Zoom lens and imaging apparatus

Abstract

To provide a zoom lens that is reduced in size and weight and has high optical performance.SOLUTION: A zoom lens comprises a first lens group L1 having a positive refractive power, a second lens group L2 having a negative refractive power, a third lens group L3 having a positive refractive power, a fourth lens group L4 having a negative refractive power, and a plurality of lens groups included in a rear group Lr, which are arranged in order from an object side to an image side. The first lens group does not move for zooming, and the second lens group and the fourth lens group move for zooming. The rear group includes an aperture stop SP. The focal length f2 of the second lens group, the focal length f3 of the third lens group, and the focal length f4 of the fourth lens group satisfy the conditions of 0.10≤|f3 / f2|≤1.70 and 2.40≤f4 / f2≤16.00.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens suitable for imaging. [Background technology]

[0002] Zoom lenses are desired to be small and lightweight and have high optical performance throughout the entire zoom range. Patent Document 1 discloses a zoom lens that is configured with, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and a fifth lens group with positive refractive power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-174758 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the zoom lens of Patent Document 1, the refractive power of the third lens group is weaker than that of the second lens group, and the effective diameter of the lens closer to the image side than the third lens group tends to be large, making it difficult to reduce the weight of the zoom lens.

[0005] The present invention provides a zoom lens that is small and lightweight and has high optical performance over the entire zoom range, and an imaging device equipped with the same. [Means for solving the problem]

[0006] A zoom lens according to one aspect of the present invention comprises lens groups arranged in order from the object side to the image side: a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and multiple lens groups included in a rear group, and the spacing between adjacent lens groups changes during zooming. The first lens group does not move for zooming, while the second and fourth lens groups move for zooming. The rear group includes an aperture stop. When the focal length of the second lens group is f2, the focal length of the third lens group is f3, and the focal length of the fourth lens group is f4, 0.10≦|f3 / f2|≦1.70 2.40≦f4 / f2≦16.00 The zoom lens according to another aspect of the present invention is characterized in that it satisfies the following conditions. The lens groups arranged in order from the object side to the image side are a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and multiple lens groups included in a rear group, and the spacing between adjacent lens groups changes during zooming. The first lens group does not move for zooming, while the second and fourth lens groups move for zooming. The first lens group has two positive lenses. The rear group includes an aperture stop. When the focal length of the second lens group is f2 and the focal length of the fourth lens group is f4, 2.40≦f4 / f2≦16.00 The present invention is characterized in that the following conditions are satisfied: An imaging device including the zoom lens described above also constitutes another aspect of the present invention. [Effects of the Invention]

[0007] The present invention can provide a zoom lens that is small and lightweight and has high optical performance over the entire zoom range. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are cross-sectional views of a zoom lens according to a first embodiment in an infinity focused state at a wide-angle end and a telephoto end. [Figure 2]4A and 4B are longitudinal aberration diagrams of the zoom lens of Example 1 at infinity focus and at the wide-angle end and the telephoto end, respectively. [Figure 3] 10A and 10B are cross-sectional views of a zoom lens according to a second embodiment in an infinity focused state at the wide-angle end and the telephoto end. [Figure 4] 10A and 10B are longitudinal aberration diagrams of the zoom lens of Example 2 at infinity focus and at the wide-angle end and the telephoto end, respectively. [Figure 5] 10A and 10B are cross-sectional views of a zoom lens according to a third embodiment in an infinity-focused state at the wide-angle end and the telephoto end. [Figure 6] 10A and 10B are longitudinal aberration diagrams of the zoom lens of Example 3 at infinity focus and at the wide-angle end and the telephoto end, respectively. [Figure 7] 10A and 10B are cross-sectional views of a zoom lens according to a fourth embodiment in an infinity focused state at the wide-angle end and the telephoto end. [Figure 8] 10A and 10B are longitudinal aberration diagrams of the zoom lens of Example 4 at infinity focus and at the wide-angle end and the telephoto end, respectively. [Figure 9] 10A and 10B are cross-sectional views of a zoom lens according to a fifth embodiment in a state focused at infinity and at the wide-angle end and telephoto end. [Figure 10] 10A and 10B are longitudinal aberration diagrams of the zoom lens of Example 5 at infinity focus and at the wide-angle end and the telephoto end, respectively. [Figure 11] FIG. 1 is a schematic diagram of an imaging device equipped with a zoom lens according to any one of Examples 1 to 5. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, before describing specific embodiments 1 to 5, matters common to all embodiments will be described.

[0010] 1, 3, 5, 7, and 9 show cross sections of the zoom lenses of Examples 1 to 5 at the wide-angle end and the telephoto end, respectively, when focused on an object at infinity (hereinafter referred to as the infinity focused state). The zoom lenses of each Example are used as imaging optical systems for various imaging devices, such as digital still cameras, video cameras, broadcast cameras, surveillance cameras, vehicle-mounted cameras, and silver halide film cameras. In each figure, the left side is the object side (front side), and the right side is the image side (rear side).

[0011] In the zoom lens of each embodiment, the lens groups arranged in order from the object side to the image side are 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 negative refractive power, and a plurality of lens groups (L5 to L7) included in the rear group Lr.

