Optical system and imaging device having the same

Abstract

The objective is to provide a compact optical system with high optical performance while performing high-speed focusing. [Solution] The optical system has a first lens group, a second lens group, and a third lens group arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing, and satisfies predetermined conditions.

Description

[Technical Field]

[0001] The disclosure herein relates to optical systems and is suitable for imaging devices such as digital video cameras, digital still cameras, broadcast cameras, and silver halide film cameras. [Background technology]

[0002] In recent years, optical systems used in imaging devices have been required to be compact yet capable of high-speed focusing.

[0003] Therefore, a compact configuration is known in which multiple lens groups move during focusing, in order to reduce the weight of the lens group that moves during focusing while suppressing the fluctuation of aberrations that occur during focusing.

[0004] Patent Document 1 discloses an optical system in which the second lens group and the fourth lens move during focusing. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-140076 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The objective is to provide a compact optical system with high optical performance while performing high-speed focusing. [Means for solving the problem]

[0007] An optical system as one aspect of the present invention comprises a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group arranged in order from the object side to the image side, wherein the distance between adjacent lens groups changes during focusing, and during focusing, the first lens group, the third lens group, and the fourth lens group remain stationary, while the second lens group and the fourth lens group move, and when the distance on the optical axis from the lens surface closest to the object to the lens surface closest to the image of the third lens group is MD, and the focal length of the entire system is f, 0.40 <MD / f<2.30 It is characterized by satisfying the following conditional expression.

[0008] Another aspect of the present invention is an optical system having a first lens group, a second lens group, and a third lens group arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing, and during focusing, two or more lens groups arranged in the optical system move. When TL is the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane, and f is the focal length of the entire system, 0.50 <TL / f<7.00 It is characterized by satisfying the following conditional expression. [Brief explanation of the drawing]

[0009] [Figure 1] Cross-sectional view of the lens when the optical system of Example 1 is focused to infinity. [Figure 2] In the optical system of Example 1, (a) aberration diagram when focused at infinity, (b) aberration diagram when focused at close range. [Figure 3] Cross-sectional view of the lens when focused to infinity in the optical system of Example 2. [Figure 4] In the optical system of Example 2, (a) aberration diagram when focused at infinity, (b) aberration diagram when focused at close range. [Figure 5]In the optical system of Example 3, lens cross-sectional view when focused at infinity [Figure 6] In the optical system of Example 3, (a) aberration diagram when focused at infinity, (b) aberration diagram when focused at the closest distance [Figure 7] In the optical system of Example 4, lens cross-sectional view when focused at infinity [Figure 8] In the optical system of Example 4, (a) aberration diagram when focused at infinity, (b) aberration diagram when focused at the closest distance [Figure 9] Schematic diagram showing an imaging device

Mode for Carrying Out the Invention

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

[0011] FIGS. 1, 3, 5, and 7 are lens cross-sectional views when focused at infinity in the optical systems L0 of Examples 1 to 4, respectively. The optical system L0 of each example is an optical system used in an imaging device such as a digital video camera, a digital still camera, a broadcast camera, a silver halide film camera, a surveillance camera, an in-vehicle camera, etc.

[0012] In each lens cross-sectional view, the left side is the object side and the right side is the image side. Note that the optical system L0 of each example may be used as a projection lens for a projector or the like. In this case, the left side is the screen side and the right side is the side of the projected image.

[0013] In each lens cross-sectional view, SP is the aperture stop. IP is the image plane. When the optical system L0 of each example is used in a digital still camera or a digital video camera, the imaging surface of a solid-state imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is disposed. When the optical system L0 of each example 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 IP.

[0014] GB is the back glass and corresponds to an infrared cut filter, a low-pass filter, etc.

[0015] The optical system L0 of each embodiment has a first lens group B1, a second lens group B2, and a third lens group B3, which are arranged in order from the object side to the image side. Each lens group may be composed of one lens or a plurality of lenses.

[0016] The solid arrows shown upward in each lens cross-sectional view represent the movement trajectories of one or more lenses during focusing from infinity to the nearest point.

[0017] Figs. 2(a), 4(a), 6(a), and 8(a) are aberration diagrams when focusing on infinity in the optical systems L0 of Embodiments 1 to 4, respectively.

[0018] Figs. 2(b), 4(b), 6(b), and 8(b) are aberration diagrams when focusing on the nearest point in the optical systems L0 of Embodiments 1 to 4, respectively.

[0019] In the spherical aberration diagram, Fno is the F-number, the solid line indicates the spherical aberration amount for the d-line (wavelength 587.6 nm), and the dashed line indicates the spherical aberration amount for the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line indicates the aberration amount ΔS in the sagittal image plane, and the dashed line indicates the aberration amount ΔM in the meridional image plane. The distortion aberration diagram shows the distortion aberration amount for the d-line. The chromatic aberration diagram shows the longitudinal chromatic aberration amount for the g-line. ω is the imaging semi-field angle (°).

