Zoom lens and image capturing device

Abstract

To provide a zoom lens which is compact, has a high zoom ratio, and offers high optical performance.SOLUTION: A zoom lens L0 disclosed herein comprises 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, and a rear group comprising multiple lens groups, arranged in order from the object side to the image side, and is configured such that distances between adjacent lens groups change while zooming. The third lens group has a cemented lens. A focal length f1 of the first lens group, a focal length ft of the zoom lens at the telephoto end, a displacement mr of a lens group LR located on the most image side in the rear group while zooming from the wide-angle end to the telephoto end, an optical axial distance bfw from a most image-side surface of the lens group LR at the wide-angle end to the image plane, and a displacement m3 of the third lens group while zooming from the wide-angle end to the telephoto end satisfy predetermined conditional expressions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens suitable for digital cameras, video cameras, surveillance cameras, etc., and an imaging device equipped with the same. [Background technology]

[0002] Patent Documents 1 to 3 disclose zoom lenses that are arranged in order from the object side to the image side, including 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 plurality of other lens groups. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-049445 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-146739 [Patent Document 3] Japanese Patent Application Publication No. 2019-20679 Summary of the Invention [Problem to be solved by the invention]

[0004] In the zoom lenses disclosed in Patent Documents 1 to 3, increasing the amount of movement of the lens groups constituting the zoom lens or strengthening the power of the lens groups is effective in achieving high magnification. However, increasing the amount of movement of the lens groups complicates the mechanical structure and increases the size of the zoom lens. Furthermore, strengthening the power of the lens groups increases aberration fluctuations during zooming, making it difficult to achieve high performance.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a zoom lens and an imaging device that are small, have a high magnification, and have excellent optical characteristics. [Means for solving the problem]

[0006] One aspect of the present invention provides 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, and a rear group including multiple lens groups, wherein the spacing between adjacent lens groups changes during zooming, and the third lens group has four or more negative lenses, and wherein the zoom lens satisfies a predetermined conditional expression, where f1 is the focal length of the first lens group, ft is the focal length of the zoom lens at the telephoto end, mr is the amount of movement of the lens group LR in the rear group located closest to the image during zooming from the wide-angle end to the telephoto end, bfw is the distance on the optical axis from the surface of the lens group LR closest to the image at the wide-angle end to the image plane, m3 is the amount of movement of the third lens group during zooming from the wide-angle end to the telephoto end, and f2 is the focal length of the second lens group.

[0007] Other objects and features of the present invention are illustrated in the following examples. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a zoom lens and an imaging device that are small, have a high magnification, and have excellent optical characteristics. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a zoom lens according to a first embodiment. [Figure 2] 4A to 4C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 1. [Figure 3] FIG. 10 is a cross-sectional view of a zoom lens according to a second embodiment. [Figure 4] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 2. [Figure 5] FIG. 10 is a cross-sectional view of a zoom lens according to a third embodiment. [Figure 6] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 3. [Figure 7]FIG. 10 is a cross-sectional view of a zoom lens according to a fourth embodiment. [Figure 8] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 4. [Figure 9] FIG. 10 is a cross-sectional view of a zoom lens according to a fifth embodiment. [Figure 10] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 5. [Figure 11] 1 is a schematic diagram of an imaging device equipped with a zoom lens according to each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] 1, 3, 5, 7, and 9 are cross-sectional views of the zoom lens (optical system) L0 of Examples 1 to 5 when focused at infinity. The zoom lens L0 of each Example is an optical system used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, and surveillance cameras.

[0012] In each cross-sectional view, the left is the object side (front) and the right is the image side (rear). The zoom lens L0 of each embodiment is configured with multiple lens groups. In each cross-sectional view, i indicates the order of the lens groups from the object side, and Li is the ith lens group. In each embodiment, a lens group is a group of lenses that move or remain stationary as a unit during zooming. That is, in the zoom lens L0 of each embodiment, the spacing between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Note that a lens group may be composed of a single lens or multiple lenses. The lens group may also include an aperture stop.

[0013] SP denotes an aperture stop. In each embodiment, the aperture stop SP is included in the third lens group L3, but is not limited to this. IP denotes an image plane, and when the zoom lens L0 of each embodiment is used as the imaging optical system of a digital still camera or digital video camera, the imaging surface of an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is disposed thereon. When the zoom lens L0 of each embodiment is used as the imaging optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is disposed at the image plane IP. In each cross-sectional view, the solid arrows schematically indicate the movement locus of each lens group when focusing at infinity during zooming from the wide-angle end to the telephoto end. Note that in each embodiment, the wide-angle end and the telephoto end refer to the zoom positions when each lens group of the zoom lens L0 is located at the ends of the mechanically movable range along the optical axis OA.

[0014] 2, 4, 6, 8, and 10 are aberration diagrams of the zoom lens L0 of Examples 1 to 5, respectively. In each aberration diagram, (A) is an aberration diagram of the zoom lens L0 at the wide-angle end, (B) is an aberration diagram of the zoom lens L0 at the intermediate zoom position, and (C) is an aberration diagram of the zoom lens L0 at the telephoto end. In the spherical aberration diagram, Fno is the F-number and shows the amount of spherical aberration for the d-line (wavelength 587.6 nm) and the g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS is the amount of astigmatism on the sagittal image plane, and ΔM is the amount of astigmatism on the meridional image plane. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration at the g-line is shown. ω is the half angle of view (degrees).

