Optical system and imaging apparatus including the same

Abstract

To provide a compact and light-weight optical system which has high optical performance and a long focal length.SOLUTION: An optical system comprises a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, arranged in order from an object side to an image side, and the distance between the adjacent lens groups changes in focusing. The first lens group and the final lens group do not move for focusing. The first lens group comprises a first partial group having a plurality of positive lenses and a second partial group, arranged in order from the object side to the image side. The first partial group and the second partial group are arranged with the largest air interval among air intervals formed in the optical system. The optical system satisfies a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system suitable for use in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, and cameras for silver halide film. [Background technology]

[0002] A known example of an optical system with a long focal length is a so-called telephoto type optical system, which has a lens group with positive refractive power arranged on the object side and a lens group with negative refractive power arranged on the image side. Telephoto type optical systems are used, for example, in single-focus super telephoto lenses.

[0003] Generally, for a given F-number, the longer the focal length of a lens, the larger the effective diameter of the lens's light beam. Therefore, particularly in optical systems with long focal lengths, there is a demand for lenses that have a small F-number, are compact and lightweight, and have excellent correction for various aberrations.

[0004] Patent Document 1 discloses a telephoto type optical system that is a photographic optical system that is composed of, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power that moves during focusing, and a third lens group with positive refractive power. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-215561 Summary of the Invention [Problem to be solved by the invention]

[0006] In the optical system of Patent Document 1, the diameter of each lens arranged in the first lens group is large because the air gap formed within the first lens group is narrow, and therefore it cannot be said that weight reduction has been sufficiently achieved.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an optical system that has high optical performance, a long focal length, and is small and lightweight. [Means for solving the problem]

[0008] An optical system according to one aspect of the present invention includes, arranged in order from an object side to an image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, in which the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, When the Abbe number based on the d-line is νd, the materials of the at least three positive lenses arranged in the second sub-group are 70.0<νd<100.0 The conditional expression is satisfied, When the air distance between the first sub-group and the second sub-group is Dmax and the focal length of the first lens group is f1, 0.70 <Dmax / f1<1.50 The present invention is characterized in that the following conditional expression is satisfied:

[0009] An optical system according to another aspect of the present invention includes, arranged in order from an object side to an image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, wherein the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, the final lens group has four or more negative lenses, When the air distance between the first sub-group and the second sub-group is Dmax and the focal length of the first lens group is f1, 0.40 <Dmax / f1<1.50 The present invention is characterized in that the following conditional expression is satisfied:

[0010] An optical system according to another aspect of the present invention includes, arranged in order from an object side to an image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, wherein the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, the final lens group has four or more negative lenses, When the Abbe number based on the d-line is νd, the materials of the at least three positive lenses arranged in the second sub-group are 70.0<νd<100.0 The present invention is characterized in that the following conditional expression is satisfied: [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an optical system that has high optical performance, a long focal length, and is small and lightweight. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of the optical system of Example 1 when focusing to infinity. [Figure 2]In the optical system of Example 1, (A) is an aberration diagram when focusing at infinity, and (B) is an aberration diagram when focusing at close range. [Figure 3] 1 is a cross-sectional view of the optical system of Example 2 when focusing to infinity. [Figure 4] In the optical system of Example 2, (A) is an aberration diagram when focusing at infinity, and (B) is an aberration diagram when focusing at close range. [Figure 5] 10 is a cross-sectional view of the optical system of Example 3 when focusing to infinity. [Figure 6] In the optical system of Example 3, (A) is an aberration diagram when focusing at infinity, and (B) is an aberration diagram when focusing at close range. [Figure 7] 10 is a cross-sectional view of the optical system of Example 4 when focusing to infinity. [Figure 8] In the optical system of Example 4, (A) is an aberration diagram when focusing at infinity, and (B) is an aberration diagram when focusing at close range. [Figure 9] 10 is a cross-sectional view of the optical system of Example 5 when focusing to infinity. [Figure 10] In the optical system of Example 5, (A) is an aberration diagram when focusing at infinity, and (B) is an aberration diagram when focusing at close range. [Figure 11] Schematic diagram showing an imaging device DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, preferred embodiments of the present invention and examples of the respective embodiments will be described with reference to the accompanying drawings.

[0014] 1, 3, 5, 7, and 9 are cross-sectional views of the optical system L0 of Examples 1 to 5 according to each embodiment when focusing 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.

[0015] 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 embodiment may be used as a projection lens for a projector, etc. In this case, the left side is the screen side and the right side is the projected image side.

[0016] The optical system L0 of each embodiment includes, in order from the object side to the image side, a first lens group L1, a middle group M having one or more lens groups, and a final lens group Lr, and the spacing between adjacent lens groups changes during focusing. Each lens group may be composed of a single lens or multiple lenses. The lens groups may also include an aperture stop.

[0017] The solid arrows pointing downward in each lens cross-sectional view indicate the movement locus of each lens group during focusing from infinity to close range.

[0018] In each lens cross-sectional view, SP denotes an aperture stop. IP denotes an image plane, and when the optical system L0 of each embodiment is used in a digital still camera or digital video camera, the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is disposed thereon. When the optical system L0 of each embodiment is used as a photographic optical system for a silver halide film camera, a photosensitive surface corresponding to the film surface is disposed at the image plane IP.

[0019] 2(A), 4(A), 6(A), 8(A), and 10(A) are aberration diagrams when focusing at infinity in the optical systems of Examples 1 to 5 according to the respective embodiments.

[0020] 2(B), 4(B), 6(B), 8(B), and 10(B) are aberration diagrams when focusing at close range in the optical systems of Examples 1 to 5 according to the respective embodiments.

[0021] In the spherical aberration diagram, Fno is the F-number, the solid line shows the amount of spherical aberration for the d-line (wavelength 587.6 nm), and the dashed line shows the amount of spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line shows the amount of aberration ΔS on the sagittal image plane, and the dashed line shows the amount of aberration ΔM on the meridional image plane. The distortion diagram shows the amount of distortion for the d-line. The chromatic aberration diagram shows the amount of lateral chromatic aberration for the g-line. ω is the half angle of view (°).

[0022] Next, the optical system L0 according to the first embodiment will be described.