[0020] Next, the optical system L0 according to the first embodiment will be described.

[0021] The optical system L0 according to the first embodiment consists of a first lens group B1, a second lens group B2, a third lens group B3, a fourth lens group B4, and a fifth lens group B5, arranged in order from the object side to the image side, and the spacing between adjacent lens groups changes during focusing. During focusing, the first lens group B1, the third lens group B3, and the fifth lens group B5 remain stationary, while the second lens group B2 and the fourth lens group B4 move.

[0022] During focusing, the first lens group B1, the third lens group B3, and the fifth lens group B5 are kept stationary, thereby reducing the weight of the lens group used for focusing. Focusing is performed by the second lens group 2 and the fourth lens group B4, which helps to suppress variations in aberrations that occur during focusing.

[0023] The optical system L0 according to the first embodiment is configured to satisfy the following condition. 0.40 <MD / f<2.30···(1)

[0024] However, MD is the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image in the third lens group B3, and f is the focal length of the entire system.

[0025] If the distance along the optical axis of the third lens group B3 becomes too long, exceeding the upper limit of condition (1), the overall lens length becomes too long, which is undesirable. Here, the overall lens length is the sum of the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image in the optical system L0, and the back focus. Here, the back focus is the distance along the optical axis between the lens surface closest to the image in the optical system L0 and the image plane, converted to an air-like distance.

[0026] If the distance of the third lens group B3 on the optical axis becomes too short, falling below the lower limit of condition (1), it becomes difficult to reduce spherical aberration and other distortions occurring in each lens group using the third lens group B3.

[0027] By satisfying the above configuration, the optical system L0 according to the first embodiment can provide a compact optical system with high optical performance while performing high-speed focusing.

[0028] Furthermore, it is more preferable that the lower limit of condition (1) be set to 0.60, 0.80, or 1.03.

[0029] The upper limit of condition (1) is more preferably set to 2.10, 1.91, or 1.62.

[0030] Next, we will describe the optical system L0 according to the second embodiment.

[0031] The optical system L0 according to the second embodiment has a first lens group B1, a second lens group B2, and a third lens group B3 arranged in order from the object side to the image side, and the spacing between adjacent lens groups changes during focusing. During focusing, two or more lens groups arranged in the optical system move, making it easier to suppress fluctuations in various aberrations that occur during focusing while performing high-speed focusing.

[0032] The optical system L0 according to the second embodiment is configured to satisfy the following condition. 0.50 <TL / f<7.00···(5)

[0033] Here, TL is the distance along the optical axis from the lens surface closest to the object in the first lens group B1 to the image plane, and f is the focal length of the entire system.

[0034] If the upper limit of condition (5) is exceeded, the overall length of the lens becomes too long, which is undesirable.

[0035] If the value falls below the lower limit of condition (5), the overall length of the lens becomes too short, and the refractive power of each lens group becomes too strong. As a result, it becomes difficult to correct various aberrations, which is undesirable.

[0036] By satisfying the above configuration, the optical system L0 according to the second embodiment can provide a compact optical system with high optical performance while performing high-speed focusing.

[0037] Furthermore, it is more preferable that the lower limit of condition (5) be set to 2.18, 2.50, or 2.80.

[0038] The upper limit of condition (5) is more preferably set to 5.97, 5.50, or 5.05.

[0039] Next, preferred configurations of the optical system L0 according to each embodiment will be described.

[0040] The first lens group B1 preferably has a negative refractive power. This makes it easier to suppress an increase in lens diameter even when the angle of view of the entire system is widened.

[0041] The third lens group B3 preferably has three or more lenses. This makes it easier to correct spherical aberration in particular.

[0042] It is preferable that the optical system be able to focus from an in-finity focus state down to an overall horizontal magnification of -0.5x. This results in an optical system that can also perform close-up photography.

[0043] It is preferable that both the second lens group B2 and the fourth lens group B4 consist of two or fewer lenses. This makes it easier to reduce the weight of the optical system L0.

[0044] It is preferable to move all or part of the lenses in any of the lens groups of the optical system L0 in a direction that includes a component perpendicular to the optical axis in order to correct image blur caused by camera shake. This makes it easier to obtain high optical performance even when image blur occurs due to camera shake.

[0045] The third lens group B3 preferably has an aperture. This makes it possible to reduce the height of the off-axis light rays incident on the third lens group B3 from the optical axis, and makes it easier to reduce the diameter of each lens in the third lens group B3.

[0046] In the optical system L0, the lens positioned closest to the object is preferably one with negative refractive power. This makes it easier to suppress an increase in lens diameter even when the overall field of view of the system is widened.

