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 a digital camera, a video camera, a surveillance camera, etc., and an imaging device including the same.

Background Art

[0002] Patent Documents 1 to 3 disclose a zoom lens including, 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 plurality of lens groups.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the zoom lenses disclosed in Patent Documents 1 to 3, in order to achieve a high magnification, it is effective to increase the moving amount of the lens groups constituting the zoom lens or to strengthen the power of the lens groups. However, when the moving amount of the lens groups is increased, the mechanical mechanism becomes complicated and the zoom lens becomes large. Further, when the power of the lens groups is strengthened, the aberration variation during zooming becomes large and it becomes difficult to improve the performance.

[0005] Therefore, an object of the present invention is to provide a zoom lens and an imaging device that are small, have a high magnification, and have high optical characteristics.

Means for Solving the Problems

[0006] A zoom lens according to one aspect of the present invention includes 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, which are arranged in order from the object side to the image side. The zoom lens is such that the distance between adjacent lens groups changes during zooming. Let the focal length of the first lens group be f1, the focal length of the zoom lens at the telephoto end be ft, the moving amount of the lens group LR, which is the lens group arranged closest to the image side among the rear groups, during zooming from the wide-angle end to the telephoto end be mr, the distance on the optical axis from the most image-side surface of the lens group LR at the wide-angle end to the image plane be bfw, the moving amount of the third lens group during zooming from the wide-angle end to the telephoto end be m3, the focal length of the second lens group be f2, the moving amount of the first lens group during zooming from the wide-angle end to the telephoto end be m1, and the sign of the moving amount of the lens group be positive when moving from the object side to the image side and negative when moving from the image side to the object side. The zoom lens is characterized by satisfying a predetermined conditional expression.

[0007] Other objects and features of the present invention will be described 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 in size, have a high magnification, and have high optical characteristics.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Modes for Carrying Out the Invention

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

[0011] FIGS. 1, 3, 5, 7, and 9 are cross-sectional views of the zoom lens (optical system) L0 in Examples 1 to 5 at infinity focus, respectively. 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, silver halide film cameras, and surveillance cameras.

[0012] In each cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). The zoom lens L0 of each example is composed of a plurality of lens groups. In each cross-sectional view, i indicates the order of the lens groups from the object side, and Li is the i-th lens group. In each example, a lens group is a collection of lenses that move or remain stationary integrally during zooming. That is, in the zoom lens L0 of each example, the interval 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 one lens or a plurality of lenses. Also, a lens group may include an aperture stop.

[0013] The SP is an aperture stop. In each embodiment, the aperture stop SP is included in the third lens group L3, but is not limited thereto. The IP is an image plane. When the zoom lens L0 of each embodiment is used as an imaging optical system of a digital still camera or a digital video camera, the imaging surface of an imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is arranged at the image plane. When the zoom lens L0 of each embodiment is used as an imaging optical system of a camera for silver halide film, a photosensitive surface corresponding to the film surface is placed at the image plane IP. Also, in each cross-sectional view, the solid-line arrow schematically shows the movement locus of each lens group at the time of focusing at infinity in zooming from the wide-angle end to the telephoto end. 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 both ends of the range where it can move on the optical axis OA due to the mechanism.

[0014] Figures 2, 4, 6, 8, and 10 are aberration diagrams of the zoom lenses L0 of Embodiments 1 to 5, respectively. In each aberration diagram, (A) is the aberration diagram of the zoom lens L0 at the wide-angle end, (B) is the aberration diagram of the zoom lens L0 at the intermediate zoom position, and (C) is the aberration diagram of the zoom lens L0 at the telephoto end. In the spherical aberration diagram, Fno is the F-number, and it shows the spherical aberration amounts with respect to the d-line (wavelength 587.6 nm) and the g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS shows the astigmatism amount in the sagittal image plane, and ΔM shows the astigmatism amount in the meridional image plane. In the distortion aberration diagram, it shows the distortion aberration amount with respect to the d-line. In the chromatic aberration diagram, it shows the chromatic aberration amount with respect to the g-line. ω is the imaging semi-field angle (degrees).

