.16 16.10 4.12 d11 2.91 1.02 1.00 d15 11.09 8.97 1.73 d18 29.61 39.68 58.93 Zoom lens group data Group starting plane focal length 1 1 108.03 2 4 -30.57 3 7 105.18 4 12 26.23 May 16 -31.13 [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 43.690 1.50 1.91082 35.2 2 32.306 5.15 1.49700 81.5 3 -1123.138 (variable) 4 -55.824 0.80 1.77250 49.6 5 14.566 2.23 2.05090 26.9 6 27.140 (variable) 7 (Aperture) ∞ 0.38 8 18.758 3.30 1.48749 70.2 9 -38.617 2.78 10 -18.849 1.00 1.84666 23.9 11 -31.951 (variable) 12 47.442 3.39 1.49700 81.5 13 -16.471 1.17 14 -15.881 1.90 1.53110 55.9 15* -30.318 (variable) 16 -109.418 1.50 1.89286 20.4 17 -33.181 0.70 1.77250 49.6 18 29.434 (variable) Image plane ∞ Aspheric data Page 15 K = 0.00000e+00 A 4= 4.11714e-05 A 6= 9.36576e-08 A 8=-3.25755e-09 A10= 1.24523e-10 A12=-1.30291e-12 Various data Zoom ratio 3.59 Wide-angle Mid-range Telephoto Focal length 55.70 91.48 200.00 F-number 5.10 7.24 7.24 Half angle of view (°) 13.78 8.49 3.91 Image height 13.66 13.66 13.66 Lens length 110.96 126.34 153.10 BF 26.82 39.34 58.77 d 3 17.43 32.81 59.57 d 6 21.33 14.70 4.18 d11 7.98 4.47 2.08 d15 11.61 9.24 2.71 d18 26.82 39.34 58.77 Zoom lens group data Group starting plane focal length 1 1 115.33 2 4 -29.99 3 7 44.52 4 12 40.10 5 16 -32.29 [Numerical Example 4] Unit: mm Surface Data Surface number rd nd νd 1 48.458 1.50 1.91082 35.2 2 35.037 5.15 1.49700 81.5 3 -366.330 (variable) 4 -56.903 0.80 1.77250 49.6 5 16.111 2.23 2.05090 26.9 6 31.017 (variable) 7 (Aperture) ∞ 0.38 8 23.604 3.30 1.48749 70.2 9 -38.962 3.39 10 -19.447 1.00 1.84666 23.9 11 -33.056 (variable) 12 58.134 3.39 1.49700 81.5 13 -19.972 1.08 14 -24.146 1.90 1.53110 55.9 15* -36.705 (variable) 16 -173.201 1.50 1.89286 20.4 17 -42.875 0.70 1.77250 49.6 18 34.214 (variable) 19 -20.708 2.00 1.67118 59.7 20 -23.875 (variable) Image plane ∞ Aspheric data Page 15 K = 0.00000e+00 A 4= 2.95366e-05 A 6= 1.01448e-07 A 8=-4.38121e-09 A10= 1.20732e-10 A12=-1.07166e-12 Various data Zoom ratio 4.10 Wide-angle Mid-range Telephoto Focal length 51.47 114.27 210.87 F-number 5.10 6.43 7.24 Half angle of view (°) 14.86 6.82 3.71 Image height 13.66 13.66 13.66 Lens length 102.52 139.32 160.37 BF 15.54 14.18 20.68 d 3 2.00 38.81 59.86 d 6 20.60 13.52 4.06 d11 9.66 3.63 1.00 d15 16.75 9.01 2.11 d18 9.65 31.86 44.34 d20 15.54 14.18 20.68 Zoom lens group data Group starting plane focal length 1 1 118.16 2 4 -33.18 3 7 57.05 4 12 39.03 5 16 -39.96 6 19 -311.63 [Numerical Example 5] Unit: mm Surface Data Surface number rd nd νd 1 46.460 1.50 1.91082 35.2 2 34.450 5.15 1.49700 81.5 3 -575.893 (variable) 4 -55.662 0.80 1.77250 49.6 5 15.390 2.23 2.05090 26.9 6 28.747 (variable) 7 (Aperture) ∞ 0.38 8 19.339 3.30 1.48749 70.2 9 -60.917 2.42 10 -18.996 1.00 1.84666 23.9 11* -30.810 (variable) 12 40.899 3.39 1.49700 81.5 13 -20.594 3.03 14 -20.033 1.90 1.53110 55.9 15* -31.946 (variable) 16 -61.564 1.50 1.89286 20.4 17 -26.333 0.70 1.77250 49.6 18 25.922 (variable) 19 -427.813 2.34 1.58419 69.2 20 -51.504 (variable) Image plane ∞ Aspheric data Page 11 K = 0.00000e+00 A 4= 1.89753e-07 A 6=-1.83776e-08 A 8= 1.98799e-10 Page 15 K = 0.00000e+00 A 4= 4.67419e-05 A 6= 1.45817e-07 A 8=-7.40629e-09 A10=2.95336e-10 A12=-3.48988e-12 Various data Zoom ratio 4.06 Wide-angle Mid-range Telephoto Focal length 49.71 102.75 201.95 F-number 5.10 6.27 7.24 Half angle of view (°) 15.36 7.57 3.87 Image height 13.66 13.66 13.66 Lens length 97.13 130.11 154.28 BF 15:00 9:10 13:16 d 3 2.00 34.98 59.15 d 6 20.48 13.79 4.13 d11 5.55 3.67 3.68 d15 14.90 12.37 6.67 d18 9.57 26.57 37.86 d20 15.00 9.10 13.16 Zoom lens group data Group starting plane focal length 1 1 116.23 2 4 -30.97 3 7 55.34 4 12 37.30 5 16 -24.91 6 19 100.00 The various values ​​in each numerical example are summarized in Tables 1 and 2 below.

