Zoom lens and imaging 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 including, 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 multiple other lens groups. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-049445 A [Patent Document 2] JP 2018-146739 A [Patent Document 3] JP 2019-20679 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the zoom lenses disclosed in Patent Documents 1 to 3, in order to realize high magnification, it is effective to increase the amount of movement of the lens groups constituting the zoom lens or to strengthen the power of the lens groups. However, if the amount of movement of the lens groups is increased, the mechanism becomes complicated and the zoom lens becomes large. Also, if the power of the lens groups is strengthened, the aberration fluctuation during zooming becomes large, making it difficult to achieve high performance.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a zoom lens and an image pickup apparatus that are small in size, have a high magnification, and have excellent optical characteristics. [Means for solving the problem]

[0006] A zoom lens according to one aspect of the present invention comprises, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a rear group including a plurality of lens groups, wherein the distance between adjacent lens groups changes during zooming, the third lens group has a cemented lens, and a focal length f1 of the first lens group, a focal length ft of the zoom lens at a telephoto end, an amount of movement mr 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, a distance bfw on the optical axis from the surface closest to the image side of the lens group LR at the wide-angle end to the image plane, and an amount of movement m3 of the third lens group during zooming from the wide-angle end to the telephoto end satisfy predetermined conditional expressions.

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

[0008] According to the present invention, it is possible to provide a zoom lens and an image pickup apparatus that are small in size, have a high magnification, and have excellent optical characteristics. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a zoom lens according to a first embodiment. [Diagram 2] 5A to 5C are aberration diagrams of the zoom lens at the wide-angle end, at a middle zoom position, and at the telephoto end in the first embodiment. [Diagram 3] FIG. 11 is a cross-sectional view of a zoom lens according to a second embodiment. [Figure 4] 8A to 8C are aberration diagrams of the zoom lens at the wide-angle end, at a middle zoom position, and at the telephoto end in Example 2. [Diagram 5] FIG. 11 is a cross-sectional view of a zoom lens according to a third embodiment. [Figure 6] 11A to 11C are aberration diagrams of the zoom lens at the wide-angle end, at a middle zoom position, and at the telephoto end in Example 3. [Figure 7] FIG. 11 is a cross-sectional view of a zoom lens according to a fourth embodiment. [Figure 8] 11A to 11C are aberration diagrams of the zoom lens at the wide-angle end, at a middle zoom position, and at the telephoto end in Example 4. [Figure 9] FIG. 13 is a cross-sectional view of a zoom lens according to a fifth embodiment. [Figure 10] 13A to 13C are aberration diagrams of the zoom lens at the wide-angle end, at a middle zoom position, and at the telephoto end in Example 5. [Figure 11] FIG. 2 is a schematic diagram of an image pickup apparatus including the zoom lens of each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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, 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 embodiment is configured to have multiple 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 embodiment, the lens group is a group of lenses that move or stand still as a whole during zooming. That is, in the zoom lens L0 of each embodiment, the distance between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Note that the lens group may be composed of one lens or multiple lenses. The lens group may also include an aperture stop.

[0013] 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. IP is an image plane, and 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, an imaging surface of an imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is disposed thereon. When the zoom lens L0 of each embodiment is used as an imaging optical system of a silver halide film camera, a photosensitive surface corresponding to a film surface is disposed on the image plane IP. In each cross-sectional view, the solid arrows show a schematic representation of the movement locus of each lens group when zooming from the wide-angle end to the telephoto end at the time of focusing on infinity. 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 in which it can move mechanically on 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 shows the amount of astigmatism in the sagittal image plane, and ΔM shows the amount of astigmatism in the meridional image plane. In the distortion aberration diagram, the amount of distortion aberration 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, a zoom lens is known that is composed of 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 this order from the object side to the image side. In such a zoom lens, if the power of the first lens group L1 is increased, it becomes easy to achieve a high magnification, but the aberration fluctuation during zooming and the chromatic aberration of magnification at the telephoto end become large, making it difficult to achieve high performance. In addition, if the movement amount of the first lens group L1 is increased, it becomes easy to achieve a high magnification, but the mechanical mechanism becomes complicated and the size increases. Therefore, in order to achieve both high magnification and compactness of the zoom lens and high optical performance, it is important to appropriately set the power of the first lens group L1. In addition, it is effective to appropriately set the configuration and movement amount of the subsequent lens groups so as to cancel various aberrations generated in the first lens group L1.

[0016] The zoom lens L0 of each embodiment has, in order from the object side to the image side, 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 multiple lens groups. By arranging multiple lens groups on the image side of the third lens group L3 and changing the spacing between adjacent lens groups during zooming, it is easy to suppress aberration fluctuation during zooming and achieve high performance. In each embodiment, the lens group 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 at the telephoto end. mr is the amount of movement 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, and the amount of movement from the object side to the image side is taken as positive. bfw is the distance on the optical axis (the distance in the direction along the optical axis OA) from the surface closest to the image side of the lens group LR arranged closest to the image side in the rear group at the wide-angle end to the image surface IP. m3 is the amount of movement of the third lens group L3 during zooming from the wide-angle end to the telephoto end, and the amount of movement from the object side to the image side is taken as positive.

