Optical system and imaging apparatus having the same

Abstract

To provide an optical system that is compact and has high optical performance despite its long focal distance and large aperture ratio, and can achieve acceleration of autofocus, and an imaging apparatus having the same.SOLUTION: An optical system is an optical system composed of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive or negative refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, which are arranged in order from an object side to an image side. In focusing from infinity to the closest range, the second lens group and the fourth lens group are movable, and the first lens group, the third lens group, and the fifth lens group are immovable. A distance on an optical axis from a lens surface on the most image side to an image surface, a focal distance of the optical system in focusing at infinity, a focal distance of the third lens group, and a focal distance of the fifth lens group are appropriately set respectively.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, there has been a demand for imaging devices that have a long focal length and a large aperture ratio, yet are compact and have high optical performance, and that can achieve high-speed autofocus.To achieve high-speed autofocus while being compact and having high optical performance, an inner focus optical system in which some lenses are moved during focusing is known (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-142601 [Patent Document 2] Japanese Patent Application Publication No. 2020-60661 Summary of the Invention [Problem to be solved by the invention]

[0004] However, optical systems with long focal lengths and large aperture ratios tend to have difficulty correcting various aberrations. In particular, when the focus lens group is made lighter to achieve faster autofocusing, it becomes difficult to suppress aberration fluctuations when focusing from infinity to the closest distance.

[0005] The present invention aims to provide an optical system that has a long focal length and a large aperture ratio, yet is small and has high optical performance, and is capable of achieving high-speed autofocus, and an imaging device having the same. [Means for solving the problem]

[0006] An optical system according to one aspect of the present invention is an optical system comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive or negative refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, wherein, during focusing from infinity to the closest distance, the second lens group and the fourth lens group move, while the first lens group, the third lens group, and the fifth lens group do not move, and when the distance on the optical axis from the lens surface closest to the image side of the optical system to the image plane is sk, the focal length of the optical system when focused at infinity is f, the focal length of the third lens group is f3, and the focal length of the fifth lens group is f5, then: 0.10 <sk / f<0.25 0.010 <f / |f3|<0.500 -3.50 <f / f5<-0.80 The present invention is characterized in that the following conditional expression is satisfied: [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an optical system that has a long focal length and a large aperture ratio, yet is small in size and has high optical performance, and is capable of achieving high-speed autofocus, and an imaging device having the same. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view of the optical system of Example 1 when focused at infinity. [Figure 2] 1A and 1B are longitudinal aberration diagrams of the optical system of Example 1 when focused at infinity and when focused at a close distance (−700 mm). [Figure 3] FIG. 10 is a cross-sectional view of the optical system of Example 2 when focused at infinity. [Figure 4] 10A and 10B are longitudinal aberration diagrams of the optical system of Example 2 when focused at infinity and when focused at a close distance (-700 mm). [Figure 5] FIG. 10 is a cross-sectional view of the optical system of Example 3 when focused at infinity. [Figure 6] 10A and 10B are longitudinal aberration diagrams of the optical system of Example 3 when focused at infinity and when focused at a close distance (-700 mm). [Figure 7] FIG. 10 is a cross-sectional view of the optical system of Example 4 when focused at infinity. [Figure 8] 10A and 10B are longitudinal aberration diagrams of the optical system of Example 4 when focused at infinity and when focused at a close distance (-1200 mm). [Figure 9] FIG. 10 is a cross-sectional view of the optical system of Example 5 when focused at infinity. [Figure 10] 10A and 10B are longitudinal aberration diagrams of the optical system of Example 5 when focused at infinity and when focused at a close distance (-700 mm). [Figure 11] FIG. 1 is a schematic diagram of an imaging device. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0010] 1, 3, 5, 7, and 9 are cross-sectional views of the optical system L0 of Examples 1 to 5 when focused at infinity. The optical system 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, surveillance cameras, and vehicle-mounted cameras.

[0011] In each cross-sectional view, the left side is the object side and the right side is the image side. The optical system L0 in each embodiment is configured with multiple lens groups. In this specification, a lens group refers to a group of lenses that move or remain stationary as a unit during focusing. In other words, in the optical system L0 in each embodiment, the spacing between adjacent lens groups changes during focusing. Note that a lens group may be configured with a single lens, or may be configured with multiple lenses.

[0012] The optical system L0 in each embodiment comprises, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive or negative refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power.

[0013] SP denotes an aperture stop. IMG denotes an image plane, on which the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed when the optical system L0 of each embodiment is used as the imaging optical system of a digital still camera or digital video camera. When the optical system L0 of each embodiment is used as the imaging optical system of a silver halide film camera, a photosensitive surface corresponding to the film surface is placed on the image plane IMG.

