Zoom lens and imaging device including same

Abstract

A zoom lens according to the present invention comprises, in order from an object side to an image side, a first lens group that has positive refractive power, a second lens group that has negative refractive power, a third lens group that has positive refractive power, an intermediate group that includes at least one lens group, and a final lens group that has positive refractive power. The distance between adjacent lens groups changes during zooming. The lens of the second lens group that is furthest to the object side has a concave surface that is oriented toward the object side. During zooming from a wide-angle end to a telephoto end, the distance between the first lens group and the second lens group increases. The amount of distortion Distw (%) at the wide-angle end and the maximum half angle of view ωw (degrees) at the wide-angle end satisfy a prescribed conditional expression.

Description

Zoom lens and imaging device having the same

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

[0002] In recent years, there has been a demand for smaller zoom lenses used in image pickup devices. A known zoom lens that satisfies this demand is a positive-lead zoom lens, in which a lens group having positive refractive power is arranged closest to the object. Patent Document 1 (JP-A-2003-125266) discloses a positive-lead zoom lens that includes, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group.

[0003] JP 2015-118127 A

[0004] In a positive-lead zoom lens such as the one described above, various mechanisms, such as an image stabilization mechanism for image shake correction and a mechanism for moving lens groups during focusing and zooming, are located closer to the image side than the lens group closest to the object. If the diameter of the lenses included in the lens group located closer to the image side than the lens group closest to the object becomes larger, the aforementioned mechanisms also become larger, resulting in a larger zoom lens. Therefore, in order to achieve a compact zoom lens, it is necessary to reduce the diameter of each lens group by appropriately setting the refractive power and arrangement of the lens groups that make up the zoom lens.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a compact zoom lens having small diameter lens groups.

[0006] One aspect of a zoom lens that achieves the above object is a zoom lens that includes, 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, an intermediate group having one or more lens groups, and a final lens group having positive refractive power, and the distance between adjacent lens groups changes during zooming, and the lens included in the second lens group that is arranged closest to the object side has a concave surface facing the object side, and the distance between the first lens group and the second lens group increases during zooming from the wide-angle end to the telephoto end, and the zoom lens is characterized in that the following conditional expressions are satisfied, where Distw [%] is the amount of distortion at the wide-angle end and ωw [degrees] is the maximum half angle of view at the wide-angle end: -20.0<Distw<-4.5, 0.1<ωw<25.0

[0007] Another aspect of a zoom lens for achieving the above object is a zoom lens that includes, 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, an intermediate group consisting of one or more lens groups, and a final lens group having positive refractive power, wherein the spacing between adjacent lens groups changes during zooming, and the second lens group includes a positive lens.

[0008] According to the present invention, it is possible to provide a compact zoom lens having a small diameter lens group.

[0009] 1. Lens cross-sectional view of the zoom lens of Example 1 at the wide-angle end. 2. Longitudinal aberration diagram of the zoom lens of Example 1 at the wide-angle end. 3. Longitudinal aberration diagram of the zoom lens of Example 2 at the wide-angle end. 4. Longitudinal aberration diagram of the zoom lens of Example 3 at the wide-angle end. 5. Longitudinal aberration diagram of the zoom lens of Example 2 at the telephoto end. 6. Lens cross-sectional view of the zoom lens of Example 3 at the wide-angle end. 7. Longitudinal aberration diagram of the zoom lens of Example 3 at the telephoto end. 8. Lens cross-sectional view of the zoom lens of Example 4 at the wide-angle end. 9. Longitudinal aberration diagram of the zoom lens of Example 4 at the telephoto end. 10. Lens cross-sectional view of the zoom lens of Example 5 at the wide-angle end. 11. Longitudinal aberration diagram of the zoom lens of Example 5 at the telephoto end. 12. Schematic diagram of an imaging device according to an embodiment.

[0010] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. For convenience, the drawings may be drawn to a scale different from the actual scale. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted. In the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zooming lens group is located at both ends of the range in which it can move mechanically on the optical axis.

[0011] 1, 3, 5, 7, and 9 are cross-sectional views of the zoom lens L0 according to Examples 1 to 5 at the wide-angle end when focused on infinity. In each cross-sectional view, IP represents the image plane. The zoom lens L0 according to each Example is used in an imaging device, and the image plane IP is located at the image plane IP, where the image plane IP is the image plane of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor. Note that the zoom lens according to each Example may also be used as the photographic optical system of a silver halide film camera, in which case a photosensitive surface corresponding to the film surface is located on the image plane IP. In addition, in each cross-sectional view, SP represents an aperture stop that determines (limits) the light beam at the maximum aperture F-number.

[0012] In each cross-sectional view, the left side is the object side (front side) and the right side is the image side (rear side). The zoom lens L0 according to each embodiment may be used as a projection lens for a projector or the like. In this case, the left side of each cross-sectional view is the screen side, and the right side is the projected image side. In each cross-sectional view, the i-th lens group arranged i-th from the object side to the image side is represented as Li. In the zoom lens L0, the spacing between adjacent lens groups changes during zooming. In other words, in this specification, a lens group refers to a group of lenses that move together during zooming, or a group of lenses that remain stationary during zooming. A lens group may consist of a single lens or multiple lenses. A lens group may also include an aperture stop.

[0013] The arrows (solid lines) shown in each cross-sectional view represent the movement locus of each lens group during zooming from the wide-angle end to the telephoto end of the zoom lens L0, and the arrows (dashed lines) shown in each cross-sectional view represent the movement locus of each lens group during focusing from infinity to a close distance.