[0012] In a zoom lens, a lens group is a group of one or more lenses that may or may not move as a unit during zooming (magnification change) between the wide-angle and telephoto ends. That is, the spacing between adjacent lens groups changes during zooming. The lens group may also include an aperture stop. The wide-angle and telephoto ends refer to the zoom states with the maximum and minimum angles of view (shortest focal lengths) when the lens group that moves during zooming is positioned at the ends of its mechanically or controllably movable range on the optical axis. SP is the aperture stop, and IP is the image plane. The image plane IP is where the imaging surface (light-receiving surface) of an image sensor such as a CCD sensor or CMOS sensor, or the film surface (photosensitive surface) of a silver halide film, is located.

[0013] In the zoom lens of each embodiment, the first lens group L1 does not move for zooming, while the second lens group L2 and the fourth lens group L3 move for zooming. By keeping the first lens group L1 fixed (unmoving) during zooming, which tends to be large in diameter and heavy during zooming, it is possible to omit a mechanism for moving the first lens group L1, which is advantageous for making the zoom lens smaller and lighter.

[0014] In the zoom lens of each embodiment, the rear unit Lr includes an aperture diaphragm SP. For example, it is preferable that the aperture diaphragm SP is located closest to the object in the rear unit Lr. By locating the aperture diaphragm SP within the rear unit Lr, which has a small diameter, the aperture diaphragm SP can be made smaller.

[0015] Furthermore, the zoom lens of each embodiment satisfies the following conditions (1) and (2) when the focal length of the second lens group L2 is f2, the focal length of the third lens group L3 is f3, and the focal length of the fourth lens group L4 is f4.

[0016] 0.10≦|f3 / f2|≦1.70 (1) 2.40≦f4 / f2≦16.00 (2) The condition of formula (1) indicates the appropriate relationship between the focal lengths f2 and f3 of the second and third lens groups L2 and L3. If the refractive power of the third lens group L3 becomes weak relative to the second lens group L2, such that |f3 / f2| exceeds the upper limit of formula (1), the effective diameter of the lens closer to the image than the third lens group L3 becomes too large, resulting in an increase in the size of the zoom lens, which is undesirable. If the refractive power of the third lens group L3 becomes strong relative to the second lens group L2, such that |f3 / f2| falls below the lower limit of formula (1), it becomes difficult to achieve good aberration correction, which is also undesirable.

[0017] The condition of formula (2) indicates the appropriate relationship between the focal lengths f2 and f4 of the second and fourth lens groups L2 and L4. If the refractive power of the fourth lens group L4 relative to the second lens group L2 becomes weak so that f4 / f2 exceeds the upper limit of formula (2), it becomes difficult to achieve good aberration correction, which is undesirable. If the refractive power of the fourth lens group L4 becomes strong so that f4 / f2 falls below the lower limit of formula (2), the effective diameter of the lens closer to the image than the fourth lens group L4 becomes too large, which undesirably increases the size of the zoom lens.

[0018] It is more preferable to set the numerical ranges of the formulas (1) and (2) as follows:

[0019] 0.70≦|f3 / f2|≦1.60 (1a) 3.00≦f4 / f2≦13.40 (2a) Furthermore, it is more preferable to set the numerical ranges of the formulas (1) and (2) as follows:

[0020] 1.22≦|f3 / f2|≦1.59 (1b) 3.55≦f4 / f2≦10.79 (2b) By satisfying the above configuration and conditions, it is possible to realize a telephoto zoom lens that is compact and lightweight yet has high optical performance over the entire zoom range.

[0021] The following describes the configurations and conditions that the zoom lens of each embodiment preferably satisfies.

[0022] In the zoom lens of each embodiment, it is preferable that at least one or part of the lens groups included in the fourth lens group L4 and the rear lens group Lr is a focus group that moves during focusing. By moving a small and lightweight focus group located near the aperture stop SP, fast and good focusing can be achieved from a state where focus is focused on a close object (hereinafter referred to as the close focus state) to a state where focus is focused on infinity.

[0023] In the zoom lens of each embodiment, it is preferable that one or part of the rear lens group Lr is an image stabilization group that moves (shifts) relative to the optical axis of the zoom lens to reduce image blur caused by camera shake such as hand shake, thereby achieving high optical performance even during image stabilization.

[0024] In the zoom lens of each embodiment, an optical unit such as an extender (magnification conversion group) for converting the magnification of the zoom lens may be inserted or removed into a predetermined space within the rear group Lr (for example, the widest air gap within the rear group Lr).

[0025] In the zoom lens of each embodiment, the focal length of the first lens group L1 is defined as f1, the combined focal length of the multiple lens groups included in the rear group Lr when focused at infinity and at the wide-angle end is defined as frw, the focal length of the zoom lens at the telephoto end is defined as ft, and the focal length of the first lens group L1 is defined as f1. Furthermore, the axial distance from the object-side lens surface of the lens closest to the object in the zoom lens to the image plane is defined as Tw, and the axial distance from the image-side lens surface of the lens closest to the image in the zoom lens when focused at infinity and at the wide-angle end is defined as skw. Furthermore, the axial distance from the aperture stop SP to the image plane IP is defined as Dsi, and the maximum air gap on the optical axis within the rear group Lr is defined as Dra. Furthermore, the axial distance from the object-side lens surface of the lens closest to the object in the first lens group L1 to the image-side lens surface of the lens closest to the image in the first lens group L1 is defined as D1, and the maximum air gap on the optical axis within the first lens group L1 is defined as D1a.

[0026] In this case, it is preferable to satisfy at least one of the conditions of the following expressions (3) to (10).