[0023] The optical system L0 according to the first embodiment is composed of a first lens group L1 with positive refractive power, an intermediate group M having one or more lens groups, and a final lens group Lr, arranged in this order from the object side to the image side, and the spacing between adjacent lens groups changes during focusing.

[0024] Because the first lens group L1 has positive refractive power, the principal point of the optical system L0 is located on the object side, shortening the overall lens length of the optical system L0. Here, the overall lens length is the sum of the distance on the optical axis from the lens surface of the optical system L0 closest to the object to the lens surface of the optical system L0 closest to the image side, and the back focus. Here, the back focus is the air-equivalent value of the distance on the optical axis between the lens surface of the optical system L0 closest to the image side and the image plane.

[0025] Furthermore, during focusing, the first lens group L1 and the final lens group Lr are kept stationary, and the lens group arranged in the intermediate group M moves during focusing. The first lens group L1 has a relatively large diameter and therefore a heavy mass, and the height of off-axial rays from the final lens group Lr is relatively high. Therefore, moving the final lens group Lr during focusing causes large fluctuations in field curvature and other factors that occur during focusing. Therefore, by keeping the first lens group L1 and the final lens group Lr stationary and moving the lens group arranged in the intermediate group M during focusing, it is possible to perform high-speed focusing while effectively correcting fluctuations in aberrations that occur during focusing.

[0026] The first lens group L1 is composed of a first subgroup L1a and a second subgroup L1b, which are arranged in order from the object side to the image side and each subgroup L1a has a plurality of positive lenses. The first subgroup L1a and the second subgroup L1b are arranged with the largest air gap between them among the air gaps formed in the optical system L0. The first subgroup L1a has a plurality of positive lenses, which enables effective correction of spherical aberrations and the like that occur in the first subgroup L1a.

[0027] Furthermore, in telephoto optical systems, the axial light beam incident from the object side generally converges toward the image side. Therefore, by arranging the first sub-unit L1a and the second sub-unit L1b with the largest air gap between them among the air gaps formed in the optical system L0, it is possible to reduce the diameter of the lenses arranged after the second sub-unit L1b. As a result, it is possible to reduce the weight of the optical system L0.

[0028] The optical system L0 according to the first embodiment is configured to satisfy the following conditional expressions. 70.0<νd<100.0 (1) 0.70 <Dmax / f1<1.50···(2)

[0029] Here, vd is the Abbe number based on the d-line, and the materials of at least three positive lenses arranged in the second sub-unit L1b satisfy conditional expression (1). Dmax is the air gap between the first sub-unit L1a and the second sub-unit L1b, and f1 is the focal length of the first lens unit L1. Note that the air gap refers to the air gap on the optical axis.

[0030] Conditional formula (1) is a conditional formula for obtaining the effect of chromatic aberration correction by the positive lens arranged in the second subunit L1b, and by having three or more positive lenses that satisfy conditional formula (1), it becomes easier to effectively correct the axial chromatic aberration and chromatic aberration of magnification that occur in the optical system L0.

[0031] If the Abbe number νd falls below the lower limit of conditional formula (1) and becomes small, the material of the positive lens will have too high dispersion, which undesirably increases axial chromatic aberration and lateral chromatic aberration. There is no optical glass that exceeds the upper limit of conditional formula (1). If the number of positive lens elements satisfying conditional formula (1) is two or less, the refractive power of the positive lens element will be strong in order to achieve sufficient chromatic aberration correction, which undesirably increases spherical aberration.

[0032] Conditional formula (2) is a conditional formula for achieving a configuration that facilitates weight reduction of the optical system L0 and an appropriate refractive power of the first lens unit L1. If Dmax becomes small and falls far below the lower limit of conditional formula (2), particularly if the lower limit is below 0.40, the diameters of the lenses disposed after the second subunit L1b become large, and the mass of the optical system L0 becomes too heavy. Preferably, Dmax is increased so that the lower limit exceeds 0.70, resulting in a configuration that facilitates weight reduction of the optical system L0.

[0033] If the upper limit of conditional expression (2) is exceeded and the refractive power of the first lens unit L1 becomes strong, the spherical aberration occurring in the first lens unit L1 becomes large, which is not preferable.

[0034] By satisfying the above configuration, the optical system L0 according to the first embodiment has high optical performance, and can provide an optical system that has a long focal length, is small, and is lightweight.

[0035] It is preferable that at least one of the upper and lower limits of the ranges of the values of the conditional expressions (1) and (2) be set to the values of the following conditional expressions (1a) and (2a). 75.0<νd<98.0 (1a) 0.72 <Dmax / f1<1.40···(2a)

[0036] It is even more preferable that at least one of the upper and lower limits of the numerical ranges of conditional expressions (1) and (2) be set to the ranges of the following conditional expressions (1b) and (2b). 80.0<νd<96.0 (1b) 0.74 <Dmax / f1<1.30···(2b)

[0037] Next, the optical system L0 according to the second embodiment will be described.

[0038] The optical system L0 according to the second embodiment is composed of a first lens group L1 with positive refractive power, an intermediate group M having one or more lens groups, and a final lens group Lr, arranged in that order from the object side to the image side, and the spacing between adjacent lens groups changes during focusing.

[0039] Because the first lens group L1 has positive refractive power, the principal point of the optical system L0 is located on the object side, shortening the overall lens length of the optical system L0. Here, the overall lens length is the sum of the distance on the optical axis from the surface of the optical system L0 closest to the object to the surface of the optical system L0 closest to the image side and the back focus. Here, the back focus is the air-equivalent value of the distance on the optical axis between the surface of the optical system L0 closest to the image side and the image plane.

[0040] Furthermore, during focusing, the first lens group L1 and the final lens group Lr are kept stationary, and the lens group arranged in the intermediate group M moves during focusing. The first lens group L1 has a relatively large diameter and is heavy in mass, and the height of off-axial rays from the final lens group Lr is relatively high, so moving the final lens group Lr during focusing causes large fluctuations in field curvature and other factors that occur during focusing. Therefore, by keeping the first lens group L1 and the final lens group Lr stationary and moving the lens group arranged in the intermediate group M during focusing, it is possible to perform high-speed focusing while suppressing fluctuations in aberrations that occur during focusing.