[0015] Conventionally, a zoom lens including 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, and a plurality of lens groups arranged in order from the object side to the image side is known. In such a zoom lens, increasing the power of the first lens group L1 facilitates high magnification, but aberration variation during zooming and longitudinal chromatic aberration at the telephoto end become large, making it difficult to achieve high performance. Also, increasing the movement amount of the first lens group L1 facilitates high magnification, but the mechanical mechanism becomes complex and the size increases. Therefore, in order to achieve both high magnification and miniaturization of the zoom lens and realize high optical performance, it is important to appropriately set the power of the first lens group L1. Also, it is effective to appropriately set the configuration and movement amount of the subsequent lens groups so as to cancel out various aberrations generated in the first lens group L1.

[0016] The zoom lens L0 of each embodiment has a first lens group L1 having a positive refractive power, a second lens group L2, a third lens group L3 having a positive refractive power, and a rear group including a plurality of lens groups, which are arranged in order from the object side to the image side. By arranging a plurality of lens groups on the image side of the third lens group L3 and changing the interval between adjacent lens groups during zooming, it becomes easy to suppress aberration variation during zooming and achieve high performance. In each embodiment, the lens group refers to a lens or a lens group having at least one lens with power and changing the air interval between each other 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 overall focal length of the zoom lens L0 at the telephoto end. mr is the amount of movement during zooming from the wide-angle end to the telephoto end of the lens group LR, which is arranged closest to the image side among the rear groups, and the movement amount from the object side to the image side is defined as positive. bfw is the distance on the optical axis from the most image-side surface of the lens group LR, which is arranged closest to the image side among the rear groups, to the image plane IP at the wide-angle end (the distance in the direction along the optical axis OA). m3 is the amount of movement during zooming from the wide-angle end to the telephoto end of the third lens group L3, and the movement amount from the object side to the image side is defined as positive.

[0019] Conditional expression (1) defines the ratio between the focal length f1 of the first lens group L1 and the overall focal length ft of the zoom lens L0 at the telephoto end. If it exceeds the upper limit of conditional expression (1), the focal length f1 of the first lens group L1 becomes large and the zoom lens L0 becomes large-sized, which is not preferable. On the other hand, if it is below the lower limit of conditional expression (1), the focal length f1 of the first lens group L1 becomes small and the aberration variation generated in the first lens group L1 becomes large, making it difficult to achieve high image quality, which is not preferable.

[0020] Conditional expression (2) defines the relationship between the movement amount of the lens group LR and the back focus. By changing the distance from the lens group LR to the image plane IP during zooming, the ray height can be changed. Therefore, by appropriately setting the relationship between the movement amount during zooming of the lens group LR, which is arranged closest to the image side, and the back focus at the wide-angle end, it becomes easy to suppress the aberration variation generated in the first lens group L1. If it is below the lower limit of conditional expression (2), the movement amount of the lens group LR becomes small, that is, the absolute value of the movement amount toward the object side becomes large, and the change in the ray height passing through the lens group LR becomes too large. As a result, the aberration correction during zooming becomes excessive, which is not preferable. On the other hand, if it exceeds the upper limit of conditional expression (2), the movement amount of the lens group LR becomes large, that is, the absolute value of the movement amount toward the object side becomes small, or the absolute value of the movement amount toward the image side becomes large. As a result, the distance from the lens group LR to the image plane IP at the telephoto end becomes short. As a result, the lens diameter of the lens group LR becomes large, making it difficult to miniaturize, which is not preferable.

[0021] Conditional expression (3) defines the relationship between the movement amount of the third lens group L3 and the back focus. If it is below the lower limit of conditional expression (3), the movement amount of the third lens group L3 becomes small, that is, the absolute value of the movement amount of the third lens group L3 toward the object side becomes large, which is not preferable because the mechanical mechanism becomes complicated and leads to an increase in size. On the other hand, if it exceeds the upper limit of conditional expression (3), the movement amount of the third lens group L3 becomes large, that is, the absolute value of the movement amount toward the object side becomes small, and it becomes difficult to achieve high magnification, which is not preferable.