[0014] The arrows in each cross-sectional view indicate the direction of movement of the lens groups during focusing from infinity to the closest distance. In the optical system L0 of each embodiment, during focusing from infinity to the closest distance, the second lens group L2 and the fourth lens group L3 move, while the first lens group L1, the third lens group L3, and the fifth lens group L5 remain stationary.

[0015] 2, 4, 6, 8, and 10 are aberration diagrams of the optical system L0 of Examples 1 to 5. In each aberration diagram, (a) is a longitudinal aberration diagram when focusing at infinity, and (b) is a longitudinal aberration diagram when focusing at a close distance.

[0016] 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 g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS shows the amount of astigmatism on the sagittal image plane, and ΔM shows the amount of astigmatism on the meridional image plane. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration for the g-line is shown. ω is the half angle of view (degrees).

[0017] Next, the characteristic configuration of the optical system L0 of each embodiment will be described.

[0018] To achieve a long focal length, a large aperture ratio, a compact size, high optical performance, and high-speed autofocus, it is important to appropriately configure and arrange the lens groups constituting the optical system L0 and the focus lens group that moves during focusing. The optical system L0 of each embodiment has multiple lens groups, and by configuring some of the lens groups to move during focusing, it achieves aberration correction and lightweight focus lens groups. By positioning the first lens group L1 with positive refractive power closest to the object, the diameter of the axial light beam incident on the second lens group L2 and the fourth lens group L4, which are the focus lens groups, is reduced, making it easy to achieve a compact and lightweight focus lens group. By positioning the third lens group L3 between the second lens group L2 and the fourth lens group L4, which are the focus lens groups, it is easy to achieve correction of spherical aberration and axial chromatic aberration. By arranging the fifth lens group L5 with negative refractive power on the image side of the second lens group L2 and the fourth lens group L4, which are focus lens groups, it is possible to easily shorten the overall length of the optical system L0 and suppress the Petzval sum.

[0019] The optical system L0 of each embodiment satisfies the following conditional expressions (1) to (3).

[0020] 0.10 <sk / f<0.25 (1) 0.010 <f / |f3|<0.500 (2) -3.50 <f / f5<-0.80 (3) Here, sk is the distance on the optical axis from the lens surface of the optical system L0 closest to the image side to the image plane (hereinafter referred to as back focus). f is the focal length of the optical system L0 when focused at infinity. f3 is the focal length of the third lens group L3. f5 is the focal length of the fifth lens group L5.

[0021] Conditional expression (1) defines the ratio between the back focus and the focal length of the optical system L0. If the back focus is short, falling below the lower limit of conditional expression (1), it becomes difficult to design a layout near the image sensor, which undesirably complicates the configuration. If the back focus is long, exceeding the upper limit of conditional expression (1), it undesirably increases the size of the optical system L0.

[0022] Conditional expression (2) defines the ratio between the focal length of the third lens group L3 and the focal length of the optical system L0. If the refractive power of the third lens group L3 is reduced below the lower limit of conditional expression (2), it becomes difficult to reduce the diameter of the on-axis light beam incident on the fourth lens group L4, which undesirably increases the size of the fourth lens group L4. If the refractive power of the third lens group L3 is increased above the upper limit of conditional expression (2), it becomes difficult to correct spherical aberration, which undesirably increases.

[0023] Conditional expression (3) defines the ratio between the focal length of the fifth lens group L5 and the focal length of the optical system L0. If the lower limit of conditional expression (3) is not met and the refractive power of the fifth lens group L5 becomes small, it becomes difficult to correct distortion, which is undesirable. If the upper limit of conditional expression (3) is met and the refractive power of the fifth lens group L5 becomes large, it becomes difficult to shorten the overall length of the optical system L0, which is undesirable because the optical system L0 becomes large.

[0024] It is preferable that the numerical ranges of the conditional expressions (1) to (3) be set to the numerical ranges of the following conditional expressions (1a) to (3a).

[0025] 0.12 <sk / f<0.22 (1a) 0.011 <f / |f3|<0.450 (2a) -2.50 <f / f5<-1.20 (3a) It is more preferable that the numerical ranges of the conditional expressions (1) to (3) be the numerical ranges of the following conditional expressions (1b) to (3b).

[0026] 0.15 <sk / f<0.20 (1b) 0.012 <f / |f3|<0.420 (2b) -2.40 <f / f5<-1.50 (3b) Next, the configuration that is preferably satisfied in the optical system L0 of each embodiment will be described.