[0047] In each embodiment, the optical system L0 preferably satisfies one or more of the following conditional expressions. 0.40 <fm / f<2.26···(2) 0.19<|fm / ff1|<1.46···(3) 0.38<|fm / ff2|<1.64···(4) 0.50 <TL / f<7.00···(5) 0.45<|ff1 / f|<4.51···(6) 0.39<|ff1 / ff2|<4.20···(7) 0.42 < |f1 / fm| < 12.30 ···(8) 0.60 < |fk / f| < 4.09 ···(9) 0.49 <MD / fm<2.43···(10) 0.16 <MD / TL<0.59···(11)

[0048] Here, fm is the focal length of the third lens group B3, ff1 is the focal length of the second lens group B2, ff2 is the focal length of the fourth lens group B4, and TL is the distance along the optical axis from the lens surface closest to the object to the image plane of the first lens group B1. f1 is the focal length of the first lens group B1, and fk is the focal length of the fifth lens group B5.

[0049] Next, we will explain the technical meaning of the aforementioned conditional equations (2) to (11).

[0050] If the positive refractive power of the third lens group B3 becomes too weak, exceeding the upper limit of condition (2), the overall length of the lens becomes too long, which is undesirable.

[0051] If the positive refractive power of the third lens group B3 becomes too strong, falling below the lower limit of condition (2), it becomes difficult to correct spherical aberration in particular, which is undesirable.

[0052] If the refractive power of the second lens group B2 becomes too strong relative to the third lens group B3, exceeding the upper limit of condition (3), it becomes particularly difficult to correct coma aberration, which is undesirable.

[0053] If the refractive power of the second lens group B2 becomes too weak relative to the third lens group B3, falling below the lower limit of condition (3), it becomes particularly difficult to correct spherical aberration, which is undesirable.

[0054] If the refractive power of the fourth lens group B4 becomes too strong relative to the third lens group B3, exceeding the upper limit of condition (4), it becomes particularly difficult to correct coma aberration, which is undesirable.

[0055] If the refractive power of the fourth lens group B4 becomes too weak relative to the third lens group B3, falling below the lower limit of condition (4), it becomes particularly difficult to correct spherical aberration, which is undesirable.

[0056] If the upper limit of condition (5) is exceeded, the overall length of the lens becomes too long, which is undesirable.

[0057] If the value falls below the lower limit of condition (5), the overall length of the lens becomes too short, and the refractive power of each lens group becomes too strong. As a result, it becomes difficult to correct various aberrations, which is undesirable.

[0058] If the refractive power of the second lens group B2 becomes too weak, exceeding the upper limit of condition (6), the overall length of the lens becomes too long, which is undesirable.

[0059] If the refractive power of the second lens group B2 becomes too strong, falling below the lower limit of condition (6), it becomes difficult to correct coma aberration in particular, which is undesirable.

[0060] If the value exceeds the upper limit or falls below the lower limit of condition (7), the refractive power of the second lens group B2 or the fourth lens group B4 becomes too strong, making it difficult to correct coma aberration, which is undesirable.

[0061] If the refractive power of the first lens group B1 becomes too weak, exceeding the upper limit of condition (8), the overall length of the lens becomes too long, which is undesirable.

[0062] If the refractive power of the first lens group B1 becomes too strong, falling below the lower limit of condition (8), it becomes difficult to correct aberrations such as field curvature and distortion, which is undesirable.

[0063] If the refractive power of the fifth lens group B5 becomes too weak, exceeding the upper limit of condition (9), the overall length of the lens becomes too long, which is undesirable.

[0064] If the refractive power of the fifth lens group B5 becomes too strong, falling below the lower limit of condition (9), it becomes difficult to correct aberrations such as field curvature and distortion, which is undesirable.

[0065] If the positive refractive power of the third lens group B3 becomes too strong, exceeding the upper limit of condition (10), it becomes difficult to correct spherical aberration in particular, which is undesirable.

[0066] If the positive refractive power of the third lens group B3 becomes too weak, falling below the lower limit of condition (10), the overall length of the lens becomes too long, which is undesirable.

[0067] If the upper limit of condition (11) is exceeded, the overall length of the lens becomes too short, and the refractive power of each lens group becomes too strong. As a result, it becomes difficult to correct various aberrations, which is undesirable.

[0068] If the value falls below the lower limit of condition (11), the overall length of the lens becomes too long, which is undesirable.

[0069] Furthermore, it is preferable to set it as follows:

[0070] The lower limit of condition (2) is more preferably set to 0.42, 0.44, or 0.46.

[0071] It is more preferable that the upper limit of condition (2) be set to 2.20, 2.10, or 2.00.

[0072] The lower limit of condition (3) is more preferably set to 0.25, 0.28, or 0.30.

[0073] The upper limit of condition (3) is more preferably set to 1.40, 1.35, or 1.30.