[0041] The first lens group L1 is composed of a first subgroup L1a and a second subgroup L1b, which are arranged in order from the object side to the image side and each subgroup L1a has a plurality of positive lenses. The first subgroup L1a and the second subgroup L1b are arranged with the largest air gap between them among the air gaps formed in the optical system L0. The first subgroup L1a has a plurality of positive lenses, which enables excellent correction of spherical aberrations and the like.

[0042] Furthermore, in telephoto optical systems, the axial light beam incident from the object side generally converges toward the image side. Therefore, by arranging the first sub-unit L1a and the second sub-unit L1b with the largest air gap between them among the air gaps formed in the optical system L0, it is possible to reduce the diameter of the lenses arranged after the second sub-unit L1b. As a result, it is possible to reduce the weight of the optical system L0.

[0043] Furthermore, the final lens group Lr has four or more negative lenses, which makes it possible to effectively reduce the Petzval sum of the optical system L0 and correct the curvature of field.

[0044] The optical system L0 according to the second embodiment is configured to satisfy the following conditional expressions. 0.40 <Dmax / f1<1.50···(2c)

[0045] Here, Dmax is the air distance between the first sub-unit L1a and the second sub-unit L1b, and f1 is the focal length of the first lens unit L1. Note that the air distance refers to the air distance on the optical axis.

[0046] Conditional formula (2c) is a conditional formula for reducing the weight of the optical system L0 and obtaining an appropriate refractive power for the first lens unit L1. If the lower limit of conditional formula (2c) is not met and Dmax becomes small, the diameter of the lenses arranged after the second partial unit L1b becomes large, and the mass of the optical system L0 becomes too heavy. If the upper limit of conditional formula (2c) is exceeded and the refractive power of the first lens unit L1 becomes strong, the spherical aberration generated in the first lens unit L1 becomes large, which is undesirable.

[0047] By satisfying the above-mentioned configuration, the optical system L0 according to the second embodiment has high optical performance, and can provide an optical system that has a long focal length, is small, and is lightweight.

[0048] It is preferable that at least one of the upper and lower limits of the range of the value of conditional formula (2c) is set to the value of the following conditional formula (2d). 0.50 <Dmax / f1<1.40···(2d)

[0049] It is even more preferable that at least one of the upper and lower limits of the numerical range of conditional formula (2c) is set to the range of the following conditional formula (2e). 0.60 <Dmax / f1<1.30···(2e)

[0050] Next, the optical system L0 according to the third embodiment will be described.

[0051] The optical system L0 according to the third embodiment is composed of a first lens group L1 with positive refractive power, an intermediate group M having one or more lens groups, and a final lens group Lr, arranged in that order from the object side to the image side, and the spacing between adjacent lens groups changes during focusing.

[0052] Because the first lens group L1 has positive refractive power, the principal point of the optical system L0 is located on the object side, shortening the overall lens length of the optical system L0. Here, the overall lens length is the sum of the distance on the optical axis from the surface of the optical system L0 closest to the object to the surface of the optical system L0 closest to the image side and the back focus. Here, the back focus is the air-equivalent value of the distance on the optical axis between the surface of the optical system L0 closest to the image side and the image plane.

[0053] Furthermore, during focusing, the first lens group L1 and the final lens group Lr are kept stationary, and the lens group arranged in the intermediate group M moves during focusing. The first lens group L1 has a relatively large diameter and is heavy in mass, and the height of off-axial rays from the final lens group Lr is relatively high, so moving the final lens group Lr during focusing causes large fluctuations in field curvature and other factors that occur during focusing. Therefore, by keeping the first lens group L1 and the final lens group Lr stationary and moving the lens group arranged in the intermediate group M during focusing, it is possible to perform high-speed focusing while suppressing fluctuations in aberrations that occur during focusing.

[0054] The first lens group L1 is composed of a first subgroup L1a and a second subgroup L1b, which are arranged in order from the object side to the image side and each subgroup L1a has a plurality of positive lenses. The first subgroup L1a and the second subgroup L1b are arranged with the largest air gap between them among the air gaps formed in the optical system L0. The first subgroup L1a has a plurality of positive lenses, which enables excellent correction of spherical aberrations and the like.

[0055] Furthermore, in telephoto optical systems, the axial light beam incident from the object side generally converges toward the image side. Therefore, by arranging the first sub-unit L1a and the second sub-unit L1b with the largest air gap between them among the air gaps formed in the optical system L0, it is possible to reduce the diameter of the lenses arranged after the second sub-unit L1b. As a result, it is possible to reduce the weight of the optical system L0.

[0056] Furthermore, the final lens group Lr has four or more negative lenses, which makes it possible to effectively reduce the Petzval sum of the optical system L0 and correct the curvature of field.

[0057] The optical system L0 according to the third embodiment is configured to satisfy the following conditional expressions. 70.0<νd<100.0 (1)

[0058] Here, νd is the Abbe number when the d-line is used as a reference, and the materials of at least three positive lenses arranged in the second subunit L1b satisfy conditional expression (1).

[0059] Conditional formula (1) is a conditional formula for obtaining the effect of chromatic aberration correction by the positive lens arranged in the second subunit L1b, and by having three or more positive lenses that satisfy conditional formula (1), it becomes easier to effectively correct the axial chromatic aberration and chromatic aberration of magnification that occur in the optical system L0.

[0060] If the Abbe number νd falls below the lower limit of conditional formula (1) and becomes small, the material of the positive lens will have too high dispersion, which undesirably increases axial chromatic aberration and lateral chromatic aberration. There is no optical glass that exceeds the upper limit of conditional formula (1). If the number of positive lens elements satisfying conditional formula (1) is two or less, the refractive power of the positive lens element will be strong in order to achieve sufficient chromatic aberration correction, which undesirably increases spherical aberration.

[0061] By satisfying the above-mentioned configuration, the optical system L0 according to the third embodiment has high optical performance, and can provide an optical system that has a long focal length, is small, and is lightweight.

[0062] It is preferable that at least one of the upper limit and lower limit of the range of the numerical value of conditional expression (1) is set to the numerical value of the following conditional expression (1a). 75.0<νd<98.0 (1a)

[0063] It is even more preferable that at least one of the upper limit and lower limit of the numerical range of conditional expression (1) is set to the range of the following conditional expression (1b). 80.0<νd<96.0 (1b)

[0064] Next, a preferred configuration of the optical system L0 according to each embodiment will be described.