[0015] Conventionally, zoom lenses have been known that include, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, and multiple other lens groups. Increasing the power of the first lens group L1 in such zoom lenses facilitates high magnification, but increases aberration fluctuations during zooming and lateral chromatic aberration at the telephoto end, making it difficult to achieve high performance. Increasing the amount of movement of the first lens group L1 also facilitates high magnification, but increases the mechanical complexity and size. Therefore, to achieve both high magnification and compactness in a zoom lens and high optical performance, it is important to appropriately set the power of the first lens group L1. It is also effective to appropriately set the configuration and movement amount of subsequent lens groups to cancel out various aberrations generated by the first lens group L1.

[0016] The zoom lens L0 in each embodiment has, 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, a third lens unit L3 having positive refractive power, and a rear group including multiple lens units. By arranging multiple lens units on the image side of the third lens unit L3 and changing the spacing between adjacent lens units during zooming, it becomes easier to suppress aberration fluctuations during zooming and achieve high performance. Note that in each embodiment, a lens unit refers to a lens or lens group that has at least one lens with power and changes the air spacing between them during zooming.

[0017] The zoom lens L0 of each embodiment satisfies the following conditional expressions (1), (2), and (3).

[0018] 0.20 <f1 / ft<0.40 ···(1) -4.0 <mr / bfw<-1.5 ···(2) -7.0 <m3 / bfw<-2.5 ···(3) Here, f1 is the focal length of the first lens L1, and ft is the focal length of the entire zoom lens L0 system at the telephoto end. mr is the amount of movement of the lens unit LR, which is located closest to the image in the rear group, during zooming from the wide-angle end to the telephoto end, with a positive value representing the amount of movement from the object side to the image side. bfw is the distance on the optical axis (the distance along the optical axis OA) from the surface closest to the image in the lens unit LR, which is located closest to the image in the rear group at the wide-angle end, to the image plane IP. m3 is the amount of movement of the third lens unit L3 during zooming from the wide-angle end to the telephoto end, with a positive value representing the amount of movement from the object side to the image side.

[0019] Conditional expression (1) defines the ratio between the focal length f1 of the first lens group L1 and the focal length ft of the entire zoom lens system L0 at the telephoto end. Exceeding the upper limit of conditional expression (1) is undesirable because the focal length f1 of the first lens group L1 increases and the zoom lens system L0 becomes large. On the other hand, falling below the lower limit of conditional expression (1) is undesirable because the focal length f1 of the first lens group L1 decreases and the aberration fluctuations generated in the first lens group L1 increase, making it difficult to achieve high image quality.

[0020] Conditional formula (2) defines the relationship between the amount of movement of the lens group LR and the back focus. Changing the distance from the lens group LR to the image plane IP during zooming allows for changes in ray height. Therefore, by appropriately setting the relationship between the amount of movement of the lens group LR positioned closest to the image side during zooming and the back focus at the wide-angle end, it becomes easy to suppress aberration fluctuations occurring in the first lens group L1. Below the lower limit of conditional formula (2), the amount of movement of the lens group LR becomes small, i.e., the absolute value of the amount of movement toward the object side becomes large. This results in excessive changes in the height of rays passing through the lens group LR, which is undesirable because aberration correction during zooming becomes excessive. On the other hand, exceeding the upper limit of conditional formula (2) results in the amount of movement of the lens group LR becoming large, i.e., the absolute value of the amount of movement toward the object side becomes small or the absolute value of the amount of movement toward the image side becomes large. This shortens the distance from the lens group LR to the image plane IP at the telephoto end. As a result, the lens diameter of the lens group LR becomes large, which is undesirable because it makes compactness difficult.

[0021] Conditional expression (3) defines the relationship between the amount of movement of the third lens group L3 and the back focus. If the lower limit of conditional expression (3) is exceeded, the amount of movement of the third lens group L3 becomes small, i.e., the absolute value of the amount of movement of the third lens group L3 toward the object side becomes large, which is undesirable because the mechanical mechanism becomes complicated and large. On the other hand, if the upper limit of conditional expression (3) is exceeded, the amount of movement of the third lens group L3 becomes large, i.e., the absolute value of the amount of movement toward the object side becomes small, which is undesirable because it becomes difficult to achieve a high zoom ratio.

[0022] In each embodiment, it is preferable that the numerical ranges of conditional expressions (1) to (3) are set to the numerical ranges of the following conditional expressions (1A) to (3A), respectively.

[0023] 0.24 <f1 / ft<0.38 ···(1A) -3.5 <mr / bfw<-1.6 ···(2A) -6.0 <m3 / bfw<-2.7 ···(3A) In each embodiment, it is more preferable that the numerical ranges of the conditional expressions (1) to (3) are set to the numerical ranges of the following conditional expressions (1B) to (3B), respectively.

[0024] 0.26 <f1 / ft<0.36 ···(1B) -2.9 <mr / bfw<-1.7 ···(2B) -5.7 <m3 / bfw<-2.9 ···(3B) Next, a preferred configuration for the zoom lens L0 of each embodiment will be described. In the zoom lens L0 of each embodiment, it is preferable to arrange an aperture stop SP in the third lens unit L3. This makes it easy to reduce the diameter of the front lens. It is also preferable that the first lens unit L1 has one negative lens and three positive lenses arranged in that order from the object side to the image side. This makes it easy to suppress aberrations occurring in the first lens unit L1 while strengthening the refractive power (power) of the first lens unit L1. In the zoom lens L0 of each embodiment, it is preferable that the lens unit LR is composed of a single lens. This makes it easy to reduce the weight of the lens unit LR and simplify the mechanical structure, which is advantageous for miniaturization.

[0025] It is preferable that the zoom lens L0 of each embodiment satisfies at least one of the following conditional expressions (4) to (10).

