Optical system and imaging device having the same

Abstract

To provide an optical system having an excellent optical performance and a plurality of focus groups and vibration prevention groups that can be smaller and lighter.SOLUTION: The optical system includes a positive first lens group L1, a negative first focus lens group LF1, and a subsequent group R, which are sequentially arranged from an object side. The subsequent group includes: a vibration prevention group LIS with a negative bending force, the vibration prevention group moving into a direction which includes a component vertical to an optica axis when image blurring is corrected; a positive second focus lens group LF2; and a final lens group located nearest to an image side. The first lens group and the final lens group do not move at the time of focusing from infinity to minimum object distance. The first focus lens group moves to an image side and the second focus lens group moves to an object side. The lens component arranged nearest to the image side has a negative bending force. The largest value LD1 of the interval of lenses in the first lens group and the distance LD on the optical axis from the lens surface nearest to the object side to the image surface at the time of infinity focusing satisfy a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system and is suitable for digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, in-vehicle cameras, and the like. [Background technology]

[0002] In telephoto lenses, which feature multiple focusing groups that move during focusing from infinity to the closest distance, and image stabilization groups to correct image blur, there is a demand for not only good optical performance but also for miniaturization and weight reduction of the entire lens system. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-6487 [Overview of the project] [Problems that the invention aims to solve]

[0004] Patent Document 1 discloses a telephoto lens equipped with multiple focusing groups and an image stabilization group. In the telephoto lens disclosed in Patent Document 1, the lens group located closest to the object, which has the largest on-axial light beam, has a dense arrangement of lens components with large outer diameters. For this reason, it is difficult to reduce the weight of the lens group located closest to the object. In other words, the weight of the lens group located closest to the object tends to account for a high proportion of the total weight of the entire lens system, making it difficult to reduce the weight of the entire lens system.

[0005] The present invention provides an optical system equipped with multiple focusing groups and vibration damping groups that offers good optical performance while also enabling miniaturization and weight reduction. [Means for solving the problem]

[0006] An optical system as one aspect of the present invention comprises a first lens group with positive refractive power, a first focusing lens group with negative refractive power, and a rear group including multiple lens groups, arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing, and the rear group includes a vibration-damping group with negative refractive power that moves in a direction including a component perpendicular to the optical axis during image shake correction, a second focusing lens group with positive refractive power, and a final lens group located closest to the image, and during focusing from infinity to the closest, the first lens group and the final lens group remain stationary, the first focusing lens group moves toward the image side, the second focusing lens group moves toward the object side, and the lens component located closest to the image has negative refractive power. The aforementioned rear group consists of the vibration-damping lens group, the second focusing lens group, and the final lens group, arranged in order from the object side to the image side. When the maximum lens spacing in the first lens group is LD1, and the distance along the optical axis from the lens surface closest to the object to the image plane at infinity focus is LD, 0.03 <LD1 / LD<0.25 It is characterized by satisfying the following conditional expression.

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

[0008] According to the present invention, in addition to good optical performance, it is possible to provide an optical system equipped with multiple focusing groups and vibration damping groups that can be miniaturized and lightened. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view of the optical system of Example 1 when it is in focus at infinity. [Figure 2] These are aberration diagrams of the optical system of Example 1 at (a) in focus at infinity and (b) at the closest focusing distance. [Figure 3] This is a cross-sectional view of the optical system of Example 2 when it is in focus at infinity. [Figure 4] These are aberration diagrams of the optical system of Example 2 at (a) in focus at infinity and (b) at the closest focusing distance. [Figure 5]It is a cross-sectional view when the optical system of Example 3 is focused at infinity. [Figure 6] It is an aberration diagram of the optical system of Example 3 at (a) infinity focus and (b) closest focusing. [Figure 7] It is a cross-sectional view when the optical system of Example 4 is focused at infinity. [Figure 8] It is an aberration diagram of the optical system of Example 4 at (a) infinity focus and (b) closest focusing. [Figure 9] It is a cross-sectional view when the optical system of Example 5 is focused at infinity. [Figure 10] It is an aberration diagram of the optical system of Example 5 at (a) infinity focus and (b) closest focusing. [Figure 11] It is a schematic diagram of the main part of the imaging device.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the optical system of the present invention and an imaging device having the same will be described based on the accompanying drawings.