[0027] 0.35≦|frw / f1|≦10.00 (3) 0.20≦f1 / ft≦0.90 (4) 0.10≦f3 / ft≦0.50 (5) 0.15≦|f4 / ft|≦3.00 (6) 0.05≦skw / Tw≦0.30 (7) 0.10≦skw / f1≦0.50 (8) 0.10≦Dra / Dsi≦0.50 (9) 0.20≦D1a / D1≦0.60 (10) The condition of equation (3) indicates the appropriate relationship between the focal length f1 of the first lens unit L1 and the combined focal length frw of the rear group Lr when focused at infinity and at the wide-angle end. If the refractive power of the rear group Lr when focused at infinity and at the wide-angle end becomes weak so that |frw / f1| exceeds the upper limit of equation (3), this undesirably leads to an increase in the size of the zoom lens. If the refractive power of the rear group Lr when focused at infinity and at the wide-angle end becomes strong so that |frw / f1| falls below the lower limit of equation (3), this undesirably makes it difficult to achieve good aberration correction.

[0028] The condition of formula (4) indicates the appropriate relationship between the focal length ft at the telephoto end of the entire zoom lens system and the focal length f1 of the first lens unit L1. If the refractive power of the first lens unit L1 becomes so strong that f1 / ft exceeds the upper limit of formula (4), it becomes difficult to achieve good aberration correction, which is undesirable. If the refractive power of the first lens unit L1 becomes so weak that f1 / ft falls below the lower limit of formula (4), it results in an increase in the size of the zoom lens, which is undesirable.

[0029] The condition of equation (5) indicates the appropriate relationship between the focal length ft at the telephoto end of the entire zoom lens system and the focal length f3 of the third lens unit L3. If the refractive power of the third lens unit L3 becomes weak so that f3 / ft exceeds the upper limit of equation (5), this is undesirable because it results in an increase in the size of the zoom lens. If the refractive power of the third lens unit L3 becomes strong so that f3 / ft falls below the lower limit of equation (5), it is undesirable because it becomes difficult to achieve good aberration correction.

[0030] Equation (6) shows the appropriate relationship between the focal length ft at the telephoto end of the entire zoom lens system and the focal length f4 of the fourth lens unit L4. If the refractive power of the fourth lens unit L4 becomes weak so that |f4 / ft| exceeds the upper limit of equation (6), this undesirably increases the size of the zoom lens. If the refractive power of the fourth lens unit L4 becomes strong so that |f4 / ft| falls below the lower limit of equation (6), this undesirably makes it difficult to achieve good aberration correction.

[0031] The condition of equation (7) indicates the appropriate relationship between the optical axial distance Tw from the object-side lens surface of the lens closest to the object to the image plane IP when the zoom lens is focused at infinity and at the wide-angle end, and the optical axial distance skw from the image-side lens surface of the lens closest to the image to the image plane IP. Note that the distances Tw and skw here are distances excluding components that do not have effective refractive power, such as parallel plates such as optical filters. By ensuring that skw / Tw falls within the numerical range of equation (7), it is possible to reduce the size of the zoom lens while maintaining its telecentricity.

[0032] The condition of equation (8) indicates an appropriate relationship between the focal length f1 of the first lens group L1 and the distance skw. When skw / f1 falls within the numerical range of equation (8), it becomes possible to reduce the size of the zoom lens while ensuring the telecentricity of the zoom lens.

[0033] The condition of equation (9) indicates the appropriate relationship between the distance Dsi on the optical axis from the aperture stop SP to the image plane IP and the maximum air gap Dra within the rear lens unit Lr. If Dra / Dsi falls within the numerical range of equation (9), it is possible to ensure enough space within the rear lens unit Lr to insert an optical unit such as an extender.

[0034] The condition of formula (10) indicates an appropriate relationship between the distance D1 on the optical axis from the object-side lens surface of the lens closest to the object in the first lens group L1 to the image-side lens surface of the lens closest to the image (the thickness of the first lens group L1) and the maximum air gap D1a within the first lens group L1. If the maximum air gap D1a within the first lens group L1 is increased so that D1a / D1 exceeds the upper limit of formula (10), it becomes difficult to achieve good aberration correction, which is undesirable. If the maximum air gap D1a within the first lens group L1 is reduced so that D1a / D1 exceeds the upper limit of formula (10), it will result in an increase in the size of the zoom lens, which is undesirable.

[0035] It is more preferable that the numerical ranges of the formulas (3) to (10) are as follows:

[0036] 0.80≦|frw / f1|≦7.20 (3a) 0.30≦f1 / ft≦0.70 (4a) 0.10≦f3 / ft≦0.40 (5a) 0.30≦|f4 / ft|≦2.30 (6a) 0.10≦skw / Tw≦0.20 (7a) 0.15≦skw / f1≦0.40 (8a) 0.20≦Dra / Dsi≦0.40 (9a) 0.30≦D1a / D1≦0.50 (10a) Furthermore, it is more preferable to set the numerical ranges of the formulas (3) to (10) as follows:

[0037] 1.31≦|frw / f1|≦4.42 (3b) 0.42≦f1 / ft≦0.47 (4b) 0.16≦f3 / ft≦0.24 (5b) 0.53≦|f4 / ft|≦1.63 (6b) 0.12≦skw / Tw≦0.15 (7b) 0.20≦skw / f1≦0.24 (8b) 0.23≦Dra / Dsi≦0.33 (9b) 0.39≦D1a / D1≦0.43 (10b) The zoom lenses of Examples 1 to 5 will be specifically described below. [Example]

[0038] 1 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with negative refractive power, and a rear lens unit Lr. The rear lens unit Lr is composed of, arranged in order from the object side, a fifth lens unit L5 with positive refractive power, a sixth lens unit L6 with negative refractive power, and a seventh lens unit L7 with negative refractive power as the final lens unit.