[0026] 0.3 <fr / f1<2.8 ···(4) -9.0 <f1 / f2<-3.5 ···(5) -1.2 <m1 / f1<-0.4 ···(6) 3.0<β2t / β2w<12.0 (7) 2.0 <dpw / fw<7.0 ···(8) 0.4 <Lt / ft<1.2 ···(9) 15.0 <VdLR<50.0 ···(10) Here, fr is the focal length of the lens unit LR, and f2 is the focal length of the second lens unit L2. m1 is the movement amount of the first lens unit L1 during zooming from the wide-angle end to the telephoto end, with the movement amount from the object side to the image side being positive. β2t is the lateral magnification of the second lens unit L2 at the telephoto end, and β2w is the lateral magnification of the second lens unit L2 at the wide-angle end. dpw is the distance on the optical axis from the aperture stop SP to the image plane IP at the wide-angle end. fw is the focal length of the entire zoom lens system L0 at the wide-angle end. Lt is the distance on the optical axis from the surface of the zoom lens L0 closest to the object to the image plane IP at the telephoto end. VdLR is the Abbe number of the lenses constituting the lens unit LR.

[0027] Conditional formula (4) defines the ratio between the focal length fr of the lens group LR and the focal length f1 of the first lens group L1. Having the lens group LR have positive refractive power and a power arrangement symmetrical with respect to the aperture stop SP facilitates aberration correction. Furthermore, by setting the focal length fr of the lens group LR to have an appropriate relationship with the focal length f1 of the first lens group L1, it becomes easy to reduce various aberrations, particularly lateral chromatic aberration and distortion. Exceeding the upper limit of conditional formula (4) increases the focal length fr of the lens group LR, resulting in insufficient aberration correction and making it difficult to reduce various aberrations, particularly lateral chromatic aberration and distortion. On the other hand, falling below the lower limit of conditional formula (4) reduces the focal length fr of the lens group LR, moving the exit pupil position at the telephoto end farther from the image plane and increasing the lens diameter of the lens group LR, undesirably increasing the size of the zoom lens L0. Furthermore, it is preferable that the lens group LR move along a locus convex toward the object side during zooming from the wide-angle end to the telephoto end (moving toward the object side and then toward the image side). This makes it easier to maximize the aberration correction effect of the lens group LR. Here, a locus convex toward the object side refers to a locus that, based on the paraxial image plane position, moves toward the object side from the wide-angle end to the intermediate zoom position during zooming from the wide-angle end to the telephoto end, and then moves toward the image side from the intermediate zoom position to the telephoto end.

[0028] Conditional expression (5) defines the ratio between the focal length f1 of the first lens group L1 and the focal length f2 of the second lens group L2. By achieving an appropriate relationship between these two, it becomes easier to reduce the front lens diameter and the overall length. Exceeding the upper limit of conditional expression (5) shortens the focal length f1 of the first lens group L1, reduces the absolute value of the focal length f2 of the second lens group L2, and causes the entrance pupil position at the wide-angle end to be too far from the surface closest to the object, resulting in an undesirably large front lens diameter. On the other hand, falling below the lower limit of conditional expression (5), shortens the focal length f1 of the first lens group L1, reduces the absolute value of the focal length f2 of the second lens group L2, and results in an undesirably large amount of movement of the first lens group L1 required for zooming, resulting in an undesirably large zoom lens.

[0029] Conditional expression (6) defines the relationship between the movement amount m1 and focal length f1 of the first lens group L1. By appropriately setting this relationship, it becomes easy to achieve a high zoom ratio and a compact design. Exceeding the upper limit of conditional expression (6) is undesirable because the focal length f1 of the first lens group L1 becomes small or the absolute value of the movement amount m1 becomes large, resulting in a large size. On the other hand, falling below the lower limit of conditional expression (6) is undesirable because the focal length f2 of the second lens group L2 becomes large or the absolute value of the movement amount m1 of the first lens group L1 becomes small, making it difficult to achieve a high zoom ratio.

[0030] Conditional expression (7) defines the relationship between the lateral magnifications of the second lens unit L2 at the wide-angle end and the telephoto end. By appropriately setting these relationships, it becomes easy to achieve high zoom ratios and high performance. Exceeding the upper limit of conditional expression (7) results in either a large absolute value for the lateral magnification at the telephoto end or a small absolute value for the lateral magnification at the wide-angle end, resulting in excessively large changes in lateral magnification. This makes it difficult to correct various aberrations, particularly to suppress fluctuations in spherical aberration and astigmatism, which is undesirable. On the other hand, falling below the lower limit of conditional expression (7) results in either a small absolute value for the lateral magnification at the telephoto end or a small absolute value for the lateral magnification at the wide-angle end, resulting in excessively small changes in lateral magnification. This makes it difficult to achieve high zoom ratios, which is undesirable.

[0031] Conditional formula (8) defines the relationship between the positions of the aperture stop SP and the image plane IP at the wide-angle end. Because the off-axial ray angle is large at the wide-angle end, appropriately setting the position of the aperture stop SP is important for reducing the diameter of the front lens element and the diameter of the rear lens element. Exceeding the upper limit of conditional formula (8) is undesirable because the distance from the aperture stop SP to the image plane IP becomes large, the diameter of the rear lens element becomes large, and the zoom lens element L0 becomes large. On the other hand, falling below the lower limit of conditional formula (8) is undesirable because the distance from the aperture stop SP to the image plane IP becomes small, the diameter of the front lens element becomes large, and the zoom lens element L0 becomes large.

