JP6769054B2 - Optical system and optical equipment - Google Patents

Description

The present invention relates to an optical system and an optical device using the same.

Conventionally, a bright wide-angle lens suitable for wide-angle photography has been proposed as an optical system used in an optical device such as a digital single-lens reflex camera or a digital video camera (see, for example, Patent Document 1). For example, some wide-angle lenses are configured by providing an afocal converter on the object side of a Gaussian lens configuration. However, in such an optical system, the total length and the diameter of the optical system become large, and the optical system may become large as a whole.

Japanese Unexamined Patent Publication No. 2014-202952

The optical system according to the first invention is substantially composed of two lens groups, that is, a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave and satisfies the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.35
0.12 << | X2 | / f <0.20
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
X2: The amount of movement of the second lens group when focusing from infinity to a short-distance object,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane.
The optical system according to the second invention is substantially composed of two lens groups, that is, a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave and satisfies the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.30
0.45 <Bf / f <0.80
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
Bf: Air conversion distance on the optical axis from the lens surface on the image side to the image surface in the optical system in the infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane.
The optical system according to the third invention is substantially composed of two lens groups, that is, a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave and satisfies the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.30
0.95 <DG1 / DG2 <1.70
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
DG1: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the first lens group,
DG2: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the second lens group.
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane.
The optical system according to the fourth invention is substantially composed of two lens groups consisting of a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave, and the lens surface on the image side of the lens arranged closest to the image side of the first lens group is convex, satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.30
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane.

The optical system according to the fifth invention is substantially composed of two lens groups, that is, a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave and satisfies the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.50 <Bf / f <0.80
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
Bf: Air conversion distance on the optical axis from the lens surface on the image side to the image surface in the optical system in the infinity focused state,
f: Focal length of the optical system in an infinity focused state.
The optical system according to the sixth invention is substantially composed of two lens groups, that is, a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave, and the lens surface on the image side of the lens arranged closest to the image side of the second lens group is convex, satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.45 <Bf / f <0.80
0.10 <f / f1 <0.55
5.20 <Y × f / TL <6.80 [Unit: mm]
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
Bf: Air conversion distance on the optical axis from the lens surface on the image side to the image surface in the optical system in the infinity focused state,
f: Focal length of the optical system in an infinity focused state,
f1: Focal length of the first lens group,
Y: Radius of the image circle of the optical system,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane.

The optical system according to the seventh invention is substantially composed of two lens groups, that is, a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave and satisfies the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.12 << | X2 | / f <0.20
0.10 <f / f1 <0.55
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
X2: The amount of movement of the second lens group when focusing from infinity to a short-distance object,
f: Focal length of the optical system in an infinity focused state,
f1: Focal length of the first lens group.
The optical system according to the eighth invention is substantially composed of two lens groups consisting of a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave, and the lens surface on the image side of the lens arranged closest to the image side of the first lens group is convex, satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.12 << | X2 | / f <0.20
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
X2: The amount of movement of the second lens group when focusing from infinity to a short-distance object,
f: Focal length of the optical system in an infinity focused state.

The optical system according to the ninth invention is substantially composed of two lens groups consisting of a first lens group and a second lens group arranged in order from the object side, and focuses on a short-range object from infinity. At that time, the first lens group is fixed, the second lens group moves toward the object along the optical axis, the distance between the adjacent lens groups changes, and the first lens group and the second lens group change. An aperture aperture is arranged between the lens groups, and the lens arranged on the most object side of the second lens group located on the image side of the aperture aperture is a negative lens, and is located on the most object side of the second lens group. The lens surface on the object side of the arranged negative lens is concave, and the lens surface on the image side of the lens arranged on the most image side of the first lens group is convex, and the most image of the second lens group. The lens surface on the image side of the lens arranged on the side is a convex surface, and satisfies the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.95 <DG1 / DG2 <1.70
5.20 <Y × f / TL <6.80 [Unit: mm]
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
DG1: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the first lens group,
DG2: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the second lens group.
Y: Radius of the image circle of the optical system,
f: Focal length of the optical system in an infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane.
Further, the optical device according to the present invention is configured to include the above optical system.

It is a figure which shows the lens structure of the optical system which concerns on 1st Example of this Embodiment. FIG. 2A is a diagram of various aberrations of the optical system according to the first embodiment during infinity focusing, and FIG. 2B is a diagram of various aberrations of the optical system according to the first embodiment during short-distance focusing. It is a figure. It is a figure which shows the lens structure of the optical system which concerns on 2nd Example of this Embodiment. FIG. 4A is a diagram of various aberrations of the optical system according to the second embodiment during infinity focusing, and FIG. 4B is a diagram of various aberrations of the optical system according to the second embodiment during short-distance focusing. It is a figure. It is a figure which shows the lens structure of the optical system which concerns on 3rd Example of this Embodiment. FIG. 6A is a diagram of various aberrations of the optical system according to the third embodiment during infinity focusing, and FIG. 6B is a diagram of various aberrations of the optical system according to the third embodiment during short-distance focusing. It is a figure. It is a figure which shows the lens structure of the optical system which concerns on 4th Example of this Embodiment. FIG. 8A is a diagram of various aberrations of the optical system according to the fourth embodiment during infinity focusing, and FIG. 8B is a diagram of various aberrations of the optical system according to the fourth embodiment during short-distance focusing. It is a figure. It is a figure which shows the lens structure of the optical system which concerns on 5th Example of this Embodiment. FIG. 10A is a diagram of various aberrations of the optical system according to the fifth embodiment during infinity focusing, and FIG. 10B is a diagram of various aberrations of the optical system according to the fifth embodiment during short-distance focusing. It is a figure. It is a figure which shows the structure of the camera provided with the optical system which concerns on this embodiment. It is a flowchart which shows the manufacturing method of the optical system which concerns on this embodiment.