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

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

[0024] 0.26 < f1 / ft < 0.36 ···(1B) -2.9 < mr / bfw < -1.7 ···(2B) -5.7 < m3 / bfw < -2.9 ···(3B) Next, the preferred configurations of the zoom lens L0 in each embodiment will be described. In the zoom lens L0 of each embodiment, it is preferable to dispose the aperture stop SP in the third lens group L3. This makes it easy to suppress the front lens diameter. Also, the first lens group L1 preferably has one negative lens and three positive lenses arranged in order from the object side to the image side. This makes it easy to suppress the aberration generated in the first lens group L1 while strengthening the refractive power (power) of the first lens group L1. In the zoom lens L0 of each embodiment, the lens group LR may be configured by a single lens. This facilitates weight reduction of the lens group LR and enables simplification of the mechanical mechanism, which is advantageous for miniaturization.

[0025] The zoom lens L0 of each embodiment preferably 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 group LR, and f2 is the focal length of the second lens group L2. m1 is the amount of movement during zooming from the wide-angle end to the telephoto end of the first lens group L1, with the amount of movement from the object side to the image side being positive. β2t is the lateral magnification of the second lens group L2 at the telephoto end, and β2w is the lateral magnification of the second lens group 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 overall focal length of the zoom lens L0 at the wide-angle end. Lt is the distance on the optical axis from the most object-side surface of the zoom lens L0 to the image plane IP at the telephoto end. VdLR is the Abbe number of the lens constituting the lens group LR.

[0027] Conditional expression (4) defines the ratio of the focal length fr of the lens group LR to the focal length f1 of the first lens group L1. By having the lens group LR have a positive refractive power and a power arrangement symmetric with respect to the aperture stop SP, aberration correction becomes easy. Also, by setting the focal length fr of the lens group LR to be in an appropriate relationship with the focal length f1 of the first lens group L1, it becomes easy to reduce various aberrations, particularly chromatic aberration of magnification and distortion aberration. When exceeding the upper limit of conditional expression (4), the focal length fr of the lens group LR becomes large, the aberration correction effect is insufficient, and it becomes difficult to reduce various aberrations, particularly chromatic aberration of magnification and distortion aberration. On the other hand, when falling below the lower limit of conditional expression (4), the focal length fr of the lens group LR becomes small, the exit pupil position at the telephoto end becomes far from the image plane, and the lens diameter of the lens group LR becomes large, so the zoom lens L0 becomes large-sized, which is not preferable. Also, it is preferable that the lens group LR moves along a locus convex toward the object side (moves toward the image side after moving toward the object side) during zooming from the wide-angle end to the telephoto end. Thereby, it becomes easy to maximize the aberration correction effect of the lens group LR. Here, the locus convex toward the object side means a locus that moves toward the object side from the wide-angle end to the intermediate zoom position and then moves toward the image side from the intermediate zoom position to the telephoto end when zooming from the wide-angle end to the telephoto end with reference to the paraxial image plane position.

[0028] Conditional expression (5) defines the ratio of the focal length f1 of the first lens group L1 to the focal length f2 of the second lens group L2. By making these relationships appropriate, it becomes easy to suppress the front lens diameter and shorten the overall length. When exceeding the upper limit of conditional expression (5), the focal length f1 of the first lens group L1 becomes small, the absolute value of the focal length f2 of the second lens group L2 becomes large, and the entrance pupil position at the wide-angle end becomes too far from the surface on the most object side, so the front lens diameter becomes large-sized, which is not preferable. On the other hand, when falling below the lower limit of conditional expression (5), the focal length f1 of the first lens group L1 becomes large, the absolute value of the focal length f2 of the second lens group L2 becomes small, and as a result, the moving amount of the first lens group L1 required for zooming becomes large, leading to an increase in size, which is not preferable.