[0027] The second lens group L2 preferably comprises a positive lens L21 and a negative lens L22 arranged in that order from the object side to the image side. By arranging the positive lens L21 closer to the object side in the second lens group L2, the lens diameter of the subsequent negative lens L22 can be reduced, which is advantageous for achieving compactness. Furthermore, by configuring the second lens group L2 with two lenses, the positive lens L21 and the negative lens L22, it becomes easier to reduce the weight.

[0028] It is preferable that a biconcave air lens be formed between the positive lens L21 and the negative lens L22, which makes it easier to suppress fluctuations in spherical aberration occurring in the second lens group L2 and to achieve high image quality across the entire focus range.

[0029] The fourth lens group L4 is composed of, in order from the object side to the image side, a positive lens L41, a negative lens L42, and a positive lens L43, and it is preferable that the positive lens L41 and the negative lens L42 are cemented lenses. The use of cemented lenses makes it easier to correct axial chromatic aberration. By configuring the fourth lens group L4 to include two positive lenses, it is possible to distribute the refractive power, making it easier to correct aberrations throughout the entire focus range.

[0030] The third lens group L3 is composed of, in order from the object side to the image side, a negative lens L31 and a positive lens L32, and it is preferable that the negative lens L31 and the positive lens L32 are cemented together. The use of cemented lenses makes it easier to suppress Petzval sum and correct axial chromatic aberration.

[0031] The third lens group L3 preferably includes an aperture stop SP. If the third lens group L3 includes an aperture stop SP, the refractive power arrangement before and after the aperture stop SP will be symmetrical, making it easier to correct distortion and coma.

[0032] It is preferable that the positive lens L11 is disposed closest to the object side, which makes it easier to shorten the overall length of the optical system L0 and to make the focus lens group smaller and lighter.

[0033] The first lens group L1 preferably includes two or more positive lenses and one or more negative lenses, which makes it easier to shorten the overall length of the optical system L0 and to suppress axial chromatic aberration and chromatic aberration of magnification.

[0034] The fifth lens group L5 preferably includes a positive lens and a negative lens. Since the fifth lens group L5 is the lens group closest to the image plane, it is effective in correcting Petzval sum, and including a positive lens and a negative lens in the fifth lens group L5 makes it easy to correct field curvature.

[0035] Next, conditions that the optical system of each embodiment should preferably satisfy will be described. The optical system of each embodiment should preferably satisfy one or more of the following conditional expressions (3) to (11).

[0036] 0.4 <f / f1<2.5 (4) -2.5 <f / f2<-0.3 (5) 1.0 <f / f4<3.5 (6) 0.7 <L / f<2.0 (7) 1.4 <b2<4.0 (8) 0.1 <b4<0.8 (9) 0.01 <M2 / f<0.30 (10) -0.20 <M4 / f<-0.01 (11) Here, f1 is the focal length of the first lens group L1. f2 is the focal length of the second lens group L2. f4 is the focal length of the fourth lens group L4. L is the distance on the optical axis from the lens surface closest to the object in the optical system L0 to the image plane (hereinafter referred to as the total optical length (total lens length)). b2 is the lateral magnification of the second lens group L2 when focusing at infinity. b4 is the lateral magnification of the fourth lens group L4 when focusing at infinity. M2 is the amount of movement of the second lens group L2 when focusing from infinity to the closest distance, with movement toward the image side being positive. M4 is the amount of movement of the fourth lens group when focusing from infinity to the closest distance, with movement toward the image side being positive.

[0037] Conditional expression (4) defines the ratio between the focal length of the first lens group L1 and the focal length of the optical system L0. If the lower limit of conditional expression (4) is not met and the refractive power of the first lens group L1 becomes small, it becomes difficult to shorten the overall length of the optical system L0, and the optical system L0 becomes large, which is undesirable. If the upper limit of conditional expression (4) is met and the refractive power of the first lens group L1 becomes large, it becomes difficult to correct the aberrations generated in the first lens group L1, particularly the spherical aberration and the chromatic aberration of magnification, which is undesirable.

[0038] Conditional expression (5) defines the ratio between the focal length of the second lens group L2 and the focal length of the optical system L0. If the refractive power of the second lens group L2 falls below the lower limit of conditional expression (5) and becomes small, it becomes difficult to correct spherical aberration occurring in the second lens group L2, and it becomes particularly difficult to suppress focus fluctuations due to spherical aberration, which is undesirable. If the refractive power of the second lens group L2 rises above the upper limit of conditional expression (5), the amount of movement of the second lens group L2 during focusing increases, which is undesirable because it increases the size of the optical system L0.