[0032] Conditional expression (9) defines the ratio of the overall length to the focal length of the zoom lens L0 at the telephoto end. By appropriately setting the ratio of the overall length to the focal length of the zoom lens L0, it becomes easy to achieve both shortening of the overall length and improvement in image quality. If it exceeds the upper limit of conditional expression (9), the overall length of the zoom lens L0 becomes long and it becomes large, which is not preferable. On the other hand, if it is below the lower limit of conditional expression (9), the overall length of the zoom lens L0 becomes short and it becomes difficult to correct aberrations. In particular, it becomes difficult to correct spherical aberration, chromatic aberration of magnification, and coma aberration at the telephoto end, which is not preferable.

[0033] Conditional expression (10) defines the Abbe number of the lenses constituting the lens group LR. If the Abbe number becomes large exceeding the upper limit of conditional expression (10), the chromatic aberration of magnification generated in the lens group LR becomes small, and it becomes difficult to cancel out the chromatic aberration of magnification generated in the first lens group L1, making it difficult to improve image quality, which is not preferable. On the other hand, if the Abbe number becomes small below the lower limit of conditional expression (10), the color shift sensitivity when eccentric becomes large, and the required accuracy at the time of assembly becomes too high, which is not preferable.

[0034] In each embodiment, it is preferable that the numerical ranges of conditional expressions (4) to (10) are respectively the numerical ranges of the following conditional expressions (4A) to (10A).

[0035] 0.5 < fr / f1 < 1.9 ···(4A) -8.0 < f1 / f2 < -4.5 ···(5A) -1.0 < m1 / f1 < -0.5 ···(6A) 4.2 < β2t / β2w < 9.0 ···(7A) 2.5 < dpw / fw < 5.5 ···(8A) 0.5 < Lt / ft < 0.9 ···(9A) 20.0 < VdLR < 46.0 ···(10A) Also, in each embodiment, it is more preferable that the numerical ranges of conditional expressions (4) to (10) are respectively the numerical ranges of the following conditional expressions (4B) to (10B).

[0036] 0.6 < fr / f1 < 1.5 ···(4B) -6.8 <f1 / f2<-5.3 ···(5B) -0.9 <m1 / f1<-0.6 ···(6B) 4.6<β2t / β2w<8.5 (7B) 3.0 <dpw / fw<4.7 ···(8B) 0.55 <Lt / ft<0.85 ···(9B) 25.0 <VdLR<41.0 ···(10B) Next, the zoom lens L0 of each embodiment will be described in detail.

[0037] As shown in FIGS. 1, 3, and 7, the zoom lens L0 of Examples 1, 2, and 4 includes, arranged in order from the object side to the image side, a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, and a third lens group L3 having positive refractive power. The zoom lens L0 of Example 1 also includes a fourth lens group L4 having positive refractive power, a fifth lens group L5 having negative refractive power, a sixth lens group L6 having negative refractive power, and a seventh lens group L7 having positive refractive power. The fourth lens group L4, the fifth lens group L5, the sixth lens group L6, and the seventh lens group L7 correspond to a plurality of lens groups located closer to the image side than the third lens group L3. The seventh lens group L7 corresponds to the lens group LR. The spacing between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Varying the spacing between the third lens group L3 and the fourth lens group L4 can particularly suppress fluctuations in astigmatism. Varying the spacing between the fourth lens group L4 and the fifth lens group L5 can particularly suppress fluctuations in coma. Varying the spacing between the fifth lens group L5 and the sixth lens group L6 can particularly suppress fluctuations in distortion. Varying the spacing between the sixth lens group L6 and the seventh lens group L7 can particularly suppress fluctuations in lateral chromatic aberration. Varying the spacing between multiple lens groups can improve correction of various aberrations throughout the entire zoom range.

[0038] As shown in FIG. 3, the zoom lens L0 of Example 3 includes, arranged in order from the object side to the image side, a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, and a third lens group L3 having positive refractive power. The zoom lens L0 of Example 3 also includes a fourth lens group L4 having negative refractive power, a fifth lens group L5 having positive refractive power, a sixth lens group L6 having negative refractive power, a seventh lens group L7 having negative refractive power, and an eighth lens group L8 having positive refractive power. In the zoom lens L0 of Example 3, the eighth lens group L8 corresponds to the lens group LR. The spacing between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Varying the spacing between the third lens group L3 and the fourth lens group L4 can suppress fluctuations in astigmatism, among other things. Varying the spacing between the fourth lens group L4 and the fifth lens group L5 can suppress fluctuations in spherical aberration, among other things. Varying the spacing between the fifth lens group L5 and the sixth lens group L6 can particularly suppress fluctuations in coma aberration. Varying the spacing between the sixth lens group L6 and the seventh lens group L7 can particularly suppress fluctuations in distortion aberration. Varying the spacing between the seventh lens group L7 and the eighth lens group L8 can particularly suppress fluctuations in lateral chromatic aberration. Varying the spacing between multiple lens groups improves correction of various aberrations throughout the entire zoom range. The third lens group L3 and the fifth lens group L5 move along the same trajectory when zooming from the wide-angle end to the telephoto end. This simplifies the mechanical structure.

[0039] As shown in FIG. 9 , the zoom lens L0 of Example 5 includes, arranged in order from the object side to the image side, a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, and a third lens group L3 having positive refractive power. The zoom lens L0 of Example 5 also includes a fourth lens group L4 having negative refractive power, a fifth lens group L5 having negative refractive power, and a sixth lens group L6 having positive refractive power. In the zoom lens L0 of Example 5, the sixth lens group L6 corresponds to the lens group LR. When zooming from the wide-angle end to the telephoto end, the spacing between adjacent lens groups changes. Varying the spacing between the third lens group L3 and the fourth lens group L4 can suppress fluctuations in coma aberration, in particular. Varying the spacing between the fourth lens group L4 and the fifth lens group L5 can suppress fluctuations in distortion, in particular. By varying the distance between the fifth lens group L5 and the sixth lens group L6, it is possible to suppress fluctuations in lateral chromatic aberration in particular. By varying the distances between multiple lens groups, various aberrations can be effectively corrected throughout the entire zoom range.