[0011] FIG. 1, FIG. 3, FIG. 5, FIG. 7, and FIG. 9 are cross-sectional views when the optical systems of Examples 1 to 5 are focused at infinity, respectively. The optical systems of each example are optical systems used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras.

[0012] In each lens cross-sectional view, the left side is the object side and the right side is the image side. The optical systems of each example are configured to have a plurality of lens groups. In this specification, a lens group is a collection of lenses that move or remain stationary integrally during focusing. That is, in the optical system of each example, the distance between adjacent lens groups changes during focusing from infinity to the closest distance. Note that a lens group may be composed of one lens or a plurality of lenses. Further, a lens group may include an aperture stop.

[0013] Also, the SP is an aperture stop. The IP is an image plane. When using the optical system of each embodiment as the imaging optical system of a digital still camera or a digital video camera, the imaging plane of a solid-state imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is arranged. When using the optical system of each embodiment as the imaging optical system of a camera for silver halide film, a photosensitive surface corresponding to the film surface is placed on the image plane IP. The GB indicates an optical block placed on the object side of the image plane IP. The arrow in the optical axis direction indicates the moving direction of the focus lens groups LF1 and LF2 during focusing from infinity to the closest distance.

[0014] Figures 2, 4, 6, 8, and 10 are aberration diagrams of the optical systems of Embodiments 1 to 5, respectively. In each aberration diagram, (a) is the aberration diagram at infinity focus, and (b) is the aberration diagram at the closest distance focus.

[0015] In the spherical aberration diagram, Fno is the F-number, indicating the amount of spherical aberration with respect to the d-line (wavelength 587.6 nm) and the g-line (wavelength 435.8 nm). In the astigmatism diagram, dS indicates the amount of astigmatism in the sagittal image plane, and dM indicates the amount of astigmatism in the meridional image plane. The distortion aberration diagram shows the amount of distortion aberration with respect to the d-line. The chromatic aberration diagram shows the amount of chromatic aberration at the g-line. ω is the imaging semi-angle (angle of view in paraxial calculation) (°).

[0016] Next, the characteristic configurations of the optical systems of each embodiment will be described.

[0017] The optical system of each embodiment consists of a first lens group L1 with positive refractive power, a first focus lens group LF1 with negative refractive power, and a rear group R including a plurality of lens groups, which are arranged in order from the object side to the image side. In the optical system of each embodiment, the interval between adjacent lens groups changes during focusing.

[0018] The rear group R includes an anti-shake group LIS with negative refractive power that moves in a direction including a component perpendicular to the optical axis during image shake correction, a second focus lens group LFz with positive refractive power, and a final lens group LR arranged on the most image side.

[0019] During focusing from infinity to the closest focus, the first lens group L1 and the final lens group LR remain stationary, while the first focusing lens group LF1 moves toward the image, and the second focusing lens group LF2 moves toward the object.

[0020] The lens component LN, located closest to the image, has negative refractive power. Note that "lens component" refers to either a single lens or a cemented lens.

[0021] By moving the first focusing lens group LF1 and the second focusing lens group LF2 during focusing, it becomes possible to correct the spherical aberration fluctuations that occur during focusing to a good level.

[0022] By giving the vibration-isolating light-intensity stimuli (LIS) group a negative refractive force, the incident light ray height to the LIS can be reduced, allowing for a smaller unit diameter for the LIS. This is advantageous for miniaturizing and lightening the entire optical system.

[0023] By giving the lens component LN, which is located closest to the image sensor, a negative refractive power, light rays can be directed obliquely onto the image sensor. This allows for a shorter back focus, making it suitable for miniaturizing the optical system.

[0024] Furthermore, the optical system of each embodiment satisfies the following condition (1).

[0025] 0.03 <LD1 / LD<0.25 ···(1) Here, LD1 is the maximum lens spacing (maximum air gap) in the first lens group L1. Lens spacing is the distance along the optical axis between two adjacent lenses. LD is the distance along the optical axis from the lens surface closest to the object to the image plane IP when the optical system is focused at infinity.