Hereinafter, the optical system and the optical device of the present embodiment will be described with reference to the drawings. As an example of the optical system (wide-angle lens) WL according to the present embodiment, the optical system WL (1) shown in FIG. 1 has a first lens group G1 and a second lens group G2 arranged in order from the object side. It is composed of. An aperture diaphragm S is arranged between the first lens group G1 and the second lens group G2. A negative lens is arranged on the most object side of the second lens group G2 located on the image side of the aperture diaphragm S. The lens surface on the object side of the negative lens arranged on the most object side of the second lens group G2 is a concave surface. In such an optical system WL (1), when focusing on a short-range object from infinity, the first lens group G1 is fixed and the second lens group G2 moves toward the object along the optical axis. , The distance between the first lens group G1 and the second lens group G2 is changed. With this configuration, it is possible to obtain an optical system having a large aperture ratio, a small size, and good optical performance.

The optical system WL according to the present embodiment may be the optical system WL (2) shown in FIG. 3, the optical system WL (3) shown in FIG. 5, or the optical system WL (4) shown in FIG. The optical system WL (5) shown in 9 may be used. The lens groups of the optical systems WL (2) to WL (5) shown in FIGS. 3, 5, 7, and 9 are configured in the same manner as the optical system WL (1) shown in FIG.

Under the above configuration, the optical system WL according to the present embodiment satisfies the following conditional expression (1).

0.10 <(R22 + R21) / (R22-R21) <3.00 ... (1)
However, R21: radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group G2,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group G2.

The conditional expression (1) is a conditional expression for defining an appropriate range of the shape factor of the negative lens arranged on the most object side of the second lens group G2. The lens surface arranged on the image side of the aperture diaphragm S is a first lens group G1 that receives an incident light ray having a sharp angle from the off-axis, and a second lens group G2 that telecentically arranges the light beam emitted from the first lens group G1. It is an important lens surface located between and. The conditional expression (1) shows an appropriate shape of the negative lens arranged on the most object side of the second lens group G2 having the lens surface. By forming this negative lens so that R21 <R22, various aberrations can be easily corrected.

If the corresponding value of the conditional expression (1) exceeds the upper limit value, the degree of meniscus of the shape of the negative lens arranged on the most object side of the second lens group G2 is too strong, and high-order aberrations occur, which is preferable. Absent. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (1) may be preferably 2.90, and more preferably 2.85.

When the corresponding value of the conditional expression (1) is less than the lower limit value, the degree to which the concave surface is directed toward the object side in the shape of the negative lens arranged on the object side of the second lens group G2 becomes stronger, so that spherical aberration and coma aberration become stronger. Is difficult to correct. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (1) may be preferably 0.20, and more preferably 0.30.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (2).

0.20 <f / TL <0.35 ... (2)
However, f: the focal length of the optical system WL in the infinity focusing state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system WL in the infinity focusing state, and the air conversion distance from the lens surface on the image side to the image plane.

The conditional expression (2) is a conditional expression for defining an appropriate range between the focal length and the total length of the optical system WL. By satisfying the conditional expression (2), good optical performance can be obtained while keeping the total length of the optical system WL as small as possible.

If the corresponding value of the conditional expression (2) exceeds the upper limit value, the total length of the optical system WL becomes short, so that it is necessary to increase the power of each group, and it becomes difficult to correct spherical aberration, coma aberration, and the like. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (2) may be preferably 0.30, and more preferably 0.28.

When the corresponding value of the conditional expression (2) is less than the lower limit value, the total length of the optical system WL becomes long, so that the diameter of the negative lens of the first lens group G1 increases, and it becomes difficult to correct off-axis aberration and chromatic aberration. .. In order to ensure the effect of the present embodiment, the lower limit value of the conditional expression (2) may be preferably 0.21 and more preferably 0.23.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (3).

0.30 <f2 / TL <0.65 ... (3)
However, f2: the focal length of the second lens group G2,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system WL in the infinity focusing state, and the air conversion distance from the lens surface on the image side to the image plane.

The conditional expression (3) is a conditional expression for defining an appropriate range between the focal length of the second lens group G2 and the total length of the optical system WL. If the corresponding value of the conditional expression (3) exceeds the upper limit value, the total length of the optical system WL is too short, and it becomes difficult to correct coma aberration and the like. Further, since the power (refractive power) of the second lens group G2 is too weak, when the second lens group G2 is set to the focusing group, the magnification required for focusing cannot be obtained, and the first lens group G1 May interfere with. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (3) may be preferably 0.62, and more preferably 0.60.

If the corresponding value of the conditional expression (3) is less than the lower limit value, the total length of the optical system WL becomes long and the entire optical system becomes large, which is not preferable. Further, since the power of the second lens group G2 is too strong, it becomes difficult to correct spherical aberration and coma. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (3) may be preferably 0.35, and more preferably 0.40.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (4).