[0040] In this way, by arranging multiple lens groups on the image side of the third lens group L3 and varying the spacing between the multiple lens groups, various aberrations can be effectively corrected throughout the entire zoom range. In particular, by arranging at least three lens groups as the multiple lens groups arranged on the image side of the third lens group L3, various aberrations can be effectively corrected. Note that the configuration of the multiple lens groups is not limited to that of each embodiment. For example, by moving the fourth lens group L4 and the fifth lens group L5 of Embodiment 1 together, the mechanical structure can be simplified. Furthermore, by dividing the third lens group L3 of Embodiment 1 and varying the spacing between each lens group, fluctuations in spherical aberration can be further reduced, resulting in higher image quality.

[0041] In the zoom lens L0 of Examples 1 to 5, image blur correction may be reduced by moving a portion of the zoom lens L0 in a direction that includes a component perpendicular to the optical axis OA. In particular, by moving the portion that is moved for image blur correction by the whole or part of the third lens group L3 or the fourth lens group L4, which have a relatively small diameter, the actuator for driving the zoom lens L0 can be made compact, and the lens device including the zoom lens L0 can be made compact.

[0042] Numerical Examples 1 to 5 corresponding to Examples 1 to 5, respectively, are shown below. In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial distance (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. Furthermore, nd represents the refractive index of each optical member with respect to the d-line, and vd represents the Abbe number of the optical member. Note that the Abbe number vd of a certain material is given by the following when the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines are Nd, NF, and NC, respectively: νd=(Nd-1) / (NF-NC) It is expressed as:

[0043] In each numerical example, d, focal length (mm), F-number, and half angle of view (degrees) are all values ​​when the optical system of each example is focused on an object at infinity. BF (back focus) is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. The total lens length is the distance on the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final lens surface plus the back focus. The lens group is not limited to cases where it is composed of multiple lenses, but also includes cases where it is composed of a single lens. In addition, if the optical surface is aspherical, a * symbol is added to the right of the surface number. The aspherical shape is given by the following equation, where X is the displacement from the vertex of the surface in the optical axis direction, H is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, K is the conic constant, and A2, A4, A6, A8, A10, and A12 are the respective aspherical coefficients.

[0044]

number

[0045] For each aspherical coefficient, "ex" is "10 -x " means. In addition to specs such as focal length and F-number, the angle of view is the half angle of the entire system (degrees), the image height is the maximum image height that determines the half angle of view, and the total lens length is the distance from the first lens surface to the image plane. The half angle of view is the paraxial value calculated from the focal length and image height. The back focus BF indicates the length from the final lens surface to the image plane. Furthermore, the data for each lens group indicates the focal length of each lens group.

[0046] Furthermore, where the distance d between each optical surface is (variable), it changes during zooming, and the surface distance corresponding to the focal length is shown in a separate table. Furthermore, the calculation results of each conditional expression based on the lens data of Numerical Examples 1 to 5 are shown in Table 1.