[0065] The first sub-unit L1a is preferably made up of two positive lenses, which makes it possible to reduce the spherical aberration occurring in the first sub-unit L1a and also to reduce the weight.

[0066] The intermediate group M preferably has negative refractive power, which allows for good correction of the curvature of field of the optical system L0.

[0067] The second sub-unit L1b preferably has two negative lenses, which allows for good correction of longitudinal chromatic aberration and the like that occurs in the first sub-unit L1a.

[0068] During image blur correction, it is preferable that part or all of the final lens group Lr move in a direction that includes a component perpendicular to the optical axis. Because the lenses arranged in the final lens group Lr have a relatively small diameter in the optical system L0, the weight of one or more lenses that move during image blur correction can be reduced.

[0069] The optical system L0 preferably has an aperture stop SP located closest to the image in the first lens group L1. By locating the aperture stop SP closest to the image in the first lens group L1, the height from the optical axis of off-axis rays passing through the final lens group Lr in particular can be reduced, and the weight of the final lens group Lr can be reduced.

[0070] It is preferable that the number of positive lenses arranged in the second sub-unit L1b is four. By configuring it with four lenses, it is possible to strengthen the refractive power of the second sub-unit L1b within an appropriate range, shorten the overall lens length of the optical system L0, and effectively correct spherical aberration and the like.

[0071] It is preferable that the intermediate group M has a negative meniscus lens with a convex surface facing the object side. By having a negative meniscus lens with a convex surface facing the object side, spherical aberrations and the like can be effectively corrected.

[0072] The final lens group Lr preferably has three or more cemented lenses. Because lenses located close to the image plane are prone to generating ghost light, by using cemented lenses located close to the image plane, it is possible to suppress ghost light while effectively correcting chromatic aberration of magnification, curvature of field, and the like.

[0073] The final lens group Lr preferably has a cemented lens made up of three lenses arranged in that order from the object side to the image side: negative, positive, and negative. Since lenses arranged close to the image plane are prone to generating ghost light, by using a cemented lens for the lenses arranged close to the image plane, it is possible to suppress ghost light while effectively correcting chromatic aberration of magnification, curvature of field, and the like.

[0074] It is preferable that the optical system L0 of each embodiment satisfies one or more of the following conditional expressions. 0.45 <OTL / f<1.20···(3) 0.20 <f1a / f<1.00···(4) 0.20 <f1 / f<0.80···(5) 1.00 <f1a_min / f1<8.00···(6) 10.0<νd_min<35.0 (7) 0.50 <Bab_max / Fno<2.00···(8) 1.3 <BF / IH<5.0···(9) 0.10 <f1b / f<0.80···(10)

[0075] Here, OTL is the distance on the optical axis from the lens surface closest to the object to the image plane in the optical system L0. f is the focal length of the entire system, i.e., the optical system L0. f1a is the focal length of the first sub-unit L1a. f1a_min is the focal length of the positive lens with the shortest focal length among the positive lenses arranged in the first sub-unit L1a. νd_min is the smallest Abbe number of the material of the positive lenses arranged in the first sub-unit L1a.

[0076] Bab_max is the maximum absolute value of the position sensitivity among the lens groups arranged in the intermediate group M that move during focusing. Fno is the F-number of the optical system L0. BF is the distance on the optical axis from the lens surface closest to the image in the optical system L0 to the image plane. IH is the maximum image height in the optical system L0. Here, the maximum image height is the image height at which the peripheral light intensity is 20% relative to the axial image point. f1b is the focal length of the second subgroup L1b.

[0077] Next, the technical meaning of the above-mentioned conditional expressions (3) to (10) will be explained.

[0078] If the lower limit of conditional expression (3) is exceeded, the distance on the optical axis from the lens surface closest to the object in optical system L0 to the image plane becomes short, which is undesirable as the refractive power of each lens group, such as the first lens group L1, becomes too strong and various aberrations become large.If the upper limit of conditional expression (3) is exceeded, the total lens length becomes long, which is undesirable.

[0079] If the lower limit of conditional expression (4) is not met and the refractive power of the first sub-unit L1a becomes too strong, spherical aberrations and the like that occur in the first sub-unit L1a become large, which is undesirable. If the upper limit of conditional expression (4) is met and the refractive power of the first sub-unit L1a becomes too weak, the principal point of the optical system L0 is located on the image side. As a result, the overall lens length becomes long, which is undesirable.

[0080] If the lower limit of conditional expression (5) is exceeded and the refractive power of the first lens unit L1 becomes too strong, spherical aberrations and the like generated in the first lens unit L1 become large, which is undesirable. If the upper limit of conditional expression (5) is exceeded and the refractive power of the first lens unit L1 becomes too weak, the principal point of the optical system L0 is located on the image side, which is undesirable because the overall lens length becomes long.

[0081] If the lower limit of conditional expression (6) is exceeded, the refractive power of the positive lens with the shortest focal length among the positive lenses arranged in the first lens group L1 becomes too strong, which is undesirable because spherical aberration and the like occurring in the positive lens with the shortest focal length become large. If the upper limit of conditional expression (6) is exceeded, the refractive power of the positive lens with the shortest focal length among the positive lenses arranged in the first lens group L1 becomes too weak. As a result, spherical aberration and the like occurring in the positive lenses other than the positive lens with the shortest focal length arranged in the first lens group L1 become large, which is undesirable.

[0082] Conditional expression (7) specifies the minimum Abbe number of the material of the positive lens disposed in the second subunit L1b in order to correct short wavelength, i.e., second-order axial chromatic aberration. Below the lower limit of conditional expression (7), the minimum Abbe number of the positive lens becomes too small, undesirably increasing first-order axial chromatic aberration. Above the upper limit of conditional expression (7), the minimum Abbe number of the positive lens becomes too large. As a result, the partial dispersion ratio of the positive lens for the g-line and F-line becomes too small, undesirably increasing second-order axial chromatic aberration.

[0083] Conditional expression (8) specifies the ratio between the position sensitivity and the F-number of the lens group that has the highest position sensitivity among the lens groups that move during focusing and are arranged in the intermediate group M, in order to achieve high-speed, high-precision focusing and compactness.