[0026] Conditional equation (1) is a conditional equation that defines the ratio of the maximum lens spacing LD1 to the distance LD in the first lens group L1, which is positioned closest to the object. If the value falls below the lower limit of conditional equation (1), the lens components constituting the first lens group L1 will be densely arranged, making it difficult to reduce the weight of the first lens group L1. If the value exceeds the upper limit of conditional equation (1), it is advantageous for reducing the weight of the first lens group L1, but it becomes difficult to position each lens component at a location with a large axial light beam, which is disadvantageous for correcting spherical aberration and axial chromatic aberration.

[0027] Furthermore, it is more preferable to set the numerical range of condition (1) to the range of condition (1a) below.

[0028] 0.038 <LD1 / LD<0.180 ···(1a) Furthermore, it is even more preferable that the numerical range of conditional expression (1) be within the range of conditional expression (1b) below.

[0029] 0.045 <LD1 / LD<0.110 ···(1b) As described above, according to each embodiment, by satisfying the above configuration and condition (1), it is possible to provide an optical system (telephoto lens) equipped with multiple focusing lens groups and image stabilization groups that offers good optical performance, as well as miniaturization and weight reduction.

[0030] Next, we will describe the configurations that are preferable to satisfy in the optical system of each embodiment.

[0031] It is preferable that the lens surface of the lens component constituting the first lens group L1 that is convex toward the object has an aspherical shape. This allows for good correction of spherical aberration occurring in the first lens group L1, which is advantageous for miniaturizing the entire optical system.

[0032] Furthermore, it is preferable that the lens component positioned closest to the object in the first lens group L1 has a positive refractive power. By converging the on-axial light beam with the lens component closest to the object, the outer diameter of the lens component closer to the image can be reduced, which is advantageous for reducing the overall weight of the optical system.

[0033] Next, we will describe the conditions that the optical systems of each embodiment should preferably satisfy. It is preferable that the optical systems of each embodiment satisfy one or more of the following conditional equations (2) to (9).

[0034] 0.2 <LD1 / BF<2.0 ···(2) 0.02 <LD1 / f<0.22 ···(3) 0.2 <fL1 / f<1.4 ···(4) -0.95 <fLN / f<-0.13 ···(5) 0.4 <fL1LF1 / f<2.8 ···(6) -0.77 <fLIS / f<-0.21 ···(7) LD / f < 1.5 ···(8) BF / f < 0.3 ···(9) Here, BF is the back focus, which is the distance along the optical axis from the lens surface closest to the image to the image plane IP when the lens is in focus at infinity (air-equivalent length). f is the focal length of the optical system. fL1 is the focal length of the first lens group L1. fLN is the focal length of the lens component LN located closest to the image in the final lens group LR. fL1LF1 is the combined focal length of the first lens group L1 and the first focus lens group LF1 when the lens is in focus at infinity. fLIS is the focal length of the image stabilization group LIS.

[0035] Conditional equation (2) is a conditional equation that defines the ratio of the maximum lens spacing LD1 in the first lens group L1, which is positioned closest to the object, to the back focus BF. If the value falls below the lower limit of conditional equation (2), it leads to an increase in the overall length of the lens, which is undesirable. If the value exceeds the upper limit of conditional equation (2), it is advantageous for miniaturizing the overall length of the lens, but it becomes difficult to correct spherical aberration and axial chromatic aberration, which is undesirable.

[0036] Conditional equation (3) is a conditional equation that defines the ratio of the maximum lens spacing LD1 in the first lens group L1, which is positioned closest to the object, to the focal length f of the optical system. If the value falls below the lower limit of conditional equation (3), it leads to an increase in the overall length of the lens, which is undesirable. If the value exceeds the upper limit of conditional equation (3), it is advantageous for miniaturizing the overall length of the lens, but it becomes difficult to correct spherical aberration and axial chromatic aberration, which is undesirable.

[0037] Conditional equation (4) is a conditional equation that defines the ratio of the focal length fL1 of the first lens group L1 to the focal length f of the optical system. If the refractive power of the first lens group L1 becomes stronger as it falls below the lower limit of conditional equation (4), it is advantageous for reducing the overall size of the lens, but it is undesirable because it becomes difficult to correct spherical aberration and axial chromatic aberration. If the refractive power of the first lens group L1 becomes weaker as it exceeds the upper limit of conditional equation (4), it leads to an increase in the overall size of the lens, which is undesirable.