[0039] Conditional expression (6) defines the ratio between the focal length of the fourth lens group L4 and the focal length of the optical system L0. If the lower limit of conditional expression (6) is not met and the refractive power of the fourth lens group L4 becomes small, the amount of movement of the fourth lens group L4 during focusing becomes large, which is undesirable because the optical system L0 becomes large. If the upper limit of conditional expression (6) is met and the refractive power of the second lens group L2 becomes large, it becomes difficult to correct spherical aberration occurring in the fourth lens group L4, and in particular, it becomes difficult to suppress focus fluctuations due to spherical aberration, which is undesirable.

[0040] Conditional expression (7) defines the ratio between the total optical length and the focal length of optical system L0. If the total optical length is shortened below the lower limit of conditional expression (7), it becomes difficult to correct various aberrations, particularly lateral chromatic aberration, which is undesirable. If the total optical length is lengthened above the upper limit of conditional expression (7), the diameter of the front lens element increases, which undesirably increases the size of optical system L0.

[0041] Conditional expression (8) defines the lateral magnification of the second lens group L2 when focusing at infinity. If the lateral magnification of the second lens group L2 decreases below the lower limit of conditional expression (8), the amount of movement of the second lens group L2 required for focusing increases, undesirably increasing the size of the optical system L0. If the lateral magnification of the second lens group L2 increases above the upper limit of conditional expression (8), the height of the light beam incident on the subsequent lens group increases, undesirably increasing the size of the optical system L0.

[0042] Conditional expression (9) defines the lateral magnification of the fourth lens unit L4 when focusing at infinity. If the lateral magnification of the fourth lens unit L4 falls below the lower limit of conditional expression (9) and the lateral magnification of the fourth lens unit L4 becomes small, the angle of incidence of the axial light beam incident on the fifth lens unit L5 becomes large, making it difficult to correct spherical aberration and coma, which is undesirable. If the lateral magnification of the fourth lens unit L4 becomes large and the upper limit of conditional expression (9) is exceeded, the amount of movement of the fourth lens unit L4 required for focusing becomes large, which is undesirable because the optical system L0 becomes large.

[0043] Conditional expression (10) defines the ratio between the amount of movement of the second lens group L2 and the focal length of the optical system L0 when focusing from infinity to the closest distance. If the amount of movement of the second lens group L2 falls below the lower limit of conditional expression (10), it becomes difficult to shoot at the closest distance, which is undesirable. If the amount of movement of the second lens group L2 exceeds the upper limit of conditional expression (10), it becomes undesirable because the optical system L0 becomes large.

[0044] Conditional expression (11) defines the ratio between the amount of movement of the fourth lens group L4 and the focal length of the optical system L0 when focusing from infinity to the closest distance. If the lower limit of conditional expression (11) is exceeded, the amount of movement of the fourth lens group L4 becomes small, i.e., the absolute value of the amount of movement of the fourth lens group L4 becomes large, which is undesirable because the optical system L0 becomes large. If the upper limit of conditional expression (11) is exceeded, the amount of movement of the fourth lens group L4 becomes large, i.e., the absolute value of the amount of movement of the fourth lens group L4 becomes small, which is undesirable because it becomes difficult to shoot at the closest distance.

[0045] It is preferable that the numerical ranges of the conditional expressions (4) to (11) be the numerical ranges of the following conditional expressions (4a) to (11a).

[0046] 0.5 <f / f1<2.0 (4a) -1.9 <f / f2<-0.5 (5a) 1.5 <f / f4<3.0 (6a) 0.8 <L / f<1.8 (7a) 1.6 <b2<3.3 (8a) 0.2 <b4<0.7 (9a) 0.02 <M2 / f<0.15 (10a) -0.10 <M4 / f<-0.03 (11a) It is more preferable that the numerical ranges of the conditional expressions (4) to (11) be the numerical ranges of the following conditional expressions (4b) to (11b).

[0047] 0.6 <f / f1<1.7 (4b) -1.6 <f / f2<-0.6 (5b) 1.7 <f / f4<2.4 (6b) 0.9 <L / f<1.7 (7b) 1.7 <b2<3.0 (8b) 0.25 <b4<0.6 (9b) 0.03 <M2 / f<0.13 (10b) -0.08 <M4 / f<-0.05 (11b) Next, the optical system L0 of each embodiment will be described in detail.

[0048] The optical system L0 of Examples 1 to 4 comprises, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with positive refractive power, and a fifth lens unit L5 with negative refractive power.