[0084] Here, the position sensitivity refers to the amount of movement of the image plane when the lens group in question moves a unit amount in the optical axis direction, and is expressed by the following equation using the lateral magnification βf of the lens group in question and the combined lateral magnification βr of all lenses arranged on the image side of the lens group in question. B=(1-βf×βf)×βr×βr

[0085] If the lower limit of conditional expression (8) is exceeded, the amount of movement of the lens group that moves during focusing increases, and therefore the air gap required for movement in the optical axis direction increases. As a result, the overall lens length of optical system L0 increases, which is undesirable. If the upper limit of conditional expression (8) is exceeded, the position sensitivity of the lens group that moves during focusing relative to the F-number becomes too high. As a result, the amount of focus deviation due to stop position shift that occurs during focusing increases, which is undesirable.

[0086] If the lower limit of conditional expression (9) is exceeded, the distance on the optical axis from the lens surface closest to the image side in optical system L0 to the image plane becomes too short. If the image sensor is located at the image plane, ghost light generated by reflection between the image sensor and the lens surface closest to the image side in optical system L0 becomes noticeable, which is undesirable. If the upper limit of conditional expression (9) is exceeded, the overall lens length of optical system L0 becomes too long, which is undesirable.

[0087] If the lower limit of conditional expression (10) is exceeded and the refractive power of the second sub-unit L1b becomes too strong, spherical aberrations and the like that occur in the second sub-unit L1b become large, which is undesirable. If the upper limit of conditional expression (10) is exceeded and the refractive power of the second sub-unit L1b becomes too weak, the principal point of the optical system L0 is located on the image side. As a result, the overall lens length becomes long, which is undesirable.

[0088] It is more preferable to set at least one of the upper and lower limits of the conditional expressions (2) to (10) to the following numerical ranges. 0.60 <OTL / f<1.15···(3a) 0.40 <f1a / f<0.95···(4a) 0.25 <f1 / f<0.70···(5a) 2.00 <f1a_min / f1<7.00···(6a) 15.0<νd_min<34.5···(7a) 1.00 <Bab_max / Fno<1.98···(8a) 1.4 <BF / IH<3.0···(9a) 0.15 <f1b / f<0.60···(10a)

[0089] It is more preferable to set at least one of the upper and lower limits of the conditional expressions (2) to (10) to the following numerical ranges. 0.80 <OTL / f<1.10···(3b) 0.60 <f1a / f<0.90···(4b) 0.30 <f1 / f<0.50···(5b) 2.50 <f1a_min / f1<6.50···(6b) 25.0<νd_min<34.0 (7b) 1.20 <Bab_max / Fno<1.95···(8b) 1.5 <BF / IH<2.0···(9b) 0.20 <f1b / f<0.50···(10b)

[0090] Next, the configuration of the optical system L0 of examples according to each embodiment will be described in detail. From Example 2 onwards, differences from Example 1 will be mainly described.

[0091] [Example 1] The optical system L0 of Example 1 comprises, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, an intermediate unit M, and a final lens unit Lr, and the spacing between adjacent lens units changes during focusing. The first lens unit L1 and the final lens unit Lr do not move during focusing.

[0092] Here, the intermediate group M is composed of the second lens group L2 and the third lens group L3, and the second lens group L3 and the third lens group L3 move by different amounts during focusing. By moving two lens groups during focusing, a configuration is achieved that makes it easy to suppress fluctuations in various aberrations that occur during focusing. Furthermore, by constructing the second lens group L2 and the third lens group L3 each using a negative single lens, the weight of the lens groups that move during focusing can be reduced.

[0093] Furthermore, of the air gaps formed in the optical system L0, the first sub-unit L1a and the second sub-unit L1b are arranged with the largest air gap between them, and the first sub-unit L1a is composed of two positive lenses, including a positive meniscus lens with a convex surface facing the object side. An on-axis marginal ray incident from the object side is incident at an angle close to perpendicular to the lens surface of the positive meniscus lens with a convex surface facing the object side, which makes it easier to suppress the occurrence of spherical aberration.

[0094] Furthermore, during image blur correction, the three lenses arranged in the final lens group Lr move in a direction that includes a component perpendicular to the optical axis. The movement of the three lenses makes it easier to suppress fluctuations in various aberrations that occur during image blur correction.

[0095] The second sub-unit L1b also has three biconvex lenses. By including three biconvex lenses, the refractive power of the second sub-unit L1b can be easily strengthened, and the overall lens length of the optical system L0 can be shortened.

[0096] [Example 2] In Example 2, a subgroup with negative refractive power is added to the image side of the final lens group Lr in Example 1. This makes it possible to achieve an even longer focal length than in Example 1. By arranging a plurality of positive lenses and a plurality of negative lenses in the subgroup with negative refractive power, it becomes easier to suppress curvature of field, chromatic aberration of magnification, and the like.

[0097] [Example 3] The intermediate unit M in Example 3 is made up of the second lens unit L2, and the second lens unit L2 moves for focusing. By moving only one lens unit for focusing, it becomes easier to suppress aberration fluctuations caused by relative decentering between adjacent lens units during focusing.

[0098] [Example 4] The first sub-unit L1a of Example 4 is made up of three positive lenses. By being made up of three positive lenses, it becomes easier to suppress spherical aberration and the like that occurs in the first sub-unit L1a.

[0099] [Example 5] The second sub lens unit L1b in the fifth embodiment has two positive meniscus lenses with convex surfaces facing the object side, which makes it easier to suppress spherical aberrations and the like.

[0100] Numerical Examples 1 to 5 corresponding to Examples 1 to 5, respectively, are shown below.

[0101] 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 at 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 Nd, NF, and NC, respectively, when the refractive indices at the Fraunhofer d-line (wavelength 587.6 nm), F-line (wavelength 486.1 nm), C-line (wavelength 656.3 nm), and g-line (wavelength 435.8 nm) are: νd=(Nd-1) / (NF-NC) It is expressed as:

[0102] BF is the back focus.

[0103] 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.