[0038] Conditional equation (5) is a conditional equation that defines the ratio of the focal length fLN of the lens component LN located closest to the image to the focal length f of the optical system. If the refractive power of the lens component LN becomes too weak, falling below the lower limit of conditional equation (5), the unit diameter near the camera mount will increase, leading to an undesirable increase in the radial size of the optical system. If the refractive power of the lens component LN becomes too strong, exceeding the upper limit of conditional equation (5), shading caused by light rays entering the image sensor at an oblique angle becomes a problem, which is also undesirable.

[0039] Conditional equation (6) is a conditional equation that defines the ratio of the combined focal length fL1LF1 of the first lens group L1 and the first focusing lens group LF1 at infinity focus to the focal length f of the optical system. If the refractive power of the first lens group L1 and the first focusing lens group LF1 becomes stronger as it falls below the lower limit of conditional equation (6), it is advantageous for reducing the overall size of the lens, but it is undesirable because it becomes difficult to correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration. If the refractive power of the first lens group L1 and the first focusing lens group LF1 becomes weaker as it exceeds the upper limit of conditional equation (6), it leads to an increase in the overall size of the lens, which is undesirable.

[0040] Conditional equation (7) is a conditional equation that defines the ratio of the focal length fLIS of the image stabilization group to the focal length f of the optical system. If the refractive power of the image stabilization group LIS becomes too weak, falling below the lower limit of conditional equation (7), it becomes difficult to appropriately set the image stabilization sensitivity, leading to an increase in the overall length of the lens, which is undesirable. If the refractive power of the image stabilization group LIS becomes too strong, exceeding the upper limit of conditional equation (7), it becomes difficult to appropriately set the image stabilization sensitivity, resulting in a decrease in optical performance during image stabilization, which is undesirable.

[0041] Conditional equation (8) is a conditional equation that defines the ratio of the distance LD on the optical axis from the lens surface closest to the object to the image plane IP when the lens is in focus at infinity to the focal length f of the optical system. Since the optical system in each embodiment is preferably a so-called telephoto lens, it satisfies conditional equation (8).

[0042] Conditional equation (9) is a conditional equation that defines the ratio of the back focus BF to the focal length f of the optical system. Exceeding the upper limit of conditional equation (9) leads to an increase in the overall length of the lens, which is undesirable.

[0043] Furthermore, it is more preferable that the numerical ranges of conditional expressions (2) to (9) be within the ranges of the following conditional expressions (2a) to (9a).

[0044] 0.28 <LD1 / BF<1.45 ···(2a) 0.03 <LD1 / f<0.17 ···(3a) 0.30 <fL1 / f<1.05 ···(4a) -0.80 <fLN / f<-0.16 ···(5a) 0.58 <fL1LF1 / f<2.10 ···(6a) -0.66 <fLIS / f<-0.26 ···(7a) LD / f < 1.28 ···(8a) BF / f < 0.23 ···(9a) Furthermore, it is even more preferable that the numerical ranges of conditional expressions (2) to (9) be within the ranges of the following conditional expressions (2b) to (9b).

[0045] 0.35 <LD1 / BF<0.90 ···(2b) 0.045 <LD1 / f<0.110 ···(3b) 0.4 <fL1 / f<0.7 ···(4b) -0.65 <fLN / f<-0.19 ···(5b) 0.75 <fL1LF1 / f<1.40 ···(6b) -0.55 <fLIS / f<-0.30 ···(7b) LD / f < 1.05 ···(8b) BF / f < 0.15 ···(9b) Next, the optical systems of each embodiment will be described in detail.

[0046] The optical system of Example 1 consists of a first lens group L1, a first focusing lens group LF1, and a rear lens group R, arranged in order from the object side to the image side. The rear lens group R consists of a lens group that is an image stabilization group LIS, a second focusing lens group LF2, and a final lens group LR, arranged in order from the object side to the image side. The aperture diaphragm SP is positioned between the first focusing lens group LF1 and the lens group that is an image stabilization group LIS. The optical block GB is positioned on the object side of the image plane IP.