[0074] The lower limit of condition (4) is more preferably set to 0.53, 0.60, or 0.69.

[0075] The upper limit of condition (4) is more preferably set to 1.42, 1.30, or 1.20.

[0076] The lower limit of condition (5) is more preferably set to 2.18, 2.50, or 2.80.

[0077] The upper limit of condition (5) is more preferably set to 5.97, 5.50, or 5.05.

[0078] The lower limit of condition (6) is more preferably set to 0.62, 0.65, or 0.69.

[0079] The upper limit of condition (6) is more preferably set to 3.91, 3.50, or 3.31.

[0080] The lower limit of condition (7) is more preferably set to 0.55, 0.60, or 0.71.

[0081] The upper limit of condition (7) is more preferably set to 3.64, 3.30, or 3.08.

[0082] The lower limit of condition (8) is more preferably set to 0.59, 0.65, or 0.75.

[0083] The upper limit of condition (8) is more preferably set to 10.66, 9.50, or 9.02.

[0084] The lower limit of conditional expression (9) is more preferably set to 0.84, 0.95, or 1.08.

[0085] The upper limit of condition (9) is more preferably set to 3.55, 3.25, or 3.00.

[0086] The lower limit of condition (10) is more preferably set to 0.68, 0.78, or 0.88.

[0087] The upper limit of condition (10) is more preferably set to 2.11, 1.90, or 1.78.

[0088] The lower limit of condition (11) is more preferably set to 0.22, 0.26, or 0.29.

[0089] The upper limit of condition (11) is more preferably set to 0.51, 0.47, or 0.43.

[0090] Next, we will describe the details of the configuration of the optical system L0 in each embodiment. From Embodiment 2 onward, we will mainly describe the differences from Embodiment 1.

[0091] [Example 1] The optical system L0 of Example 1 consists of a first lens group B1 with negative refractive power, a second lens group B2 with positive refractive power, a third lens group B3 with positive refractive power, a fourth lens group B4 with negative refractive power, and a fifth lens group B5 with positive refractive power, arranged in order from the object side to the image side. The spacing between adjacent lens groups changes during focusing. During focusing, the first lens group B1, the third lens group B3, and the fifth lens group B5 remain stationary. When focusing from infinity to close, the second lens group B2 moves towards the object side and the fourth lens group B4 moves towards the image side, resulting in a well-symmetrical arrangement of the optical system L0 at infinity and close, making it easy to obtain high optical performance.

[0092] Furthermore, the fourth lens group B4 has a negative meniscus lens with its convex surface facing the object, which makes it easier to suppress fluctuations in spherical aberration that occur during focusing.

[0093] [Example 2] The optical system L0 of Example 2 consists of a first lens group B1 with negative refractive power, a second lens group B2 with positive refractive power, a third lens group B3 with positive refractive power, a fourth lens group B4 with positive refractive power, and a fifth lens group B5 with negative refractive power, arranged in order from the object side to the image side. The spacing between adjacent lens groups changes during focusing. During focusing, the first lens group B1, the third lens group B3, and the fifth lens group B5 remain stationary. When focusing from infinity to near, the second lens group B2 and the fourth lens group B4 move towards the object side.

[0094] The fourth lens group B4 has a positive refractive power, and the fifth lens group B5 has a negative refractive power, which positions the principal point of the optical system L0 on the object side, making it easier to shorten the overall length of the lens.

[0095] [Example 3] The optical system L0 of Example 3 consists of a first lens group B1 with negative refractive power, a second lens group B2 with negative refractive power, a third lens group B3 with positive refractive power, a fourth lens group B4 with positive refractive power, and a fifth lens group B5 with negative refractive power, arranged in order from the object side to the image side. The spacing between adjacent lens groups changes during focusing. During focusing, the first lens group B1, the third lens group B3, and the fifth lens group B5 remain stationary. When focusing from infinity to close, the second lens group B2 moves towards the image side, and the fourth lens group B4 moves towards the object. As a result, the optical system L0 has good symmetry at infinity and close range, making it easy to obtain high optical performance.

[0096] The first lens group B1 and the second lens group B2 have negative refractive power, which helps to share the negative refractive power and makes it easier to correct image field curvature, spherical aberration, and other issues.

[0097] [Example 4] The optical system L0 of Example 4 consists of a first lens group B1 with negative refractive power, a second lens group B2 with negative refractive power, a third lens group B3 with positive refractive power, a fourth lens group B4 with negative refractive power, and a fifth lens group B5 with positive refractive power, arranged in order from the object side to the image side. The spacing between adjacent lens groups changes during focusing. During focusing, the first lens group B1, the third lens group B3, and the fifth lens group B5 remain stationary. When focusing from infinity to near, the second lens group B2 and the fourth lens group B4 move towards the image side.

[0098] The fifth lens group B5 is composed of a positive meniscus lens with its convex surface facing the image side, making it easier to correct image field curvature and other issues.