0.45 <Bf / f <0.80 ... (4)
However, Bf: the air conversion distance on the optical axis from the lens plane on the image side to the image plane in the optical system WL in the infinity focused state,
f: Focal length of the optical system WL in the infinity focused state.

The conditional expression (4) is a conditional expression for defining an appropriate range between the focal length of the optical system WL and the back focus. If the corresponding value of the conditional expression (4) exceeds the upper limit value, the back focus is too long and the telecentric property is maintained, but the entire optical system becomes large, which is not preferable. Further, since the focal length of each lens group is shortened, it becomes difficult to correct spherical aberration and coma. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (4) may be preferably 0.75, and more preferably 0.68.

If the corresponding value of the conditional expression (4) is less than the lower limit value, the back focus is too short, and it is not possible to secure a space for arranging the filter or the like. Further, since the position of the exit pupil is close to the image plane I, shading becomes remarkable, and the resolution is particularly lowered around the screen. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (4) may be preferably 0.50, and more preferably 0.55.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (5).

0.10 <f / f1 <0.55 ... (5)
However, f: the focal length of the optical system WL in the infinity focusing state,
f1: Focal length of the first lens group G1.

The conditional expression (5) is a conditional expression for defining an appropriate range of the focal length of the first lens group G1 with respect to the focal length of the optical system WL. If the corresponding value of the conditional expression (5) exceeds the upper limit value, the power (refractive power) of the first lens group G1 is too strong, and it is difficult to correct off-axis aberrations such as curvature of field, astigmatism, and coma. become. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (5) may be preferably 0.50, and more preferably 0.47.

If the corresponding value of the conditional expression (5) is less than the lower limit value, the power of the first lens group G1 becomes weak and the entire optical system becomes large, which is not preferable. Further, the power balance between the first lens group G1 and the second lens group G2 is lost, and the distortion aberration changes, which is not preferable. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (5) may be preferably 0.13, and more preferably 0.16.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (6).

0.95 <DG1 / DG2 <1.70 ... (6)
However, DG1: the distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the first lens group G1.
DG2: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the second lens group G2.

The conditional expression (6) is a conditional expression for defining an appropriate distribution between the total thickness (lens thickness) of the first lens group G1 and the total thickness of the second lens group G2. In an optical system of the type as in this embodiment, the second lens group G2 often takes charge of focusing, so weight reduction is required. Further, shortening the total thickness of the first lens group G1 is directly linked to shortening the lens barrel. Further, considering that there is an aperture diaphragm S between the first lens group G1 and the second lens group G2, the total thickness of the first lens group G1 and the total thickness of the second lens group G2 are used to determine the exit pupil. It is possible to infer the position.

If the corresponding value of the conditional expression (6) exceeds the upper limit value, the total thickness of the second lens group G2 is too thin, and it becomes difficult to correct spherical aberration, coma aberration, and the like. Further, since the total thickness of the second lens group G2 is too thin, it becomes difficult to secure a sufficient distance from the image plane I to the position of the exit pupil. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (6) may be preferably 1.65, and more preferably 1.61.

If the corresponding value of the conditional expression (6) is less than the lower limit value, the total thickness of the first lens group G1 is too thin, and it becomes difficult to correct the distortion. Further, since the total thickness of the second lens group G2 is too thick, the weight load of the second lens group G2 becomes large at the time of focusing. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (6) may be preferably 1.00, and more preferably 1.08.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (7).

-12.0 <R1b / φ1b <8.0 ... (7)
However, R1b: radius of curvature of the lens surface on the image side of the lens arranged on the image side of the first lens group G1.
φ1b: Effective diameter on the image side lens surface of the lens arranged on the image side of the first lens group G1.

The conditional expression (7) is a conditional expression for defining an appropriate shape of the lens surface on the image side of the lens arranged on the most image side of the first lens group G1. When the corresponding value of the conditional expression (7) exceeds the upper limit value, the radius of curvature of the lens surface on the image side of the lens arranged on the most image side of the first lens group G1 is on the plus side (the side in which the convex surface faces the object side). Since it becomes too large, the curvature of the lens surface becomes small on the plus side, and it becomes difficult to correct spherical aberration and coma. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (7) may be preferably 5.0, more preferably 2.0.

When the corresponding value of the conditional expression (7) is less than the lower limit value, the radius of curvature of the lens surface on the image side of the lens arranged on the most image side of the first lens group G1 is on the minus side (the side where the convex surface faces the image side). Since it becomes too large, the curvature of the lens surface becomes small on the minus side, and it becomes difficult to correct off-axis coma aberration and the like. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (7) may be preferably −0.7, and more preferably -4.0.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (8).

0.10 <Y / BL <0.56 ... (8)
However, Y: the radius of the image circle of the optical system WL,
BL: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the optical system WL in the infinity focused state.

The conditional expression (8) is a conditional expression for defining an appropriate range between the radius (that is, the maximum image height) of the image circle of the optical system WL and the lens thickness. When the corresponding value of the conditional expression (8) exceeds the upper limit value, the lens configuration is thin with respect to the format size of the image sensor, but it becomes difficult to correct off-axis aberrations such as coma. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (8) may be preferably 0.50, and more preferably 0.40.