[0064] [Table 1]

[0065] [Table 2]

[0066] [Imaging device] Next, an embodiment of a digital still camera (image capture device) 10 that uses a zoom lens L0 of the present invention as an image capture optical system will be described with reference to Fig. 16. In Fig. 16, 13 denotes a camera body, and 11 denotes an image capture optical system configured with any of the zoom lenses L0 described in Examples 1 to 5. 12 denotes a solid-state image capture element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body 13 and receives and photoelectrically converts an optical image formed by the image capture optical system 11. The camera body 13 may be a so-called single-lens reflex camera that has a quick-return mirror, or a so-called mirrorless camera that does not have a quick-return mirror.

[0067] In this way, by applying the zoom lens L0 of the present invention to an imaging device such as a digital still camera, an imaging device with a compact lens can be obtained.

[0068] [Imaging system] An imaging system (surveillance camera system) may be configured that includes the zoom lens L0 of each embodiment and a control unit that controls the zoom lens L0. 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 stabilization. In this case, the control unit does not need to be configured integrally with the zoom lens L0; the control unit may be configured separately from the zoom lens L0. For example, a control unit (control device) located far from the drive units that drive each lens of the zoom lens L0 may include a transmission unit that sends control signals (commands) to control the zoom lens L0. Such a control unit allows the zoom lens L0 to be remotely controlled.

[0069] Alternatively, the control unit may be provided with an operation unit such as a controller or buttons for remotely operating the zoom lens L0, thereby controlling the zoom lens in response to user input to the operation unit. For example, the operation unit may be provided with a zoom-in button and a zoom-out button. The control unit may then send a signal to a drive unit for the zoom lens L0 so that the magnification of the zoom lens increases when the user presses the zoom-in button, and decreases when the user presses the zoom-out button.

[0070] The imaging system may also have a display unit such as a liquid crystal panel that displays information (movement state) related to the zoom of the zoom lens L0. Information related to the zoom of the zoom lens L0 may be, for example, the zoom magnification (zoom state) or the movement amount (movement state) of each lens group. In this case, the user can remotely operate the zoom lens L0 via an operation unit while viewing the information related to the zoom of the zoom lens L0 displayed on the display unit. In this case, the display unit and operation unit may be integrated by using, for example, a touch panel.