[0099] In the optical system L0 of each embodiment, it is preferable to deposit a fluorine coating on the object-side lens surface of the lens positioned closest to the object and the image-side lens surface of the lens positioned closest to the image. Since the object-side lens surface of the lens positioned closest to the object and the image-side lens surface of the lens positioned closest to the image are more susceptible to external exposure, depositing a fluorine coating enhances water and oil repellency, suppresses flare, and allows for high optical performance. In particular, since the object-side lens surface of the lens positioned closest to the object has a large diameter, it is preferable to deposit a fluorine coating there.

[0100] In the cemented lens arranged in the optical system L0 of each embodiment, it is preferable that the positive and negative lenses constituting at least one cemented lens are bonded together with an adhesive having a thickness of 0.005 mm or more and 0.05 mm or less along the optical axis. If it is less than 0.005 mm, it is prone to peeling, and if it is greater than 0.03 mm, the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image becomes longer, thus increasing the overall length of the lens. It is more preferable to satisfy the condition of 0.008 mm or more and 0.02 mm or less.

[0101] In each embodiment, at least one lens arranged in the optical system L0 is coated with an anti-reflective coating to prevent reflection, and the anti-reflective coating is composed of multiple films. Here, it is preferable that the anti-reflective coating PC has a refractive index of 1.32 or less when Nd is the refractive index of the film closest to the air interface with respect to the d line. By setting Nd to 1.32 or less, the refractive index difference with air can be reduced, making it possible to further reduce light reflection and reduce ghosting.

[0102] Specific examples of the configuration of the anti-reflective coating PC include, but are not limited to, the multilayer film using the wet method described in Japanese Patent Publication No. 2012-230211 and Japanese Patent Publication No. 2014-95877. More preferably, ghosting can be further reduced by setting Nd to 1.30 or less.

[0103] Here, it is preferable to apply an anti-reflective coating PC to the image-side lens surface of the negative lens with its concave surface facing the image side, among the negative lenses arranged in the optical system L0. Light reflected by a negative lens with its concave surface facing the image side tends to be reflected at a large angle with respect to the normal direction of the lens surface of the negative lens with its concave surface facing the image side, so the reflectivity tends to be high. Also, light reflected by a negative lens with its concave surface facing the image side tends to be focused at the image plane, so ghosting is likely to be noticeable. Therefore, by applying an anti-reflective coating PC to the image-side lens surface of a negative lens with its concave surface facing the image side, ghosting can be reduced.

[0104] The numerical values ​​corresponding to Examples 1 to 4 are shown below.

[0105] In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axial spacing (distance along the optical axis) between the m-th surface and the (m+1)-th surface. Here, m is the surface number counted from the light incidence side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and νd represents the Abbe number of the optical element. Note that the Abbe number νd of a certain material is given by Nd, NF, and NC, respectively, when the refractive indices of the Fraunhofer lines at the d-line (wavelength 587.6 nm), F-line (wavelength 486.1 nm), and C-line (wavelength 656.3 nm), respectively. νd = (Nd-1) / (NF-NC) It is represented as follows.

[0106] BF stands for back focus. Back focus is the distance from the lens surface closest to the object in the optical system L0 to the image plane, expressed in terms of air distance.

[0107] Furthermore, if the optical surface is aspherical, the sign * is added to the right of the surface number. The aspherical shape is defined as follows, where X is the displacement from the surface vertex in the optical axis direction, h is the height from the optical axis perpendicular to the optical axis, R is the paraaxial radius of curvature, k is the cone constant, and A4, A6, A8, A10, and A12 are the aspherical coefficients of their respective orders. 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 It is expressed as follows. In addition, "e±XX" in each aspherical coefficient means "×10± XX ".

[0108] Also, in the intervals between each lens group, inf represents the interval between each lens group when focusing at infinity, and β - 0.5 represents the interval between each lens group when focusing at an object distance with a lateral magnification of -0.5 times.