[0104] [Numerical Example 1] Unit: mm Surface Data Surface number rd nd νd 1 361.590 8.96 1.48749 70.2 2 -23384.147 0.30 3 165.569 12.81 1.43387 95.1 4 622.689 132.44 5 87.354 12.05 1.43875 94.7 6 -239.145 2.50 1.80610 33.3 7 57.954 0.18 8 56.866 12.48 1.43387 95.1 9 -360.152 0.20 10 76.054 7.94 1.43387 95.1 11 814.525 2.12 12 -268.908 2.00 1.61340 44.3 13 59.417 10.11 1.66382 27.4 14 -194.105 4.41 15 (Aperture) ∞ (Variable) 16 25372.899 1.70 1.59522 67.7 17 71.961 (variable) 18 119.836 1.70 1.59522 67.7 19 58.499 (variable) 20 196.399 1.50 1.98612 16.5 21 116.011 3.12 1.73800 32.3 22 -606.051 2.33 23 -179.127 3.48 1.80000 29.8 24 -60.919 1.50 1.57144 71.6 25 86.488 1.47 26 855.808 1.50 1.80400 46.5 27 119.682 7.35 28 -42.017 2.00 1.49700 81.5 29 -49.197 2.00 30 146.161 6.69 1.85026 32.3 31 -56.569 1.60 1.98612 16.5 32 -95.361 56.03 33 -3569.656 2.00 1.72825 28.5 34∞BF Image plane ∞ Various data Focal length 387.98 F-number 2.91 Half angle of view 3.19 Image height 21.64 Lens total length 372.01 BF 38.28 The distance between adjacent lens groups on the optical axis when focused at infinity d15 3.44 d17 5.07 d19 20.74 d34 38.28 The distance on the optical axis between adjacent lens groups when focused at close range (2500 mm from the image plane toward the object) d15 18.74 d17 5.34 d19 5.17 d34 38.28 Lens group data Group starting plane focal length L1 1 172.37 L2 16 -121.24 L3 18 -194.02 Lr 20 207.60

[0105] [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 361.590 8.96 1.48749 70.2 2 -23384.147 0.30 3 165.569 12.81 1.43387 95.1 4 622.689 132.44 5 87.354 12.05 1.43875 94.7 6 -239.145 2.50 1.80610 33.3 7 57.954 0.18 8 56.866 12.48 1.43387 95.1 9 -360.152 0.20 10 76.054 7.94 1.43387 95.1 11 814.525 2.12 12 -268.908 2.00 1.61340 44.3 13 59.417 10.11 1.66382 27.4 14 -194.105 4.41 15 (Aperture) ∞ (Variable) 16 25372.899 1.70 1.59522 67.7 17 71.961 (variable) 18 119.836 1.70 1.59522 67.7 19 58.499 (variable) 20 196.399 1.50 1.98612 16.5 21 116.011 3.12 1.73800 32.3 22 -606.051 2.33 23 -179.127 3.48 1.80000 29.8 24 -60.919 1.50 1.57144 71.6 25 86.488 1.47 26 855.808 1.50 1.80400 46.5 27 119.682 7.35 28 -42.017 2.00 1.49700 81.5 29 -49.197 2.00 30 146.161 6.69 1.85026 32.3 31 -56.569 1.60 1.98612 16.5 32 -95.361 2.48 33 22.976 8.53 1.48749 70.2 34 167.264 0.17 35 51.442 3.74 1.57501 41.5 36 121.848 1.00 1.90525 35.0 37 27.926 10.16 38 -672.196 0.95 1.72916 54.7 39 14.961 14.43 1.59270 35.3 40 -15.436 0.95 1.81600 46.6 41 75.686 0.65 42 31.712 9.96 1.60342 38.0 43 -22.105 1.05 2.00100 29.1 44 -102.267 1.99 45 -3569.656 2.00 1.72825 28.5 46∞BF Image plane ∞ Various data Focal length 543.19 F-number 4.12 Half angle of view: 2.28 Image height 21.64 Lens total length 372.05 BF 38.30 The distance between adjacent lens groups on the optical axis when focused at infinity d15 3.44 d17 5.07 d19 20.74 d46 38.30 The distance on the optical axis between adjacent lens groups when focused at close range (2500 mm from the image plane toward the object) d15 18.74 d17 5.34 d19 5.17 d46 38.30 Lens group data Group starting plane focal length L1 1 172.37 L2 16 -121.24 L3 18 -194.02 Lr 20 -186.53

[0106] [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 327.048 9.19 1.48749 70.2 2 5245.194 0.30 3 162.489 13.09 1.43387 95.1 4 608.498 127.87 5 82.472 12.23 1.43875 94.7 6 -289.667 2.50 1.80610 33.3 7 58.126 0.38 8 57.018 12.94 1.43387 95.1 9 -276.265 0.20 10 81.977 6.07 1.43387 95.1 11 249.715 3.52 12 -218.769 2.00 1.61340 44.3 13 63.275 9.73 1.66382 27.4 14 -182.170 4.41 15 (Aperture) ∞ (Variable) 16 2790.085 1.70 1.59522 67.7 17 81.683 3.94 18 90.304 1.70 1.59522 67.7 19 53.932 (variable) 20 150.289 1.50 1.98612 16.5 21 94.557 2.95 1.73800 32.3 22 1100.197 2.43 23 -268.743 3.39 1.80000 29.8 24 -68.308 1.50 1.57144 71.6 25 91.910 1.49 26 -2327.604 1.50 1.80400 46.5 27 108.456 7.61 28 -38.536 2.00 1.49700 81.5 29 -43.990 2.00 30 151.525 6.64 1.85026 32.3 31 -57.952 1.60 1.98612 16.5 32 -92.318 52.26 33 -2821.222 2.00 1.72825 28.5 34∞BF Image plane ∞ Various data Focal length 387.99 F-number 2.91 Half angle of view 3.19 Image height 21.64 Lens total length 366.59 BF 38.51 The distance between adjacent lens groups on the optical axis when focused at infinity d15 3.40 d19 24.03 d34 38.51 The distance on the optical axis between adjacent lens groups when focused at close range (2500 mm from the image plane toward the object) d15 21.69 d19 5.74 d34 38.51 Lens group data Group starting plane focal length L1 1 182.22 L2 16 -85.88 Lr 20 241.88