[0014] 2A, 2B, 4A, 4B, 6A, 6B, 8A, 8B, 10A, and 10B are longitudinal aberration diagrams of the zoom lens L0 according to Examples 1 to 5 when focused at infinity at the wide-angle end. In each longitudinal aberration diagram, from left to right, diagram A shows longitudinal aberration at the wide-angle end, and diagram B shows longitudinal aberration at the telephoto end.

[0015] In each longitudinal aberration diagram, Fno is the F-number, and ω is the half angle of view (degrees). In each spherical aberration diagram, the solid line indicates the amount of spherical aberration for the d-line (wavelength 587.6 nm), and the two-dot chain line indicates the amount of spherical aberration for the g-line (wavelength 435.8 nm). In each astigmatism diagram, ΔS (solid line) indicates the amount of astigmatism on the sagittal image plane, and ΔM (dashed line) indicates the amount of astigmatism on the meridional image plane. In each distortion diagram, the solid line indicates the amount of distortion for the d-line. In each chromatic aberration diagram, the two-dot chain line indicates the amount of chromatic aberration for the g-line.

[0016] Next, the characteristic configuration of the zoom lens L0 according to Examples 1 to 5 will be described.

[0017] The zoom lens L0 in each embodiment comprises, arranged in order from the object side to the image side, a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, an intermediate lens unit LM having one or more lens units, and a final lens unit LR having positive refractive power.

[0018] In the zoom lens L0 according to each embodiment, the final lens unit LR, which is located closest to the image side, has positive refractive power. This produces strong barrel distortion and shifts the exit pupil position toward the object side. As a result, the height of off-axial rays incident on the second lens unit L2 can be reduced, allowing the diameter of the second lens unit L2 to be made smaller.

[0019] In the zoom lens L0 according to each embodiment, the distance between the first lens unit L1 and the second lens unit L2 increases during zooming from the wide-angle end to the telephoto end. This reduces the positive refractive power of the first lens unit L1, thereby reducing the occurrence of spherical aberration at the telephoto end. Furthermore, the height of the axial marginal ray incident on the second lens unit L2 at the telephoto end can be reduced, allowing the diameter of the second lens unit L2 to be reduced.

[0020] With the above-described characteristic configuration, it is possible to provide a compact zoom lens having small-diameter lens groups.

[0021] Next, conditions that are preferably satisfied in the zoom lens L0 according to each embodiment will be described.

[0022] In the zoom lens L0 according to each embodiment, it is preferable that the lens closest to the object among the lenses included in the second lens unit L2 has a concave surface facing the object side. This makes it possible to suppress the occurrence of spherical aberration and coma at the wide-angle end while generating strong barrel distortion and shifting the position of the exit pupil toward the object side. As a result, the height of off-axial rays incident on the second lens unit L2 can be reduced, allowing the diameter of the second lens unit L2 to be made smaller.

[0023] In the zoom lens L0 according to each embodiment, it is preferable that the second lens group has a positive lens. By converging light incident on the second lens group by the positive lens, it is possible to reduce the diameter of the lens group disposed closer to the image side than the second lens group.

[0024] In the zoom lens L0 according to each embodiment, it is preferable that the third lens unit L3 has a positive refractive power, so that light rays diverged by the second lens unit L2 converge at the third lens unit L3, allowing the diameter of the lens unit located closer to the image side than the third lens unit L3 to be small.

[0025] It is preferable that the middle unit LM of the zoom lens L0 in each embodiment has at least one lens unit with negative refractive power, which makes it possible to reduce the curvature of field over the entire zoom range.

[0026] In the zoom lens L0 according to each embodiment, it is preferable that the second lens unit L2 is stationary relative to the image plane during zooming, thereby minimizing deviation in relative position with the first lens unit L1, which moves during zooming, due to manufacturing errors, and minimizing coma aberration that occurs at the telephoto end due to decentering.

[0027] The zoom lens L0 according to each example preferably has a negative lens located closest to the object among the lenses included in the second lens unit L2, which allows off-axis rays incident on the second lens unit L2 to bend gently, thereby reducing coma and astigmatism at the wide-angle end.

[0028] In the zoom lens L0 according to each embodiment, it is preferable to move the second lens unit L2 in a direction that includes a component perpendicular to the optical axis for vibration reduction, such as image shake correction. In a positive-lead zoom lens, light rays converge at the first lens unit L1, so by using the second lens unit L2 as a vibration reduction unit, the diameter of the vibration reduction mechanism can be made smaller. However, it is not limited to this, and a lens unit other than the second lens unit L2 may also be moved for vibration reduction.

[0029] In the zoom lens L0 according to each embodiment, barrel distortion occurs in order to reduce the diameter of the second lens unit L2. In order to maintain optical performance while reducing the diameter of each lens unit in the zoom lens L0, it is preferable to suppress the occurrence of various aberrations in the zoom lens L0 or to effectively correct the various aberrations.

[0030] Therefore, in order to maintain high optical performance while realizing a small diameter for each lens group, it is preferable to appropriately set the amount of distortion and half angle of view of the zoom lens L0. Specifically, it is preferable that the zoom lens L0 according to each example satisfy the following conditional expressions (1) and (2): -20.0<Distw<-4.5 (1) 0.1<ωw<25.0 (2)

[0031] Conditional expression (1) defines the amount of distortion at the maximum image height when the zoom lens is focused at infinity at the wide-angle end. Here, when the ideal image height in the central projection method is y and the actual image height is yp, the amount of distortion Distw [%] at any image height at the wide-angle end is defined by the following formula: Distw [%] = ((yp - y) / y) x 100

[0032] The ideal image height y in the central projection method is defined by the following equation, where f is the focal length of the zoom lens L0 and θi is the half angle of view of the actual light ray at an arbitrary image height: y=f×tan θi

[0033] If the upper limit of conditional expression (1) is exceeded, barrel distortion is suppressed and the position of the exit pupil moves toward the image side. As a result, the height of off-axial rays incident on the second lens unit L2 increases, which undesirably increases the lens diameter of the second lens unit L2. If the lower limit of conditional expression (1) is exceeded, the absolute value of the radius of curvature of the lens surface closest to the object in the second lens unit L2 decreases, which undesirably causes strong spherical aberration and coma at the wide-angle end.