[0047] The optical system of Example 2 consists of a first lens group L1, a first focusing lens group LF1, and a rear lens group R, arranged in order from the object side to the image side. The rear lens group R consists of a lens group comprising a lens and an image stabilization group (partial group) LIS, a second focusing lens group LF2, and a final lens group LR, arranged in order from the object side to the image side. For the lens group comprising a lens and an image stabilization group (partial group) LIS, the lens and the image stabilization group LIS are considered together as a single lens group. The aperture diaphragm SP is located between the first lens group L1 and the first focusing lens group LF1. The optical block GB is located on the object side of the image plane IP.

[0048] The optical system of Example 3 consists of a first lens group L1, a first focusing lens group LF1, and a rear group R, arranged in order from the object side to the image side. The rear group R consists of a lens group comprising a lens and an image stabilization group (partial group) LIS, a second focusing lens group LF2, and a final lens group LR, arranged in order from the object side to the image side. The aperture diaphragm SP is positioned between the first focusing lens group LF1 and the lens group comprising the image stabilization group LIS. The optical block GB is positioned on the object side of the image plane IP.

[0049] The optical system of Example 4 consists of a first lens group L1, a first focusing lens group LF1, and a rear lens group R, arranged in order from the object side to the image side. The rear lens group R consists of a second focusing lens group LF2 and a final lens group LR, arranged in order from the object side to the image side. The vibration isolation group (partial group) LIS is located on the object side of the final lens group LR. The aperture diaphragm SP is located between the first focusing lens group LF1 and the second focusing lens group LF2. The optical block GB is located on the object side of the image plane IP.

[0050] The optical system of Example 5 consists of a first lens group L1, a first focusing lens group LF1, and a rear group R, arranged in order from the object side to the image side. The rear group R consists of a lens group comprising a lens and an image stabilization group LIS (partial group), a second focusing lens group LF2, and a final lens group LR, arranged in order from the object side to the image side. The aperture diaphragm SP is positioned between the first focusing lens group LF1 and the lens group comprising the image stabilization group LIS. The optical block GB is positioned on the object side of the image plane IP.

[0051] The numerical values ​​corresponding to Examples 1 to 5 are shown below.

[0052] 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 m-th surface and the (m + 1)-th surface. Here, m is the surface number counted from the light incident side. Also, 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 for 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 the Fraunhofer lines are Nd, NF, and NC, νd = (Nd - 1) / (NF - NC) is expressed as.

[0053] Note that in each numerical example, d, focal length (mm), F-number, and semi-aperture angle (°) are all values when the optical system of each example is focused on an infinitely distant object. "Back focus BF" is the distance on the optical axis from the final surface of the lens (the lens surface closest to the image side) to the paraxial image plane, expressed in terms of the air-equivalent length. "Overall lens length" is the length obtained by adding the back focus to the distance on the optical axis from the frontmost surface of the optical system (the lens surface closest to the object side) to the final surface. "Lens group" includes not only cases composed of multiple lenses but also cases composed of a single lens.

[0054] Also, when the optical surface is an aspherical surface, a * sign is attached to the right side of the surface number. The aspherical shape is expressed as follows 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 radius of curvature, k is the conic constant, and A4, A6, A8, A10, A12 are the aspherical coefficients of each order: x = (h 2 / R) / [1 + {1 - (1 + k)(h / R) 2}^ 1 / 2 + A4×h 4 + A6×h 6 + A8×h 8 + A10×h 10 + A12×h 12 Note that "e±XX" in each aspherical coefficient means "×10± XX ".