[0049] The optical system L0 of Example 5 is composed of, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power.

[0050] In the optical system L0 of each embodiment, during focusing from infinity to the closest distance, the second lens group L2 and the fourth lens group L4 move, while the first lens group L1, the third lens group L3, and the fifth lens group L5 remain stationary.

[0051] In the optical systems L0 of Examples 1, 2 and 5, the first lens unit L1 is composed of, arranged in order from the object side to the image side, a positive lens L11, a positive lens L12, a positive lens L13 and a negative lens L14. The positive lens L13 and the negative lens L14 are cemented together.

[0052] In the optical system L0 of Example 3, the first lens unit L1 is composed of, arranged in order from the object side to the image side, a positive lens L11, a positive lens L12, a positive lens L13, a negative lens L14, and a positive lens L15. The positive lens L13 and the negative lens L14 are cemented together.

[0053] In the optical system L0 of Example 4, the first lens unit L1 is composed of, arranged in order from the object side to the image side, a positive lens L11, a positive lens L12, a positive lens L13, a positive lens L14, a negative lens L15, and a positive lens L16. The positive lens L14 and the negative lens L15 are cemented together.

[0054] In the optical system L0 of each embodiment, the second lens unit L2 is made up of a positive lens L21 and a negative lens L22, arranged in this order from the object side to the image side.

[0055] In the optical system L0 of each embodiment, the third lens unit L3 is composed of a negative lens L31 and a positive lens L32, arranged in this order from the object side to the image side. The negative lens L31 and the positive lens L32 form a cemented lens.

[0056] In the optical system L0 of each embodiment, the third lens unit L3 includes an aperture stop SP.

[0057] In the optical system L0 of each embodiment, the fourth lens unit L4 is composed of, in order from the object side to the image side, a positive lens L41, a negative lens L42, and a positive lens L43. The positive lens L41 and the negative lens L42 form a cemented lens.

[0058] In the optical systems L0 of Examples 1 to 3, the fifth lens unit L5 is composed of, in order from the object side to the image side, a positive lens L51, a negative lens L52, and a negative lens L53. The positive lens L51 and the negative lens L52 form a cemented lens.

[0059] In the optical system L0 of Example 4, the fifth lens unit L5 is composed of, in order from the object side to the image side, a positive lens L51, a negative lens L52, and a positive lens L53. The positive lens L51 and the negative lens L52 are cemented together.

[0060] In the optical system L0 of the fifth embodiment, the fifth lens unit L5 is composed of, in order from the object side to the image side, a positive lens L51, a negative lens L52, a negative lens L53, and a positive lens L54. The positive lens L51 and the negative lens L52 are cemented together.

[0061] Numerical examples 1 to 5 corresponding to the first to fifth embodiments, respectively, are shown below.

[0062] In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial spacing (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incident side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and vd represents the Abbe number of the optical element. Note that the Abbe number vd of a certain material is given by the following equation, where Nd, NF, and NC are 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: νd=(Nd-1) / (NF-NC) It is expressed as:

[0063] Additionally, the variable axial distance d is shown for infinity and close-up focusing. The object distance when focusing close up is shown in parentheses. The object distance is the distance from the image plane to the object position.

[0064] In each numerical example, d, focal length (mm), F-number, and half angle of view (degrees) are all values ​​when the optical system L0 of each example is focused on an object at infinity. "Back focus" is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. "Total lens length" is the length on the optical axis from the forefront lens surface (the lens surface closest to the object) to the final lens surface plus the back focus.