[0019] Conditional formula (1) specifies the ratio between the focal length f1 of the first lens group L1 and the focal length ft of the entire zoom lens L0 at the telephoto end. If the upper limit of conditional formula (1) is exceeded, the focal length f1 of the first lens group L1 becomes large, which is undesirable as the zoom lens L0 becomes large. On the other hand, if the lower limit of conditional formula (1) is exceeded, the focal length f1 of the first lens group L1 becomes small, which increases the aberration fluctuations generated in the first lens group L1, which is undesirable as it becomes difficult to achieve high image quality.

[0020] Conditional formula (2) specifies the relationship between the movement amount of the lens group LR and the back focus. The ray height can be changed by changing the distance from the lens group LR to the image plane IP during zooming. Therefore, by appropriately setting the relationship between the movement amount during zooming of the lens group LR arranged on the most image side and the back focus at the wide-angle end, it becomes easy to suppress the aberration fluctuation generated in the first lens group L1. If the lower limit of conditional formula (2) is not satisfied, 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, which is undesirable because the aberration correction during zooming becomes excessive. On the other hand, if the upper limit of conditional formula (2) is exceeded, 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, so 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, which is undesirable because it is difficult to reduce the size.

[0021] Conditional formula (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 formula (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 formula (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 of 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 group L3. This makes it easy to reduce the front lens diameter. In addition, it is preferable that the first lens group L1 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 aberrations occurring 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, it is preferable that the lens group LR is composed of a single lens. This makes it easy to reduce the weight of the lens group 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 group LR, and f2 is the focal length of the second lens group L2. m1 is the amount of movement of the first lens group L1 during zooming from the wide-angle end to the telephoto end, and the amount of movement from the object side to the image side is taken as 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 focal length of the entire system of the zoom lens 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 group LR.

[0027] Conditional formula (4) specifies the ratio between the focal length fr of the lens group LR and the focal length f1 of the first lens group L1. The lens group LR has a positive refractive power and has a symmetrical power arrangement with respect to the aperture stop SP, which facilitates aberration correction. In addition, 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 aberration. If the upper limit of conditional formula (4) is exceeded, the focal length fr of the lens group LR becomes large, the aberration correction effect becomes insufficient, and it becomes difficult to reduce various aberrations, particularly lateral chromatic aberration and distortion aberration. On the other hand, if the lower limit of conditional formula (4) is exceeded, 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, which is undesirable. Furthermore, it is preferable that the lens group LR moves along a locus that is convex toward the object side when zooming from the wide-angle end to the telephoto end (moves toward the object side and then toward the image side). This makes it easy to maximize the aberration correction effect of the lens group LR. Here, the locus that is convex toward the object side refers to a locus that moves toward the object side from the wide-angle end to the intermediate zoom position when zooming from the wide-angle end to the telephoto end, with the paraxial image plane position as the reference, and moves toward the image side from the intermediate zoom position to the telephoto end.

[0028] Conditional formula (5) specifies 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 setting these relationships appropriately, it is easy to suppress the front lens diameter and shorten the overall length. If the upper limit of conditional formula (5) is exceeded, 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 closest to the object, so the front lens diameter becomes large, which is undesirable. On the other hand, if the lower limit of conditional formula (5) is exceeded, the focal length f1 of the first lens group L1 becomes large, and the absolute value of the focal length f2 of the second lens group L2 becomes small, which results in a large amount of movement of the first lens group L1 required for zooming, which is undesirable because it becomes large.

[0029] Conditional formula (6) specifies the relationship between the movement amount m1 and focal length f1 of the first lens group L1. By appropriately setting these relationships, it becomes easy to achieve high zoom ratios and compact size. If the upper limit of conditional formula (6) is exceeded, 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, which is not preferable. On the other hand, if the lower limit of conditional formula (6) is exceeded, 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, which is not preferable, making it difficult to achieve high zoom ratios.

[0030] Conditional formula (7) specifies the relationship between the lateral magnifications of the second lens group 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. If the upper limit of conditional formula (7) is exceeded, the absolute value of the lateral magnification at the telephoto end becomes large, or the absolute value of the lateral magnification at the wide-angle end becomes small, and the change in lateral magnification becomes too large. This makes it difficult to correct various aberrations, and in particular, it is difficult to suppress the fluctuations of spherical aberration and astigmatism, which is undesirable. On the other hand, if the lower limit of conditional formula (7) is exceeded, the absolute value of the lateral magnification at the telephoto end becomes small, or the absolute value of the lateral magnification at the wide-angle end becomes small, and the change in lateral magnification becomes too small. This makes it difficult to achieve high zoom ratios, which is undesirable.

[0031] Conditional formula (8) specifies the relationship between the positions of the aperture stop SP and the image plane IP at the wide-angle end. Because the off-axis ray angle is large at the wide-angle end, appropriately setting the position of the aperture stop SP is important for reducing the front lens diameter and the rear lens diameter. 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 rear lens diameter becomes large, and the zoom lens 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 front lens diameter becomes large, and the zoom lens 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. When 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 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, when the Abbe number becomes small falling below the lower limit of conditional expression (10), 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 embodiment will be described in detail.