[0029] Conditional expression (6) defines the relationship between the movement amount m1 of the first lens group L1 and the focal length f1. By appropriately setting these relationships, high magnification and miniaturization become easier. If it exceeds the upper limit of conditional expression (6), the focal length f1 of the first lens group L1 becomes smaller, or the absolute value of the movement amount m1 becomes larger, resulting in an increase in size, which is not preferable. On the other hand, if it is below the lower limit of conditional expression (6), the focal length f2 of the second lens group L2 becomes larger, or the absolute value of the movement amount m1 of the first lens group L1 becomes smaller, making high magnification difficult, which is not preferable.

[0030] Conditional expression (7) defines the relationship between the lateral magnification at the wide-angle end and the telephoto end of the second lens group L2. By appropriately setting these relationships, high magnification and high performance become easier. If it exceeds the upper limit of conditional expression (7), the absolute value of the lateral magnification at the telephoto end becomes larger, or the absolute value of the lateral magnification at the wide-angle end becomes smaller, and the change in lateral magnification becomes too large. Therefore, it becomes difficult to correct various aberrations, especially to suppress the fluctuations of spherical aberration and astigmatism, which is not preferable. On the other hand, if it is below the lower limit of conditional expression (7), the absolute value of the lateral magnification at the telephoto end becomes smaller, or the absolute value of the lateral magnification at the wide-angle end becomes smaller, and the change in lateral magnification becomes too small. Therefore, high magnification becomes difficult, which is not preferable.

[0031] Conditional expression (8) defines the relationship between the aperture stop SP and the position of the image plane IP at the wide-angle end. Since the off-axis ray angle is large at the wide-angle end, appropriately setting the position of the aperture stop SP is important for suppressing the front lens diameter and the rear lens diameter. If it exceeds the upper limit of conditional expression (8), the distance from the aperture stop SP to the image plane IP becomes large and the rear lens diameter becomes large, resulting in an increase in size of the zoom lens L0, which is not preferable. On the other hand, if it is below the lower limit of conditional expression (8), the distance from the aperture stop SP to the image plane IP becomes small and the front lens diameter becomes large, resulting in an increase in size of the zoom lens L0, which is not preferable.

[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 aberration correction becomes difficult, especially correction of spherical aberration, chromatic aberration of magnification, and coma aberration at the telephoto end becomes difficult, 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, it becomes difficult to cancel the chromatic aberration of magnification generated in the first lens group L1, and it becomes difficult to improve the image quality, which is not preferable. On the other hand, if it is below the lower limit of conditional expression (10) and the Abbe number becomes small, the color shift sensitivity when eccentric becomes large, and the required accuracy during 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 example will be described in detail.

[0037] As shown in FIGS. 1, 3, and 7, the zoom lenses L0 of Examples 1, 2, and 4 include a first lens group L1 having a positive refractive power, a second lens group L2 having a negative refractive power, and a third lens group L3 having a positive refractive power, which are arranged in order from the object side to the image side. The zoom lens L0 of Example 1 further includes a fourth lens group L4 having a positive refractive power, a fifth lens group L5 having a negative refractive power, a sixth lens group L6 having a negative refractive power, and a seventh lens group L7 having a 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 arranged on the image side with respect to the third lens group L3. The seventh lens group L7 corresponds to the lens group LR. When zooming from the wide-angle end to the telephoto end, the interval between adjacent lens groups changes. By changing the interval between the third lens group L3 and the fourth lens group L4, it is possible to particularly suppress fluctuations in astigmatism. By changing the interval between the fourth lens group L4 and the fifth lens group L5, it is possible to particularly suppress fluctuations in coma. By changing the interval between the fifth lens group L5 and the sixth lens group L6, it is possible to particularly suppress fluctuations in distortion. By changing the interval between the sixth lens group L6 and the seventh lens group L7, it is possible to particularly suppress fluctuations in longitudinal chromatic aberration. By changing the intervals between the plurality of lens groups, correction of various aberrations throughout the zoom range becomes good.