[0065] If the optical surface is aspherical, an asterisk (*) is added to the right of the surface number. The aspherical shape is expressed as follows: X is the displacement from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, A10, and 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 In addition, "e±XX" in each aspherical coefficient is "×10± XX " means. [Numerical Example 1] Unit: mm Surface Data Surface number rd nd νd 1 77.785 4.68 1.76385 48.5 2 172.845 0.20 3 63.371 5.95 1.49700 81.5 4 170.333 0.20 5 54.700 13.38 1.49700 81.5 6 -89.309 1.60 1.83400 37.2 7 115.572 (variable) 8 686.201 3.52 1.94594 18.0 9 -143.362 0.20 10 457.173 1.40 1.67300 38.3 11 36.221 (variable) 12 (Aperture) ∞ 4.29 13 -68.576 1.40 1.72825 28.5 14 34.701 9.22 1.87070 40.7 15 -101.270 (variable) 16 40.392 4.86 1.72916 54.7 17 192.612 1.40 1.67270 32.1 18 76.112 2.50 19* 206.498 5.26 1.85135 40.1 20* -91.873 (variable) 21 75.769 4.06 1.92286 20.9 22 -274.316 1.20 1.77047 29.7 23 29.541 8.48 24* -73.133 3.03 1.58313 59.4 25* -253.666 16.31 Image plane ∞ Aspheric data Page 19 K = 0.00000e+00 A 4=-9.07618e-06 A 6=-6.11165e-09 A 8=-1.04661e-11 Page 20 K = 0.00000e+00 A 4=-5.22186e-06 A 6=-4.28155e-09 A 8=-8.68689e-12 Page 24 K = 0.00000e+00 A 4=-2.25980e-05 A 6= 2.43830e-08 A 8=-3.13250e-11 Page 25 K = 0.00000e+00 A 4=-2.22797e-05 A 6= 2.16423e-08 A 8=-1.32136e-11 Focal length 84.00 F-number 1.44 Half angle of view (degrees) 14.44 Image height 21.64 Lens length 117.50 BF 16.31 Infinity Near distance (-700mm) d 7 4.26 10.25 d11 13.31 7.33 d15 5.79 1.00 d20 1.00 5.79 d25 16.31 6.01 Lens group data Group starting plane focal length 1 1 93.82 2 8 -111.97 3 12 405.35 4 16 46.82 5 21 -54.20 [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 75.910 7.60 1.76385 48.5 2 278.185 0.20 3 81.251 4.11 1.59282 68.6 4 137.891 0.83 5 75.102 13.89 1.49700 81.5 6 -89.633 1.86 1.89190 37.1 7 128.606 (variable) 8 -1506.651 4.06 1.94594 18.0 9 -117.758 0.20 10 -19994.632 1.40 1.80610 33.3 11 52.584 (variable) 12 (Aperture) ∞ 4.81 13 -83.985 1.40 1.69895 30.1 14 47.790 10.25 1.87070 40.7 15 -110.778 (variable) 16 41.915 8.74 1.69680 55.5 17 -173.265 1.40 1.69895 30.1 18 89.247 1.05 19* 88.271 8.63 1.85135 40.1 20* -134.588 (variable) 21 71.964 4.69 1.92286 20.9 22 -316.497 1.20 1.77047 29.7 23 27.700 8.93 24* -37.015 2.00 1.88202 37.2 25* -58.504 15.69 Image plane ∞ Aspheric data Page 19 K = 0.00000e+00 A 4=-4.61083e-06 A 6=-2.59781e-09 A 8=-1.59591e-12 Page 20 K = 0.00000e+00 A 4=-1.47775e-06 A 6=-2.06115e-09 A 8=-1.05938e-12 Page 24 K = 0.00000e+00 A 4= 1.57806e-05 A 6=-2.19149e-08 A 8= 4.05207e-11 Page 25 K = 0.00000e+00 A 4= 1.37873e-05 A 6=-1.94341e-08 A 8= 4.25441e-11 Focal length 83.00 F-number 1.25 Half angle of view (degrees) 14.61 Image height 21.64 Lens length 133.01 BF 15.69 Infinity Near distance (-700mm) d 7 6.52 16.70 d11 17.27 7.09 d15 5.29 1.00 d20 1.00 5.29 d25 15.69 5.18 Lens group data Group starting plane focal length 1 1 125.21 2 8 -127.16 3 12 293.03 4 16 43.02 5 21 -45.00 [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 86.709 7.20 1.61800 63.4 2 369.488 0.20 3 69.023 7.29 1.49700 81.5 4 197.730 0.20 5 61.193 14.21 1.49700 81.5 6 -127.175 2.00 1.87070 40.7 7 93.340 0.21 8 95.976 5.85 1.49700 81.5 9 178.462 (variable) 10 392.711 3.45 1.94594 18.0 11 -223.486 0.20 12 247.577 1.85 1.83481 42.7 13 40.471 (variable) 14 (Aperture) ∞ 4.82 15 -63.837 1.40 1.72825 28.5 16 44.300 9.51 1.87070 40.7 17 -74.293 (variable) 18 43.005 4.33 1.72916 54.7 19 141.112 1.40 