Optical system, optical device, and method for manufacturing optical system

Abstract

The invention provides an optical system, an optical apparatus, and a method for manufacturing the optical system, which can ensure good optical performance when the photographing magnification is more than 0.5 times while realizing light weight and miniaturization. An optical system (OL) for an optical device such as a camera (1) is configured from a front group (GF), an intermediate group (GM), and a rear group (GR) in this order from the object side, and when focusing, the intermediate group (GM) moves in the optical axis direction and satisfies the condition of the following expression: 0.54 < d1 / f < 1.00, d1 is the distance on the optical axis from the lens surface closest to the image surface of the front group (GF) to the lens surface closest to the object side of the intermediate group (GM) when focusing on an infinity object, and f is the focal length of the entire optical system (OL) when focusing on an infinity object.

Description

Technical Field

[0001] The present invention relates to an optical system, an optical device, and a method for manufacturing an optical system. Background Art

[0002] Conventionally, a small and lightweight macro lens has been proposed (for example, refer to Patent Document 1). However, further improvement in optical performance is required.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-148808 Summary of the Invention

[0006] The optical system according to the first aspect of the present invention includes a front group, an intermediate group, and a rear group in this order from the object side. When focusing, the intermediate group moves in the optical axis direction, and the optical system satisfies the condition of the following formula: 0.54 < d1 / f < 1.00 wherein d1: The distance on the optical axis from the lens surface closest to the image side of the front group to the lens surface closest to the object side of the intermediate group when focusing on an object at infinity, f: The focal length of the entire optical system when focusing on an object at infinity.

[0007] The optical system according to the second aspect of the present invention includes a front group, an intermediate group, and a rear group in this order from the object side. When focusing, the intermediate group moves in the optical axis direction, and the optical system satisfies the conditions of the following formulas: 32.00 < TL / DF < 80.00 1.00 < DM / DR < 4.00 wherein TL: The overall optical length of the optical system when focusing on an object at infinity, DF: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the front group, DM: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the intermediate group when focusing on an object at infinity, DR: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the rear group.

[0008] A method for manufacturing an optical system according to the first aspect of the present invention, the optical system includes a front group, an intermediate group, and a rear group in this order from the object side, wherein the intermediate group is configured to move in the optical axis direction when focusing, and is configured to satisfy the condition of the following formula: 0.54 < d1 / f < 1.00 wherein d1: the distance on the optical axis from the lens surface closest to the image plane of the front group to the lens surface closest to the object side of the intermediate group when focusing on an infinitely distant object, f: the focal length of the entire optical system when focusing on an infinitely distant object.

[0009] A method for manufacturing an optical system according to a second aspect of the present invention, the optical system being composed of a front group, an intermediate group, and a rear group in sequence from the object side, wherein the intermediate group is configured to move in the optical axis direction during focusing, and is configured to satisfy the condition of the following formula: 32.00 < TL / DF < 80.00 1.00 < DM / DR < 4.00 wherein TL: the overall optical length of the optical system when focusing on an infinitely distant object, DF: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image plane side of the front group, DM: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image plane side of the intermediate group when focusing on an infinitely distant object, DR: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image plane side of the rear group. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a cross-sectional view showing the lens structure of the optical system according to the first embodiment.

[0011] Figure 2A are aberration diagrams of the optical system according to the first embodiment when focusing on an infinitely distant object.

[0012] Figure 2B are aberration diagrams of the optical system according to the first embodiment when focusing on a nearby object.

[0013] Figure 3 is a cross-sectional view showing the lens structure of the optical system according to the second embodiment.

[0014] Figure 4A are aberration diagrams of the optical system according to the second embodiment when focusing on an infinitely distant object.

[0015] Figure 4B are aberration diagrams of the optical system according to the second embodiment when focusing on a nearby object.

[0016] Figure 5 is a cross-sectional view showing the lens structure of the optical system according to the third embodiment.

[0017] Figure 6A These are aberration diagrams when focusing on an infinitely distant object for the optical system of the third embodiment.

[0018] Figure 6B These are aberration diagrams when focusing on a nearby object for the optical system of the third embodiment.

[0019] Figure 7 This is a cross-sectional view showing the lens structure of the optical system of the fourth embodiment.

[0020] Figure 8A These are aberration diagrams when focusing on an infinitely distant object for the optical system of the fourth embodiment.

[0021] Figure 8B These are aberration diagrams when focusing on a nearby object for the optical system of the fourth embodiment.

[0022] Figure 9 This is a cross-sectional view showing the lens structure of the optical system of the fifth embodiment.

[0023] Figure 10A These are aberration diagrams when focusing on an infinitely distant object for the optical system of the fifth embodiment.

[0024] Figure 10B These are aberration diagrams when focusing on a nearby object for the optical system of the fifth embodiment.

[0025] Figure 11 This is a cross-sectional view showing the lens structure of the optical system of the sixth embodiment.

[0026] Figure 12A These are aberration diagrams when focusing on an infinitely distant object for the optical system of the sixth embodiment.

[0027] Figure 12B These are aberration diagrams when focusing on a nearby object for the optical system of the sixth embodiment.

[0028] Figure 13 This is a cross-sectional view showing the lens structure of the optical system of the seventh embodiment.

[0029] Figure 14A These are aberration diagrams when focusing on an infinitely distant object for the optical system of the seventh embodiment.

[0030] Figure 14B These are aberration diagrams when focusing on a nearby object for the optical system of the seventh embodiment.

[0031] Figure 15 This is a cross-sectional view of a camera equipped with the above optical system.

[0032] Figure 16 This is a flowchart for explaining the manufacturing method of the above optical system. Detailed Embodiments

[0033] Hereinafter, preferred embodiments will be described with reference to the accompanying drawings.

[0034] (First Embodiment)

[0035] As Figure 1 shown, the optical system OL of the first embodiment is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. When focusing, the intermediate group GM moves in the optical axis direction. With this structure, while achieving weight reduction and miniaturization of the optical system OL, good optical performance can be ensured when the photographic magnification is 0.5 times or more.

[0036] In addition, the optical system OL of the first embodiment preferably satisfies the conditional expression (1) shown below.

[0037] 0.54 < d1 / f < 1.00 (1) Where d1: The distance on the optical axis from the lens surface closest to the image plane of the front group GF to the lens surface closest to the object side of the intermediate group GM when focusing on an infinitely distant object f: The focal length of the entire optical system OL when focusing on an infinitely distant object

[0038] The conditional expression (1) defines the ratio of the distance on the optical axis from the lens surface closest to the image plane of the front group GF to the lens surface closest to the object side of the intermediate group GM, that is, the interval between the front group GM and the intermediate group GM, with respect to the focal length of the entire optical system OL when focusing on an infinitely distant object. By satisfying this conditional expression (1), in the optical system OL, while achieving light weight, small size, and a photographic magnification of 0.5 times or more, aberration correction during focusing can be performed well. If it exceeds the upper limit value of the conditional expression (1), although spherical aberration, field curvature, coma, etc. during focusing at the intermediate group GM can be corrected well, it is difficult to achieve weight reduction and miniaturization of the optical system OL, so it is not preferred. In addition, in order to make the effect of the conditional expression (1) reliable, it is more preferable to set the upper limit value of the conditional expression (1) to 0.90, 0.85, 0.80, and further to 0.75. Also, if it is lower than the lower limit value of the conditional expression (1), the optical system OL can be miniaturized, but it is difficult to correct spherical aberration, field curvature, coma, etc. during focusing at the intermediate group GM, so it is not preferred. In addition, in order to make the effect of the conditional expression (1) reliable, it is more preferable to set the lower limit value of the conditional expression (1) to 0.58, 0.60, and further to 0.63.