[0038] As shown in FIG. 3, the zoom lens L0 of Example 3 has a first lens group L1 having a positive refractive power, a second lens group L2 having a negative refractive power, and a third lens group L3 having a positive refractive power, which are arranged in order from the object side to the image side. The zoom lens L0 of Example 3 also has a fourth lens group L4 having a negative refractive power, a fifth lens group L5 having a positive refractive power, a sixth lens group L6 having a negative refractive power, a seventh lens group L7 having a negative refractive power, and an eighth lens group L8 having a positive refractive power. In the zoom lens L0 of Example 3, the eighth lens group 8 corresponds to the lens group LR. When zooming from the wide-angle end to the telephoto end, the interval between adjacent lens groups changes. By changing the interval between the third lens group L3 and the fourth lens group L4, it is possible to particularly suppress the variation of the astigmatism. By changing the interval between the fourth lens group L4 and the fifth lens group L5, it is possible to particularly suppress the variation of the spherical aberration. By changing the interval between the fifth lens group L5 and the sixth lens group L6, it is possible to particularly suppress the variation of the coma aberration. By changing the interval between the sixth lens group L6 and the seventh lens group L7, it is possible to particularly suppress the variation of the distortion aberration. By changing the interval between the seventh lens group L7 and the eighth lens group L8, it is possible to particularly suppress the variation of the longitudinal chromatic aberration. By changing the intervals between the plurality of lens groups, the correction of various aberrations over the entire zoom range becomes good. The third lens group L3 and the fifth lens group L5 move along the same locus when zooming from the wide-angle end to the telephoto end. Thereby, the simplification of the mechanical mechanism can be realized.

[0039] As shown in FIG. 9, the zoom lens L0 of Example 5 has a first lens group L1 having a positive refractive power, a second lens group L2 having a negative refractive power, and a third lens group L3 having a positive refractive power, which are arranged in order from the object side to the image side. Further, the zoom lens L0 of Example 5 has a fourth lens group L4 having a negative refractive power, a fifth lens group L5 having a negative refractive power, and a sixth lens group L6 having a 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 interval between adjacent lens groups changes. By changing the interval between the third lens group L3 and the fourth lens group L4, it is possible to particularly suppress the variation of coma aberration. By changing the interval between the fourth lens group L4 and the fifth lens group L5, it is possible to particularly suppress the variation of distortion aberration. By changing the interval between the fifth lens group L5 and the sixth lens group L6, it is possible to particularly suppress the variation of longitudinal chromatic aberration. By changing the intervals between a plurality of lens groups, the correction of various aberrations over the entire zoom range becomes good.

[0040] Thus, by arranging a plurality of lens groups on the image side of the third lens group L3 and changing the intervals between the plurality of lens groups, the correction of various aberrations over the entire zoom range becomes good. In particular, by arranging at least three lens groups as the plurality of lens groups arranged on the image side of the third lens group L3, the correction of various aberrations becomes good. Note that the configuration of the plurality of lens groups is not limited to the configuration of each embodiment. For example, by moving the fourth lens group L4 and the fifth lens group L5 of Example 1 integrally, the mechanical mechanism can be simplified. Further, by dividing the third lens group L3 of Example 1 and changing the intervals between the lens groups, the variation of spherical aberration can be further reduced and high image quality can be achieved.

[0041] In the zoom lenses L0 of Examples 1 to 5, image blur correction may be reduced by moving a part of the zoom lens L0 in a direction including a component perpendicular to the optical axis OA. In particular, by making the part to be moved during image blur correction be the whole or a part of the relatively small-diameter third lens group L3 or fourth lens group L4, an actuator for driving can be configured to be small, and a lens device including the zoom lens L0 can be miniaturized.