[0055] (Numerical Example 1) Unit: mm Surface data Face number rd nd νd 1 123.084 8.15 1.48749 70.2 2 323.360 2.91 3 80.070 12.53 1.43875 94.7 4 247.663 20.00 5 60.411 14.30 1.49700 81.5 6 -1649.369 2.11 1.72047 34.7 7 149.836 0.40 8* 52.593 1.56 1.85135 40.1 9 32.389 14.66 1.49700 81.5 10 162.354 (variable) 11 96.412 3.56 1.98612 16.5 12 207.658 1.32 1.67300 38.3 13 31.544 (variable) 14 (aperture) ∞ 3.00 15 207.006 1.20 2.00069 25.5 16 49.781 3.00 17 -77.191 1.58 1.83400 37.2 18 32.647 6.25 1.85478 24.8 19 -98.165 (variable) 20 56.482 9.66 1.66565 35.6 21 -38.983 2.48 1.98612 16.5 22 -63.502 (variable) 23 -342.856 4.81 1.84666 23.8 24 -49.585 2.08 25 -42.437 2.03 2.00100 29.1 26 410.149 20.56 27 ∞ 1.50 1.51633 64.1 28 ∞ 0.80 Image plane ∞ Aspherical data Side 8 K= 0.00000e+00 A4=-2.85989e-07 A6=-9.93124e-11 A8=-4.64036e-14 Various data Focal length 195.00 F-number 2.05 Half-angle (°): 6.33 Image height 21.64 Lens length: 184.49 BF 22.35 Infinity Closest d10 1.68 6.36 d13 22.38 6.76 d19 11.44 2.28 d22 9.06 18.21 (Numerical Example 2) Unit: mm Surface data Face number rd nd νd 1 91.943 11.24 1.48749 70.2 2 297.714 0.40 3 72.670 12.76 1.43875 94.7 4 203.740 13.00 5 67.486 11.98 1.49700 81.5 6 533.244 2.15 1.73037 32.2 7 101.441 5.59 8* 77.137 1.64 1.85400 40.4 9 35.624 13.58 1.49700 81.5 10 515.880 2.60 11 (aperture) ∞ (variable) 12 142.276 3.08 1.98612 16.5 13 -908.537 1.25 1.66565 35.6 14 32.748 (Variable) 15 31.800 3.36 1.48749 70.2 16 47.169 4.46 17 243.622 1.08 2.00069 25.5 18 51.478 3.92 19 -99.841 1.12 1.76200 40.1 20 37.330 7.09 1.85478 24.8 21 -128.890 (variable) 22 68.194 10.88 1.74951 35.3 23 -45.139 2.04 1.92286 20.9 24 -83.371 (variable) 25 1168.798 7.36 1.69895 30.1 26 -33.396 1.15 2.00330 28.3 27 148.750 21.34 28 ∞ 1.50 1.51633 64.1 29 ∞ 0.80 Image plane ∞ Aspherical data Side 8 K= 0.00000e+00 A4=-5.20255e-07 A6=-1.03596e-10 A8= 1.95038e-14 Various data Focal length 194.99 F-number 2.05 Half-angle (°): 6.33 Image height 21.64 Lens length: 184.49 BF 23.12 Infinity Closest d11 2.99 10.74 d14 11.03 3.28 d21 8.55 4.35 d24 17.06 21.25 (Numerical Example 3) Unit: mm Surface data Face number rd nd νd 1 100.457 9.59 1.48749 70.2 2 281.439 20.00 3 70.214 14.75 1.43875 94.7 4 451.777 0.39 5 73.098 13.19 1.49700 81.5 6 -702.915 2.01 1.72047 34.7 7 123.640 1.15 8* 58.617 1.31 1.85135 40.1 9 37.178 13.38 1.49700 81.5 10 169.033 (variable) 11 167.206 3.11 1.98612 16.5 12 -712.610 1.27 1.67300 38.3 13 33.287 (Variable) 14 (aperture) ∞ 3.00 15 108.726 1.54 1.80400 46.5 16 163.246 3.00 17 116.157 1.01 2.00069 25.5 18 42.246 2.98 19 -115.506 1.04 1.77250 49.6 20 34.888 4.28 1.85478 24.8 21 -301.638 (variable) 22 55.021 8.35 1.67003 47.2 23 -42.643 1.01 1.92286 20.9 24 -71.653 (variable) 25 -642.856 4.34 1.78470 26.3 26 -49.683 1.95 27 -43.574 1.15 2.00100 29.1 28 435.786 22.92 29 ∞ 1.50 1.51633 64.1 30 ∞ 0.80 Image plane ∞ Aspherical data Side 8 K= 0.00000e+00 A4=-2.96320e-07 A6=-9.63532e-11 A8=-3.88811e-14 Various data Focal length 195.00 F-number 2.05 Half-angle (°): 6.33 Image height 21.64 Lens length: 184.49 BF 24.71 Infinity Closest d10 6.70 11.58 d13 20.39 15.51 d21 10.06 3.99 d24 8.84 14.90 (Numerical Example 4) Unit: mm Surface data Face number rd nd νd 1 83.316 18.17 1.43875 94.7 2 -2642.520 10.01 3 80.308 16.82 1.49700 81.5 4 -296.610 3.02 1.66565 35.6 5 572.828 5.90 6* 197.928 2.50 1.59551 39.2 7 49.435 9.51 1.49700 81.5 8 123.578 (variable) 9 3568.030 3.67 1.94594 18.0 10 -204.653 2.02 1.58144 40.8 11 58.665 (Variable) 12 (aperture) ∞ (variable) 13 293.536 4.14 1.95375 32.3 14 -100.174 1.16 1.92286 20.9 15 -238.870 (variable) 16 119.709 1.09 2.00100 29.1 17 51.343 4.02 18 -118.840 1.51 1.77250 49.6 19 40.012 6.46 1.77047 29.7 20 -110.022 3.00 21 49.199 6.02 1.49700 81.5 22 -331.966 23.48 23 -175.538 2.06 1.92286 20.9 24 187.908 23.80 25 ∞ 1.50 1.51633 64.1 26 ∞ 0.80 Image plane ∞ Aspherical data Side 6 K= 0.00000e+00 A4=-5.11837e-07 A6=-3.31746e-11 A8= 1.23353e-14 Various data Focal length 195.00 F-number 2.05 Half-angle (°): 6.33 Image height 21.64 Lens length: 199.49 BF 25.59 Infinity Closest d 8 5.74 14.83 d11 33.06 23.99 d12 8.52 1.99 d15 2.00 8.51 (Numerical Example 5) Unit: mm Surface data Face number rd nd νd 1 239.899 4.59 1.48749 70.2 2 694.025 0.40 3 123.175 11.82 1.43875 94.7 4 -1106.622 12.50 5 87.366 15.20 1.49700 81.5 6 -246.391 2.44 1.66565 35.6 7 175.616 0.40 8 49.068 11.58 1.49700 81.5 9 119.236 1.46 10* 61.868 2.62 1.85400 40.4 11 39.909 (variable) 12 1152.649 4.13 1.94594 18.0 13 -196.928 2.08 1.59551 39.2 14 53.821 (Variable) 15 (aperture) ∞ 2.49 16 107.686 2.19 1.83481 42.7 17 716.084 2.99 18 74.046 1.03 2.00069 25.5 19 40.531 3.89 20 -353.315 1.07 1.80100 35.0 21 34.342 4.84 1.92286 20.9 22 249.854 (variable) 23 59.700 7.66 1.61772 49.8 24 -55.120 2.03 1.92286 20.9 25 -89.831 (variable) 26 -104.567 1.16 1.92286 20.9 27 -1508.744 22.19 28 ∞ 1.50 1.51633 64.1 29 ∞ 0.80 Image plane ∞ Aspherical data Side 10 K= 0.00000e+00 A4=-2.13929e-07 A6=-1.67464e-11 A8=-7.12394e-14 A10 = 2.72845e-17 Various data Focal length 195.00 F-number 2.05 Half-angle (°): 6.33 Image height 21.64 Lens length: 194.49 BF 23.98 Infinity Closest d11 13.42 22.37 d14 26.23 17.28 d22 7.49 13.48 d25 24.79 18.79 The various values ​​in each numerical example are summarized in Table 1 below.