[0039] (Second Embodiment)

[0040] As Figure 1As shown, the optical system OL of the second embodiment is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. During focusing, the intermediate group GM moves in the optical axis direction. With this structure, while achieving weight reduction and miniaturization of the optical system OL, good optical performance can be ensured when the photographic magnification is 0.5 times or more.

[0041] In addition, the optical system OL of the second embodiment preferably satisfies the conditional expression (2) shown below.

[0042] 32.00 < TL / DF < 80.00 (2) Among them, TL: The overall optical length (air-equivalent length) of the optical system OL when focusing on an object at infinity DF: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the front group GF

[0043] The conditional expression (2) defines the ratio of the overall optical length of the optical system OL when focusing on an object at infinity to the distance on the optical axis (the thickness on the optical axis of the front group GF) from the lens surface closest to the object side to the lens surface closest to the image side of the front group GF. By satisfying this conditional expression (2), while achieving weight reduction and miniaturization of the optical system OL, aberration correction can be easily performed. If it exceeds the upper limit value of the conditional expression (2), the thickness on the optical axis of the front group GF (the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side) becomes thick relative to the overall optical length of the optical system OL. Therefore, although spherical aberration, chromatic aberration, coma, etc. can be corrected well, if the overall optical length of the optical system OL becomes too short, the curvature of the image surface, astigmatism, and the generation of coma during focusing become large, so it is not preferred. In addition, in order to make the effect of the conditional expression (2) reliable, it is more preferably to set the upper limit value of the conditional expression (2) to 75.00, and further to 70.00. Also, if it is lower than the lower limit value of the conditional expression (2), the thickness on the optical axis of the front group GF becomes thin relative to the overall optical length of the optical system OL. Therefore, although the overall optical length of the optical system OL can be shortened, aberration correction at the front group GF becomes insufficient, and it is difficult to achieve correction of spherical aberration, coma, etc., and curvature of the image surface, etc., so it is not preferred. In addition, in order to make the effect of the conditional expression (2) reliable, it is more preferably to set the lower limit value of the conditional expression (2) to 33.50, and further to 35.00.

[0044] In addition, the optical system OL of the second embodiment preferably satisfies the conditional expression (3) shown below.

[0045] 1.00 < DM / DR < 4.00 (3) Among them, DM: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the intermediate group GM when focusing on an infinitely distant object DR: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the rear group GR

[0046] Conditional expression (3) defines the ratio of the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the intermediate group GM (the thickness on the optical axis of the intermediate group GM) to the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the rear group GR (the thickness on the optical axis of the rear group GR) when focusing on an infinitely distant object. By satisfying this conditional expression (3), it is possible to achieve weight reduction and miniaturization of the optical system OL while performing good aberration correction for brightness and field angle. If the upper limit value of conditional expression (3) is exceeded, the thickness on the optical axis of the intermediate group GM becomes thicker relative to the thickness on the optical axis of the rear group GR. Therefore, although spherical aberration, coma, etc. can be corrected well, it is difficult to correct aberrations for the field angle such as field curvature and astigmatism when the overall length of the optical system OL is shortened. Thus, it is not preferred. In addition, in order to make the effect of conditional expression (3) reliable, it is more preferable to set the upper limit value of conditional expression (3) to 3.50, 3.00, and further to 2.50. Also, if the lower limit value of conditional expression (3) is exceeded, the thickness on the optical axis of the rear group GR becomes thicker relative to the thickness on the optical axis of the intermediate group GM. Therefore, although field curvature, astigmatism, etc. can be corrected well, it is difficult to correct aberrations for brightness, i.e., spherical aberration, coma, etc., when the overall length of the optical system OL is short. Thus, it is not preferred. In addition, in order to make the effect of conditional expression (3) reliable, it is more preferable to set the lower limit value of conditional expression (3) to 1.25, 1.50, and further to 1.75.

[0047] In addition, the optical system OL of the first and second embodiments (hereinafter, simply referred to as "the present embodiment") preferably satisfies the conditional expression (4) shown below.

[0048] 0.20 < d1 / TL < 0.40 (4) Among them, d1: The distance on the optical axis from the lens surface closest to the image side of the front group GF to the lens surface closest to the object side of the intermediate group GM when focusing on an infinitely distant object TL: The overall optical length (air equivalent length) of the optical system OL when focusing on an infinitely distant object

[0049] The conditional expression (4) defines the ratio of the distance on the optical axis from the lens surface closest to the image plane of the front group GF to the lens surface closest to the object plane of the intermediate group GM (the interval between the front group GF and the intermediate group GM) to the overall optical length of the optical system OL when focusing on an infinitely distant object. By satisfying this conditional expression (4), in the optical system OL, it is possible to achieve light weight, small size, and a photographic magnification of 0.5 times or more while satisfactorily correcting the aberrations during focusing. If the upper limit value of the conditional expression (4) is exceeded, although it is possible to satisfactorily correct the spherical aberration, field curvature, coma, etc. during focusing at the intermediate group GM, it is difficult to miniaturize the optical system OL, so it is not preferred. In addition, in order to make the effect of the conditional expression (4) reliable, it is more preferable to set the upper limit value of the conditional expression (4) to 0.38, and further to 0.35. Additionally, if the lower limit value of the conditional expression (4) is exceeded, although it is possible to miniaturize the optical system OL, it is difficult to correct the spherical aberration, field curvature, coma, etc. during focusing at the intermediate group GM, so it is not preferred. In addition, in order to make the effect of the conditional expression (4) reliable, it is more preferable to set the lower limit value of the conditional expression (4) to 0.23, and further to 0.25.

[0050] In addition, the optical system OL of the present embodiment preferably satisfies the following conditional expression (5).

[0051] 17.00 < (DF + DM + DR) / DF < 40.00 (5) where DF: the distance on the optical axis from the lens surface closest to the object plane to the lens surface closest to the image plane of the front group GF DM: the distance on the optical axis from the lens surface closest to the object plane to the lens surface closest to the image plane of the intermediate group GM when focusing on an infinitely distant object DR: the distance on the optical axis from the lens surface closest to the object plane to the lens surface closest to the image plane of the rear group GR

[0052] Conditional expression (5) stipulates the ratio of the sum of the thicknesses on the optical axis of the front group GF, the middle group GM, and the rear group GR to the thickness on the optical axis of the front group GF. By satisfying this conditional expression (5), it is possible to correct the field curvature, astigmatism, spherical aberration, coma, etc. of the optical system OL well. If the upper limit value of conditional expression (5) is exceeded, the thickness on the optical axis of the front group GF becomes thinner relative to the overall thickness (the sum of the thicknesses on the optical axis of the front group GF, the middle group GM, and the rear group GR). Therefore, although the spherical aberration, coma, etc. of the optical system OL can be corrected well, it is difficult to correct the field curvature, astigmatism, etc. well, so it is not preferred. In addition, in order to make the effect of conditional expression (5) reliable, it is more preferred to set the upper limit value of conditional expression (5) to 39.00, 38.00, 37.00, and further to 36.50. Additionally, if it is lower than the lower limit value of conditional expression (5), the thickness on the optical axis of the front group GF becomes thicker relative to the overall thickness. Therefore, although the field curvature, astigmatism, etc. of the optical system OL can be corrected well, it is difficult to correct the spherical aberration, coma, etc. well, so it is not preferred. In addition, in order to make the effect of conditional expression (5) reliable, it is more preferred to set the lower limit value of conditional expression (5) to 17.50, 18.00, 18.50, and further to 18.80.