[0034] Conditional expression (2) defines the half angle of view (maximum half angle of view) at the maximum image height at the wide-angle end of the zoom lens. In the zoom lens L0 according to the embodiment of the present invention, when Y is the radius of the image circle and fw is the focal length of the zoom lens L0 at the wide-angle end, the half angle of view ωw [degrees] is defined by the following expression: ωw=arctan(Y / fw).

[0035] If the upper limit of conditional expression (2) is exceeded, the height of off-axial rays incident on the subsequent lens unit LR increases, making it difficult to reduce the diameter of the final lens unit LR, which is undesirable.If the lower limit of conditional expression (2) is exceeded, the zoom lens L0 will not be able to obtain a sufficient zooming effect, which is undesirable.

[0036] It is preferable that the barrel distortion caused by the above-described configuration be corrected within the zoom lens, or preferably within the imaging device. By effectively correcting the distortion, it is possible to improve the optical performance of the zoom lens L0.

[0037] It is more preferable to set the numerical ranges of the conditional expressions (1) and (2) as the following conditional expressions (1a) and (2a): −12.0<Distw<−4.9 (1a) 10.0<ωw<24.5 (2a)

[0038] Furthermore, it is more preferable to set the numerical ranges of the conditional expressions (1) and (2) as the following conditional expressions (1b) and (2b): −9.0<Distw<−5.0 (1b) 15.0<ωw<24.0 (2b)

[0039] By setting the numerical ranges to satisfy the conditional expressions (2a) and (2b), it is possible to suppress the occurrence of various aberrations such as curvature of field and astigmatism at the wide-angle end.

[0040] Furthermore, it is preferable that the zoom lens L0 according to each embodiment satisfies one or more of the following conditional expressions (3) to (9): −2.00<(r211+r1N2) / (r211−r1N2)<1.00 (3) 1.00<fLR / f3<9.00 (4) −7.00<f1 / f2<−2.50 (5) 1.00<fLR×LS2 / (f1×LS1)<3.00 (6) −1.00<(r212+r211) / (r212−r211)<1.00 (7) 0.50<f21 / f2<2.00 (8) −4.00<(1−β2T)×β2RT<−1.20 (9)

[0041] Here, r1N2 is the radius of curvature of the image-side lens surface of the lens located closest to the image in the first lens unit L1. r211 is the radius of curvature of the object-side lens surface of the lens located closest to the object in the second lens unit L2. f3 is the focal length of the third lens unit L3. fLR is the focal length of the final lens unit LR. f1 is the focal length of the first lens unit L1. f2 is the focal length of the second lens unit L2. LS1 is the distance on the optical axis from the object-side lens surface of the lens located closest to the object in the zoom lens at the wide-angle end to the aperture stop. LS2 is the distance on the optical axis from the aperture stop to the image plane in the zoom lens at the wide-angle end.

[0042] r212 is the radius of curvature of the image-side lens surface of the lens located closest to the object in the second lens unit L2. f21 is the focal length of the lens located closest to the object in the second lens unit L2. β2T is the lateral magnification of the second lens unit L2 when the zoom lens is focused at infinity at the telephoto end. β2RT is the combined lateral magnification of the lens units from the third lens unit L3 to the final lens unit LR when the zoom lens is focused at infinity at the telephoto end.

[0043] The technical meanings of conditional expressions (3) to (9) will be explained below.

[0044] Conditional expression (3) defines the relationship between the radius of curvature of the image-side lens surface of the lens located closest to the image in the first lens unit L1 and the radius of curvature of the object-side lens surface of the lens located closest to the object in the second lens unit L2. Exceeding the upper limit of conditional expression (3) suppresses barrel distortion at the wide-angle end generated by the first lens unit L1, and shifts the position of the exit pupil toward the image. As a result, the height of off-axial rays incident on the second lens unit L2 increases, undesirably increasing the lens diameter of the second lens unit L2. Failing the lower limit of conditional expression (3) undesirably increases the curvature of the object-side lens surface of the lens located closest to the object in the second lens unit L2, undesirably causing significant spherical aberration and coma at the telephoto end.

[0045] Conditional expression (4) defines the ratio between the focal length of the third lens unit L3 and the focal length of the final lens unit LR. If the upper limit of conditional expression (4) is exceeded, the positive refractive power of the final lens unit LR becomes too weak. As a result, the ray height of off-axis light rays incident on the second lens unit L2 increases, undesirably increasing the lens diameter of the second lens unit L2. If the lower limit of conditional expression (4) is exceeded, the positive refractive power of the third lens unit L3 becomes too weak. As a result, the diameter of the lens unit located closer to the image side than the third lens unit L3 becomes undesirably large.

[0046] Conditional expression (5) defines the ratio between the focal length of the first lens unit L1 and the focal length of the second lens unit L2. Exceeding the upper limit of conditional expression (5) results in the refractive power of the first lens unit L1 being too strong compared to the second lens unit L2. As a result, it becomes difficult to effectively correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end, which is undesirable. Falling below the lower limit of conditional expression (5), the refractive power of the second lens unit L2 becomes too strong compared to the first lens unit L1. As a result, strong coma and lateral chromatic aberration occur at the wide-angle end, which is undesirable.