[0056] [Table 1]

[0057] [Imaging device] Next, an embodiment of a digital still camera (imaging device) 1 using the optical system of the present invention as an imaging optical system will be described with reference to Figure 11. In Figure 11, 13 is the camera body, and 11 is the imaging optical system composed of any of the optical systems described in Examples 1 to 5. 12 is a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor, which is built into the camera body and receives the optical image formed by the imaging optical system 11 and converts it into photoelectric energy. The camera body 13 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

[0058] By applying the optical system of the present invention to an imaging device such as a digital still camera, an imaging device with a compact lens can be obtained.

[0059] Although preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various combinations, modifications, and changes are possible within the scope of its gist. [Explanation of symbols]

[0060] L1 First lens group LF1 First Focusing Lens Group R rear group LF2 Second Focusing Lens Group LR Final Lens Group LIS vibration isolation group

Claims

1. An optical system consisting of a first lens group with positive refractive power, a first focusing lens group with negative refractive power, and a rear group containing multiple lens groups, arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing. The aforementioned rear group includes a negative refractive force vibration damping group that moves in a direction containing a component perpendicular to the optical axis during image shake correction, a second focusing lens group with positive refractive force, and a final lens group positioned closest to the image. During focusing from infinity to the closest focusing point, the first lens group and the final lens group remain stationary, the first focusing lens group moves toward the image, and the second focusing lens group moves toward the object. The lens component positioned closest to the image has a negative refractive power. The aforementioned rear group consists of the vibration-damping lens group, the second focusing lens group, and the final lens group, arranged in order from the object side to the image side. When the maximum lens spacing in the first lens group is LD1, and LD is the distance along the optical axis from the lens surface closest to the object to the image plane when in focus at infinity, 0.03<LD1 / LD<0.25 An optical system characterized by satisfying the following conditional equation.

2. When BF is the distance along the optical axis from the lens surface closest to the image plane to the image plane at infinity focus, 0.2<LD1 / BF<2.0 The optical system according to claim 1, characterized in that it satisfies the following condition.

3. When the focal length of the optical system is f, 0.02<LD1 / f<0.22 The optical system according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. When the focal length of the first lens group is fL1 and the focal length of the optical system is f, 0.2<fL1 / f<1.4 The optical system according to any one of claims 1 to 3, characterized in that it satisfies the following conditional expression.

5. When the focal length of the aforementioned lens component is fLN, -0.95<fLN / f<-0.13 The optical system according to any one of claims 1 to 4, characterized in that it satisfies the following conditional expression.

6. When the combined focal length of the first lens group and the first focus lens group at infinity focus is fL1LF1, and the focal length of the optical system is f, 0.4<fL1LF1 / f<2.8 The optical system according to any one of claims 1 to 5, characterized in that it satisfies the following conditional expression.

7. When the focal length of the vibration isolation group is fLIS and the focal length of the optical system is f, -0.77<fLIS / f<-0.21 The optical system according to any one of claims 1 to 6, characterized in that it satisfies the following conditional expression.

8. When the focal length of the optical system is f, LD / f < 1.5 The optical system according to any one of claims 1 to 7, characterized in that it satisfies the following conditional expression.

9. When the optical system is in focus at infinity, let BF be the distance along the optical axis from the lens surface closest to the image to the image plane, and let f be the focal length of the optical system. BF / f < 0.3 The optical system according to any one of claims 1 to 8, characterized in that it satisfies the following conditional expression.

10. The optical system according to any one of claims 1 to 9, characterized in that the lens surface of the lens component constituting the first lens group that is convex toward the object has an aspherical shape.

11. The optical system according to any one of claims 1 to 10, characterized in that the lens component positioned closest to the object in the first lens group has a positive refractive power.

12. The optical system according to any one of claims 1 to 11, characterized in that the rear group comprises a lens group having lenses and the vibration damping group, the second focusing lens group, and the final lens group, arranged in order from the object side to the image side.

13. An optical system comprising a first lens group with positive refractive power, a first focusing lens group with negative refractive power, and a rear group including a plurality of lens groups, arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing, The aforementioned rear group includes a negative refractive force vibration damping group that moves in a direction containing a component perpendicular to the optical axis during image shake correction, a second focusing lens group with positive refractive force, and a final lens group positioned closest to the image. During focusing from infinity to the closest focusing point, the first lens group and the final lens group remain stationary, the first focusing lens group moves toward the image, and the second focusing lens group moves toward the object. The lens component positioned closest to the image has a negative refractive power. The aforementioned rear group consists of a lens group comprising lenses and the vibration damping group, the second focusing lens group, and the final lens group, arranged in order from the object side to the image side. When the maximum lens spacing in the first lens group is LD1, and LD is the distance along the optical axis from the lens surface closest to the object to the image plane when in focus at infinity, 0.03<LD1 / LD<0.25 An optical system characterized by satisfying the following conditional equation.

14. The optical system according to any one of claims 1 to 11, characterized in that the rear group consists of the second focusing lens group and the final lens group, arranged in order from the object side to the image side, and the vibration isolation group is positioned closest to the object side of the final lens group.

15. An imaging device characterized by having an optical system according to any one of claims 1 to 14 and an image sensor that receives an image formed by the optical system.

Images