[0053] In addition, the optical system OL of the present embodiment preferably satisfies the conditional expression (6) shown below.

[0054] 0.80 < (1 - βM 2 ) × βR 2 <2.00 (6) where βM: The lateral magnification of the middle group GM when focusing on an infinitely distant object βR: The lateral magnification of the rear group GR when focusing on an infinitely distant object

[0055] The conditional expression (6) stipulates the conditions for focusing in the intermediate group GM. By satisfying this conditional expression (6), in the optical system OL, it is possible to appropriately ensure the change in the image plane position during focusing while achieving light weight, miniaturization, and suppressing the aberration variation during focusing. If it exceeds the upper limit value of the conditional expression (6), although it is possible to suppress the aberration variation and miniaturize the optical system OL during focusing, the change in the image plane position during focusing becomes large, restricting the selection of the actuator that actuates the intermediate group GM as the focusing group, so it is not preferred. In addition, in order to make the effect of the conditional expression (6) reliable, it is more preferred to set the upper limit value of the conditional expression (6) to 1.90, 1.85, and further to 1.80. Additionally, if it is lower than the lower limit value of the conditional expression (6), although the change in the image plane position during focusing of the optical system OL becomes small and the selection of the actuator is not restricted, so it is preferred, it is difficult to achieve the suppression of aberration variation and miniaturization during focusing, so it is not preferred. In addition, in order to make the effect of the conditional expression (6) reliable, it is more preferred to set the lower limit value of the conditional expression (6) to 0.90, 1.00, and further to 1.10.

[0056] In addition, the optical system OL of the present embodiment preferably satisfies the following conditional expression (7).

[0057] -0.50 < f / fF < 0.30 (7) Wherein, f: The focal length of the entire optical system OL when focusing on an infinitely distant object fF: The focal length of the front group GF

[0058] The conditional expression (7) stipulates the ratio of the focal length of the entire optical system OL when focusing on an infinitely distant object to the focal length of the front group GF. By satisfying this conditional expression (7), in the optical system OL, it is possible to well correct various aberrations such as spherical aberration, coma, field curvature, and astigmatism, and it is also possible to well suppress the aberration variation during focusing. In addition, in order to make the effect of the conditional expression (7) reliable, it is more preferred to set the upper limit value of the conditional expression (7) to 0.25, 0.20, and further to 0.15. Additionally, in order to make the effect of the conditional expression (7) reliable, it is more preferred to set the lower limit value of the conditional expression (7) to -0.40, -0.30, and further to -0.20.

[0059] In addition, in the optical system OL of the present embodiment, the lens component LL disposed closest to the image plane side preferably has a negative optical power. According to this structure, it is possible to well correct the field curvature and astigmatism of the optical system OL.

[0060] In addition, in the optical system OL of the present embodiment, the front group GF preferably consists of one lens. According to this structure, it is possible to achieve light weight and miniaturization of the optical system OL while well suppressing the aberration variation during focusing.

[0061] In addition, the optical system OL of the present embodiment preferably has an aperture (e.g., the aperture stop S in Figure 1 ) within the intermediate group GM. During focusing, the aperture moves in the optical axis direction. During focusing, the aperture moves in the optical axis direction together with the intermediate group GM, thereby being able to well suppress the variations in field curvature, astigmatism, and coma during focusing.

[0062] In addition, in the optical system OL of the present embodiment, the intermediate group GM preferably has a positive optical power. According to this structure, various aberrations such as field curvature, spherical aberration, coma, and distortion of the optical system OL can be well corrected.

[0063] In addition, in the optical system OL of the present embodiment, the rear group GR preferably has a negative optical power. According to this structure, various aberrations such as field curvature, spherical aberration, coma, and distortion of the optical system OL can be well corrected.

[0064] In addition, the optical system OL of the present embodiment preferably satisfies the following conditional expression (8).

[0065] 0.50 < fM / f < 1.10 (8) Wherein, fM: Focal length of the intermediate group GM when focusing on an object at infinity f: Focal length of the entire optical system OL when focusing on an object at infinity

[0066] Conditional expression (8) defines the ratio of the focal length of the intermediate group GM to the focal length of the entire optical system OL when focusing on an object at infinity. By satisfying this conditional expression (8), spherical aberration, coma, etc. can be well corrected in the optical system OL. In addition, in order to make the effect of conditional expression (8) reliable, it is more preferable to set the upper limit value of conditional expression (8) to 1.05, and further to 1.00. In addition, in order to make the effect of conditional expression (8) reliable, it is more preferable to set the lower limit value of conditional expression (8) to 0.55, 0.60, and further to 0.65.

[0067] In addition, the optical system OL of the present embodiment preferably satisfies the following conditional expression (9).

[0068] 0.50 < (-fR) / f < 3.00 (9) Wherein, fR: Focal length of the rear group GR f: Focal length of the entire optical system OL when focusing on an object at infinity

[0069] The conditional expression (9) defines the ratio of the focal length of the rear group GR to the overall focal length of the entire optical system OL when focused on an object at infinity. By satisfying this conditional expression (9), in the optical system OL, it is possible to well correct field curvature, lateral chromatic aberration, distortion, etc. Further, in order to make the effect of the conditional expression (9) reliable, it is more preferable to set the upper limit value of the conditional expression (9) to 2.90, 2.75, 2.60, 2.50, and further to 2.40. Additionally, in order to make the effect of the conditional expression (9) reliable, it is more preferable to set the lower limit value of the conditional expression (9) to 0.60, 0.75, 0.90, and further to 1.00.

[0070] In addition, the optical system OL of the present embodiment preferably satisfies the conditional expression (10) shown below.

[0071] 1.00 < (-fR) / fM < 3.00 (10) Wherein, fR: Focal length of the rear group GR fM: Focal length of the intermediate group GM when focused on an object at infinity

[0072] The conditional expression (10) defines the ratio of the focal length of the rear group GR to the focal length of the intermediate group GM when focused on an object at infinity. By satisfying this conditional expression (10), it is possible to well suppress the aberration variation during focusing. If it exceeds the upper limit value of the conditional expression (10), in the optical system OL, the optical power of the rear group GR becomes weaker relative to the intermediate group GM. Although it is possible to well correct axial chromatic aberration, lateral chromatic aberration, etc., the aberration variation during focusing becomes larger, so it is not preferable. Further, in order to make the effect of the conditional expression (10) reliable, it is more preferable to set the upper limit value of the conditional expression (10) to 2.90, 2.80, 2.70, and further to 2.60. Additionally, if it is lower than the lower limit value of the conditional expression (10), in the optical system OL, the optical power of the rear group GR becomes stronger relative to the intermediate group GM. Although it is possible to well suppress the aberration variation during focusing, it is difficult to achieve the correction of axial chromatic aberration, lateral chromatic aberration, etc., so it is not preferable. Further, in order to make the effect of the conditional expression (10) reliable, it is more preferable to set the lower limit value of the conditional expression (10) to 1.10, 1.20, 1.30, 1.40, and further to 1.45.

[0073] In addition, the optical system OL of the present embodiment preferably satisfies the conditional expression (11) shown below.

[0074] 0.10 < BF / TL < 0.30 (11) Wherein, BF: Back focal length (air equivalent length) of the optical system OL when focused on an object at infinity TL: Overall optical length (air equivalent length) of the optical system OL when focused on an object at infinity

[0075] Conditional expression (11) defines the ratio of the back focal length of the optical system OL to the overall optical length when focusing on an infinitely distant object. By satisfying this conditional expression (11), it is possible to achieve weight reduction and miniaturization of the optical system OL while satisfactorily correcting various aberrations such as spherical aberration and field curvature. In addition, in order to make the effect of conditional expression (11) reliable, it is more preferable to set the upper limit value of conditional expression (11) to 0.28, and further to 0.25. Also, in order to make the effect of conditional expression (11) reliable, it is more preferable to set the lower limit value of conditional expression (11) to 0.11, 0.12, and further to 0.13.