[0047] Conditional expression (6) relates to the focal length of the first lens unit L1, the focal length of the final lens unit LR, and the location of the aperture stop at the wide-angle end. Exceeding the upper limit of conditional expression (6) reduces the positive refractive power of the final lens unit LR, which is located closer to the image side than the aperture stop at the wide-angle end, thereby suppressing barrel distortion. As a result, the height of off-axial rays incident on the second lens unit L2 increases, undesirably increasing the lens diameter of the second lens unit L2. Falling below the lower limit of conditional expression (6) reduces the positive refractive power of the lens unit located closer to the object side than the aperture stop at the wide-angle end, undesirably increasing the diameter of the lens unit located closer to the image side than the aperture stop.

[0048] Conditional expression (7) defines the relationship between the radii of curvature of the object-side lens surface and the image-side lens surface of the lens located closest to the object in the second lens unit L2. Exceeding the upper limit of conditional expression (7) results in the refractive power of the object-side lens surface of the lens located closest to the object in the second lens unit L2 being too strong compared to the image-side lens surface. This is undesirable because it makes it difficult to correct coma throughout the entire zoom range. Falling below the lower limit of conditional expression (7), the refractive power of the object-side lens surface of the lens located closest to the object in the second lens unit L2 becomes too weak, suppressing barrel distortion at the wide-angle end. This is undesirable because it increases the ray height of off-axial rays incident on the second lens unit L2 and increases the lens diameter of the second lens unit L2.

[0049] Conditional expression (8) defines the ratio between the focal length of the lens in the second lens unit L2 located closest to the object and the focal length of the second lens unit L2. If the upper limit of conditional expression (8) is exceeded, the positive refractive power of the lens in the second lens unit L2 located closest to the object becomes too weak, suppressing barrel distortion at the wide-angle end. As a result, the height of off-axial rays incident on the second lens unit L2 increases, undesirably increasing the lens diameter of the second lens unit L2.

[0050] Below the lower limit of conditional expression (8), the positive refractive power of the second lens group becomes too strong, which results in significant coma, axial chromatic aberration, and chromatic aberration of magnification at the wide-angle end, which is undesirable.

[0051] Conditional expression (9) defines the decentering sensitivity of the second lens unit L2 when focused on an object at infinity at the telephoto end. When the second lens unit L2 is focused on an object at infinity at the telephoto end and moved in a direction perpendicular to the optical axis, the amount of movement of the second lens unit L2 is ΔL and the amount of movement of the image on the image plane is ΔI. The decentering sensitivity TS is expressed by the following equation: TS=ΔI / ΔL

[0052] If the upper limit of conditional expression (9) is exceeded, the positive refractive power of the second lens unit L2 becomes too weak. As a result, the height of off-axial rays incident on the second lens unit L2 increases, undesirably increasing the lens diameter of the second lens unit L2. If the lower limit of conditional expression (9) is exceeded, the positive refractive power of the second lens unit L2 becomes too strong. As a result, undesirably, strong coma, axial chromatic aberration, and chromatic aberration of magnification occur at the telephoto end.

[0053] It is more preferable to set the numerical ranges of the conditional expressions (3) to (9) to satisfy the following conditional expressions (3a) to (9a): −1.90<(r211+r1N2) / (r211−r1N2)<0.00 (3a) 1.30<fLR / f3<5.00 (4a) −6.00<f1 / f2<−3.00 (5a) 1.20<fLR×LS2 / (f1×LS1)<2.50 (6a) −0.90<(r212+r211) / (r212−r211)<0.00 (7a) 0.80<f21 / f2<1.80 (8a) −3.00<(1−β2T)×β2RT<−1.50 (9a)

[0054] Furthermore, it is more preferable to set the numerical ranges of conditional expressions (3) to (9) to satisfy the following conditional expressions (3b) to (9b): −1.80<(r211+r1N2) / (r211-r1N2)<−0.50 (3b) 1.40<fLR / f3<3.50 (4b) −5.50<f1 / f2<−3.50 (5b) 1.30<fLR×LS2 / (f1×LS1)<2.30 (6b) −0.70<(r212+r211) / (r212-r211)<−0.30 (7b) 0.90<f21 / f2<1.70 (8b) −2.80<(1-β2T)×β2RT<−1.70 (9b)

[0055] By setting the numerical ranges to satisfy the conditional expressions (3a) and (9b), it is possible to suppress the occurrence of various aberrations such as curvature of field and astigmatism at the wide-angle end.

[0056] Next, the configuration of the zoom lens L0 according to each example will be described in detail. Note that, in the zoom lens L0 according to each example, a description of the configuration equivalent to that of the zoom lens L0 according to Example 1 will be omitted.

[0057] [Examples 1 and 2] The zoom lens L0 of Examples 1 and 2 comprises, arranged in order from the object side to the image side, a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, a third lens unit L3 having positive refractive power, an intermediate unit LM, and a final lens unit LR having positive refractive power. The intermediate unit LM comprises a fourth lens unit L4 having negative refractive power, a fifth lens unit L5 having positive refractive power, and a sixth lens unit L6 having negative refractive power.

[0058] During zooming from the wide-angle end to the telephoto end, the second lens unit L2 and the final lens unit LR remain stationary relative to the image plane, while the first lens unit L1 moves toward the object side relative to the image plane. This reduces the ray height of the on-axis marginal ray incident on the second lens unit L2 at the telephoto end, allowing the diameter of the second lens unit L2 to be small. Furthermore, during zooming from the wide-angle end to the telephoto end, the third lens unit L3 and the fifth lens unit L5 move along the same locus. This simplifies the zooming mechanism, making it easier to reduce the size of the zoom lens.