[0047] (Numerical Example 1) Surface Data Surface number rd nd νd 1 255.425 1.60 1.87070 40.7 2 85.494 7.53 1.43875 94.7 3 -1859.867 0.15 4 115.473 4.70 1.49700 81.5 5 757.187 0.15 6 81.241 6.72 1.53775 74.7 7 1516.193 (variable) 8* 2688.270 1.00 1.88300 40.8 9 21.226 7.81 10 -39.142 0.80 1.72916 54.7 11 81.078 0.39 12 51.907 4.85 1.85478 24.8 13 -48.997 2.20 14 -23.647 1.00 1.59282 68.6 15 -60.312 (variable) 16 (Aperture) ∞ 0.50 17 35.307 6.08 1.65412 39.7 18 -52.038 1.50 1.59522 67.7 19 -238.158 1.98 20 44.197 4.56 1.48749 70.2 21 -61.611 1.30 1.95375 32.3 22 81.466 2.78 23 1589.792 1.20 2.05090 26.9 24 31.846 4.93 1.48749 70.2 25 -84.723 0.15 26 42.427 4.90 1.67270 32.1 27 -57.733 2.57 28 -37.849 2.57 1.85478 24.8 29 -23.648 1.20 1.80400 46.6 30 395.421 (variable) 31 35.831 8.43 1.49700 81.5 32 -33.018 1.20 2.05090 26.9 33 -92.495 0.15 34* 95.764 7.09 1.58313 59.4 35* -30.813 (variable) 36 94.522 3.12 1.85478 24.8 37 -145.150 1.00 1.80400 46.5 38 29.187 (variable) 39* -35.535 1.20 1.58313 59.4 40* -390.712 (variable) 41 182.834 2.61 1.72047 34.7 42 -309.086 (variable) Image plane ∞ Aspheric data Side 8 K = 0.00000e+000 A 4= 5.11258e-006 A 6= 2.33796e-010 A 8=-1.55382e-011 A10= 4.35749e-014 Page 34 K = 0.00000e+000 A 4=-1.35080e-005 A 6=-6.25836e-009 Page 35 K = 0.00000e+000 A 4= 4.06644e-006 A 6=-9.27789e-009 A 8= 3.24854e-012 Page 39 K = 0.00000e+000 A 4=-1.62256e-005 A 6= 6.95891e-008 Page 40 K = 0.00000e+000 A 4=-1.69549e-005 A 6= 8.34948e-008 A 8=-1.23021e-010 A10= 1.79021e-013 Various data Zoom ratio 15.68 Wide-angle Mid-range Telephoto Focal length 24.74 76.74 387.90 F-number 3.60 5.30 6.50 Half angle of view 39.51 15.75 3.19 Image height 20.40 21.64 21.64 Lens length 194.51 241.18 287.86 BF 13.32 48.47 46.46 d 7 0.80 32.19 75.34 d15 41.25 24.57 1.49 d30 8.70 1.35 1.50 d35 2.75 1.32 3.40 d38 26.36 26.53 26.10 d40 1.39 6.82 33.63 d42 13.32 48.47 46.46 Zoom lens group data Group starting plane focal length 1 1 117.12 2 8 -19.07 3 16 69.43 4 31 32.56 5 36 -56.83 6 39 -67.12 7 41 159.81 (Numerical Example 2) Surface Data Surface number rd nd νd 1 199.405 1.60 1.90043 37.4 2 75.771 7.61 1.43875 94.7 3 2140.436 0.15 4 115.473 4.66 1.49700 81.5 5 1098.547 0.15 6 69.666 7.10 1.59522 67.7 7 846.408 (variable) 8* 551.105 1.00 1.88300 40.8 9 20.523 6.99 10 -39.928 0.80 1.77250 49.6 11 72.405 0.40 12 46.081 4.80 1.85478 24.8 13 -43.915 1.53 14 -24.602 1.00 1.59282 68.6 15 -125.843 (variable) 16 (Aperture) ∞ 0.50 17 30.968 4.13 1.65412 39.7 18 -217.058 1.50 1.59522 67.7 19 -448.901 3.35 20 56.088 3.24 1.48749 70.2 21 -67.751 1.30 1.95375 32.3 22 141.265 2.14 23 226.016 1.20 2.05090 26.9 24 32.840 3.60 1.48749 70.2 25 -123.382 0.15 26 40.663 3.54 1.67270 32.1 27 -78.743 2.82 28 -32.963 1.50 1.72825 28.5 29 -25.296 1.20 1.80400 46.6 30 -351.179 (variable) 31 29.318 7.97 1.49700 81.5 32 -35.576 1.20 2.05090 26.9 33 -80.849 0.15 34* 97.098 5.81 1.58313 59.4 35* -31.216 (variable) 36 74.951 2.88 1.85478 24.8 37 -213.306 1.00 1.80400 46.5 38 23.473 (variable) 39* -27.665 1.20 1.58313 59.4 40* -341.237 (variable) 41 104.931 3.23 1.72047 34.7 42 -326.245 (variable) Image plane ∞ Aspheric data Side 8 K = 0.00000e+000 A 4= 3.30413e-006 A 6=-2.34829e-010 A 8=-7.25877e-012 A10= 3.62542e-014 Page 34 K = 0.00000e+000 A 4=-2.52752e-005 A 6=-1.72796e-008 Page 35 K = 0.00000e+000 A 4= 1.03432e-006 A 6=-1.72341e-008 A 8=-2.03279e-012 Page 39 K = 0.00000e+000 A 4=-8.73928e-006 A 6= 3.74509e-008 Page 40 K = 0.00000e+000 A 4=-1.11329e-005 A 6= 5.14822e-008 A 8=-1.29169e-010 A10= 2.27948e-013 Various data Zoom ratio 11.73 Wide-angle Mid-range Telephoto Focal length 24.72 69.39 289.87 F-number 3.60 5.30 5.88 Half angle of view 39.53 17.32 4.27 Image height 20.40 21.64 21.64 Lens total length 168.78 202.25 235.73 BF 13.34 39.12 36.81 d 7 0.80 26.27 60.83 d15 33.80 18.89 1.50 d30 7.45 2.46 1.50 d35 1.70 1.20 1.20 d38 18.58 18.88 19.79 d40 1.72 4.03 22.71 d42 13.34 39.12 36.81 Zoom lens group data Group starting plane focal length 1 1 100.42 2 8 -17.92 3 16 57.20 4 31 28.10 5 36 -45.90 6 39 -51.70 7 41 110.55 (Numerical Example 3) Surface Data Surface number rd nd νd 1 225.740 1.60 1.83400 37.2 2 108.865 6.89 1.43875 94.7 3 -1600.000 0.15 4 134.358 5.00 1.43875 94.7 5 2064.513 0.15 6 80.623 6.63 1.43875 94.7 7 448.566 (variable) 8* 397.426 1.00 1.88300 40.8 9 20.687 7.82 10 -37.394 0.80 1.72916 54.7 11 118.335 0.31 12 60.610 5.48 1.76182 26.5 13 -33.730 1.26 14 -23.918 1.00 1.53775 74.7 15 -161.887 (variable) 16 34.423 3.74 1.85478 24.8 17 160.877 2.50 18 (Aperture) ∞ 0.00 19 41.440 1.20 1.92286 20.9 20 21.729 5.67 1.48749 70.2 21 341.505 0.15 22 35.787 5.42 1.49700 81.5 23 -54.438 1.00 2.00100 29.1 24 -132.964 (variable) 25 -839.627 1.00 1.95375 32.3 26 58.544 1.77 27 -88.361 1.00 1.76200 40.1 28 24.743 4.00 1.85478 24.8 29 371.204 (variable) 30 26.029 7.41 1.48749 70.2 31 -26.003 1.00 1.95375 32.3 32 -211.831 2.00 33* 36.433 7.20 1.58313 59.4 34* -31.674 (variable) 35 69.957 2.71 1.80810 22.8 36 -273.805 1.00 1.80400 46.5 37 24.333 (variable) 38* -32.780 1.20 1.58313 59.4 39* -278.467 (variable) 40 348.028 2.86 1.72047 34.7 41 -138.495 (variable) Image plane ∞ Aspheric data Side 8 K = 0.00000e+000 A 4= 3.75838e-006 A 6= 1.01163e-009 A 8=-2.25190e-011 A10= 6.72743e-014 Page 33 K = 0.00000e+000 A 4=-2.30192e-005 A 6=-1.02293e-008 Page 34 K = 0.00000e+000 A 4= 7.93294e-006 A 6=-2.74475e-008 A 8= 2.05118e-011 Page 38 K = 0.00000e+000 A 4=-3.40508e-005 A 6= 1.11351e-007 Page 39 K = 0.00000e+000 A 4=-3.59306e-005 A 6= 1.49211e-007 A 8=-2.96761e-010 A10= 4.90321e-013 Various data Zoom ratio 15.67 Wide-angle Mid-range Telephoto Focal length 24.76 83.42 387.85 F-number 3.60 5.10 6.50 Half angle of view 39.49 14.54 3.19 Image height 20.40 21.64 21.64 Lens total length 171.65 227.55 283.44 BF 12.35 51.91 46.44 d 7 0.80 35.74 79.26 d15 36.55 17.95 0.79 d24 1.00 2.89 5.44 d29 5.94 4.04 1.50 d34 1.19 1.58 1.73 d37 21.84 13.95 21.35 d39 1.05 8.54 36.00 d41 12.35 51.91 46.44 Zoom lens group data Group starting plane focal length 1 1 127.84 2 8 -19.14 3 16 32.42 4 25 -40.11 May 30, 28.16 6 35 -48.33 7 38 -63.83 8 40 137.85 (Numerical Example 4) Surface Data Surface number rd nd νd 1 220.056 1.60 1.88300 40.8 2 93.279 8.03 1.43875 94.7 3 -1293.245 0.15 4 97.100 5.97 1.49700 81.5 5 459.954 0.15 6 117.399 5.37 1.49700 81.5 7 1179.051 (variable) 8* 287.064 1.00 1.88300 40.8 9 25.736 7.94 10 -53.742 0.80 1.72916 54.7 11 82.289 0.15 12 47.361 5.44 1.85478 24.8 13 -68.849 3.86 14 -25.876 1.00 1.59282 68.6 15 -165.250 (variable) 16 (Aperture) ∞ 0.50 17 31.300 5.94 1.65412 39.7 18 -78.341 1.50 1.53775 74.7 19 184.715 0.64 20 40.252 4.37 1.48749 70.2 21 -87.206 1.30 1.95375 32.3 22 81.666 2.63 23 349.412 1.20 2.05090 26.9 24 27.148 5.60 1.48749 70.2 25 -69.169 0.15 26 35.657 5.32 1.67270 32.1 27 -53.436 2.40 28 -37.138 2.92 1.85478 24.8 29 -21.053 1.20 1.80400 46.6 30 91.373 (variable) 31 27.579 8.08 1.49700 81.5 32 -31.348 1.20 2.05090 26.9 33 -116.343 0.15 34* 70.266 6.46 1.58313 59.4 35* -29.189 (variable) 36 70.017 2.72 1.85478 24.8 37 -298.217 1.00 1.80400 46.5 38 22.447 (variable) 39* -28.961 1.20 1.49700 81.5 40* 170.942 (variable) 41 85.814 3.17 1.72047 29.0 42 -2568.107 (variable) Image plane ∞ Aspheric data Side 8 K = 0.00000e+000 A 4= 1.78579e-006 A 6= 1.38483e-009 A 8=-3.45739e-012 A10= 1.70654e-014 Page 34 K = 0.00000e+000 A 4=-2.29409e-005 A 6=-1.68589e-008 Page 35 K = 0.00000e+000 A 4= 2.22442e-006 A 6=-1.75687e-008 A 8=-2.35901e-012 Page 39 K = 0.00000e+000 A 4=-1.54091e-006 A 6= 2.39947e-008 Page 40 K = 0.00000e+000 A 4=-6.09353e-006 A 6= 3.17194e-008 A 8=-1.07433e-010 A10= 2.14422e-013 Various data Zoom ratio 16.83 Wide-angle Mid-range Telephoto Focal length 28.81 94.89 484.70 F-number 3.60 5.30 7.20 Half angle of view 35.30 12.84 2.56 Image height 20.40 21.64 21.64 Lens total length 194.00 240.17 286.34 BF 13.85 43.81 39.37 d 7 0.80 42.00 89.13 d15 46.22 22.88 1.50 d30 3.17 1.31 1.50 d35 1.19 4.12 1.20 d38 25.44 19.33 26.49 d40 2.23 5.61 26.05 d42 13.85 43.81 39.37 Zoom lens group data Group starting plane focal length 1 1 134.78 2 8 -21.22 3 16 70.23 4 31 29.22 5 36 -44.34 6 39 -49.73 7 41 115.31 (Numerical Example 5) Surface Data Surface number rd nd νd 1 223.853 1.60 1.88300 40.8 2 113.461 8.76 1.43875 94.7 3 -7333.776 0.15 4 115.066 7.20 1.43875 94.7 5 647.350 0.15 6 159.127 4.98 1.49700 81.5 7 765.639 (variable) 8 91.064 1.80 1.80311 46.7 9 26.688 9.72 10 -83.582 1.40 1.72788 54.9 11 76.171 0.15 12 45.585 5.11 1.84666 23.8 13 -571.011 8.84 14 -36.426 1.40 1.59282 68.6 15 -209.675 (variable) 16 (Aperture) ∞ 0.50 17 33.903 5.16 1.65412 39.7 18 -96.183 1.50 1.53775 74.7 19 108.454 3.24 20 41.851 3.65 1.48749 70.2 21 -137.968 1.30 1.95375 32.3 22 80.578 2.63 23 282.536 1.20 2.05090 26.9 24 27.481 5.52 1.48749 70.2 25 -59.637 0.15 26 34.183 5.19 1.67270 32.1 27 -55.307 2.44 28 -36.723 5.58 1.85478 24.8 29 -23.880 1.20 1.80400 46.6 30 140.439 1.82 31 32.792 6.67 1.49700 81.5 32 -36.536 1.20 2.05090 26.9 33 -107.126 0.15 34* 1059.034 5.43 1.58313 59.4 35* -27.868 (variable) 36 65.301 2.63 1.85478 24.8 37 -432.146 1.00 1.80400 46.5 38 21.709 (variable) 39* -28.832 1.20 1.49700 81.5 40* 245.015 (variable) 41 74.912 3.12 1.72047 40.0 42 586.438 (variable) Image plane ∞ Aspheric data Page 34 K = 0.00000e+000 A 4=-2.02740e-005 A 6=-8.62308e-009 Page 35 K = 0.00000e+000 A 4=-1.55557e-006 A 6=-4.58763e-009 A 8=-7.70161e-012 Page 39 K = 0.00000e+000 A 4= 8.69486e-006 A 6=-6.30755e-009 Page 40 K = 0.00000e+000 A 4= 3.44567e-006 A 6=-1.80194e-008 A 8= 2.95620e-011 A10=-7.04293e-014 Various data Zoom ratio 17.61 Wide-angle Mid-range Telephoto Focal length 33.05 140.67 581.87 F-number 4.10 5.90 7.20 Half angle of view 31.69 8.74 2.13 Image height 20.40 21.64 21.64 Lens length 218.72 276.34 333.97 BF 14.32 39.28 46.78 d 7 0.80 69.66 117.45 d15 56.37 17.64 1.52 d35 1.20 7.70 1.36 d38 30.79 19.31 24.32 d40 1.50 9.01 28.80 d42 14.32 39.28 46.78 Zoom lens group data Group starting plane focal length 1 1 176.42 2 8 -26.51 3 16 37.19 4 36 -43.72 5 39 -51.83 6 41 118.90