[0039] During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fifth lens group L5, and the seventh lens group L7 do not move, and the second lens group L2 moves toward the image side, the fourth lens group L4 moves toward the image side, and the sixth lens group L6 moves toward the object side, as indicated by the arrows in the figure.

[0040] During 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, as indicated by the arrow focus in the drawing.

[0041] An optical unit such as an extender may be inserted into the maximum air gap within the rear group Lr (seventh lens group L7) in a removable manner. A subgroup that is part of the fifth lens group L5 can be shifted relative to the optical axis as an image stabilization group Lis. The insertion and removal of optical units and the image stabilization group Lis are the same in other embodiments described below. [Example]

[0042] 3 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with negative refractive power, and a rear lens unit Lr. The rear lens unit Lr is composed of, arranged in order from the object side, a fifth lens unit L5 with positive refractive power, a sixth lens unit L6 with positive refractive power, and a seventh lens unit L7 with negative refractive power as the final lens unit.

[0043] During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fifth lens group L5, and the seventh lens group L7 do not move, and the second lens group L2, the fourth lens group L4, and the sixth lens group L6 all move toward the object side.

[0044] During focusing from infinity to a close distance, both the fourth lens unit L4 and the sixth lens unit L6 move toward the object side. [Example]

[0045] 5 is composed of, as in Example 2, 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 negative refractive power, and a rear lens group Lr, which are arranged in that order from the object side to the image side. The rear lens group Lr is composed of, in that order from the object side, a fifth lens group L5 having positive refractive power, a sixth lens group L6 having positive refractive power, and a seventh lens group L7 having negative refractive power as the final lens group.

[0046] During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fifth lens group L5, and the seventh lens group L7 do not move, and the second lens group L2, the fourth lens group L4, and the sixth lens group L6 all move toward the object side.

[0047] During focusing from infinity to a close distance, both the fourth lens unit L4 and the sixth lens unit L6 move toward the object side. [Example]

[0048] 7 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with negative refractive power, and a rear lens unit Lr. The rear lens unit Lr is composed of, arranged in order from the object side, a fifth lens unit L5 with positive refractive power, a sixth lens unit L6 with negative refractive power, and a seventh lens unit L7 with positive refractive power as the final lens unit.

[0049] During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fifth lens group L5, and the seventh lens group L7 do not move, and the second lens group L2 moves toward the image side, the fourth lens group L4 moves toward the image side, and the sixth lens group L6 moves toward the object side.

[0050] During 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. [Example]

[0051] 9 is composed of, 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, a fourth lens unit L4 having negative refractive power, and a rear lens unit Lr. The rear lens unit Lr is composed of, arranged in order from the object side, a fifth lens unit L5 having positive refractive power, a sixth lens unit L6 having negative refractive power, and a seventh lens unit L7 having negative refractive power as the final lens unit.

[0052] During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fifth lens group L5, and the seventh lens group L7 do not move, and the second lens group L2 moves toward the image side, the fourth lens group L4 moves toward the image side, and the sixth lens group L6 moves toward the object side.

[0053] During 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.

[0054] Numerical Examples 1 to 5 corresponding to Examples 1 to 5 are shown below. In each numerical example, surface number i indicates the order of the surface when counted from the object side. r is the radius of curvature (mm) of the ith surface from the object side, and d is the lens thickness or air gap (mm) on the optical axis between the ith and (i+1)th surfaces. The (variable) part of d changes according to changes in object distance (magnification), and d is listed separately for the wide-angle end when focused at infinity, the intermediate zoom position, and the telephoto end. nd is the refractive index at the d-line of the optical material between the ith and (i+1)th surfaces. νd is the Abbe number, based on the d-line of the optical material between the ith and (i+1)th surfaces.

[0055] The Abbe number νd based on the d-line is expressed as νd=(Nd-1) / (NF-NC), where Nd, NF, and NC are the refractive indices at the Fraunhofer d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm).

[0056] BF represents back focal length (mm). Back focal length is the distance on the optical axis from the final surface of a zoom lens (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 frontmost surface of a zoom lens (the lens surface closest to the object) to the final surface plus the back focal length.

[0057] An "*" 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, the direction of light travel is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are aspherical coefficients. The conic constant and the aspherical coefficient "e±Z" are multiplied by 10. ±Z means.

[0058] X=(H 2 / R) / [1+√{1-(1+K)(H / R) 2}] +A4×H 4 +A6×H 6 +A8×H 8 +A10×H 10 Moreover, values ​​corresponding to the conditions of the above-mentioned formulas (1) to (10) in Numerical Examples 1 to 5 are summarized in Table 1. Each of the Numerical Examples satisfies all of the conditions of formulas (1) to (10).

[0059] Furthermore, Figures 2, 4, 6, 8, and 10 respectively show longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) at (a) the wide-angle end and (b) the telephoto end when the zoom lenses of Numerical Examples 1 to 4 are focused at infinity. In the spherical aberration diagrams, Fno indicates the F-number, the solid line indicates spherical aberration at the d-line (wavelength 587.6 nm), and the two-dot chain line indicates spherical aberration at the g-line (wavelength 435.8 nm). In the astigmatism diagrams, the solid line S indicates astigmatism at the sagittal image plane, and the dashed line M indicates astigmatism at the meridional image plane. The distortion diagrams show distortion at the d-line. The chromatic aberration diagrams show chromatic aberration of magnification at the g-line. ω is the half angle of view (°) in paraxial calculations.