[0059] When focusing from infinity to a close distance, the fourth lens unit L4 moves toward the object side, and the sixth lens unit L6 moves toward the image side. By moving multiple lens units, it becomes easier to suppress fluctuations in aberrations that occur during focusing. Furthermore, by moving a small-diameter lens unit with negative refractive power during focusing, the diameter of the zoom lens can be made small.

[0060] In addition, for vibration reduction, the second lens unit L2 moves in a direction that includes a component perpendicular to the optical axis. By moving the second lens unit L2, which has a smaller diameter than the other lens units, the vibration reduction mechanism can be made more compact, and the zoom lens can be made more compact.

[0061] A zoom lens L0 of Example 3 includes, arranged in order from the object side to the image side, a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, a third lens unit L3 having positive refractive power, an intermediate lens unit LM, and a final lens unit LR having positive refractive power. The intermediate lens unit LM includes a fourth lens unit L4 having negative refractive power.

[0062] During focusing from infinity to a close distance, the fourth lens unit L4 moves toward the image side relative to the image plane. By moving a small-diameter unit having negative refractive power during focusing, the diameter of the zoom lens can be made small.

[0063] In the zoom lens L0 according to Example 3, the fourth lens unit L4 has one positive lens and one negative lens, which makes it possible to suppress fluctuations in axial chromatic aberration and chromatic aberration of magnification that occur during focusing.

[0064] In the zoom lens L0 according to Example 3, the third lens unit L3 has four positive lens units, which increases the positive refractive power of the third lens unit L3, making it possible to suppress spherical aberration, particularly at the wide-angle end.

[0065] A zoom lens L0 of Example 4 includes, arranged in order from the object side to the image side, a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, a third lens unit L3 having positive refractive power, an intermediate lens unit LM, and a final lens unit LR having positive refractive power. The intermediate lens unit LM includes a fourth lens unit L4 having negative refractive power and a fifth lens unit L5 having negative refractive power.

[0066] During focusing from infinity to a close distance, the fourth lens unit L4 and the fifth lens unit L5 move toward the object side relative to the image plane. By moving multiple lens units, it becomes easier to suppress fluctuations in aberrations that occur during focusing. Furthermore, by moving a small-diameter unit with negative refractive power during focusing, the focusing mechanism can be simplified, allowing the diameter of the zoom lens to be made smaller.

[0067] In the zoom lens L0 according to Example 4, the lens in the final lens group LR that is located closest to the image side has a positive meniscus shape with its convex surface facing the image side, which makes it possible to suppress chromatic aberration of magnification, particularly at the wide-angle end.

[0068] A zoom lens L0 of Example 5 includes, arranged in order from the object side to the image side, a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, a third lens unit L3 having positive refractive power, an intermediate lens unit LM, and a final lens unit LR having positive refractive power. The intermediate lens unit LM includes a fourth lens unit L4 having positive refractive power, a fifth lens unit L5 having negative refractive power, and a sixth lens unit L6 having negative refractive power.

[0069] During focusing from infinity to a close distance, the fifth lens unit L5 and the sixth lens unit L6 move toward the object. By moving multiple lens units, it becomes easier to suppress fluctuations in aberrations that occur during focusing. Furthermore, by moving a small-diameter unit with negative refractive power during focusing, the diameter of the zoom lens can be made small.

[0070] In the zoom lens L0 according to Example 5, the lens in the final lens unit LR that is located closest to the image side has a negative meniscus shape with its concave surface facing the image side, which makes it possible to suppress field curvature aberration, particularly at the wide-angle end.

[0071] Numerical Examples 1 to 5 corresponding to the zoom lenses L0 according to Examples 1 to 5, respectively, are shown below.

[0072] In the surface data of each numerical example, r 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. nd represents the refractive index of each optical element with respect to the d-line, and vd represents the Abbe number of the optical element. The Abbe number vd of a certain material is expressed as follows, where nd, nF, nC, and ng are the refractive indices at the Fraunhofer d-line (587.6 nm), F-line (486.1 nm), C-line (656.3 nm), and g-line (wavelength 435.8 nm).

[0073] In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values ​​when the optical system of each example is focused on an object at infinity. BF is the back focus, which is the air-equivalent distance from the final lens surface of a lens having refractive power to the image plane. The total lens length is the value obtained by adding BF to the distance from the surface closest to the object to the final lens surface.

[0074] An asterisk (*) next to a surface number indicates that the surface has an aspherical shape. The aspherical shape is expressed by the following formula, 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 a 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 aspherical coefficients of each order: x=(h ２ / R) / [1+{1-(1+k)(h / R) ２} １／２ ] + A4 × h ４ + A6 x h ６ +A ８ ×h ８ + A10 x h １０ + A12 x h １２

[0075] It should be noted that "e±XX" in each aspherical coefficient means "×10±XX".