[0076] In addition, the optical system OL of the present embodiment preferably satisfies the following conditional expression (12).

[0077] -0.40 < f / fL1 < 0.30 (12) Wherein, f: The focal length of the entire optical system OL when focusing on an infinitely distant object fL1: The focal length of the lens component L1 disposed closest to the object side

[0078] Conditional expression (12) defines the ratio of the focal length of the entire optical system OL to the focal length of the lens component L1 disposed closest to the object side of the optical system OL when focusing on an infinitely distant object. By satisfying this conditional expression (12), it is possible to satisfactorily correct various aberrations such as spherical aberration, coma, field curvature, and astigmatism in the optical system OL, and it is also possible to satisfactorily suppress aberration variation during focusing. In addition, in order to make the effect of conditional expression (12) reliable, it is more preferable to set the upper limit value of conditional expression (12) to 0.25, 0.20, 0.15, and further to 0.12. Also, in order to make the effect of conditional expression (12) reliable, it is more preferable to set the lower limit value of conditional expression (12) to -0.35, -0.30, -0.25, and further to -0.20.

[0079] In addition, the above-described conditions and structures can each exhibit the above effects, and it is not limited to having to satisfy all conditions and structures. Even if only any one condition or structure is satisfied, or any combination of conditions or structures is satisfied, the above effects can be obtained.

[0080] Next, based on Figure 15Describe a camera as an optical device having the optical system OL of this embodiment. The camera 1 is a so-called mirrorless camera with interchangeable lenses that has the optical system OL of this embodiment as a photographic lens 2. In this camera 1, light from an object (subject) (not shown) is converged by the photographic lens 2 and forms a subject image on the imaging surface of the imaging unit 3 via an OLPF (Optical Low Pass Filter) (not shown). Then, the subject image is photoelectrically converted by a photoelectric conversion element (imaging element) provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic View Finder) 4 provided in the camera 1. Thus, the photographer can observe the subject through the EVF 4.

[0081] In addition, when the photographer presses a shutter button (not shown), the image photoelectrically converted by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can take a picture of the subject with this camera 1. In addition, in this embodiment, a mirrorless camera is used as an example for explanation, but even when the optical system OL of this embodiment is mounted on a single-lens reflex camera in which the camera body has a quick-return mirror and the subject is observed through the viewfinder optical system, the same effect as that of the above camera 1 can be obtained.

[0082] In addition, the following descriptions can be appropriately adopted within the range that does not affect the optical performance.

[0083] In this embodiment, as described later, an optical system OL having a three-group or four-group structure is shown, but the above structural conditions, etc. can also be applied to other group structures such as five groups and six groups. In addition, a structure in which a lens or a lens group is added on the object side closest to the object or a structure in which a lens or a lens group is added on the image plane side closest to the image plane can also be adopted. Specifically, a structure in which a lens group fixed in position relative to the image plane during focusing is added on the image plane side closest to the image plane of the optical system OL can be considered. In addition, unless otherwise specified, a lens group refers to a part that is separated by an air interval that changes during focusing and includes at least one lens. In addition, a lens component refers to a single lens or a cemented lens formed by joining multiple lenses.

[0084] In addition, a single or multiple lens groups, or a part of a lens group can be used as a focusing group that moves in the optical axis direction to achieve focusing from an infinitely distant object to a close object. In this case, the focusing group is also applicable to autofocus and is applicable to motor drive for autofocus (such as an ultrasonic motor, etc.). In particular, preferably, in the case of a three-group structure, the second lens group G2 is used as the focusing group, and in the case of a four-group structure, at least one of the second lens group G2 and the third lens group G3 is used as the focusing group, and the positions of the other lenses relative to the image plane are fixed during focusing.

[0085] Alternatively, a lens group or a part of the lens group can be used as an anti-shake group that moves in a direction having a displacement component orthogonal to the optical axis or rotates (swings) in a plane direction including the optical axis to correct image blurring caused by camera shake. In particular, preferably, in the case of a three-group structure, at least a part of the second lens group G2 is used as the anti-shake group, and in the case of a four-group structure, at least a part of the second lens group G2 or the third lens group G3 is used as the anti-shake group.

[0086] In addition, the lens surface can be formed by a spherical surface or a plane surface, or can be formed by an aspherical surface. When the lens surface is a spherical surface or a plane surface, lens processing and assembly adjustment are relatively easy, and deterioration of optical performance due to errors in processing and assembly adjustment can be prevented, so it is preferred. In addition, even if the image plane is shifted, deterioration of the description performance can be reduced, so it is preferred. When the lens surface is an aspherical surface, the aspherical surface can be any one of an aspherical surface obtained by grinding, a glass molded aspherical surface formed by molding glass into an aspherical shape using a mold, and a composite aspherical surface formed by molding resin into an aspherical shape on the glass surface. In addition, the lens surface can also be a diffractive surface, and the lens can be a gradient index lens (GRIN lens) or a plastic lens.

[0087] The aperture stop S is preferably disposed within the intermediate group GM, but a member serving as the aperture stop may not be provided, and the function thereof can be replaced by the frame of the lens.

[0088] Furthermore, in order to reduce glare and ghosting and achieve high optical performance with high contrast, an anti-reflection film having a high transmittance in a wide wavelength band can also be applied to each lens surface.

[0089] The following refers to Figure 16 to outline the manufacturing method of the optical system OL of the present embodiment. First, the front group GF, the intermediate group GM, and the rear group GR are prepared in sequence from the object side (step S100). Next, it is configured such that, during focusing, the intermediate group GM moves in the optical axis direction (step S200), and it is configured such that these lens groups satisfy a predetermined condition (for example, the above conditional expression (1) in the case of the first embodiment, and the above conditional expressions (2) and (3) in the case of the second embodiment) (step S300).

[0090] In the above manner, it is possible to provide an optical system, an optical device, and a manufacturing method of an optical system that, while achieving light weight and miniaturization, can ensure good optical performance when the photographing magnification is 0.5 times or more.

[0091] Examples

[0092] Hereinafter, each example will be described based on the drawings. In addition, Figure 1 , Figure 3 ,Figure 5 , Figure 7 , Figure 9 , Figure 11 and Figure 13 are cross-sectional views showing the structures and power distributions of the optical systems OL (OL1 to OL7) of the respective embodiments. In addition, at the lower parts of the cross-sectional views of these optical systems OL1 to OL7, the moving directions of the respective lens groups along the optical axis when focusing from an infinite object (∞) to a nearby object are indicated by arrows.

[0093] In the second to seventh embodiments, when the height in the direction perpendicular to the optical axis is set to y, the distance along the optical axis (recess amount) from the tangent plane of the vertex of each aspherical surface at the height y to each aspherical surface is set to S(y), the radius of curvature of the reference spherical surface (paraxial radius of curvature) is set to r, the conic constant is set to K, and the aspherical coefficient of the nth order is set to An, the aspherical surface is represented by the following formula (a). In addition, in the following embodiments, "e-n" represents "×10 -n ".