[0042] Hereinafter, Numerical Examples 1 to 5 corresponding to Examples 1 to 5 are shown. In the surface data of each numerical example, r is the curvature radius of each optical surface, and d (mm) represents the on-axis interval (distance on the optical axis) between the m-th surface and the (m + 1)-th surface. However, m is the surface number counted from the light incident side. Also, nd represents the refractive index with respect to the d-line of each optical member, and νd represents the Abbe number of the optical member. Note that the Abbe number νd of a certain material, when the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of Fraunhofer lines are Nd, NF, and NC, νd = (Nd - 1) / (NF - NC) is represented by.

[0043] In each numerical example, d, focal length (mm), F-number, and semi-field angle (degrees) are all values when the optical system of each example is focused on an infinite object. BF (back focus) is the distance on the optical axis from the final lens surface (the lens surface closest to the image side) to the paraxial image plane, expressed in terms of the air-equivalent length. The overall length of the lens is the length obtained by adding the back focus to the distance on the optical axis from the frontmost surface (the lens surface closest to the object side) to the final surface of the zoom lens. The lens group includes not only cases where it is composed of a plurality of lenses but also cases where it is composed of a single lens. Also, when the optical surface is an aspherical surface, an asterisk symbol is attached to the right side of the surface number. The aspherical shape is given by the following formula when X is the displacement amount from the vertex of the surface in the optical axis direction, H is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial curvature radius, K is the conic constant, and A2, A4, A6, A8, A10, A12 are the aspherical coefficients respectively.

[0044] [Number]

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

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

[0047] (Numerical Example 1) Surface Data Surface Number r d 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 ∞ Aspherical data The 8th surface K = 0.00000e+000 A4 = 5.11258e-006 A6 = 2.33796e-010 A8 = -1.55382e-011 A10 = 4.35749e-014 The 34th surface K = 0.00000e+000 A4 = -1.35080e-005 A6 = -6.25836e-009 The 35th surface K = 0.00000e+000 A4 = 4.06644e-006 A6 = -9.27789e-009 A8 = 3.24854e-012 The 39th surface K = 0.00000e+000 A4 = -1.62256e-005 A6 = 6.95891e-008 The 40th surface K = 0.00000e+000 A4 = -1.69549e-005 A6 = 8.34948e-008 A8 = -1.23021e-010 A10 = 1.79021e-013 Various data Zoom ratio 15.68 Wide angle, medium, telephoto Focal length 24.74, 76.74, 387.90 F-number 3.60, 5.30, 6.50 Half field angle 39.51, 15.75, 3.19 Image height 20.40, 21.64, 21.64 Overall lens length 194.51, 241.18, 287.86 BF 13.32, 48.47, 46.46 d7 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 surface 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 r d 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 ∞ Aspherical data The 8th surface K = 0.00000e+000 A 4= 3.30413e-006 A 6=-2.34829e-010 A 8=-7.25877e-012 A10= 3.62542e-014 The 34th surface K = 0.00000e+000 A 4=-2.52752e-005 A 6=-1.72796e-008 The 35th surface K = 0.00000e+000 A 4= 1.03432e-006 A 6=-1.72341e-008 A 8=-2.03279e-012 The 39th surface K = 0.00000e+000 A 4=-8.73928e-006 A 6= 3.74509e-008 The 40th surface 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, medium, 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 Overall lens 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 surface 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 r d 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 ∞ Aspherical data The 8th surface 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, medium, 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 Overall lens 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 surface Focal length 1 1 127.84 2 8 -19.14 3 16 32.42 4 25 -40.11 5 30 28.16 6 35 -48.33 7 38 -63.83 8 40 137.85 (Numerical Example 4) Surface data Surface number r d 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 ∞ Aspherical data Surface 8 K = 0.00000e+000 A 4= 1.78579e-006 A 6= 1.38483e-009 A 8=-3.45739e-012 A10= 1.70654e-014 Surface 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, middle, telephoto Focal length 28.81 94.89 484.70 F-number 3.60 5.30 7.20 Half field angle 35.30 12.84 2.56 Image height 20.40 21.64 21.64 Overall lens 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 surface, 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 r d 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 ∞ Aspherical data Surface 34 K = 0.00000e+000 A 4=-2.02740e-005 A 6=-8.62308e-009 Surface 35 K = 0.00000e+000 A 4=-1.55557e-006 A 6=-4.58763e-009 A 8=-7.70161e-012 Surface 39 K = 0.00000e+000 A 4= 8.69486e-006 A 6=-6.30755e-009 The 40th surface 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, middle, telephoto Focal length 33.05 140.67 581.87 F number 4.10 5.90 7.20 Half field angle 31.69 8.74 2.13 Image height 20.40 21.64 21.64 Overall 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 surface, 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, with reference to FIG. 11, an example of a digital still camera (imaging device 10) using the zoom lens L0 of each example as an imaging optical system will be described. FIG. 11 is a schematic diagram of the imaging device 10 equipped with the zoom lens L0 of each example.