[0076] [Numerical Example 1] Unit: mm Surface data Surface number rd nd νd 1 126.433 1.50 1.72047 34.7 2 67.508 8.93 1.48749 70.2 3 325.380 0.20 4 98.130 7.34 1.49700 81.7 5 -1046.940 (Variable) 6 -149.149 1.45 1.76385 48.5 7 37.715 4.63 8 -56.686 1.30 1.49700 81.7 9 42.912 4.64 1.90366 31.3 10 -946.232 (Variable) 11 (Aperture) ∞ 0.48 12 79.782 6.03 1.59522 67.7 13 -78.116 (Variable) 14 -36.499 1.20 1.67270 32.1 15 70.747 3.61 2.05090 26.9 16 -595.435 (Variable) 17 81.685 6.27 1.49700 81.7 18 -51.527 0.15 19 69.167 7.81 1.53775 74.7 20 -32.977 1.35 1.61340 44.3 21 33.252 0.14 22* 29.719 6.69 1.58313 59.4 23* -150.041 (variable) 24 214.923 1.20 1.61800 63.4 25 34.003 (variable) 26 -185.456 0.95 1.90525 35.0 27 215.602 1.83 28 103.937 5.06 1.89190 37.1 29 -141.626 41.56 Image surface ∞ Aspheric surface data Surface 22 K = 0.00000e+00 A 4=-1.68734e-06 A 6=-2.63035e-09 A 8= 6.96592e-13 Surface 23 K = 0.00000e+00 A 4= 3.67767e-06 A 6=-3.79218e-09 A 8= 9.41782e-12 A10=-1.09116e-14 Various data Zoom ratio 2.83 Wide angle Mid-range Telephoto Focal length 51.50 85.04 145.50 F-number 2.89 2.89 2.91 Half angle of view 22.79 14.14 8.28 Image height 20.53 21.63 21.63 Total lens length 176.15 208.50 234.55 BF 41.56 41.56 41.56 d 5 5.16 37.51 63.56 d10 22.15 13.93 4.09 d13 5.24 9.88 14.97 d16 11.92 7.28 2.19 d23 8.53 6.60 2.97 d25 8.82 18.98 32.45 Zoom lens group data Group Initial surface Focal length L1 1 160.87 L2 6 -43.07 L3 11 67.27 L4 14 -89.40 L5 17 40.10 L6 24 -65.53 LR 26 164.54 .

[0077] [Numerical Example 2] Unit: mm Surface data Surface number rd nd νd 1 110.486 1.50 1.72047 34.7 2 67.323 10.36 1.49700 81.7 3 358.622 0.20 4 104.174 7.56 1.48749 70.2 5 -2248.250 (Variable) 6 -120.828 1.45 1.76385 48.5 7 35.216 5.01 8 -63.129 1.30 1.49700 81.7 9 38.472 4.24 1.90366 31.3 10 668.992 (Variable) 11 (Aperture) ∞ 0.36 12 68.446 6.82 1.49700 81.7 13 -51.002 (Variable) 14 -38.580 1.20 1.67270 32.1 15 42.224 4.90 2.05090 26.9 16 -284.561 (Variable) 17 78.900 7.87 1.59522 67.7 18 -28.277 1.00 1.67300 38.3 19 37.493 0.65 20 35.429 4.11 1.49700 81.7 21 154.883 0.11 22* 50.719 6.13 1.58313 59.4 23* -50.718 (variable) 24 448.649 1.20 1.61800 63.4 25 38.366 (variable) 26 -729.285 1.00 1.90525 35.0 27 116.782 2.09 28 88.887 6.45 1.89190 37.1 29 -188.034 44.51 Image surface ∞ Aspheric surface data Surface 22 K = 0.00000e+00 A 4=-5.25447e-06 A 6=-2.10957e-09 A 8=-8.82508e-12 Surface 23 K = 0.00000e+00 A 4= 2.26673e-06 A 6=-2.28795e-09 A 8=-1.01735e-11 A10= 8.00333e-15 Various data Zoom ratio 2.83 Wide angle Mid-range Telephoto Focal length 51.50 84.96 145.50 F-number 2.89 2.89 2.91 Half angle of view 22.82 14.29 8.27 Image height 20.45 21.63 21.63 Total lens length 176.16 205.72 234.56 BF 44.51 44.51 44.51 d 5 5.14 34.70 63.54 d10 21.98 12.26 4.01 d13 2.44 6.30 9.69 d16 9.37 5.51 2.13 d23 9.35 7.92 2.91 d25 7.85 19.00 32.27 Zoom lens group data Group Initial surface Focal length L1 1 150.97 L2 6 -37.94 L3 11 59.94 L4 14 -219.57 L5 17 50.20 L6 24 -67.96 LR 26 165.36 .

[0078] [Numerical Example 3] Unit: mm Surface data Surface number rd nd νd 1 109.916 1.50 1.72047 34.7 2 66.222 9.14 1.49700 81.7 3 299.512 0.20 4 178.050 5.68 1.59522 67.7 5 -451.039 (Variable) 6 -103.769 1.45 1.81600 46.6 7 45.014 5.93 8 -43.071 1.30 1.49700 81.7 9 64.303 3.94 2.05090 26.9 10 -664.889 (Variable) 11 (Aperture) ∞ 0.46 12 42.562 7.17 1.49700 81.7 13 -384.816 0.30 14 52.730 5.90 1.49700 81.7 15 -708.459 2.67 16 -67.217 1.20 1.62588 35.7 17 58.613 6.80 2.05090 26.9 18 -94.074 1.54 19 -92.784 1.00 1.85478 24.8 20 32.674 0.29 21 30.510 2.48 1.59522 67.7 22 39.431 0.52 23* 34.786 7.27 1.58313 59.4 24* -57.473 (variable) 25 166.726 1.47 1.64850 53.0 26 26.575 2.44 2.05090 26.9 27 32.975 (variable) 28* -250.008 1.00 1.72000 46.0 29* 157.867 0.97 30 50.059 10.56 1.48749 70.2 31 -85.993 50.21 Image surface ∞ Aspheric surface data Surface 23 K = 0.00000e+00 A 4=-8.35017e-06 A 6=-1.53422e-09 A 8=-1.59483e-11 Surface 24 K = 0.00000e+00 A 4= 1.34828e-06 A 6=-1.01836e-10 A 8=-1.63731e-11 A10= 1.04688e-14 Surface 28 K = 0.00000e+00 A 4=-2.63360e-06 A 6= 1.02522e-08 A 8= 2.25163e-12 Surface 29 K = 0.00000e+00 A 4=-1.60776e-06 A 6= 1.09513e-08 Various data Zoom ratio 2.83 Wide angle Medium Telephoto Focal length 51.50 85.38 145.50 F-number 2.89 2.89 2.91 Half angle of view 22.78 14.11 8.28 Image height 19.96 21.63 21.63 Lens Length 176.15 214.79 236.15 BF 50.21 50.21 50.21 d 5 3.99 42.63 63.99 d10 26.83 18.18 4.07 d24 2.95 2.97 6.63 d27 8.99 17.63 28.07 Zoom Lens Group Data Group Initial Surface Focal Length L1 1 163.86 L2 6 -36.73 L3 11 40.87 L4 25 -82.92 LR 28 125.00 .