[0109] [Numerical Example 1] Unit: mm Surface data Surface number r d nd νd 1 2579.703 1.50 1.48749 70.2 2 16.960 (Variable) 3* 85.543 3.66 1.73037 32.2 4 -48.044 (Variable) 5 -134.607 1.00 1.59551 39.2 6 41.131 6.05 7 89.281 8.59 1.65160 58.5 8 -26.206 2.00 9 (Aperture) ∞ 3.00 10 68.995 7.13 1.59522 67.7 11 -23.422 1.00 1.77047 29.7 12 31.625 4.05 13* 37.533 5.71 1.80400 46.6 14* -33.091 (Variable) 15* 112.261 1.20 1.58313 59.4 16* 21.376 4.00 17 -133.858 1.20 1.61772 49.8 18 83.767 (Variable) 19 83.521 5.02 1.85150 40.8 20 -245.039 13.607 21 ∞ 1.00 1.54400 66.3 22 ∞ 1.747 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4=-1.26034e-05 A 6=-6.87765e-09 A 8= 1.74807e-11 A10=-4.90388e-14 Page 13 K = 0.00000e+00 A 4=-7.86720e-06 A 6= 1.69370e-08 A 8=-1.08487e-10 A10= 3.76156e-13 Side 14 K = 0.00000e+00 A 4= 2.76631e-06 A 6= 1.56465e-08 A 8=-1.33479e-10 A10= 4.28263e-13 Page 15 K = 0.00000e+00 A 4=-2.62038e-05 A 6= 1.58072e-07 A 8=-9.45454e-10 A10= 2.35221e-12 Page 16 K = 0.00000e+00 A 4=-2.44456e-05 A 6= 1.46489e-07 A 8=-1.01640e-09 A10= 2.54465e-12 Focal length 31.43 F-number 1.85 Half-angle 32.47 Image height 20.00 Lens length: 97.33 BF 16.03 Spacing between each lens group inf β-0.5 d2 12.77 8.52 d4 1.49 5.74 d14 2.00 10.43 d18 9.93 1.50

[0110] [Numerical Example 2] Unit: mm Surface data Face number rd nd νd 1 100.257 1.50 1.65160 58.5 2 16.672 (variable) 3* -376.641 4.36 1.68948 31.0 4* -44.967 (variable) 5 -275.633 1.02 1.59522 67.7 6 34.880 5.78 7 75.794 10.36 1.65160 58.5 8 -33.256 2.93 9 (aperture) ∞ 3.00 10 -205.424 1.00 1.65412 39.7 11 20.034 11.91 1.65160 58.5 12 -38.225 (variable) 13* 27.789 4.43 1.49700 81.5 14* -144.632 (variable) 15* 39.291 1.20 2.00069 25.5 16* 17.569 4.71 17 -46.213 1.20 1.92286 20.9 18 122.257 2.33 19 104.415 6.66 1.84666 23.8 20 -34.712 19.37 21 ∞ 2.50 1.54400 66.3 22 ∞ 0.83 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4= 3.94351e-06 A 6= 9.59327e-08 A 8=-1.06147e-11 A10= 1.43979e-12 Side 4 K = 0.00000e+00 A 4= 1.23753e-05 A 6= 9.36734e-08 A 8=-2.66501e-10 A10= 2.66741e-12 Page 13 K = 0.00000e+00 A 4=-1.67986e-06 A 6=-5.35818e-08 A 8= 4.61823e-10 A10=-1.39503e-12 Side 14 K = 0.00000e+00 A 4= 8.86601e-06 A 6=-8.26080e-08 A 8= 7.47386e-10 A10=-2.32471e-12 Page 15 K = 0.00000e+00 A 4=-3.89326e-05 A 6=-3.19683e-08 A 8= 1.33137e-09 A10=-5.37650e-12 Page 16 K = 0.00000e+00 A 4=-3.94500e-05 A 6=-7.60089e-08 A 8= 1.47024e-09 A10=-6.99139e-12 Focal length 24.50 F-number 1.85 Half-angle 39.23 Image height 20.00 Lens length: 112.45 BF 2.45 Spacing between each lens group inf β-0.5 d2 17.07 9.17 d4 1.48 9.37 d12 7.70 1.20 d14 2.00 8.50

[0111] [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 49.829 1.50 1.69680 55.5 2 21.344 5.28 3 220.001 2.70 1.85478 24.8 4 -94.458 (variable) 5* -49.850 1.01 1.58313 59.4 6 * 28.540 (variable) 7 98.207 11.84 1.75500 52.3 8 -37.470 8.65 9 (aperture) ∞ 3.00 10 47.348 2.43 1.77047 29.7 11 21.082 13.99 1.49700 81.5 12 -41.666 (variable) 13* 45.915 5.01 1.58313 59.4 14* -44.235 (variable) 15* 430.818 1.20 2.00069 25.5 16* 29.503 5.08 17 -28.029 1.20 1.77047 29.7 18 106.327 1.50 19 97.030 6.99 1.92286 20.9 20 -39.383 20.81 21 ∞ 1.00 1.54400 66.3 22 ∞ 1.80 Image plane ∞ Aspherical data 5th page K = 0.00000e+00 A 4=-1.74580e-05 A 6= 1.63603e-07 A 8=-9.54496e-10 A10= 2.00785e-12 Side 6 K = 0.00000e+00 A 4=-1.12397e-05 A 6= 1.96924e-07 A 8=-1.30676e-09 A10= 2.90333e-12 Page 13 K = 0.00000e+00 A 4= 2.51412e-06 A 6=-1.10485e-07 A 8= 8.64000e-10 A10=-3.05367e-12 Side 14 K = 0.00000e+00 A 4= 8.58702e-06 A 6=-1.22027e-07 A 8= 8.64933e-10 A10=-2.94512e-12 Page 15 K = 0.00000e+00 A 4= 4.09492e-05 A 6=-4.58084e-07 A 8= 2.06030e-09 A10=-4.10605e-12 Page 16 K = 0.00000e+00 A 4= 5.71855e-05 A 6=-4.58182e-07 A 8= 2.08664e-09 A10=-4.33636e-12 Focal length 34.80 F-number 1.85 Half-angle 29.88 Image height 20.00 Lens length: 119.33 BF 23.25 Spacing between each lens group inf β-0.5 d4 2.49 7.45 d6 10.60 5.65 d12 9.61 2.38 d14 2.00 9.24