[0060] [Numerical example 1] Unit: mm Surface Data Surface number rd nd νd 1 159.034 10.43 1.49700 81.5 2 -334.178 17.04 3 112.432 9.43 1.43387 95.1 4 -481.315 1.78 5 -311.250 3.60 1.65412 39.7 6 200.014 (variable) 7 80.465 2.00 1.90043 37.4 8 45.704 7.32 9 -175.412 1.80 1.59282 68.6 10 204.419 0.20 11 68.636 6.25 1.77047 29.7 12 -357.183 1.53 13 -120.628 1.80 1.72916 54.7 14 211.087 (variable) 15 69.679 6.39 1.49700 81.5 16 -282.092 (variable) 17 -111.304 1.80 1.48749 70.2 18 -523.275 (variable) 19 (Aperture) ∞ 1.50 20 147.508 1.50 1.88300 40.8 21 56.902 2.89 22 89.572 4.45 1.77250 49.6 23 -139.386 0.20 24 71.485 4.98 1.49700 81.5 25 -96.638 1.20 1.88300 40.8 26 125.706 1.50 27 51.078 5.25 1.49700 81.5 28 -156.726 (variable) 29 -505.718 1.20 1.60311 60.6 30 47.901 (variable) 31 -324.712 1.20 1.43875 94.7 32 28.138 3.03 1.61340 44.3 33 51.508 48.00 34 137.296 9.08 1.61340 44.3 35 -34.960 1.50 1.69680 55.5 36 -344.759 48.83 Image plane ∞ Various data Zoom ratio 2.35 Wide-angle Mid-range Telephoto Focal length 206.00 304.60 485.00 F-number 5.77 5.77 5.77 Half angle of view (°) 6.00 4.06 2.55 Image height 21.64 21.64 21.64 Lens total length 345.00 345.00 345.00 BF 48.83 48.83 48.83 d 6 2.00 31.75 61.50 d14 60.70 30.95 1.20 d16 11.16 20.11 43.76 d18 35.21 26.27 2.62 d28 19.89 15.92 2.17 d30 8.38 12.34 26.09 Lens group data Group starting plane focal length 1 1 227.23 2 8 -91.92 3 16 113.11 4 18 -290.42 5 19 72.34 6 30 -72.49 7 32 -663.99 [Numerical example 2] Unit: mm Surface Data Surface number rd nd νd 1 127.092 12.60 1.49700 81.5 2 -327.252 18.28 3 136.849 9.82 1.43875 94.7 4 -251.147 0.67 5 -214.304 2.00 1.83481 42.7 6 373.689 (variable) 7 73.764 2.00 1.95375 32.3 8 42.643 6.76 9 -189.199 1.80 1.59522 67.7 10 143.025 0.20 11 64.283 5.06 2.00069 25.5 12 264.121 3.40 13 -93.392 2.00 1.59522 67.7 14 258.404 (variable) 15 68.630 6.50 1.49700 81.5 16 -212.371 (variable) 17 -82.519 1.80 1.53172 48.8 18 47.877 7.68 1.56732 42.8 19 -132.859 (variable) 20 (Aperture) ∞ 1.50 21 285.000 4.18 1.60311 60.6 22 -79.453 0.20 23 76.392 6.33 1.49700 81.5 24 -52.662 1.50 2.00069 25.5 25 -3686.123 1.50 26 229.079 4.87 1.90366 31.3 27 -46.242 1.50 1.85150 40.8 28 181.429 1.13 29 -196.724 1.50 1.85150 40.8 30 91.436 2.62 31 180.827 2.04 1.92286 20.9 32 1756.968 (variable) 33 55.691 3.62 1.48749 70.2 34 -244.258 (variable) 35 171.594 1.50 1.49700 81.5 36 33.519 2.87 37 -216.764 1.50 1.49700 81.5 38 27.217 3.94 1.57135 53.0 39 74.468 40.00 40 87.732 7.60 1.58144 40.8 41 -57.268 1.50 1.72916 54.7 42 -687.489 45.00 Image plane ∞ Various data Zoom ratio 2.35 Wide-angle Mid-range Telephoto Focal length 206.00 303.15 484.99 F-number 5.77 5.77 5.77 Half angle of view (°) 6.00 4.08 2.55 Image height 21.64 21.64 21.64 Lens total length 345.00 345.00 345.00 BF 45.00 45.00 45.00 d 6 7.22 34.18 61.15 d14 55.13 28.16 1.20 d16 4.39 12.50 33.87 d19 30.69 22.57 1.20 d32 11.29 13.07 29.44 d34 19.35 17.57 1.20 Lens group data Group starting plane focal length 1 1 214.75 2 7 -72.87 3 15 105.17 4 17 -785.77 5 20 3502.62 6 33 93.40 7 35 -98.24 [Numerical example 3] Unit: mm Surface Data Surface number rd nd νd 1 139.646 11.66 1.49700 81.5 2 -298.263 17.00 3 106.647 9.66 1.43387 95.1 4 -477.343 1.12 5 -280.555 2.50 1.65412 39.7 6 185.182 (variable) 7 87.295 2.00 1.66565 35.6 8 41.193 6.27 9 -163.112 1.80 1.59282 68.6 10 160.490 0.20 11 61.156 4.11 2.00069 25.5 12 214.357 2.99 13 -95.317 1.80 1.59282 68.6 14 128.699 (variable) 15 63.692 5.78 1.49700 81.5 16 -260.058 (variable) 17 -61.219 1.80 1.49700 81.5 18 -86.881 (variable) 19 (Aperture) ∞ 1.50 20 -5193.753 3.69 1.88300 40.8 21 -69.926 0.20 22 85.716 6.23 1.49700 81.5 23 -49.433 1.50 2.05090 26.9 24 351.295 1.63 25 654.113 3.07 1.92286 20.9 26 -87.688 1.50 1.85400 40.4 27 119.584 0.78 28 1142.749 1.50 2.05090 26.9 29 121.226 2.00 30 135.107 2.76 1.90043 37.4 31 -286.163 (variable) 