If the corresponding value of the conditional expression (8) is less than the lower limit value, the maximum image height of the optical system WL becomes small, so that a sufficient angle of view cannot be secured. In addition, it becomes difficult to correct spherical aberration and the like. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (8) may be preferably 0.15, and more preferably 0.20.

The optical system WL of this embodiment preferably satisfies the following conditional expression (9).

0.12 << | X2 | / f <0.20 ... (9)
However, X2: the amount of movement of the second lens group G2 when focusing from infinity to a short-distance object,
f: Focal length of the optical system WL in the infinity focused state.

The conditional expression (9) is a conditional expression for defining an appropriate range of the amount of movement of the second lens group G2 during focusing. If the corresponding value of the conditional expression (9) exceeds the upper limit value, the power (refractive power) of the second lens group G2 needs to be weakened, so that the optical performance at the time of close-range focusing cannot be maintained well. , It becomes difficult to correct the curvature of field. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (9) may be preferably 0.19, more preferably 0.18.

When the corresponding value of the conditional expression (9) is less than the lower limit value, it is necessary to increase the power of the second lens group G2, so that it becomes difficult to correct spherical aberration, coma aberration, and the like. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (9) may be preferably 0.13, and more preferably 0.14.

The optical system WL of the present embodiment preferably satisfies the following conditional expression (10).

5.20 <Y × f / TL <6.80 ... (10)
However, Y: the radius of the image circle of the optical system WL,
f: Focal length of the optical system WL in the infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system WL in the infinity focusing state, and the air conversion distance from the lens surface on the image side to the image plane.

The conditional expression (10) is a conditional expression for defining an appropriate range of the total length of the optical system WL with respect to the combination of the radius and the focal length of the image circle of the optical system WL. If the corresponding value of the conditional expression (10) exceeds the upper limit value, the total length of the optical system WL becomes short, so that it is necessary to increase the power of each lens group, and it is difficult to correct various aberrations such as spherical aberration and coma. become. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (10) may be preferably 6.50, and more preferably 6.00.

When the corresponding value of the conditional expression (10) is less than the lower limit value, the total length of the optical system WL becomes long, so that the diameter of the negative lens of the first lens group G1 becomes large, and it becomes difficult to correct the off-axis aberration. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (10) may be preferably 5.22, more preferably 5.25.

In the optical system WL of the present embodiment, it is preferable that the lens surface on the image side of the lens arranged on the image side of the second lens group G2 is a convex surface. As a result, the Petzval sum can be appropriately corrected, and the position of the exit pupil sufficiently distant from the image plane I can be secured.

In the optical system WL of the present embodiment, it is preferable that the lens surface on the image side of the lens arranged on the image side of the first lens group G1 is a convex surface. As a result, distortion, curvature of field, and astigmatism can be satisfactorily corrected.

In the optical system WL of the present embodiment, the second lens group G2 includes a meniscus-shaped first negative lens having a convex surface facing the image side and a biconvex first positive lens arranged in order from the object side. , A second negative lens having a biconcave shape and a second positive lens having a biconvex shape may be included. This makes it possible to satisfactorily correct coma aberration and spherical aberration.

The optical device of the present embodiment is configured to include the optical system WL having the above-described configuration. As a specific example thereof, a camera (optical device) provided with the above optical system WL will be described with reference to FIG. As shown in FIG. 11, the camera 1 is a digital camera provided with the optical system WL according to the above embodiment as the photographing lens 2. In the camera 1, the light from an object (subject) (not shown) is collected by the photographing lens 2 and reaches the image sensor 3. As a result, the light from the subject is captured by the image sensor 3 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1. The camera 1 may be a mirrorless camera or a single-lens reflex type camera having a quick return mirror. Further, the camera 1 is not limited to a single-lens reflex type camera in which the lens barrel and the camera body body can be attached and detached, and even if the lens barrel and the camera body body are integrated into a compact type camera. Good. According to such a configuration, by mounting the optical system WL as a photographing lens, it is possible to obtain an optical device having a large aperture ratio, a small size, and good optical performance.

Subsequently, the method for manufacturing the above-mentioned optical system WL will be outlined with reference to FIG. First, the first lens group G1 and the second lens group G2 are arranged in order from the object side in the lens barrel (step ST1). At this time, the aperture diaphragm S is arranged between the first lens group G1 and the second lens group G2. Further, a negative lens is arranged on the most object side of the second lens group G2 located on the image side of the aperture diaphragm S, and the negative lens is formed so that the lens surface on the object side is concave. Then, when focusing from infinity to a short-range object, the first lens group G1 is fixed, the second lens group G2 moves toward the object along the optical axis, and the first lens group G1 and the second lens group G1 and the second lens group G1 It is configured so that the distance from the lens group G2 changes (step ST2). Further, each lens is arranged in the lens barrel so as to satisfy at least the above conditional expression (1) (step ST3). According to such a manufacturing method, it is possible to manufacture an optical system having a large diameter ratio, a small size, and good optical performance.

Hereinafter, the optical system (wide-angle lens) WL according to the embodiment of the present embodiment will be described with reference to the drawings. 1, FIG. 3, FIG. 5, FIG. 7, and FIG. 9 are cross-sectional views showing the configuration and refractive power distribution of the optical systems WL {WL (1) to WL (5)} according to the first to fifth embodiments. is there. Each cross-sectional view describes the position of each group (denoted as "infinity" and "short distance") when focusing from infinity to a short-range object.