[0112] [Numerical Example 4] Unit: mm Surface data Face number rd nd νd 1 224.044 1.50 1.53136 75.1 2 16.200 4.73 3* 317.484 2.36 1.92286 20.9 4* -265.425 (variable) 5 -63.557 1.01 1.92286 20.9 6 625.767 (variable) 7 5742.431 5.44 1.91249 36.8 8 -27.874 6.91 9 (aperture) ∞ 3.00 10 -855.933 1.00 1.68413 40.8 11 18.955 13.36 1.49700 81.5 12 -27.102 3.37 13* 40.824 6.36 1.60445 64.3 14* -33.844 (variable) 15* -241.604 1.20 1.58065 42.4 16* 21.994 4.81 17 -55.409 1.20 1.80635 25.2 18 -1432.828 (variable) 19 -84.023 3.65 1.88300 40.8 20 -34.546 19.30 21 ∞ 2.50 1.54400 66.3 22 ∞ 0.82 Image plane ∞ Aspherical data 3rd page K = 0.00000e+00 A 4= 3.78433e-05 A 6= 1.18119e-07 A 8=-9.79737e-10 A10=-2.70513e-12 Side 4 K = 0.00000e+00 A 4= 4.97025e-05 A 6= 2.34231e-07 A 8=-1.78089e-09 A10=-1.32669e-12 Page 13 K = 0.00000e+00 A 4=-7.84649e-06 A 6=-8.10863e-09 A 8=-6.40641e-11 A10= 1.49456e-13 Side 14 K = 0.00000e+00 A 4= 2.54601e-06 A 6=-1.83892e-08 A 8=-3.97523e-11 A10= 8.86396e-14 Page 15 K = 0.00000e+00 A 4= 1.97418e-05 A 6=-3.93672e-07 A 8= 2.04045e-09 A10=-4.28961e-12 Page 16 K = 0.00000e+00 A 4= 3.73341e-05 A 6=-4.79322e-07 A 8= 2.38787e-09 A10=-5.56070e-12 Focal length 29.48 F-number 1.85 Half-angle 34.16 Image height 20.00 Lens length: 99.33 BF 21.74 Spacing between each lens group inf β-0.5 d4 2.79 7.32 d6 5.86 1.32 d14 2.00 7.52 d18 7.05 1.54

[0113] The various values ​​in each numerical example are summarized in Table 1 below.

[0114] [Table 1]

[0115] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the optical system of the present invention as an imaging optical system will be described with reference to Figure 9. In Figure 9, 11 is an imaging optical system composed of any of the optical systems described in Examples 1 to 4. 12 is an image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor, which is built into the camera body 10 and receives the optical image formed by the imaging optical system 11 and converts it into photoelectric light. The camera body 10 may be a so-called single-lens reflex camera with a quick-return mirror, or a so-called mirrorless camera without a quick-return mirror.

[0116] Thus, by applying the optical system of the present invention to an imaging device such as a digital still camera, it is possible to obtain lightweight images with good correction of various aberrations, even with a long focal length.

[0117] Each embodiment disclosed includes the following configuration:

[0118] (Composition 1) An optical system consisting of a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing. During focusing, the first lens group, the third lens group, and the fifth lens group remain stationary, while the second lens group and the fourth lens group move. When MD is the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image of the third lens group, and f is the focal length of the entire system, 0.40 <MD / f<2.30 An optical system characterized by satisfying the following conditional equation.

[0119] (Configuration 2) An optical system having a first lens group, a second lens group, and a third lens group arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing, During focusing, two or more lens groups arranged in the optical system move, When TL is the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane, and f is the focal length of the entire system, 0.50 <TL / f<7.00 An optical system characterized by satisfying the following conditional equation.

[0120] (Composition 3) The third lens group has a positive refractive power, and when the focal length of the third lens group is fm, 0.40 <fm / f<2.26 The optical system according to configuration 1 or 2, characterized by satisfying the following conditional expression.