[0050] In FIG. 11, 13 is the camera body, and 11 is an imaging optical system composed of the zoom lens L0 of any one of Examples 1 to 5. 12 is an imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that is built into the camera body 13 and receives and photoelectrically converts the optical image formed by the imaging optical system 11. The camera body 13 may be a so-called single-lens reflex camera having a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

[0051] By applying the zoom lens of the present invention to an imaging device 10 such as a digital still camera in this way, an imaging device having high optical performance can be obtained. Note that the zoom lens of each example can be similarly applied to a video camera.

[0052] According to each example, a zoom lens and an imaging device that are small, have a high magnification, and have high optical characteristics can be provided.

[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 thereof.

Description of Reference Numerals

[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, 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 distance between adjacent lens groups changes during zooming, 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 movement amount of the lens group LR, which is the most image-side lens group among the rear groups, during zooming from the wide-angle end to the telephoto end, bfw is the distance on the optical axis from the most image-side surface of the lens group LR at the wide-angle end to the image plane, m3 is the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end, f2 is the focal length of the second lens group, m1 is the movement amount of the first lens group during zooming from the wide-angle end to the telephoto end, and the sign of the movement amount of the lens group is positive when moving from the object side to the image side and negative when moving from the image side to the object side, 0.20 < f1 / ft < 0.40 -4.0 < mr / bfw < -1.5 -7.0 < m3 / bfw < -2.5 -8.0 < f1 / f2 < -4.5 -0.797 ≦ m1 / f1 < -0.400 A zoom lens characterized by satisfying the following conditional expressions.

2. The zoom lens according to claim 1, wherein the rear group has at least three lens groups.

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

4. The zoom lens according to any one of claims 1 to 3, wherein the lens group LR moves to the image side after moving to the object side during zooming from the wide-angle end to the telephoto end.

5. When the focal length of the lens group LR is fr, 0.3 < fr / f1 < 2.8 A zoom lens characterized by satisfying the following conditional expressions, according to any one of claims 1 to 4.

6. When β2t is the lateral magnification of the second lens group at the telephoto end and β2w is the lateral magnification of the second lens group at the wide-angle end, 3.0 < β2t / β2w < 12.0 A zoom lens characterized by satisfying the following conditional expressions, according to any one of claims 1 to 5.

7. Further comprising a diaphragm, When dpw is the distance on the optical axis from the diaphragm at the wide-angle end to the image plane and fw is the focal length of the zoom lens at the wide-angle end, 2.0 < dpw / fw < 7.0 The zoom lens according to any one of claims 1 to 6, characterized by satisfying the following conditional expression.

8. When the distance on the optical axis from the most object-side surface of the zoom lens at the telephoto end to the image plane is Lt, 0.4 < Lt / ft < 1.2 The zoom lens according to any one of claims 1 to 7, characterized by satisfying the following conditional expression.

9. The zoom lens according to any one of claims 1 to 8, characterized in that the lens group LR is composed of a single lens.

10. When the Abbe number of the single lens is VdLR, 15.0 < VdLR < 50.0 The zoom lens according to claim 9, characterized by satisfying the following conditional expression.

11. An imaging device, comprising: the zoom lens according to any one of claims 1 to 10; and an imaging element that receives an image formed by the zoom lens.

Images