[0107] [Numerical Example 4] Unit: mm Surface Data Surface number rd nd νd 1 425.413 5.58 1.48749 70.2 2 1011.838 0.20 3 160.647 9.15 1.43387 95.1 4 296.502 4.68 5 296.502 7.00 1.52841 76.5 6 774.718 156.50 7 73.158 14.86 1.43875 94.7 8 -88.608 2.50 1.80610 33.3 9 49.119 0.18 10 49.167 11.92 1.43387 95.1 11 -393.429 0.20 12 86.394 4.64 1.53775 74.7 13 179.098 0.25 14 77.706 2.00 1.61340 44.3 15 62.770 10.09 1.66382 27.4 16 -131.534 4.41 17 (Aperture) ∞ (Variable) 18 -312.795 1.70 1.59522 67.7 19 71.714 (variable) 20 -413.700 1.70 1.59522 67.7 21 47.958 (variable) 22 1834.208 1.50 1.98612 16.5 23 78.236 5.09 1.73800 32.3 24 -58.171 1.00 25 822.148 3.48 1.80000 29.8 26 -71.260 1.50 1.57144 71.6 27 -552.268 0.88 28 -152.904 1.50 1.80400 46.5 29 51.689 10.07 30 -34.092 2.00 1.49700 81.5 31 -44.191 5.00 32 92.722 4.77 1.85026 32.3 33 -256.516 1.60 1.98612 16.5 34 -271.981 23.21 35 487.337 2.00 1.51742 52.4 36∞BF Image plane ∞ Various data Focal length 387.73 F-number 2.91 Half angle of view 3.19 Image height 21.64 Lens total length 372.08 BF 38.09 The distance between adjacent lens groups on the optical axis when focused at infinity d17 3.22 d19 5.52 d21 24.08 d36 38.09 The distance on the optical axis between adjacent lens groups when focused at close range (2500 mm from the image plane toward the object) d17 4.48 d19 22.67 d21 5.67 d36 38.09 Lens group data Group starting plane focal length L1 1 125.88 L2 18 -97.85 L3 20 -72.10 Lr 22 156.02

[0108] [Numerical Example 5] Surface Data Surface number rd nd νd 1* 218.187 5.14 1.48749 70.2 2* 531.225 0.30 3 112.850 15.44 1.43387 95.1 4 -824.686 86.36 5 72.081 7.08 1.43875 94.7 6 -240.031 2.00 1.77047 29.7 7 29.896 0.15 8 29.769 8.41 1.43387 95.1 9 155.824 0.20 10 41.829 4.70 1.43387 95.1 11 83.309 3.40 12 104.933 1.00 1.61340 44.3 13 31.853 8.02 1.66382 27.4 14 -149.804 4.41 15 (Aperture) ∞ (Variable) 16 82.652 1.00 1.59522 67.7 17 23.645 (variable) 18 -63.608 1.00 1.59522 67.7 19 96.881 (variable) 20 44.040 1.00 1.98612 16.5 21 29.858 4.60 1.73800 32.3 22 2010.829 1.36 23 202.596 2.67 1.80000 29.8 24 -142.939 1.00 1.49700 81.5 25 36.341 3.50 26 -124.648 1.00 1.80400 46.5 27 172.170 2.30 28 65.689 6.92 1.59270 35.3 29 -49.837 1.60 1.98612 16.5 30 -63.773 5.61 31 259.527 2.00 1.77047 29.7 32∞BF Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 4=-2.06568e-08 A 6=-9.98483e-12 A 8=-8.83084e-16 A10=-8.74981e-19 2nd side K = 0.00000e+00 A 4= 3.66431e-08 A 6=-8.68897e-12 A 8=-9.59089e-16 A10=-7.91548e-19 Various data Focal length 289.77 F-number 2.91 Half angle of view: 4.27 Image height 21.64 Lens length 240.23 BF 37.97 The distance between adjacent lens groups on the optical axis when focused at infinity d15 2.68 d17 10.08 d19 7.31 d32 37.97 The distance on the optical axis between adjacent lens groups when focused at close range (2500 mm from the image plane toward the object) d15 9.83 d17 7.30 d19 2.95 d32 37.97 Lens group data Group starting plane focal length L1 1 120.96 L2 16 -56.00 L3 18 -64.36 Lr 20 70.39

[0109] The various values in each numerical example are summarized in Table 1 below.

[0110] [Table 1]

[0111] [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 Fig. 11. In Fig. 11, 11 denotes an imaging optical system configured using any of the optical systems described in Examples 1 to 5. 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into a camera body 10 and receives and photoelectrically converts an optical image formed by the imaging optical system 11. The 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.

[0112] In this way, by applying the optical system L0 of the present invention to an imaging device such as a digital still camera, it is possible to obtain a high-resolution image with a wide angle of view.

[0113] The disclosure of each embodiment includes the following configuration.

[0114] (Configuration 1) An optical system comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, in which the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, When the Abbe number based on the d-line is νd, the material of the at least three positive lenses arranged in the second sub-group is 70.0<νd<100.0 The conditional expression is satisfied, When the air distance between the first sub-group and the second sub-group is Dmax and the focal length of the first lens group is f1, 0.70 <Dmax / f1<1.50 An optical system characterized by satisfying the following conditional expression:

[0115] (Configuration 2) In the optical system, when the distance on the optical axis from the lens surface closest to the object side to the image plane is OTL and the focal length of the entire system is f, 0.45 <OTL / f<1.20 The optical system according to configuration 1, characterized in that the following condition is satisfied:

[0116] (Configuration 3) When the focal length of the first subgroup is f1a and the focal length of the entire system is f, 0.20 <f1a / f<1.00 3. The optical system according to configuration 1 or 2, wherein the following condition is satisfied:

[0117] (Configuration 4) When the focal length of the entire system is f, 0.20 <f1 / f<0.80 4. The optical system according to any one of configurations 1 to 3, wherein the following condition is satisfied:

[0118] (Configuration 5) When the focal length of the positive lens with the shortest focal length among the positive lenses arranged in the first lens group is f1a_min, 1.50 <f1a_min / f1<8.00 5. The optical system according to any one of configurations 1 to 4, wherein the following condition is satisfied:

[0119] (Configuration 6) When the minimum Abbe number of the material of the positive lens arranged in the second subgroup is νd_min, 10.0<νd_min<35.0 6. The optical system according to any one of configurations 1 to 5, wherein the following condition is satisfied:

[0120] (Configuration 7) Among the lens groups disposed in the intermediate group that move during focusing, the maximum absolute value of the position sensitivity is defined as Bab_max, and the F-number of the optical system is defined as Fno. 0.50 <Bab_max / Fno<2.00 7. The optical system according to any one of configurations 1 to 6, wherein the following condition is satisfied:

[0121] (Configuration 8) When the distance on the optical axis from the lens surface closest to the image side in the optical system to the image plane is BF and the maximum image height is IH, 1.3 <BF / IH<5.0 8. The optical system according to any one of configurations 1 to 7, wherein the following condition is satisfied:

[0122] (Configuration 9) When the focal length of the second subgroup is f1b and the focal length of the entire system is f, 0.10 <f1b / f<0.80 9. The optical system according to any one of configurations 1 to 8, wherein the following condition is satisfied:

[0123] (Configuration 10) 10. The optical system according to any one of configurations 1 to 9, wherein the first subgroup is made up of two positive lenses.

[0124] (Configuration 11) 11. The optical system according to any one of configurations 1 to 10, wherein the intermediate group has negative refractive power.

[0125] (Configuration 12) 12. The optical system according to any one of configurations 1 to 11, wherein the second subgroup has two negative lenses.

[0126] (Configuration 13) 13. The optical system according to any one of configurations 1 to 12, wherein, during image blur correction, part or all of the final lens group moves in a direction that includes a component perpendicular to the optical axis.

[0127] (Configuration 14) 14. The optical system according to any one of configurations 1 to 13, wherein the optical system has an aperture stop arranged closest to the image side in the first lens group.

[0128] (Configuration 15) An optical system comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, in which the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, the final lens group has four or more negative lenses, When the air distance between the first sub-group and the second sub-group is Dmax and the focal length of the first lens group is f1, 0.40 <Dmax / f1<1.50 An optical system characterized by satisfying the following conditional expression:

[0129] (Configuration 16) An optical system comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, in which the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, the final lens group has four or more negative lenses, When the Abbe number based on the d-line is νd, the material of the at least three positive lenses arranged in the second sub-group is 70.0<νd<100.0 An optical system characterized by satisfying the following conditional expression:

[0130] (Configuration 17) the optical system according to any one of configurations 1 to 16; an imaging device having an imaging element that receives an image formed by the optical system;

[0131] 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]

[0132] L0 optical system L1 First lens group M intermediate group Lr: Final lens group L1a 1st subgroup L1b second subgroup

Claims

1. An optical system comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, in which the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, When the Abbe number based on the d-line is νd, the material of the at least three positive lenses arranged in the second sub-group is 70.0<νd<100.0 The following condition is satisfied: When the air distance between the first sub-group and the second sub-group is Dmax and the focal length of the first lens group is f1, 0.70<Dmax / f1<1.50 An optical system characterized by satisfying the following conditional expression:

2. In the optical system, when the distance on the optical axis from the lens surface closest to the object side to the image plane is OTL and the focal length of the entire system is f, 0.45<OTL / f<1.20 2. The optical system according to claim 1, wherein the following condition is satisfied:

3. When the focal length of the first subgroup is f1a and the focal length of the entire system is f, 0.20<f1a / f<1.00 2. The optical system according to claim 1, wherein the following condition is satisfied:

4. When the focal length of the entire system is f, 0.20<f1 / f<0.80 2. The optical system according to claim 1, wherein the following condition is satisfied:

5. When the focal length of the positive lens with the shortest focal length among the positive lenses arranged in the first lens group is denoted by f1a_min, 1.50<f1a_min / f1<8.00 2. The optical system according to claim 1, wherein the following condition is satisfied:

6. When the minimum Abbe number of the material of the positive lens arranged in the second subgroup is denoted by νd_min, 10.0<νd_min<35.0 2. The optical system according to claim 1, wherein the following condition is satisfied:

7. Among the lens groups disposed in the intermediate group that move during focusing, the maximum absolute value of the position sensitivity is Bab_max, and the F-number of the optical system is Fno. 0.50<Bab_max / Fno<2.00 2. The optical system according to claim 1, wherein the following condition is satisfied:

8. When the distance on the optical axis from the lens surface closest to the image side in the optical system to the image plane is BF and the maximum image height is IH, 1.3<BF / IH<5.0 2. The optical system according to claim 1, wherein the following condition is satisfied:

9. When the focal length of the second subgroup is f1b and the focal length of the entire system is f, 0.10<f1b / f<0.80 2. The optical system according to claim 1, wherein the following condition is satisfied:

10. 2. The optical system according to claim 1, wherein the first sub-group is made up of two positive lenses.

11. 2. The optical system according to claim 1, wherein the intermediate group has negative refractive power.

12. The optical system according to claim 1 , wherein the second sub-group includes two negative lenses.

13. 2. The optical system according to claim 1, wherein, during image blur correction, a part or all of the final lens group moves in a direction including a component perpendicular to the optical axis.

14. 2. The optical system according to claim 1, wherein the optical system has an aperture stop arranged closest to the image side in the first lens group.

15. An optical system comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, in which the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, the final lens group has four or more negative lenses, When the air distance between the first sub-group and the second sub-group is Dmax and the focal length of the first lens group is f1, 0.40<Dmax / f1<1.50 An optical system characterized by satisfying the following conditional expression:

16. An optical system comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, an intermediate group having one or more lens groups, and a final lens group, in which the spacing between adjacent lens groups changes during focusing, For focusing, the first lens group and the final lens group are stationary, the first lens group includes a first subgroup having a plurality of positive lenses and a second subgroup arranged in order from the object side to the image side, the first subgroup and the second subgroup are disposed with the largest air gap between them among air gaps formed in the optical system, the final lens group has four or more negative lenses, When the Abbe number based on the d-line is νd, the material of the at least three positive lenses arranged in the second sub-group is 70.0<νd<100.0 An optical system characterized by satisfying the following conditional expression:

17. An optical system according to any one of claims 1 to 16; an imaging device having an imaging element that receives an image formed by the optical system;

Images