[0094] S(y)=(y 2 / r) / {1+(1-K×y 2 / r 2 ) 1 / 2} +A4×y 4 +A6×y 6 +A8×y 8 +A10×y 10 +A12×y 12 +A14×y 14 (a)

[0095] In addition, in each embodiment, the aspherical coefficient A2 of the second order is 0. In addition, in the tables of each embodiment, an asterisk mark is added to the right of the surface number for the aspherical surface.

[0096] [First Embodiment]

[0097] Figure 1 is a view showing the structure of the optical system OL1 of the first embodiment. The optical system OL1 is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. The front group GF is composed of a first lens group G1 having a positive power. The intermediate group GM is composed of a second lens group G2 having a positive power and a third lens group G3 having a positive power, and has a positive power as a whole. The rear group GR is composed of a fourth lens group G4 having a negative power.

[0098] The first lens group G1 is composed of a positive meniscus lens L11 (L1) with its convex surface facing the object side. In addition, the second lens group G2 is composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive meniscus lens L22 with its convex surface facing the object side in sequence from the object side. In addition, the third lens group G3 is composed of a negative lens L31 with a double concave shape, a positive meniscus lens L32 with its concave surface facing the object side, and a positive lens L33 with a double convex shape in sequence from the object side. In addition, the fourth lens group G4 is composed of a negative lens L41 with a double concave shape, a positive meniscus lens L42 with its concave surface facing the object side, and a negative lens L43 (LL) with a double concave shape in sequence from the object side.

[0099] In this optical system OL1, the aperture stop S is disposed between the second lens group G2 and the third lens group G3 within the intermediate group GM. In addition, a filter group FL is disposed between the fourth lens group G4 and the image plane I.

[0100] In addition, when this optical system OL1 focuses from an infinite object to a near object, the second lens group G2 and the third lens group G3, which serve as the intermediate group GM, move along the optical axis toward the object side. In addition, during focusing, the aperture stop S moves together with the second lens group G2.

[0101] In Table 1 below, the parameter values of the optical system OL1 are listed. In this Table 1, f indicated by the overall parameters represents the focal length of the entire system, Fno represents the F-number, ω represents the half field of view angle [°], Y represents the maximum image height, TL represents the overall optical length, and Bf represents the back focal length, all of which are values when focusing on an infinite object. Here, the back focal length Bf represents the distance on the optical axis from the lens surface closest to the image plane (the 39th surface) to the image plane I. In addition, the overall optical length TL represents the length obtained by adding the back focal length to the distance on the optical axis from the lens surface closest to the object side (the 1st surface) to the lens surface closest to the image plane (the 39th surface). In addition, in the lens data, the first column m represents the order (surface number) of the lens surfaces starting from the object side along the light traveling direction, the second column r represents the curvature radius of each lens surface, the third column d represents the distance on the optical axis from each optical surface to the next optical surface (surface interval), and the fourth column nd and the fifth column νd represent the refractive index and Abbe number for the d-line (λ = 587.6 nm). In addition, the curvature radius ∞ represents a plane, and the refractive index of air 1.00000 is omitted. In addition, the focal length of each lens group shows the surface number of the starting surface of each lens group and the focal length.

[0102] Here, the focal length f, curvature radius r, surface interval d, and other length units listed in all the following parameter values generally use "mm", but since the optical system can still obtain the same optical performance after being magnified or reduced in proportion, this is not limited thereto. In addition, the explanations of these symbols and the explanations of the parameter table also apply to the subsequent embodiments.

[0103] (Table 1) First Embodiment

[0104] [Overall Parameters]

[0105] [Lens Data]

[0106] [Focal Length of Lens Group]

[0107] In this optical system OL1, the on-axis air gap d1 between the first lens group G1 and the second lens group G2, the on-axis air gap d2 between the second lens group G2 and the third lens group G3, and the on-axis air gap d3 between the third lens group G3 and the fourth lens group G4 change during focusing. Table 2 lists the variable gaps when focusing on an object at infinity and when focusing on a nearby object. In addition, f represents the focal length and β represents the photographic magnification. This description also applies to the subsequent embodiments.

[0108] (Table 2)

[0109] [Variable Gap Data]

[0110] Figure 2 shows the spherical aberration diagram, astigmatism diagram, distortion diagram, lateral color diagram, and coma diagram of the optical system OL1 when focusing on an object at infinity and when focusing on a nearby object. In each aberration diagram, FNo represents the F-number, NA represents the numerical aperture, and Y represents the image height. In addition, in the spherical aberration diagram, the value of the F-number or numerical aperture corresponding to the maximum aperture is shown, in the astigmatism diagram and distortion diagram, the maximum value of the image height is shown, and in the coma diagram, the values of each image height are shown. d represents the d-line (λ = 587.6 nm), and g represents the g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line represents the sagittal image plane and the dashed line represents the meridional image plane. Additionally, the same symbols as in this embodiment are also used in the aberration diagrams of the subsequent embodiments shown. From these various aberration diagrams, it can be seen that the optical system OL1 corrects various aberrations well and has excellent imaging performance.

[0111] [Second Embodiment]

[0112] Figure 3This is a diagram showing the structure of the optical system OL2 of the second embodiment. The optical system OL2 is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. The front group GF is composed of a first lens group G1 having a positive optical power. The intermediate group GM is composed of a second lens group G2 having a positive optical power. The rear group GR is composed of a third lens group G3 having a negative optical power.

[0113] The first lens group G1 is composed of a positive lens L11 (L1) having a plano-convex shape with the convex surface facing the object side. In addition, the second lens group G2 is composed of a cemented positive lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22, a cemented negative lens formed by cementing a biconcave negative lens L23 and a biconvex positive lens L24, and a biconvex positive lens L25 having an aspherical surface formed on the lens surface on the image side in order from the object side. In addition, the third lens group G3 is composed of a meniscus-shaped positive lens L31 with the concave surface facing the object side and a biconcave negative lens L32 (LL) in order from the object side.

[0114] In this optical system OL2, the aperture stop S is disposed between the negative lens L22 and the negative lens L23 within the second lens group G2 which is the intermediate group GM. In addition, a filter group FL is disposed between the third lens group G3 and the image plane I.

[0115] In addition, when this optical system OL2 focuses from an infinitely distant object to a nearby object, the second lens group G2 which is the intermediate group GM moves toward the object side along the optical axis. In addition, during focusing, the aperture stop S moves together with the second lens group G2.

[0116] In Table 3 below, the parameter values of the optical system OL2 are listed.

[0117] (Table 3) Second embodiment

[0118] [Overall parameters]

[0119] [Lens data]

[0120] [Focal length of lens group]

[0121] In this optical system OL2, the 11th surface is formed as an aspherical surface. In Table 4 below, the aspherical data, that is, the conic constant K and the values of each aspherical constant A4 to A14 are shown.

[0122] (Table 4)

[0123] [Aspherical data]

[0124] The 11th surface K = 1.00000 A4 = 3.71185E - 05 A6 = -6.46471E - 07 A8 = 3.01332E - 08 A10 = -7.16019E - 10 A12 = 8.76060E - 12 A14 = 4.29930E - 14

[0125] In addition, in this optical system OL2, the on - axis air space d1 between the first lens group G1 and the second lens group G2, and the on - axis air space d2 between the second lens group G2 and the third lens group G3 vary during focusing. In Table 5 below, the variable spaces during focusing on an object at infinity and an object at a short distance are shown.

[0126] (Table 5)

[0127] [Variable space data]

[0128] In FIG. 4, the spherical aberration diagrams, astigmatism diagrams, distortion diagrams, longitudinal chromatic aberration diagrams, and coma diagrams of the optical system OL2 during focusing on an object at infinity and an object at a short distance are shown. From these aberration diagrams, it can be seen that the optical system OL2 corrects various aberrations well and has excellent imaging performance.