32 52.477 4.01 1.53775 74.7 33 -334.170 (variable) 34 -824.948 1.50 1.60311 60.6 35 66.061 1.59 36 -110.438 1.50 1.49700 81.5 37 28.273 3.30 1.61340 44.3 38 71.465 55.36 39 123.557 8.55 1.56732 42.8 40 -39.899 1.50 1.77250 49.6 41 -155.885 45.29 Image plane ∞ Various data Zoom ratio 2.37 Wide-angle Mid-range Telephoto Focal length 204.56 302.78 484.99 F-number 5.77 5.77 5.77 Half angle of view (°) 6.04 4.09 2.55 Image height 21.64 21.64 21.64 Lens total length 345.00 345.00 345.00 BF 45.29 45.29 45.29 d 6 19.07 43.38 67.68 d14 49.81 25.50 1.20 d16 7.40 13.69 31.21 d18 26.87 20.59 3.07 d31 9.44 10.78 23.00 d33 14.75 13.42 1.20 Lens group data Group starting plane focal length 1 1 208.70 2 7 -65.39 3 15 103.56 4 17 -426.97 5 19 363.59 6 32 84.65 7 34 -101.76 [Numerical example 4] Unit: mm Surface Data Surface number rd nd νd 1 125.713 12.39 1.49700 81.5 2 -330.725 17.41 3 103.342 9.48 1.43875 94.7 4 -574.573 2.21 5 -284.065 2.50 1.65412 39.7 6 165.449 (variable) 7 83.708 2.00 1.63980 34.5 8 37.317 6.36 9 -159.660 1.80 1.65160 58.5 10 119.026 0.17 11 59.480 4.90 1.96300 24.1 12 319.638 2.99 13 -79.732 1.80 1.61800 63.4 14 205.820 (variable) 15 54.604 6.72 1.53775 74.7 16 -198.229 (variable) 17 -73.342 1.80 1.51742 52.4 18 -141.865 (variable) 19 (Aperture) ∞ 3.92 20 -14933.430 3.44 1.83481 42.7 21 -70.484 0.15 22 54.085 6.81 1.49700 81.5 23 -45.963 1.50 2.05090 26.9 24 176.337 2.69 25 -633.267 2.16 1.94594 18.0 26 -153.199 1.50 1.72916 54.7 27 123.017 0.88 28 -3991.482 1.50 1.91082 35.2 29 133.660 1.56 30 67.676 3.52 1.91082 35.2 31 -166.259 (variable) 32 -134.328 1.50 1.59349 67.0 33 83.699 (variable) 34 -301.357 6.97 1.57135 53.0 35 -23.728 1.50 1.55032 75.5 36 2000.714 44.99 37 72.732 8.06 1.59551 39.2 38 -56.342 1.50 1.83481 42.7 39 341.577 44.49 Image plane ∞ Various data Zoom ratio 2.37 Wide-angle Mid-range Telephoto Focal length 204.72 308.84 484.97 F-number 5.77 5.77 5.77 Half angle of view (°) 6.03 4.01 2.55 Image height 21.64 21.64 21.64 Lens total length 345.00 345.00 345.00 BF 44.99 44.99 44.99 d 6 15.91 40.52 65.13 d14 50.41 25.80 1.19 d16 5.44 6.62 12.43 d18 25.70 24.52 18.70 d31 10:30 11:90 1:18 d33 25.59 23.99 34.70 Lens group data Group starting plane focal length 1 1 207.04 2 7 -58.27 3 15 80.36 4 17 -296.11 5 19 99.52 6 32 -86.67 7 34 1739.51 [Numerical example 5] Unit: mm Surface Data Surface number rd nd νd 1 145.487 11.20 1.49700 81.5 2 -314.571 17.00 3 103.793 10.16 1.43387 95.1 4 -362.455 1.98 5 -259.633 2.89 1.65412 39.7 6 184.668 (variable) 7 63.637 2.00 1.85033 42.7 8 42.788 7.86 9* -97.299 2.00 1.55332 71.7 10 408.370 0.19 11 65.366 6.55 1.77047 29.7 12 -169.003 0.95 13 -103.516 2.00 1.80400 46.5 14 93.195 (variable) 15 60.809 6.53 1.49700 81.5 16 -183.770 (variable) 17 -99.438 1.80 1.48749 70.2 18 -456.690 (variable) 19 (Aperture) ∞ 1.50 20 106.666 1.50 1.90043 37.4 21 52.865 2.92 22 82.006 4.78 1.70154 41.2 23 -117.639 0.20 24 68.353 5.07 1.49700 81.5 25 -92.094 1.50 1.91082 35.2 26 126.314 1.52 27 48.832 4.73 1.49700 81.5 28 -226.977 (variable) 29 -401.445 1.53 1.61800 63.4 30 51.499 (variable) 31 -1410.781 1.50 1.49700 81.5 32 24.556 3.24 1.63930 44.9 33 44.807 48.00 34 84.266 9.79 1.61340 44.3 35 -36.956 1.50 1.69680 55.5 36 1070.479 48.13 Image plane ∞ Aspheric data 9th page K = 0.00000e+00 A 4= 3.29276e-07 A 6= 5.06490e-11 A 8= 1.15207e-13 A10=-8.40062e-18 Various data Zoom ratio 2.35 Wide-angle Mid-range Telephoto Focal length 206.00 306.55 485.00 F-number 5.77 5.77 5.77 Half angle of view (°) 6.00 4.04 2.55 Image height 21.64 21.64 21.64 Lens total length 325.01 325.01 325.01 BF 48.13 48.13 48.13 d 6 5.52 31.54 57.57 d14 53.25 27.22 1.19 d16 4.01 10.25 28.78 d18 25.97 19.73 1.20 d28 16.88 13.98 1.20 d30 8.88 11.78 24.55 Lens group data Group starting plane focal length 1 1 207.96 2 7 -73.45 3 15 92.75 4 17 -261.19 5 19 70.60 6 29 -73.76 7 31 -399.72