In FIGS. 1, 3, 5, 7, and 9, each lens group is represented by a combination of reference numerals G and numbers, and each lens is represented by a combination of reference numerals L and numbers. In this case, in order to prevent the types and numbers of codes and numbers from becoming large and complicated, the lens group and the like are represented by independently using combinations of signs and numbers for each embodiment. Therefore, even if the same combination of reference numerals and numbers is used between the examples, it does not mean that they have the same configuration.

Tables 1 to 5 are shown below. Of these, Table 1 is the first embodiment, Table 2 is the second embodiment, Table 3 is the third embodiment, Table 4 is the fourth embodiment, and Table 5 is the first embodiment. It is a table which shows each specification data in 5 Examples.
In each embodiment, d-line (wavelength λ = 587.6 nm) and g-line (wavelength λ = 435.8 nm) are selected as the calculation targets of the aberration characteristics.

In the [Overall Specifications] table, f indicates the focal length of the entire system in the optical system WL in the infinity focusing state, and FNO indicates the F number. 2ω indicates the angle of view (the unit is ° (degrees), and ω is the half angle of view), and Y indicates the image height (maximum image height). Bf indicates the air conversion distance (back focus) on the optical axis from the lens surface on the image side to the image plane I in the optical system WL in the infinity focusing state, and TL indicates the air conversion distance (back focus) in the optical system WL in the infinity focusing state. The distance (total length) on the optical axis from the lens surface on the most object side to the image plane I is shown. In TL, the air conversion distance from the lens surface on the image side of the optical system WL to the image surface I is shown. Further, the values of TL and Bf are shown in the [variable interval data] described later for each of the infinity in-focus state and the short-distance (close-distance) in-focus state.

Further, φ1b indicates the effective diameter of the lens arranged on the image side of the first lens group G1 on the image side, and X2 indicates the effective diameter of the second lens group G2 when focusing on a short-distance object from infinity. Indicates the amount of movement of. The amount of movement X2 is positive in the direction from the object side to the image side.

In the [Lens Specifications] table, the surface numbers indicate the order of the optical surfaces from the object side along the direction in which the light beam travels, and R is the radius of curvature of each optical surface (the surface whose center of curvature is located on the image side). (Positive value), D is the distance on the optical axis from each optical surface to the next optical surface (or image surface), nd is the refractive index of the material of the optical member with respect to the d line, and νd is optical. The Abbe number based on the d-line of the material of the member is shown. The radius of curvature "∞" indicates a plane or an aperture, and (aperture S) indicates an aperture stop S. The description of the refractive index of air nd = 1.00000 is omitted. When the lens surface is aspherical, the surface number is marked with * and the radius of curvature R indicates the paraxial radius of curvature.

In the table of [Aspherical surface data], the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (a). X (y) is the distance (zag amount) along the optical axis direction from the tangent plane at the aspherical apex to the position on the aspherical surface at the height y, and R is the radius of curvature of the reference sphere (near-axis radius of curvature). , Κ indicates the conical constant, and Ai indicates the i-th order aspherical coefficient. "E-n" indicates " ^{x10 -n} ". For example, 1.234E-05 = 1.234 × 10 ^-5 . The second-order aspherical coefficient A2 is 0, and the description thereof is omitted.

X (y) = (y ² / R) / {1 + (1-κ × y ² / R ² ) ^1/2 } + A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ + A10 × y ¹⁰ ... (a) )

In the table of [lens group data], the start surface (the surface closest to the object side) and the focal length of each of the first lens group G1 and the second lens group G2 are shown.

The table of [variable spacing data] shows the plane spacing Di to the next plane at the plane number i in which the plane spacing is "variable" in the table showing [lens specifications]. For example, in the first embodiment, the surface spacings D7 and D19 at the surface numbers 7 and 19 are shown. These values are shown for each of the infinity in-focus state and the short-distance (close-distance) in-focus state.

The table of [Conditional expression corresponding values] shows the values corresponding to the above conditional expressions (1) to (10).

Hereinafter, in all the specification values, "mm" is generally used for the focal length f, the radius of curvature R, the plane spacing D, other lengths, etc., unless otherwise specified, but the optical system is expanded proportionally. Alternatively, it is not limited to this because the same optical performance can be obtained even if the proportional reduction is performed.

The description of the table so far is common to all the examples, and the duplicate description below is omitted.

(First Example)
The first embodiment will be described with reference to FIGS. 1 to 2 and Table 1. FIG. 1 is a diagram showing a lens configuration of an optical system according to a first embodiment of the present embodiment. The optical system WL (1) according to the first embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power arranged in order from the object side. .. Further, an aperture diaphragm S is arranged between the first lens group G1 and the second lens group G2. The symbol (+) or (-) attached to the symbol of each lens group indicates the refractive power of each lens group, and this also applies to all the following examples.

The first lens group G1 includes a meniscus-shaped first negative lens L11 having a convex surface facing the object side, a biconcave second negative lens L12, and a biconvex first negative lens L11 arranged in order from the object side. It is composed of a junction lens made of a positive lens L13 and a second positive lens L14 having a biconvex shape. That is, the first lens group G1 is composed of four lenses. The first negative lens L11 has an aspherical lens surface on the object side.