[0048] [Table 1]

[0049] Next, an embodiment of a digital still camera (image capture device 10) using the zoom lens L0 of each embodiment as an image capture optical system will be described with reference to Fig. 11. Fig. 11 is a schematic diagram of the image capture device 10 equipped with the zoom lens L0 of each embodiment.

[0050] 11, reference numeral 13 denotes a camera body, and 11 denotes an imaging optical system constituted by the zoom lens L0 of any one of 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 camera body 13 and receives and photoelectrically converts an optical image formed by imaging optical system 11. Camera body 13 may be a so-called single-lens reflex camera that has a quick-turn mirror, or a so-called mirrorless camera that does not have a quick-turn mirror.

[0051] In this way, by applying the zoom lens of the present invention to an imaging device 10 such as a digital still camera, an imaging device with high optical performance can be obtained. Note that the zoom lens of each embodiment can also be applied to a video camera in the same way.

[0052] According to each embodiment, it is possible to provide a zoom lens and an imaging device that are small, have a high magnification, and have excellent optical characteristics.

[0053] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0054] L0 zoom lens L1 First lens group L2 Second lens group L3: Third lens group LR lens group

Claims

1. A zoom lens comprising, arranged in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a rear group including a plurality of lens groups, wherein the spacing between adjacent lens groups changes during zooming, the third lens group has four or more negative lenses, Let f1 be the focal length of the first lens group, ft be the focal length of the zoom lens at the telephoto end, mr be the movement amount of the lens group LR arranged closest to the image side in the rear group during zooming from the wide-angle end to the telephoto end, bfw be the distance on the optical axis from the surface of the lens group LR closest to the image side at the wide-angle end to the image plane, m3 be the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end, and f2 be the focal length of the second lens group. 0.20<f1 / ft<0.40 -4.0<mr / bfw<-1.5 -7.0<m3 / bfw<-2.5 -8.0<f1 / f2<-4.5 A zoom lens characterized by satisfying the following conditional expressions:

2. 2. The zoom lens according to claim 1, wherein the first lens group comprises one negative lens and three positive lenses.

3. 3. The zoom lens according to claim 1, wherein the lens unit LR moves toward the object side and then moves toward the image side during zooming from the wide-angle end to the telephoto end.

4. When the focal length of the lens group LR is fr, 0.3<fr / f1<2.8 4. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. When the amount of movement of the first lens unit during zooming from the wide-angle end to the telephoto end is m1, -1.2<m1 / f1<-0.4 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. When the lateral magnification of the second lens group at the telephoto end is β2t and the lateral magnification of the second lens group at the wide-angle end is β2w, 3.0<β2t / β2w<12.0 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. further comprising an aperture stop; When the distance on the optical axis from the aperture stop to the image plane at the wide-angle end is dpw and the focal length of the zoom lens at the wide-angle end is fw, 2.0<dpw / fw<7.0 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. When the distance on the optical axis from the surface of the zoom lens closest to the object to the image plane at the telephoto end is Lt, 0.4<Lt / ft<1.2 8. The zoom lens according to claim 1, wherein the following condition is satisfied:

9. 9. The zoom lens according to claim 1, wherein the lens group LR is composed of one single lens.

10. When the Abbe number of the single lens is VdLR, 15.0<VdLR<50.0 10. The zoom lens according to claim 9, wherein the following condition is satisfied:

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

Images