1.69895 30.1 20 66.919 2.02 21* 114.498 8.30 1.76450 49.1 22* -112.430 (variable) 23 89.498 2.96 1.92286 20.9 24 1396.785 1.20 1.67300 38.3 25 29.039 8.92 26* -57.271 2.00 1.58313 59.4 27* -140.719 17.24 Image plane ∞ Aspheric data Page 21 K = 0.00000e+00 A 4=-6.61737e-06 A 6=-5.27557e-09 A 8=-7.47702e-12 Page 22 K = 0.00000e+00 A 4=-4.30497e-06 A 6=-4.81815e-09 A 8=-3.46829e-12 Page 26 K = 0.00000e+00 A 4=-1.91464e-05 A 6= 2.29584e-08 A 8=-2.64435e-11 Page 27 K = 0.00000e+00 A 4=-1.95897e-05 A 6= 2.30203e-08 A 8=-1.63145e-11 Focal length 99.00 F-number 1.44 Half angle of view (degrees) 12.33 Image height 21.64 Lens length 133.50 BF 17.24 Infinity Near distance (-700mm) d 9 3.01 11.26 d13 15.82 7.57 d17 6.91 1.00 d22 1.00 6.91 d27 17.24 3.35 Lens group data Group starting plane focal length 1 1 95.26 2 10 -96.82 3 14 240.85 4 18 52.62 5 23 -52.76 [Numerical Example 4] Unit: mm Surface Data Surface number rd nd νd 1 174.540 5.00 1.59349 67.0 2 289.447 0.20 3 98.775 13.84 1.43387 95.1 4 1295.204 0.20 5 84.449 9.87 1.49700 81.5 6 232.436 0.20 7 73.986 17.37 1.49700 81.5 8 -295.998 2.00 1.87070 40.7 9 69.370 4.61 10 70.644 6.30 1.49700 81.5 11 177.413 (variable) 12 478.926 4.01 1.94594 18.0 13 -478.755 0.20 14 148.546 3.00 1.80400 46.5 15 46.627 (variable) 16 (Aperture) ∞ 4.56 17 -79.969 1.40 1.77250 49.6 18 800.000 6.02 1.51742 52.4 19 -53.956 (variable) 20 41.447 4.25 1.83400 37.2 21 225.784 1.40 1.84666 23.8 22 51.524 3.72 23* -230.448 4.98 1.76450 49.1 24* -69.264 (variable) 25 -106.542 1.49 1.84666 23.8 26 -80.086 1.20 1.49700 81.5 27 39.190 7.26 28 55.080 3.12 1.58313 59.4 29* 88.761 38.05 Image plane ∞ Aspheric data Page 23 K = 0.00000e+00 A 4=-9.23397e-06 A 6=-6.40417e-09 A 8=-9.52243e-12 Page 24 K = 0.00000e+00 A 4=-7.11589e-06 A 6=-4.70098e-09 A 8=-6.63629e-12 Page 29 K = 0.00000e+00 A 4=-6.74980e-07 A 6=-3.45420e-10 A 8=-7.82351e-13 Focal length 198.00 F-number 2.05 Half angle of view (degrees) 6.24 Image height 21.64 Lens length 188.50 BF 38.05 Infinity Near distance (-700mm) d11 4.82 11.16 d15 24.36 18.02 d19 14.09 1.00 d24 1.00 14.09 d29 38.05 10.80 Lens group data Group starting plane focal length 1 1 119.40 2 12 -132.23 3 16 16396.06 4 20 84.65 5 25 -84.19 [Numerical Example 5] Unit: mm Surface Data Surface number rd nd νd 1 90.525 4.22 1.76385 48.5 2 209.644 0.20 3 61.314 6.71 1.59522 67.7 4 204.455 0.20 5 50.907 12.20 1.49700 81.5 6 -130.720 1.60 1.80610 33.3 7 72.226 (variable) 8 155.728 3.81 1.94594 18.0 9 -273.024 0.20 10 493.162 1.40 1.67300 38.3 11 34.600 (variable) 12 (Aperture) ∞ 1.57 13 323.382 1.40 1.73465 28.3 14 24.447 6.95 1.87070 40.7 15 86.688 (variable) 16 37.184 4.58 1.90043 37.4 17 282.676 1.40 1.68167 31.4 18 38.658 3.09 19* 86.149 6.00 1.85135 40.1 20* -89.241 (variable) 21 355.236 5.36 2.00069 25.5 22 -41.762 1.20 1.77047 29.7 23 32.530 9.05 24 -28.121 1.20 1.85478 24.8 25 -48.897 0.15 26 207.303 4.46 2.00100 29.1 27 -93.322 13.00 Image plane ∞ Aspheric data Page 19 K = 0.00000e+00 A 4=-1.35818e-05 A 6=-1.76204e-08 A 8=-5.55965e-11 Page 20 K = 0.00000e+00 A 4=-9.59369e-06 A 6=-1.32570e-08 A 8=-3.11565e-11 Focal length 84.00 F-number 1.44 Half angle of view (degrees) 14.44 Image height 21.64 Lens length 114.50 BF 13.00 Infinity Near distance (-700mm) d 7 3.99 10.11 d11 13.37 7.24 d15 6.20 1.00 d20 1.00 6.20 d27 13.00 2.09 Zoom lens group data Group starting plane focal length 1 1 93.36 2 8 -122.52 3 12 -524.52 4 16 41.31 5 21 -95.79 The various values ​​in each numerical example are summarized in Table 1 below.