[0079] [Numerical Example 4] Unit: mm Surface data Surface number rd nd νd 1 159.158 1.80 1.72047 34.7 2 90.004 9.24 1.49700 81.7 3 -421.124 0.24 4 187.175 3.61 1.61800 63.4 5 788.760 (Variable) 6 -130.768 1.74 1.78800 47.4 7 50.668 5.41 8 -46.465 1.56 1.49700 81.7 9 70.007 3.56 2.05090 26.9 10 2846.774 (Variable) 11 (Aperture) ∞ 0.35 12 63.384 5.99 1.49700 81.7 13 -298.638 0.36 14 43.238 5.90 1.49700 81.7 15 167.085 14.30 16 -46.226 1.40 1.65412 39.7 17 37.166 10.10 1.84666 23.8 18 -60.950 0.38 19 -79.709 1.20 1.85478 24.8 20 26.219 9.45 1.59522 67.7 21 -227.534 0.47 22* 33.438 10.01 1.58313 59.4 23* -55.995 (variable) 24 48.264 1.47 1.80400 46.5 25 27.951 (variable) 26 -42.545 1.00 1.51633 64.1 27 -273.571 (Variable) 28* -188.756 0.06 1.53344 52.7 29 -440.914 3.33 2.00069 25.5 30 -82.988 (Variable) Image surface ∞ Aspheric surface data Surface 22 K = 0.00000e+00 A 4=-5.22140e-06 A 6=-1.43014e-09 A 8=-1.93715e-12 Surface 23 K = 0.00000e+00 A 4= 2.95766e-06 A 6=-3.33083e-09 Surface 28 K = 0.00000e+00 A 4= 2.73039e-06 A 6=-4.47790e-10 A 8= 6.51103e-13 Various data Zoom ratio 2.84 Wide-angle Mid-range Telephoto Focal length 61.51 101.60 174.60 F-number 2.89 2.89 2.91 Half angle of view 19.37 11.96 6.91 Image height 20.57 21.63 21.63 Lens length 197.48 232.04 262.48 BF 37.73 48.93 59.79 d 5 11.89 46.45 76.89 d10 25.99 14.80 3.93 d23 5.95 4.69 0.97 d25 18.18 17.65 20.94 d27 4.80 6.59 7.03 d30 37.73 48.93 59.79 Zoom lens group data Group Initial surface Focal length L1 1 175.47 L2 6 -40.06 L3 11 45.06 L4 24 -85.35 L5 26 -97.72 LR 28 121.19 .

[0080] [Numerical Example 5] Unit: mm Surface data Surface number rd nd νd 1 104.296 1.80 1.77047 29.7 2 76.349 9.34 1.49700 81.7 3 -1745.623 0.24 4 609.108 2.92 1.43875 94.7 5 -994.784 (variable) 6 -167.311 1.70 1.58913 61.1 7 42.179 7.43 8 -35.349 1.55 1.49700 81.7 9 79.919 5.04 1.84666 23.8 10 -1540.602 2.50 11 (Aperture) ∞ (Variable) 12 91.759 6.75 1.49700 81.7 13 -116.434 0.36 14 89.426 6.13 1.49700 81.7 15 -196.104 1.29 16 68.660 11.91 1.62041 60.3 17 -51.465 1.40 1.90525 35.0 18 461.284 (Variable) 19 -129.956 1.20 1.72047 34.7 20 33.738 5.87 1.71300 53.9 21 136.933 0.48 22 102.641 3.92 1.87070 40.7 23 -212.291 0.50 24* 208.050 4.21 1.58313 59.4 25* -77.394 (variable) 26 2043.885 5.05 1.84666 23.8 27 -37.930 1.35 1.80100 35.0 28 55.708 (Variable) 29 -254.783 1.00 1.77250 49.6 30 105.960 (Variable) 31 48.353 9.53 1.64000 60.1 32 -52.044 6.61 33* -33.014 1.75 1.80400 46.5 34* -86.725 37.71 Image surface ∞ Aspheric surface data Surface 24 K = 0.00000e+00 A 4=-2.99882e-06 A 6=-1.96238e-09 A 8=-3.78022e-13 Surface 25 K = 0.00000e+00 A 4= 3.33264e-08 A 6=-2.51128e-09 Surface 33 K = 0.00000e+00 A 4=-3.99455e-06 A 6= 6.52892e-09 A 8= 4.71708e-12 Surface 34 K = 0.00000e+00 A 4=-4.13066e-06 A 6= 5.73681e-09 Various data Zoom ratio 2.61 Wide angle Medium Telephoto Focal length 66.97 99.83 174.59 F number 2.89 2.89 2.91 Half angle of view 17.90 12.23 6.90 Image height 20.50 21.58 21.63 Total lens length 197.87 238.18 262.87 BF 37.71 37.71 37.71 d 5 12.06 52.36 77.06 d11 20.00 15.68 0.96 d18 4.03 2.64 8.05 d25 2.29 0.93 5.42 d28 18.78 26.06 30.92 d30 1.19 0.97 0.94 Zoom lens group data Group Initial surface Focal length L1 1 191.29 L2 6 -36.12 L3 12 49.79 L4 19 80.28 L5 26 -78.57 L6 29 -96.76 LR 31 76.57 .