The second lens group G2 includes a meniscus-shaped first negative lens L21 arranged in order from the object side and having a convex surface facing the image side, a biconvex first positive lens L22, and a biconvex second lens. L23, a meniscus-shaped second negative lens L24 with a convex surface facing the object side, a meniscus-shaped third negative lens L25 with a convex surface facing the object side, and a biconvex third positive lens. It is composed of a junction lens made of L26. That is, the second lens group G2 is composed of six lenses. The first positive lens L22 has an aspherical lens surface on the image side.

The image plane I is arranged on the image side of the second lens group G2. In order to cut a spatial frequency equal to or higher than the limit resolution of an image sensor (for example, CCD, CMOS, etc.) arranged on the image plane I in the vicinity of the image plane I between the second lens group G2 and the image plane I. Low-pass filter FL is arranged. In the optical system WL (1) according to the first embodiment, the first lens group G1 is fixed and the second lens group G2 is on the object side along the optical axis when focusing on a short-range object from infinity. The distance between the first lens group G1 and the second lens group G2 is changed (reduced) by moving to. Further, at the time of focusing, the aperture diaphragm S is configured to move along the optical axis together with the second lens group G2.

Table 1 below lists the specifications of the optical system according to the first embodiment.

(Table 1)
[Overall specifications]
f = 24.03
FNO = 1.95
2ω = 86.2
Y = 21.60
Bf = 27.018 (air equivalent length)
TL = 98.489 (air equivalent length)
φ1b = 25.01
X2 = -3.592
[Lens specifications]
Surface number RD nd νd
1 61.00000 1.524 1.49710 81.6
2 * 16.07881 19.148
3-39.52997 1.000 1.72825 28.4
4 25.44383 6.899 1.90265 35.7
5 -58.29655 0.200
6 94.37151 2.095 1.95375 32.3
7 -299.84325 D7 (variable)
8 ∞ 4.568 (Aperture S)
9 -23.12889 1.000 1.72825 28.4
10 -52.88931 4.545
11 108.15411 4.892 1.95150 29.8
12 * -91.29359 0.100
13 39.72911 4.198 1.75500 52.3
14 -42.52504 0.100
15 72.26139 3.584 1.66446 35.9
16 21.80180 2.060
17 1631.11840 1.000 1.79504 28.7
18 21.79336 4.991 1.49700 81.7
19 -37.70133 D19 (variable)
20 ∞ 1.500 1.51680 64.2
21 ∞ 0.000
[Aspherical data]
Second side κ = 7.44500E-01
A4 = -1.11688E-06, A6 = 1.89520E-08, A8 = -8.66722E-11, A10 = 1.04786E-13
Side 12 κ = -1.73400E-01
A4 = 1.56771E-05, A6 = 7.15689E-09, A8 = 5.77717E-13, A10 = 3.50489E-14
[Lens group data]
Focal length
G1 1 141.96
G2 9 41.08
[Variable interval data]
Infinity in-focus state Short-distance in-focus state f = 24.03 β = -0.1474
D0 ∞ 151.00
D7 9.567 5.975
D19 25.929 29.521
Bf (air) 27.018 30.610
TL (air) 98.489 98.489
[Conditional expression correspondence value]
Conditional expression (1) (R22 + R21) / (R22-R21) = 2.55
Conditional expression (2) f / TL = 0.24
Conditional expression (3) f2 / TL = 0.41
Conditional expression (4) Bf / f = 1.12
Conditional expression (5) f / f1 = 0.17
Conditional expression (6) DG1 / DG2 = 1.17
Conditional expression (7) R1b / φ1b = -11.99
Conditional expression (8) Y / BL = 0.302
Conditional expression (9) | X2 | / f = 0.15
Conditional expression (10) Y × f / TL = 5.24

FIG. 2A is a diagram of various aberrations of the optical system according to the first embodiment at infinity focusing. In each aberration diagram of FIG. 2A, FNO indicates an F number and A indicates a half angle of view. The spherical aberration diagram shows the value of the F number corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum value of the half angle of view, and the transverse aberration diagram shows the value of each half angle of view. FIG. 2B is a diagram of various aberrations at the time of short-distance (close-distance) focusing of the optical system according to the first embodiment. In each aberration diagram of FIG. 2B, NA indicates the numerical aperture and H0 indicates the object height. The spherical aberration diagram shows the numerical aperture value corresponding to the maximum aperture, the astigmatism diagram and the distortion aberration diagram show the maximum value of the object height, and the transverse aberration diagram shows the value of each object height. Further, in each aberration diagram of FIGS. 2 (a) and 2 (b), d indicates a d line (wavelength λ = 587.6 nm) and g indicates a g line (wavelength λ = 435.8 nm). In the astigmatism diagram, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. In the aberration diagrams of each of the following examples, the same reference numerals as those of the present embodiment are used, and duplicate description is omitted.

From each aberration diagram, it can be seen that the optical system according to the first embodiment satisfactorily corrects various aberrations and has excellent imaging performance.

(Second Example)
The second embodiment will be described with reference to FIGS. 3 to 4 and Table 2. FIG. 3 is a diagram showing a lens configuration of an optical system according to a second embodiment of the present embodiment. The optical system WL (2) according to the second embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power arranged in order from the object side. .. Further, an aperture diaphragm S is arranged between the first lens group G1 and the second lens group G2.