[0129] [The Third Embodiment]

[0130] Figure 5 FIG. shows the structure of the optical system OL3 of the third embodiment. This optical system OL3 is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. The front group GF is composed of the first lens group G1, the intermediate group GM is composed of the second lens group G2 having a positive optical power and the third lens group G3 having a positive optical power, and has a positive optical power as a whole. The rear group GR is composed of the fourth lens group G4 having a negative optical power.

[0131] The first lens group G1 is composed of a parallel flat plate L11 (L1). In addition, the second lens group G2 is composed of a cemented positive lens formed by sequentially cementing a biconvex positive lens L21 and a biconcave negative lens L22 from the object side. In addition, the third lens group G3 is composed of a cemented negative lens formed by sequentially cementing a biconcave negative lens L31 and a biconvex positive lens L32 from the object side, and a biconvex positive lens L33 with an aspherical surface formed on the lens surface on the image side. In addition, the positive lens L33 is a composite lens with an aspherical surface formed by setting a resin layer on the surface on the image side of a glass lens body. In addition, the fourth lens group G4 is composed of a cemented positive lens formed by sequentially cementing a biconvex positive lens L41 and a biconcave negative lens L42 from the object side, and a biconcave negative lens L43 (LL) with an aspherical surface formed on the lens surface on the object side. In addition, the negative lens L43 is a composite lens with an aspherical surface formed by setting a resin layer on the surface on the image side of a glass lens body.

[0132] In this optical system OL3, the aperture stop S is disposed between the second lens group G2 and the third lens group G3 within the intermediate group GM. In addition, a filter group FL is disposed between the fourth lens group G4 and the image plane I.

[0133] In addition, when this optical system OL3 focuses from an infinite object to a near object, the second lens group G2 and the third lens group G3 as the intermediate group GM move along the optical axis toward the object side. In addition, during focusing, the aperture stop S moves together with the third lens group G3.

[0134] In Table 6 below, the parameter values of the optical system OL3 are listed.

[0135] (Table 6) Third Embodiment

[0136] [Overall Parameters]

[0137] [Lens Data]

[0138] [Focal Length of Lens Group]

[0139] In this optical system OL3, the 12th surface and the 16th surface are formed into aspherical shapes. In Table 7 below, the aspherical data, that is, the conic constant K and the values of each aspherical constant A4 to A14 are shown.

[0140] (Table 7)

[0141] [Aspherical Data]

[0142] Page 12 K = 1.00000 A4 = 2.46184E-05 A6 = -2.41773E-07 A8 = 1.11585E-08 A10 = -2.69002E-10 A12 = 3.24180E-12 A14 = 1.52330E-14

[0143] Page 16 K = 1.00000 A4 = -3.88298E-05 A6 = 1.22826E-07 A8 = -2.32494E-09 A10 = 9.49732E-12 A12 = 0.00000E+00 A14 = 0.00000E+00

[0144] In addition, in this optical system OL3, the on-axis air space d1 between the first lens group G1 and the second lens group G2, the on-axis air space d2 between the second lens group G2 and the third lens group G3, and the on-axis air space d3 between the third lens group G3 and the fourth lens group G4 change during focusing. In Table 8 below, the variable spaces during focusing on an object at infinity and on a nearby object are shown.

[0145] (Table 8)

[0146] [Variable space data]

[0147] Figure 6 shows the spherical aberration diagrams, astigmatism diagrams, distortion diagrams, longitudinal chromatic aberration diagrams, and coma diagrams of the optical system OL3 when focusing on an object at infinity and on a nearby object. From these aberration diagrams, it can be seen that the optical system OL3 corrects various aberrations well and has excellent imaging performance.

[0148] [Embodiment 4]

[0149] Figure 7 is a diagram showing the structure of the optical system OL4 of Embodiment 4. This optical system OL4 is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. The front group GF is composed of the first lens group G1 having a negative optical power, the intermediate group GM is composed of the second lens group G2 having a positive optical power, and the rear group GR is composed of the third lens group G3 having a negative optical power.

[0150] The first lens group G1 is composed of a meniscus-shaped negative lens L11 (L1) with its convex surface facing the object side. In addition, the second lens group G2 is composed of, in order from the object side, a meniscus-shaped positive lens L21 with its convex surface facing the object side, a cemented negative lens formed by cementing a biconcave negative lens L22 and a biconvex positive lens L23, and a biconvex positive lens L24 with an aspherical surface formed on the lens surface on the image side. In addition, the positive lens L24 is a composite lens with an aspherical surface formed by providing a resin layer on the surface on the image side of a glass lens body. In addition, the third lens group G3 is composed of, in order from the object side, a meniscus-shaped positive lens L31 with its concave surface facing the object side and a meniscus-shaped negative lens L32 (LL) with its concave surface facing the object side.

[0151] In this optical system OL4, the aperture stop S is disposed between the positive lens L21 and the negative lens L22 within the second lens group G2 which serves as the intermediate group GM. In addition, a filter group FL is disposed between the third lens group G3 and the image plane I.

[0152] In addition, when this optical system OL4 focuses from an infinitely distant object to a nearby object, the second lens group G2 which serves as the intermediate group GM moves toward the object side along the optical axis. In addition, during focusing, the aperture stop S moves together with the second lens group G2.

[0153] In Table 9 below, the parameter values of the optical system OL4 are listed.

[0154] (Table 9) Example 4

[0155] [Overall parameters]

[0156] [Lens data]

[0157] [Focal length of lens group]

[0158] In this optical system OL4, the 11th surface is formed in an aspherical shape. In the following Table 10, the aspherical data, that is, the conic constant K and the values of each aspherical constant A4 to A14 are shown.

[0159] (Table 10)

[0160] [Aspherical data]

[0161] 11th surface K = 1.00000 A4 = 3.47586E - 05 A6 = -1.66949E - 07 A8 = 5.09420E - 09 A10 = -4.45933E - 11 A12 = 0.00000E + 00 A14 = 0.00000E + 00

[0162] In addition, in this optical system OL4, the on - axis air space d1 between the first lens group G1 and the second lens group G2, and the on - axis air space d2 between the second lens group G2 and the third lens group G3 change during focusing. In Table 11 below, the variable spaces during focusing on an infinitely - distant object and a nearby object are shown.

[0163] (Table 11)

[0164] [Variable space data]

[0165] The spherical aberration diagrams, astigmatism diagrams, distortion diagrams, lateral color diagrams, and coma diagrams of the optical system OL4 during focusing on an infinitely - distant object and a nearby object are shown in FIG. 8. From these aberration diagrams, it can be seen that the optical system OL4 corrects various aberrations well and has excellent imaging performance.

[0166] [Embodiment 5]

[0167] Figure 9 FIG. shows the structure of the optical system OL5 of Embodiment 5. This optical system OL5 is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. The front group GF is composed of the first lens group G1 having a negative optical power. The intermediate group GM is composed of the second lens group G2 having a positive optical power. The rear group GR is composed of the third lens group G3 having a negative optical power.

[0168] The first lens group G1 is composed of a meniscus - shaped negative lens L11 (L1) with its convex surface facing the object side. In addition, the second lens group G2 is composed of, in order from the object side, a meniscus - shaped positive lens L21 with its convex surface facing the object side, a meniscus - shaped negative lens L22 with its convex surface facing the object side and having an aspherical surface formed on the lens surface on the object side and the lens surface on the image side, a cemented positive lens formed by joining a biconcave - shaped negative lens L23 and a biconvex - shaped positive lens L24, and a meniscus - shaped positive lens L25 with its concave surface facing the object side. In addition, the third lens group G3 is composed of a meniscus - shaped positive lens L31 with its concave surface facing the object side and a meniscus - shaped negative lens L32 (LL) with its concave surface facing the object side.