[0037] As shown in FIG. 1, FIG. 3, and FIG. 7, the zoom lens L0 of the first, second, and fourth embodiments 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 this order from the object side to the image side. The zoom lens L0 of the first embodiment has 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 closer to the image side than 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 distance between the third lens group L3 and the fourth lens group L4, it is possible to suppress fluctuations in astigmatism in particular. By changing the distance between the fourth lens group L4 and the fifth lens group L5, it is possible to suppress fluctuations in coma in particular. By changing the distance between the fifth lens group L5 and the sixth lens group L6, it is possible to suppress fluctuations in distortion in particular. By changing the distance between the sixth lens group L6 and the seventh lens group L7, it is possible to suppress fluctuations in lateral chromatic aberration in particular. By changing the distances between multiple lens groups, various aberrations can be favorably corrected throughout the entire zoom range.

[0038] As shown in FIG. 3, the zoom lens L0 of the third embodiment 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 the third embodiment 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 the third embodiment, 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 the adjacent lens groups changes. By changing the interval between the third lens group L3 and the fourth lens group L4, it is possible to suppress the fluctuation of astigmatism in particular. By changing the interval between the fourth lens group L4 and the fifth lens group L5, it is possible to suppress the fluctuation of spherical aberration in particular. By changing the distance between the fifth lens group L5 and the sixth lens group L6, it is possible to suppress fluctuations in coma aberration in particular. By changing the distance between the sixth lens group L6 and the seventh lens group L7, it is possible to suppress fluctuations in distortion in particular. By changing the distance between the seventh lens group L7 and the eighth lens group L8, it is possible to suppress fluctuations in lateral chromatic aberration in particular. By changing the distances between multiple lens groups, it is possible to improve the 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 during zooming from the wide-angle end to the telephoto end. This makes it possible to simplify the mechanical structure.

[0039] As shown in FIG. 9, the zoom lens L0 of the fifth embodiment 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 this order from the object side to the image side. The zoom lens L0 of the fifth embodiment also 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 the fifth embodiment, 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 the adjacent lens groups changes. By changing the interval between the third lens group L3 and the fourth lens group L4, it is possible to suppress the fluctuation of coma aberration in particular. By changing the interval between the fourth lens group L4 and the fifth lens group L5, it is possible to suppress the fluctuation of distortion aberration 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 the 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 changing the intervals between the multiple lens groups, various aberrations are corrected well throughout the 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 are corrected well. The configuration of the multiple 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 the first embodiment together, the mechanical mechanism can be simplified. In addition, by dividing the third lens group L3 of the first embodiment 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 lens L0 of the first to fifth embodiments, 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 moving the part to be moved for image blur correction to the whole or part of the third lens group L3 or the fourth lens group L4, which has a relatively small diameter, it is possible to configure a compact actuator for driving the zoom lens L0 and to reduce the size of the lens device including the zoom lens L0.

[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. In addition, nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. Note that the Abbe number νd 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 surface expressed in 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) of the zoom lens to the final surface plus the back focus. The lens group is not limited to being composed of multiple lenses, but also includes being composed of one lens. In addition, if the optical surface is aspheric, a sign * is added to the right of the surface number. The aspheric shape is given by the following formula, where X is the displacement from the surface apex 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 aspheric coefficients.

[0044]

number

[0045] For each aspheric coefficient, "ex" is "10 -x " 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 calculated 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] In addition, the distance d between each optical surface is variable, and changes during zooming, and the surface distance corresponding to the focal length is shown in a separate table. In addition, 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-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-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 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-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 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 5 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-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-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 (imaging device 10) using the zoom lens L0 of each embodiment as an imaging optical system will be described with reference to Fig. 11. Fig. 11 is a schematic diagram of an imaging 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 a CMOS sensor that is built into the camera body 13 and receives and photoelectrically converts an 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 may be a so-called mirrorless camera having no 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, it is possible to obtain an imaging device having high optical performance. The zoom lens of each embodiment can also be applied to a video camera in the same manner.

[0052] According to each embodiment, it is possible to provide a zoom lens and an imaging device that are small in size, 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, in order from an object side to an 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, in which the spacing between adjacent lens groups changes during zooming, the third lens group includes a cemented lens, 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 among 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, and m3 be the movement amount of the third 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 A zoom lens characterized by satisfying the following conditional expressions:

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

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

4. 4. The zoom lens according to claim 1, wherein the lens group LR moves toward the object side and then moves toward the image 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 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. When the focal length of the second lens group is f2, -9.0<f1 / f2<-3.5 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end is m1, -1.2<m1 / f1<-0.4 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. 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 8. The zoom lens according to claim 1, wherein the following condition is satisfied:

9. 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 9. The zoom lens according to claim 1, wherein the following condition is satisfied:

10. Let Lt be 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. 0.4<Lt / ft<1.2 10. The zoom lens according to claim 1, wherein the following condition is satisfied:

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

12. When the Abbe number of the single lens is VdLR, 15.0<VdLR<50.0 12. The zoom lens according to claim 11, which satisfies the following condition:

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

Images