[0121] (Composition 4) When the focal length of the third lens group is fm and the focal length of the second lens group is ff1, 0.19<|fm / ff1|<1.46 An optical system according to any one of configurations 1 to 3, characterized by satisfying the following conditional expression.

[0122] (Composition 5) When the focal length of the third lens group is fm and the focal length of the fourth lens group is ff2, 0.38<|fm / ff2|<1.64 An optical system according to any one of configurations 1 to 4, characterized in that it satisfies the following conditional expression.

[0123] (Composition 6) When TL is the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane, 0.50 <TL / f<7.00 An optical system according to any one of configurations 1 to 5, characterized in that it satisfies the following conditional expression.

[0124] (Composition 7) When the focal length of the second lens group is ff1, 0.45<|ff1 / f|<4.51 An optical system according to any one of configurations 1 to 6, characterized in that it satisfies the following conditional expression.

[0125] (Composition 8) When the focal length of the second lens group is ff1 and the focal length of the fourth lens group is ff2, 0.39<|ff1 / ff2|<4.20 An optical system according to any one of configurations 1 to 7, characterized by satisfying the following conditional expression.

[0126] (Composition 9) When the focal length of the first lens group is f1 and the focal length of the third lens group is fm, 0.42 < |f1 / fm| < 12.30 An optical system according to any one of configurations 1 to 8, characterized by satisfying the following conditional expression.

[0127] (Composition 10) When the focal length of the fifth lens group is fk, 0.60 < |fk / f| < 4.09 An optical system according to any one of configurations 1 to 9, characterized by satisfying the following conditional expression.

[0128] (Composition 11) When the focal length of the third lens group is fm, 0.49 <MD / fm<2.43 An optical system according to any one of configurations 1 to 10, characterized by satisfying the following conditional expression.

[0129] (Composition 12) When TL is the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane, 0.16 <MD / TL<0.59 An optical system according to any one of configurations 1 to 11, characterized by satisfying the following conditional expression.

[0130] (Composition 13) The optical system according to any one of configurations 1 to 12, characterized in that the first lens group has a negative refractive power.

[0131] (Composition 14) The optical system according to any one of configurations 1 to 13, characterized in that the third lens group has three or more lenses.

[0132] (Composition 15) An imaging device characterized by having an optical system described in any one of configurations 1 to 14 and an image sensor that receives an image formed by the optical system.

[0133] 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]

[0134] L0 optical system B1 First lens group B2 Second lens group B3 Third lens group

Claims

1. An optical system consisting of a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing. During focusing, the first lens group, the third lens group, and the fifth lens group remain stationary, while the second lens group and the fourth lens group move. When MD is the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image of the third lens group, and f is the focal length of the entire system, 0.40<MD / f<2.30 An optical system characterized by satisfying the following conditional equation.

2. The third lens group has a positive refractive power, and when the focal length of the third lens group is fm, 0.40<fm / f<2.26 The optical system according to claim 1, characterized in that it satisfies the following condition.

3. When the focal length of the third lens group is fm and the focal length of the second lens group is ff1, 0.19<|fm / ff1|<1.46 The optical system according to claim 1, characterized in that it satisfies the following condition.

4. When the focal length of the third lens group is fm and the focal length of the fourth lens group is ff2, 0.38<|fm / ff2|<1.64 The optical system according to claim 1, characterized in that it satisfies the following condition.

5. When TL is the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane, 0.50<TL / f<7.00 The optical system according to claim 1, characterized in that it satisfies the following condition.

6. When the focal length of the second lens group is ff1, 0.45<|ff1 / f|<4.51 The optical system according to claim 1, characterized in that it satisfies the following condition.

7. When the focal length of the second lens group is ff1 and the focal length of the fourth lens group is ff2, 0.39<|ff1 / ff2|<4.20 The optical system according to claim 1, characterized in that it satisfies the following condition.

8. When the focal length of the first lens group is f1 and the focal length of the third lens group is fm, 0.42<|f1 / fm|<12.30 The optical system according to claim 1, characterized in that it satisfies the following condition.

9. When the focal length of the fifth lens group is fk, 0.60<|fk / f|<4.09 The optical system according to claim 1, characterized in that it satisfies the following condition.

10. When the focal length of the third lens group is fm, 0.49<MD / fm<2.43 The optical system according to claim 1, characterized in that it satisfies the following condition.

11. When TL is the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane, 0.16<MD / TL<0.59 The optical system according to claim 1, characterized in that it satisfies the following condition.

12. The optical system according to claim 1, characterized in that the first lens group has a negative refractive power.

13. The optical system according to claim 1, characterized in that the third lens group has three or more lenses.

14. An optical system having a first lens group, a second lens group, and a third lens group arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during focusing, During focusing, two or more lens groups arranged in the optical system move, When TL is the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane, and f is the focal length of the entire system, 0.50<TL / f<7.00 An optical system characterized by satisfying the following conditional equation.

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