[0169] In the optical system OL5, the aperture stop S is disposed between the negative lens L22 and the negative lens L23 within the second lens group G2 that serves as the intermediate group GM. Additionally, a filter group FL is disposed between the third lens group G3 and the image plane I.

[0170] Furthermore, when the optical system OL5 focuses from an infinitely distant object to a nearby object, the second lens group G2 that serves as the intermediate group GM moves axially toward the object side. Additionally, during focusing, the aperture stop S moves together with the second lens group G2.

[0171] In Table 12 below, the parameter values of the optical system OL5 are listed.

[0172] (Table 12) Example 5

[0173] [Overall Parameters]

[0174] [Lens Data]

[0175] [Lens Group Focal Length]

[0176] In the optical system OL5, the fifth and sixth surfaces are formed as aspherical surfaces. In Table 13 below, the aspherical data, namely the conic constant K and the values of the aspherical constants A4 to A14, are shown.

[0177] (Table 13)

[0178] [Aspherical Data]

[0179] Fifth Surface K = 1.00000 A4 = 2.14608E-04 A6 = -6.37110E-07 A8 = 4.09234E-09 A10 = 0.00000E+00 A12 = 0.00000E+00 A14 = 0.00000E+00

[0180] Sixth Surface K = 1.00000 A4 = 2.71565E-04 A6 = -6.66060E-07 A8 = 1.26067E-08 A10 = 0.00000E+00 A12 = 0.00000E+00 A14 = 0.00000E+00

[0181] In addition, in this optical system OL5, the on-axis air space d1 between the first lens group G1 and the second lens group G2, and the on-axis air space d2 between the second lens group G2 and the third lens group G3 change during focusing. In Table 14 below, the variable spaces during focusing on an object at infinity and an object at a short distance are shown.

[0182] (Table 14)

[0183] [Variable space data]

[0184] In FIG. 10, spherical aberration diagrams, astigmatism diagrams, distortion diagrams, longitudinal chromatic aberration diagrams, and coma diagrams of the optical system OL5 during focusing on an object at infinity and an object at a short distance are shown. From these aberration diagrams, it can be seen that the optical system OL5 corrects various aberrations well and has excellent imaging performance.

[0185] [Sixth Embodiment]

[0186] Figure 11 FIG. shows the structure of the optical system OL6 of the sixth embodiment. This optical system OL6 is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. The front group GF is composed of a first lens group G1 having a negative optical power. The intermediate group GM is composed of a second lens group G2 having a positive optical power and a third lens group G3 having a positive optical power, and has a positive optical power as a whole. The rear group GR is composed of a fourth lens group G4 having a negative optical power.

[0187] The first lens group G1 is composed of a negative lens L11 (L1) having a plano-concave shape with the plane facing the object side. In addition, the second lens group G2 is composed of a positive lens L21 having a meniscus shape with the convex surface facing the object side. In addition, the third lens group G3 is composed of a cemented negative lens formed by cementing a biconcave negative lens L31 and a biconvex positive lens L32 in order from the object side, a positive lens L33 having a meniscus shape with the concave surface facing the object side and having an aspherical surface formed on the lens surface on the image side, and a biconvex positive lens L34. In addition, the fourth lens group G4 is composed of a positive lens L41 having a meniscus shape with the concave surface facing the object side, a negative lens L42 having a meniscus shape with the concave surface facing the object side and having an aspherical surface formed on the lens surface on the object side, and a negative lens L43 (LL) having a meniscus shape with the concave surface facing the object side.

[0188] In this optical system OL6, the aperture stop S is disposed between the second lens group G2 and the third lens group G3 within the intermediate group GM. In addition, a filter group FL is disposed between the fourth lens group G4 and the image plane I.

[0189] In addition, when the optical system OL6 focuses from an infinitely distant object to a close object, the second lens group G2 and the third lens group G3 of the intermediate group GM move along the optical axis toward the object side. In addition, during focusing, the aperture stop S moves together with the third lens group G3.

[0190] In Table 15 below, the parameter values of the optical system OL6 are listed.

[0191] (Table 15) Sixth Embodiment

[0192] [Overall Parameters]

[0193] [Lens Data]

[0194] [Focal Length of Lens Group]

[0195] In this optical system OL6, the 10th surface and the 15th surface are formed as aspherical surfaces. In the following Table 16, the aspherical data, that is, the conic constant K and the values of each aspherical constant A4 to A14 are shown.

[0196] (Table 16)

[0197] [Aspherical Data]

[0198] 10th Surface K = 1.00000 A4 = 4.22622E-05 A6 = -2.61315E-07 A8 = 1.23491E-08 A10 = -2.58085E-10 A12 = 2.70030E-12 A14 = -1.11010E-14

[0199] 15th Surface K = 1.00000 A4 = 7.42581E-06 A6 = 4.99661E-08 A8 = -2.94414E-10 A10 = 1.20068E-12 A12 = 0.00000E+00 A14 = 0.00000E+00

[0200] In addition, in this optical system OL6, the on-axis air spaces d1 between the first lens group G1 and the second lens group G2, the on-axis air space d2 between the second lens group G2 and the third lens group G3, and the on-axis air space d3 between the third lens group G3 and the fourth lens group G4 change during focusing. In Table 17 below, the variable spaces during focusing on an object at infinity and on a close object are shown.

[0201] (Table 17)

[0202] [Variable space data]

[0203] In FIG. 12, spherical aberration diagrams, astigmatism diagrams, distortion diagrams, longitudinal chromatic aberration diagrams, and coma diagrams of the optical system OL6 during focusing on an object at infinity and on a close object are shown. From these aberration diagrams, it can be seen that the optical system OL6 corrects various aberrations well and has excellent imaging performance.

[0204] [Embodiment 7]

[0205] Figure 13 FIG. shows the structure of an optical system OL7 according to Embodiment 7. This optical system OL7 is composed of a front group GF, an intermediate group GM, and a rear group GR in order from the object side. The front group GF is composed of a first lens group G1 having a negative refractive power. The intermediate group GM is composed of a second lens group G2 having a positive refractive power and a third lens group G3 having a positive refractive power, and has a positive refractive power as a whole. The rear group GR is composed of a fourth lens group G4 having a negative refractive power.

[0206] The first lens group G1 is composed of a negative lens L11 (L1) having a plano-concave shape with the plane facing the object side. In addition, the second lens group G2 is composed of a positive lens L21 having a meniscus shape with the convex surface facing the object side. In addition, the third lens group G3 is composed, in order from the object side, of a cemented negative lens formed by cementing a biconcave negative lens L31 and a biconvex positive lens L32, a positive lens L33 having a meniscus shape with the concave surface facing the object side and having an aspherical surface formed on the lens surface on the image side, and a biconvex positive lens L34. In addition, the fourth lens group G4 is composed, in order from the object side, of a positive lens L41 having a meniscus shape with the concave surface facing the object side and a biconcave negative lens L42 (LL).

[0207] In this optical system OL7, the aperture stop S is disposed between the second lens group G2 and the third lens group G3 within the intermediate group GM. In addition, a filter group FL is disposed between the fourth lens group G4 and the image plane I.

[0208] In addition, when the optical system OL7 focuses from an infinitely distant object to a nearby object, the second lens group G2 and the third lens group G3, which are the intermediate groups GM, move along the optical axis toward the object side. Further, during focusing, the aperture stop S moves together with the third lens group G3.