[0081] The values ​​corresponding to the conditional expressions (1) to (9) in each numerical example are shown in Table 1 below.

[0082]

[0083] [Imaging Device] Next, an embodiment of a digital still camera (imaging device) 10 that uses the optical system of the present invention as an imaging optical system will be described with reference to Fig. 11. In Fig. 11, reference numeral 11 denotes an imaging optical system configured with any of the zoom lenses L0 according to Examples 1 to 5. Reference numeral 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into a camera body 13 and captures an image by receiving an optical image formed by the imaging optical system 11 and photoelectrically converting it. The camera body 13 may be a so-called single-lens reflex camera having a quick-return mirror, or may be a mirrorless camera without a quick-return mirror.

[0084] [Modifications] 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.

[0085] In the zoom lens L0 according to each embodiment, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves toward the object side relative to the image plane, and the second lens unit L2 remains stationary relative to the image plane. Alternatively, each lens unit may move so that the distance between the first lens unit L1 and the second lens unit L2 increases. For example, during zooming from the wide-angle end to the telephoto end, the second lens unit L2 may move toward the image side relative to the image plane, and the first lens unit L1 may move toward the object side relative to the image plane. Alternatively, the second lens unit L2 may move toward the object side relative to the image plane, and the first lens unit L1 may move toward the object side relative to the image plane by an amount greater than the amount of movement of the second lens unit L2. Alternatively, the first lens unit L1 may remain stationary relative to the image plane, and the second lens unit may move toward the image side relative to the image plane.

[0086] The zoom lens L0 according to each of the above-described embodiments may be used in an imaging device having an image processing function for correcting various aberrations (distortion and chromatic aberration of magnification). By effectively correcting various aberrations that occur in the zoom lens L0, it becomes possible to achieve high optical performance despite the small size.

[0087] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0088] This application claims priority based on Japanese Patent Application No. 2024-049495, filed on March 26, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A zoom lens comprising, 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, an intermediate group having one or more lens groups, and a final lens group having positive refractive power, wherein the spacing between adjacent lens groups changes during zooming, and the lens in the second lens group that is positioned closest to the object has a concave surface facing the object side, and wherein the spacing between the first lens group and the second lens group increases during zooming from the wide-angle end to the telephoto end, and wherein the zoom lens satisfies the following conditional expressions: -20.0<Distw<-4.5 0.1<ωw<25.0 where Distw is the amount of distortion at the wide-angle end and ωw is the maximum half angle of view at the wide-angle end.

2. The zoom lens according to claim 1, wherein the following condition is satisfied: -2.00<(r211+r1N2) / (r211-r1N2)<1.00, where r1N2 is the radius of curvature of the image-side lens surface of the lens in the first lens group that is located closest to the image, and r211 is the radius of curvature of the object-side lens surface of the lens in the second lens group that is located closest to the object.

3. A zoom lens according to claim 1 or 2, wherein the following condition is satisfied: 1.00<fLR / f3<9.00, where f3 is the focal length of the third lens group and fLR is the focal length of the final lens group.

4. A zoom lens according to any one of claims 1 to 3, characterized in that the following condition is satisfied: -7.00<f1 / f2<-2.50, where f1 is the focal length of the first lens group and f2 is the focal length of the second lens group.

5. The zoom lens according to any one of claims 1 to 4, characterized in that the zoom lens has an aperture stop, and satisfies the condition: 1.00<fLR×LS2 / (f1×LS1)<3.00, where f1 is the focal length of the first lens group, fLR is the focal length of the final lens group, LS1 is the distance on 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 aperture stop, and LS2 is the distance on the optical axis from the aperture stop to the image plane at the wide-angle end.

6. A zoom lens according to any one of claims 1 to 5, wherein the intermediate group has one or more lens groups with negative refractive power.

7. A zoom lens according to any one of claims 1 to 6, wherein the second lens group does not move during zooming.

8. A zoom lens according to any one of claims 1 to 7, characterized in that, of the lenses included in said second lens group, the lens arranged closest to the object side has negative refractive power.

9. A zoom lens according to any one of claims 1 to 8, characterized in that, when the radius of curvature of the object-side lens surface of the lens included in the second lens group that is located closest to the object is r211 and the radius of curvature of the image-side lens surface is r212, the following condition is satisfied: -1.00<(r212+r211) / (r212-r211)<1.

00.

10. A zoom lens according to any one of claims 1 to 9, characterized in that the following condition is satisfied: 0.50<f21 / f2<2.00, where f21 is the focal length of the lens located closest to the object among the lenses included in the second lens group, and f2 is the focal length of the second lens group.

11. A zoom lens according to any one of claims 1 to 10, characterized in that the second lens group moves in a direction including a component perpendicular to the optical axis for image blur correction.

12. A zoom lens according to any one of claims 1 to 11, characterized in that the following condition is satisfied: -4.00<(1-β2T)×β2RT<-1.20, where β2T is the lateral magnification of the second lens group when the zoom lens is focused on infinity at the telephoto end, and β2RT is the combined lateral magnification of the lens groups from the third lens group to the final lens group when the zoom lens is focused on infinity at the telephoto end.

13. A zoom lens comprising, 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, an intermediate group consisting of one or more lens groups, and a final lens group having positive refractive power, wherein the spacing between adjacent lens groups changes during zooming, and wherein the second lens group has a positive lens.

14. An imaging device comprising the zoom lens according to any one of claims 1 to 13 and an imaging element for capturing an image of an object via the zoom lens.

Images