The first lens group G1 includes a meniscus-shaped first negative lens L11 having a convex surface facing the object side, and a meniscus-shaped second negative lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of a biconvex first positive lens L13, a biconcave third negative lens L14, and a biconvex second positive lens L15. That is, the first lens group G1 is composed of five lenses. The first positive lens L13 has an aspherical lens surface on the object side.

The second lens group G2 includes a biconcave first negative lens L21 arranged in order from the object side, a meniscus-shaped first positive lens L22 with a convex surface facing the image side, and a biconvex second lens. A junction lens consisting of a positive lens L23, a second negative lens L24 having a meniscus shape with a convex surface facing the object side, a third negative lens L25 having a biconcave shape, and a third positive lens L26 having a biconvex shape. , Consists of. That is, the second lens group G2 is composed of six lenses. The first negative lens L21 has an aspherical lens surface on the object side. The lens surface of the second positive lens L23 on the image side is aspherical.

The image plane I is arranged on the image side of the second lens group G2. In order to cut a spatial frequency equal to or higher than the limit resolution of an image sensor (for example, CCD, CMOS, etc.) arranged on the image plane I in the vicinity of the image plane I between the second lens group G2 and the image plane I. Low-pass filter FL is arranged. In the optical system WL (2) according to the second embodiment, the first lens group G1 is fixed and the second lens group G2 is on the object side along the optical axis when focusing on a short-range object from infinity. The distance between the first lens group G1 and the second lens group G2 is changed (reduced) by moving to. Further, at the time of focusing, the aperture diaphragm S is configured to move along the optical axis together with the second lens group G2.

Table 2 below lists the specifications of the optical system according to the second embodiment.

(Table 2)
[Overall specifications]
f = 24.09
FNO = 1.85
2ω = 85.4
Y = 21.60
Bf = 16.046 (air equivalent length)
TL = 98.489 (air equivalent length)
φ1b = 27.98
X2 = -4.192
[Lens specifications]
Surface number RD nd νd
1 61.00000 1.980 1.67270 32.2
2 23.15274 7.051
3 107.22972 1.000 1.66755 41.9
4 28.01217 9.439
5 * 45.38890 4.210 1.95150 29.8
6 -240.05180 7.560
7 -49.14202 1.000 1.69895 30.1
8 35.49623 7.421 1.88300 40.7
9 -41.96879 D9 (variable)
10 ∞ 3.319 (Aperture S)
11 * -55.74290 2.391 1.84681 23.6
12 157.34103 2.383
13 -114.23645 3.509 1.80610 41.0
14 -25.00000 1.500
15 38.65454 6.108 1.77250 49.5
16 * -34.03812 0.100
17 366.29782 3.109 1.80100 34.9
18 21.06154 3.672
19 -2295.36810 1.000 1.69895 30.1
20 23.32581 5.870 1.58913 61.2
21 -190.00000 D21 (variable)
22 ∞ 1.500 1.51680 64.2
23 ∞ 0.100
[Aspherical data]
Side 5 κ = 4.61700E-01
A4 = -7.16734E-07, A6 = -1.63781E-09, A8 = 2.70647E-12, A10 = -1.86351E-14
Side 11 κ = 7.55290E + 00
A4 = -3.49326E-05, A6 = -2.664640E-08, A8 = 1.07434E-10, A10 = 4.95139E-15
16th surface κ = 5.78000E-02
A4 = 1.66911E-07, A6 = 1.21571E-08, A8 = -1.13971E-11, A10 = 3.58849E-14
[Lens group data]
Focal length
G1 1 53.41
G2 11 52.51
[Variable interval data]
Infinity focusing state Short range focusing state f = 24.09 β = -0.1448
D0 ∞ 151.00
D9 9.821 5.629
D21 14.957 19.148
Bf (air) 16.046 20.237
TL (air) 98.489 98.489
[Conditional expression correspondence value]
Conditional expression (1) (R22 + R21) / (R22-R21) = 0.48
Conditional expression (2) f / TL = 0.24
Conditional expression (3) f2 / TL = 0.53
Conditional expression (4) Bf / f = 0.67
Conditional expression (5) f / f1 = 0.45
Conditional expression (6) DG1 / DG2 = 1.34
Conditional expression (7) R1b / φ1b = -1.50
Conditional expression (8) Y / BL = 0.262
Conditional expression (9) | X2 | / f = 0.17
Conditional expression (10) Y × f / TL = 5.26

FIG. 4A is an aberration diagram at infinity focusing of the optical system according to the second embodiment. FIG. 4B is a diagram of various aberrations at the time of short-distance (close-distance) focusing of the optical system according to the second embodiment. From each aberration diagram, it can be seen that the optical system according to the second embodiment satisfactorily corrects various aberrations and has excellent imaging performance.

(Third Example)
The third embodiment will be described with reference to FIGS. 5 to 6 and Table 3. FIG. 5 is a diagram showing a lens configuration of an optical system according to a third embodiment of the present embodiment. The optical system WL (3) according to the third embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power arranged in order from the object side. .. Further, an aperture diaphragm S is arranged between the first lens group G1 and the second lens group G2.