[0209] In Table 18 below, the parameter values of the optical system OL7 are listed.

[0210] (Table 18) Seventh Embodiment

[0211] [Overall Parameters]

[0212] [Lens Data]

[0213] [Focal Length of Lens Group]

[0214] In this optical system OL7, the 10th surface is formed in an aspherical shape. In the following Table 19, the aspherical data, that is, the conic constant K and the values of the respective aspherical constants A4 to A14 are shown.

[0215] (Table 19)

[0216] [Aspherical Data]

[0217] 10th Surface K = 1.00000 A4 = 4.27018E-05 A6 = -3.39344E-07 A8 = 1.47524E-08 A10 = -2.99211E-10 A12 = 3.04550E-12 A14 = -1.22760E-14

[0218] In addition, in this optical system OL7, the on-axis air gap d1 between the first lens group G1 and the second lens group G2, the on-axis air gap d2 between the second lens group G2 and the third lens group G3, and the on-axis air gap d3 between the third lens group G3 and the fourth lens group G4 change during focusing. In the following Table 20, the variable gaps during focusing on an infinitely distant object and a nearby object are shown.

[0219] (Table 20)

[0220] [Variable Gap Data]

[0221] The spherical aberration diagrams, astigmatism diagrams, distortion diagrams, longitudinal chromatic aberration diagrams, and coma diagrams of the optical system OL7 when focusing on an infinitely distant object and when focusing on a nearby object are shown in FIG. 14. From these aberration diagrams, it can be seen that the optical system OL7 corrects various aberrations well and has excellent imaging performance.

[0222] [Conditional corresponding values]

[0223] The corresponding values of conditional expressions (1) to (12) in the first to seventh embodiments are shown in Table 21 below.

[0224] (Table 21) (1) d1 / f (2) TL / DF (3) DM / DR (4) d1 / TL (5) (DF + DM + DR) / DF (6) (1 - βM 2 )×βR 2 (7) f / fF (8) fM / f (9) (-fR) / f (10) (-fR) / fM (11) BF / TL (12) f / fL1

[0225] Reference numeral description 1 Camera (optical device) OL (OL1 to OL7) Optical system GF Front group GM Middle group GR Rear group S Aperture stop (aperture)

Claims

1. An optical system, wherein, the optical system is composed of a front group, an intermediate group, and a rear group in sequence from the object side, during focusing, the intermediate group moves in the optical axis direction, the optical system satisfies the condition of the following formula: 0.54 < d1 / f < 1.00 wherein, d1: the distance on the optical axis from the lens surface closest to the image side of the front group to the lens surface closest to the object side of the intermediate group when focusing on an object at infinity, f: the focal length of the entire optical system when focusing on an object at infinity.

2. An optical system, wherein, the optical system is composed of a front group, an intermediate group, and a rear group in sequence from the object side, during focusing, the intermediate group moves in the optical axis direction, the optical system satisfies the conditions of the following formulas: 32.00 < TL / DF < 80.00 1.00 < DM / DR < 4.00 wherein, TL: the overall optical length of the optical system when focusing on an object at infinity, DF: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the front group, DM: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the intermediate group when focusing on an object at infinity, DR: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the rear group.

3. The optical system according to claim 1 or 2, wherein, the optical system satisfies the condition of the following formula: 0.20 < d1 / TL < 0.40 wherein, d1: the distance on the optical axis from the lens surface closest to the image side of the front group to the lens surface closest to the object side of the intermediate group when focusing on an object at infinity, TL: the overall optical length of the optical system when focusing on an object at infinity.

4. The optical system according to any one of claims 1 to 3, wherein, the optical system satisfies the condition of the following formula: 17.00 < (DF + DM + DR) / DF < 40.00 wherein, DF: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the front group, DM: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the intermediate group when focusing on an object at infinity, DR: the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the rear group.

5. The optical system according to any one of claims 1 to 4, wherein, the optical system satisfies the condition of the following formula: 0.80 < (1 - βM 2 ) × βR 2 < 2.00 wherein, βM: the lateral magnification of the intermediate group when focusing on an object at infinity, βR: the lateral magnification of the rear group when focusing on an object at infinity.

6. The optical system according to any one of claims 1 to 5, wherein, the optical system satisfies the condition of the following formula: -0.50 < f / fF < 0.30 wherein, f: the focal length of the entire optical system when focusing on an object at infinity, fF: the focal length of the front group.

7. The optical system according to any one of claims 1 to 6, wherein, the lens component disposed closest to the image side has a negative optical power.

8. The optical system according to any one of claims 1 to 7, wherein, The front group consists of one lens.

9. The optical system according to any one of claims 1 to 8, wherein the optical system has an aperture within the intermediate group, and the aperture moves in the optical axis direction during focusing.

10. The optical system according to any one of claims 1 to 9, wherein the intermediate group has a positive optical power.

11. The optical system according to any one of claims 1 to 10, wherein the rear group has a negative optical power.

12. The optical system according to any one of claims 1 to 11, wherein the optical system satisfies the condition of the following formula: 0.50 < fM / f < 1.10 wherein fM: the focal length of the intermediate group when focusing on an object at infinity, f: the focal length of the entire optical system when focusing on an object at infinity.

13. The optical system according to any one of claims 1 to 12, wherein the optical system satisfies the condition of the following formula: 0.50 < (-fR) / f < 3.00 wherein fR: the focal length of the rear group, f: the focal length of the entire optical system when focusing on an object at infinity.

14. The optical system according to any one of claims 1 to 13, wherein the optical system satisfies the condition of the following formula: 1.00 < (-fR) / fM < 3.00 wherein fR: the focal length of the rear group, fM: the focal length of the intermediate group when focusing on an object at infinity.

15. The optical system according to any one of claims 1 to 14, wherein the optical system satisfies the condition of the following formula: 0.10 < BF / TL < 0.30 wherein BF: the back focal length of the optical system when focusing on an object at infinity, TL: the overall optical length of the optical system when focusing on an object at infinity.

16. The optical system according to any one of claims 1 to 15, wherein the optical system satisfies the condition of the following formula: -0.40 < f / fL1 < 0.30 wherein f: the focal length of the entire optical system when focusing on an object at infinity, fL1: the focal length of the lens component disposed closest to the object side.

17. An optical device having the optical system according to any one of claims 1 to 16.

18. A method for manufacturing an optical system, the optical system being composed of a front group, an intermediate group, and a rear group in sequence from the object side, wherein it is configured such that the intermediate group moves in the optical axis direction during focusing, and it is configured to satisfy the condition of the following formula: 0.54 < d1 / f < 1.00 wherein d1: the distance on the optical axis from the lens surface closest to the image side of the front group to the lens surface closest to the object side of the intermediate group when focusing on an object at infinity, f: the focal length of the entire optical system when focusing on an object at infinity.

19. A method for manufacturing an optical system, the optical system being composed of a front group, an intermediate group, and a rear group in sequence from the object side, wherein it is configured such that the intermediate group moves in the optical axis direction during focusing, and it is configured to satisfy the conditions of the following formulas: 32.00 < TL / DF < 80.00 1.00 < DM / DR < 4.00 wherein TL: The overall optical length of the optical system when focusing on an infinitely distant object, DF: The distance on the optical axis of the front group from the lens surface closest to the object side to the lens surface closest to the image side, DM: The distance on the optical axis of the intermediate group from the lens surface closest to the object side to the lens surface closest to the image side when focusing on an infinitely distant object, DR: The distance on the optical axis of the rear group from the lens surface closest to the object side to the lens surface closest to the image side.

Images