[0061] [Table 1]

[0062] [Imaging device] Fig. 11 shows a digital still camera as an imaging device that uses, as an imaging optical system, any of the zoom lenses of Examples 1 to 5. In Fig. 11, 10 denotes a camera body, and 11 denotes an imaging optical system constituted by any of the zoom lenses of Examples 1 to 5. 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body 10 and photoelectrically converts the subject image formed by the imaging optical system 11 (capturing an image of the subject through the zoom lens).

[0063] By using the zoom lenses according to Examples 1 to 5 as an imaging optical system, it is possible to realize a small, lightweight imaging device capable of generating high-quality images.

[0064] The above embodiment includes the following configurations.

[0065] (Configuration 1) A zoom lens in which the lens groups arranged in order from the object side to the image side are composed of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and a plurality of lens groups included in a rear group, and the spacing between adjacent lens groups changes during zooming, the first lens group does not move for zooming, and the second lens group and the fourth lens group move for zooming, the rear group includes an aperture stop, When the focal length of the second lens group is f2, the focal length of the third lens group is f3, and the focal length of the fourth lens group is f4, 0.10≦|f3 / f2|≦1.70 2.40≦f4 / f2≦16.00 A zoom lens characterized by satisfying the following conditions: (Configuration 2) When the focal length of the first lens group is f1 and the composite focal length of the plurality of lens groups included in the rear group at the wide-angle end in a state where the lens is focused on an object at infinity is frw, 0.35≦|frw / f1|≦10.00 The zoom lens according to configuration 1, characterized in that the following condition is satisfied: (Configuration 3) When the focal length of the zoom lens at the telephoto end is ft and the focal length of the first lens group is f1, 0.20≦f1 / ft≦0.90 3. The zoom lens according to configuration 1 or 2, characterized in that the following conditions are satisfied: (Configuration 4) When the focal length of the zoom lens at the telephoto end is ft, 0.10≦f3 / ft≦0.50 4. The zoom lens according to any one of configurations 1 to 3, wherein the following condition is satisfied: (Configuration 5) When the focal length of the zoom lens at the telephoto end is ft, 0.15≦|f4 / ft|≦3.00 5. The zoom lens according to any one of configurations 1 to 4, wherein the following condition is satisfied: (Configuration 6) When the distance on the optical axis from the object-side lens surface of the lens closest to the object side of the zoom lens to the image plane is Tw, and the distance on the optical axis from the image-side lens surface of the lens closest to the image side of the zoom lens to the image plane when focused on an object at infinity and at the wide-angle end is skw, 0.05≦skw / Tw≦0.30 6. The zoom lens according to any one of configurations 1 to 5, wherein the following condition is satisfied: (Configuration 7) Let f1 be the focal length of the first lens group, and skw be the distance on the optical axis from the image-side lens surface of the lens closest to the image side of the zoom lens to the image plane when the zoom lens is focused on an object at infinity and at the wide-angle end. 0.10≦skw / f1≦0.50 7. The zoom lens according to any one of configurations 1 to 6, wherein the following condition is satisfied: (Configuration 8) Let Dsi be the distance on the optical axis from the aperture stop to the image plane, and Dra be the maximum air gap on the optical axis within the rear group. 0.10≦Dra / Dsi≦0.50 8. The zoom lens according to any one of configurations 1 to 7, wherein the following condition is satisfied: (Configuration 9) Let D1 be the distance on the optical axis from the object-side lens surface of the lens closest to the object in the first lens group to the image-side lens surface of the lens closest to the image in the first lens group, and let D1a be the maximum air gap on the optical axis within the first lens group. 0.20≦D1a / D1≦0.60 9. The zoom lens according to any one of configurations 1 to 8, wherein the following condition is satisfied: (Configuration 10) 10. A zoom lens according to any one of configurations 1 to 9, wherein the fourth lens group and the lens group included in the rear group move for zooming and focusing. (Configuration 11) the plurality of lens groups included in the rear group are configured to be, in order from the object side to the image side, a fifth lens group having positive refractive power, a sixth lens group having negative refractive power, and a seventh lens group having negative refractive power; 11. A zoom lens according to any one of configurations 1 to 10, wherein the sixth lens group moves for zooming. (Configuration 12) the plurality of lens groups included in the rear group are configured to be, in order from the object side to the image side, a fifth lens group having positive refractive power, a sixth lens group having positive refractive power, and a seventh lens group having negative refractive power; 11. A zoom lens according to any one of configurations 1 to 10, wherein the sixth lens group moves for zooming. (Configuration 13) the plurality of lens groups included in the rear group are configured to be, in order from the object side to the image side, a fifth lens group having positive refractive power, a sixth lens group having negative refractive power, and a seventh lens group having positive refractive power; 11. A zoom lens according to any one of configurations 1 to 10, wherein the sixth lens group moves for zooming. (Configuration 14) A zoom lens in which the lens groups arranged in order from the object side to the image side are composed of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and a plurality of lens groups included in a rear group, and the spacing between adjacent lens groups changes during zooming, the first lens group does not move for zooming, and the second lens group and the fourth lens group move for zooming, the first lens group has two positive lenses, the rear group includes an aperture stop, When the focal length of the second lens group is f2 and the focal length of the fourth lens group is f4, 2.40≦f4 / f2≦16.00 A zoom lens characterized by satisfying the following conditions: (Configuration 15) a zoom lens according to any one of configurations 1 to 14; and an image sensor for capturing an image of a subject through the zoom lens.