[0071] Although the 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 the gist of the present invention. [Explanation of symbols]

[0072] L0 zoom lens L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group L5 Fifth lens group

Claims

1. A zoom lens having, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, wherein the spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side, the distance between the third lens group and the fourth lens group narrows, and the distance between the fourth lens group and the fifth lens group narrows, the first lens group is composed of two or less optical elements having refractive power, When the focal length of the first lens group is f1, the focal length of the third lens group is f3, the amount of change in the distance between the third lens group and the fourth lens group during zooming from the wide-angle end to the telephoto end is M34, the amount of change in the distance between the fourth lens group and the fifth lens group during zooming from the wide-angle end to the telephoto end is M45, the amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end is M1, and the amount of movement of the third lens group during zooming from the wide-angle end to the telephoto end is M3, 0.50<f1 / f3<2.70 0.18<|M34 / M45|<0.70 2.0<|M1 / M3|<4.0 A zoom lens characterized by satisfying the following conditional expressions:

2. When the distance on the optical axis from the surface of the zoom lens closest to the object to the image plane at the telephoto end is TTLt and the focal length of the zoom lens at the telephoto end is ft, 0.50<TTLt / ft<1.00 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. When the magnification variation share of the second lens group during zooming from the wide-angle end to the telephoto end is β2wt, and the magnification variation share of the composite lens group from the fourth lens group to the lens group arranged closest to the image during zooming from the wide-angle end to the telephoto end is βRwt, 0.90<|β2wt / βRwt|<10.00 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. When the focal length of the zoom lens at the telephoto end is ft, 0.3<f1 / ft<0.7 4. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. When the focal length of the third lens group is f3 and the focal length of the zoom lens at the telephoto end is ft, 0.18<f3 / ft<0.70 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. When the focal length of the fourth lens group is f4 and the focal length of the zoom lens at the telephoto end is ft, 0.10<f4 / ft<0.30 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the focal length of the fifth lens group is f5 and the focal length of the zoom lens at the telephoto end is ft, -0.22<f5 / ft<-0.10 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. 8. The zoom lens according to claim 1, wherein an optical element having a positive refractive power is disposed on the most image-side side of the first lens group.

9. 9. The zoom lens according to claim 1, wherein an aperture stop is disposed between the second lens group and the third lens group.

10. 10. The zoom lens according to claim 1, wherein the second lens group is stationary relative to an image plane during zooming from the wide-angle end to the telephoto end.

11. 11. The zoom lens according to claim 1, wherein the third lens group is made up of two or less lenses.

12. 12. The zoom lens according to claim 1, wherein the fourth lens group is made up of two or less lenses.

13. 13. The zoom lens according to claim 1, wherein at least one of the lens surfaces of the third lens group and the fourth lens group is aspherical.

14. 14. The zoom lens according to claim 1, wherein the fifth lens group moves during focusing from infinity to a close distance.

15. 15. The zoom lens according to claim 1, wherein, during image blur correction, the second lens group moves in a direction including a component perpendicular to the optical axis.

16. 16. The zoom lens according to claim 1, wherein the zoom lens comprises, in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group.

17. 16. The zoom lens according to claim 1, wherein the zoom lens comprises, in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and a sixth lens group.

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

19. 18. An imaging system comprising: a zoom lens according to claim 1; and a control unit that controls the zoom lens during zooming.

20. 20. The imaging system according to claim 19, wherein the control unit is configured as a separate unit from the zoom lens and includes a transmission unit that transmits a control signal for controlling the zoom lens.

21. 21. The imaging system according to claim 19, wherein the control unit is configured as a separate unit from the zoom lens and has an operation unit for operating the zoom lens.

22. 22. The imaging system according to claim 19, further comprising a display unit that displays information related to the zoom of the zoom lens.

Images