[0066] [Table 1]

[0067] [Imaging device] Next, an embodiment of a digital still camera (image capture device) using the optical system of each embodiment will be described with reference to Fig. 11. In Fig. 11, 10 denotes a camera body, and 11 denotes any of the optical systems described in Embodiments 1 to 5. 12 denotes a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body and receives and photoelectrically converts an optical image formed by optical system 11. Camera body 10 may be a so-called single-lens reflex camera that has a quick-turn mirror, or a so-called mirrorless camera that does not have a quick-turn mirror.

[0068] In this way, by applying the optical system of each embodiment to an imaging device such as a digital still camera, an imaging device with a small lens can be obtained.

[0069] Although the 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 the gist of the present invention. [Explanation of symbols]

[0070] L0 optical system L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group L5 Fifth lens group IMG image plane

Claims

1. An optical system including, arranged 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 or negative refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power, During focusing from infinity to a closest distance, the second lens group and the fourth lens group move, and the first lens group, the third lens group, and the fifth lens group do not move, Let sk be the distance on the optical axis from the lens surface closest to the image side of the optical system to the image plane, f be the focal length of the optical system when focused on infinity, f3 be the focal length of the third lens group, f5 be the focal length of the fifth lens group, and f2 be the focal length of the second lens group. 0.10<sk / f<0.25 0.010<f / |f3|<0.500 -3.50<f / f5<-0.80 -1.6<f / f2<-0.3 An optical system characterized in that the following condition is satisfied:

2. When the focal length of the first lens group is f1, 0.4<f / f1<2.5 2. The optical system according to claim 1, wherein the following condition is satisfied:

3. When the focal length of the fourth lens group is f4, 1.0<f / f4<3.5 3. The optical system according to claim 1, wherein the following condition is satisfied:

4. Let L be the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. 0.7<L / f<2.0 4. The optical system according to claim 1, wherein the following condition is satisfied:

5. When the lateral magnification of the second lens group when focused on infinity is b2, 1.4<b2<4.0 5. The optical system according to claim 1, wherein the following condition is satisfied:

6. When the lateral magnification of the fourth lens group when focused on infinity is b4, 0.1<b4<0.8 6. The optical system according to claim 1, wherein the following condition is satisfied:

7. When the movement toward the image side is taken as positive, the amount of movement of the second lens group during focusing from infinity to the closest distance is taken as M2, 0.01<M2 / f<0.30 7. The optical system according to claim 1, wherein the following condition is satisfied:

8. When the movement toward the image side is taken as positive, the amount of movement of the fourth lens group during focusing from infinity to the closest distance is taken as M4, -0.20<M4 / f<-0.01 8. The optical system according to claim 1, wherein the following condition is satisfied:

9. 9. The optical system according to claim 1, wherein the second lens group is made up of a positive lens L21 and a negative lens L22, arranged in this order from the object side to the image side.

10. 10. The optical system according to claim 9, wherein a biconcave air lens is formed between the positive lens and the negative lens.

11. The fourth lens group includes a positive lens L41, a negative lens L42, and a positive lens L43, which are arranged in this order from the object side to the image side.

11. The optical system according to claim 1, wherein the positive lens L41 and the negative lens L42 form a cemented lens.

12. The third lens group includes a negative lens L31 and a positive lens L32, which are arranged in this order from the object side to the image side.

12. The optical system according to claim 1, wherein the negative lens L31 and the positive lens L32 form a cemented lens.

13. 13. The optical system according to claim 1, wherein the third lens group includes an aperture stop.

14. 14. The optical system according to claim 1, wherein a positive lens L11 is disposed closest to the object side.

15. 15. The optical system according to claim 1, wherein the first lens group includes two or more positive lenses and one or more negative lenses.

16. 16. The optical system according to claim 1, wherein the fifth lens group includes a positive lens and a negative lens.

17. 17. An imaging apparatus comprising: the optical system according to claim 1; and an imaging element that receives an image formed by the optical system.

Images