[0066] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0067] L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group Lr rear group

Claims

1. A zoom lens in which the lens groups arranged in order from the object side to the image side are composed of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and a plurality of lens groups included in a rear group, and the spacing between adjacent lens groups changes during zooming, the first lens group does not move for zooming, and the second lens group and the fourth lens group move for zooming; the rear group includes an aperture stop, When the focal length of the second lens group is f2, the focal length of the third lens group is f3, and the focal length of the fourth lens group is f4, 0.10≦|f3 / f2|≦1.70 2.40≦f4 / f2≦16.00 A zoom lens characterized by satisfying the following conditions:

2. When the focal length of the first lens group is f1 and the composite focal length of the plurality of lens groups included in the rear group at the wide-angle end in a state where the lens is focused on an object at infinity is frw, 0.35≦|frw / f1|≦10.00 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. When the focal length of the zoom lens at the telephoto end is ft and the focal length of the first lens group is f1, 0.20≦f1 / ft≦0.90 2. 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, 0.10≦f3 / ft≦0.50 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. When the focal length of the zoom lens at the telephoto end is ft, 0.15≦|f4 / ft|≦3.00 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. When the distance on the optical axis from the object-side lens surface of the lens closest to the object side of the zoom lens to the image plane is Tw, and the distance on the optical axis from the image-side lens surface of the lens closest to the image side of the zoom lens to the image plane when focused on an object at infinity and at the wide-angle end is skw, 0.05≦skw / Tw≦0.30 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the focal length of the first lens group is f1, and the distance on the optical axis from the image-side lens surface of the lens closest to the image side of the zoom lens to the image plane at the wide-angle end in a state where the lens is focused on an object at infinity is skw, 0.10≦skw / f1≦0.50 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. When the distance on the optical axis from the aperture stop to the image plane is Dsi and the maximum air gap on the optical axis within the rear group is Dra, 0.10≦Dra / Dsi≦0.50 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

9. Let D1 be the distance on the optical axis from the object-side lens surface of the lens closest to the object in the first lens group to the image-side lens surface of the lens closest to the image in the first lens group, and let D1a be the maximum air gap on the optical axis within the first lens group. 0.20≦D1a / D1≦0.60 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

10. 2. The zoom lens according to claim 1, wherein the fourth lens group and the lens group included in the rear group move for zooming and focusing.

11. the plurality of lens groups included in the rear group are configured to be, in order from the object side to the image side, a fifth lens group having a positive refractive power, a sixth lens group having a negative refractive power, and a seventh lens group having a negative refractive power; 2. The zoom lens according to claim 1, wherein the sixth lens group moves for zooming.

12. the plurality of lens groups included in the rear group are configured to be, in order from the object side to the image side, a fifth lens group having a positive refractive power, a sixth lens group having a positive refractive power, and a seventh lens group having a negative refractive power; 2. The zoom lens according to claim 1, wherein the sixth lens group moves for zooming.

13. the plurality of lens groups included in the rear group are configured to be, in order from the object side to the image side, a fifth lens group having a positive refractive power, a sixth lens group having a negative refractive power, and a seventh lens group having a positive refractive power; 2. The zoom lens according to claim 1, wherein the sixth lens group moves for zooming.

14. A zoom lens in which the lens groups arranged in order from the object side to the image side are composed of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and a plurality of lens groups included in a rear group, and the spacing between adjacent lens groups changes during zooming, the first lens group does not move for zooming, and the second lens group and the fourth lens group move for zooming; the first lens group has two positive lenses, the rear group includes an aperture stop, When the focal length of the second lens group is f2 and the focal length of the fourth lens group is f4, 2.40≦f4 / f2≦16.00 A zoom lens characterized by satisfying the following conditions:

15. a zoom lens according to any one of claims 1 to 14; and an image sensor for capturing an image of a subject through the zoom lens.

Images