The first lens group G1 includes a meniscus-shaped first negative lens L11 having a convex surface facing the object side, a meniscus-shaped first positive lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of a meniscus-shaped second positive lens L13 with a convex surface facing the image side, a junction lens composed of a biconcave second negative lens L14, and a biconvex third positive lens L15. That is, the first lens group G1 is composed of five lenses. The first positive lens L12 has an aspherical lens surface on the image side.

The second lens group G2 consists of a meniscus-shaped first negative lens L21 having a convex surface facing the image side, a biconvex first positive lens L22, and a convex surface facing the image side, arranged in order from the object side. A junction lens composed of a second negative lens L23 having a meniscus shape, a second positive lens L24 having a biconvex shape, a third negative lens L25 having a biconcave shape, and a meniscus-shaped first lens having a convex surface facing the image side. It is composed of a junction lens including a negative lens L26 of No. 4 and a third positive lens L27 having a meniscus shape with a convex surface facing the image side. That is, the second lens group G2 is composed of seven lenses. The lens surface of the second positive lens L24 on the image side is aspherical. The third positive lens L27 has an aspherical lens surface on the image side.

The image plane I is arranged on the image side of the second lens group G2. In order to cut a spatial frequency equal to or higher than the limit resolution of an image sensor (for example, CCD, CMOS, etc.) arranged on the image plane I in the vicinity of the image plane I between the second lens group G2 and the image plane I. Low-pass filter FL is arranged. In the optical system WL (3) according to the third embodiment, the first lens group G1 is fixed and the second lens group G2 is on the object side along the optical axis when focusing on a short-range object from infinity. The distance between the first lens group G1 and the second lens group G2 is changed (reduced) by moving to. Further, at the time of focusing, the aperture diaphragm S is configured to be fixed together with the first lens group G1.

Table 3 below lists the specifications of the optical system according to the third embodiment.

(Table 3)
[Overall specifications]
f = 24.14
FNO = 1.85
2ω = 85.2
Y = 21.60
Bf = 16.092 (air equivalent length)
TL = 98.489 (air equivalent length)
φ1b = 23.98
X2 = -3.954
[Lens specifications]
Surface number RD nd νd
1 103.66156 1.800 1.58913 61.2
2 20.42084 16.831
3 64.27053 1.860 1.88202 37.2
4 * 135.57264 9.763
5 -55.25307 6.230 1.80604 40.7
6 -20.58872 1.200 1.66446 35.9
7 92.74950 0.500
8 55.32621 4.140 1.80400 46.6
9 -51.80704 3.761
10 ∞ D10 (variable) (aperture S)
11 -41.48146 2.000 1.68893 31.2
12 -87.94541 0.600
13 25.38767 7.248 1.69350 53.2
14 -26.98527 1.000 1.80100 34.9
15 -216.57089 2.720
16 121.88390 2.962 1.82080 42.7
17 * -56.93890 1.616
18 -217.18037 2.039 1.69895 30.1
19 32.18253 5.258
20 -25.67890 1.000 1.71736 29.6
21 -188.05035 3.000 1.80610 40.7
22 * -30.00000 D22 (variable)
23 ∞ 1.500 1.51680 64.2
24 ∞ 0.000
[Aspherical data]
4th surface κ = 4.20000E + 01
A4 = 6.07770E-07, A6 = 2.82158E-11, A8 = 3.48783E-12, A10 = -1.69590E-14
Surface 17 κ = -8.18280E + 00
A4 = 1.15224E-05, A6 = -1.65861E-08, A8 = -1.36830E-10, A10 = 3.82021E-13
Side 22 κ = 2.41950E + 00
A4 = 2.89965E-05, A6 = 6.30910E-08, A8 = 3.81139E-10, A10 = 7.26525E-13
[Lens group data]
Focal length
G1 1 67.39
G2 11 56.98
[Variable interval data]
Infinity in-focus state Short-distance in-focus state f = 24.14 β = -0.1469
D0 ∞ 151.00
D10 6.869 2.915
D22 15.003 18.957
Bf (air) 16.092 20.046
TL (air) 98.489 98.489
[Conditional expression correspondence value]
Conditional expression (1) (R22 + R21) / (R22-R21) = 2.79
Conditional expression (2) f / TL = 0.24
Conditional expression (3) f2 / TL = 0.58
Conditional expression (4) Bf / f = 0.67
Conditional expression (5) f / f1 = 0.36
Conditional expression (6) DG1 / DG2 = 1.57
Conditional expression (7) R1b / φ1b = -2.16
Conditional expression (8) Y / BL = 0.262
Conditional expression (9) | X2 | / f = 0.16
Conditional expression (10) Y × f / TL = 5.27

FIG. 6A is an aberration diagram at infinity focusing of the optical system according to the third embodiment. FIG. 6B is a diagram of various aberrations at the time of short-distance (close-distance) focusing of the optical system according to the third embodiment. From each aberration diagram, it can be seen that the optical system according to the third embodiment satisfactorily corrects various aberrations and has excellent imaging performance.

(Fourth Example)
A fourth embodiment will be described with reference to FIGS. 7 to 8 and Table 4. FIG. 7 is a diagram showing a lens configuration of an optical system according to a fourth embodiment of the present embodiment. The optical system WL (4) according to the fourth embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power arranged in order from the object side. .. Further, an aperture diaphragm S is arranged between the first lens group G1 and the second lens group G2.

The first lens group G1 includes a meniscus-shaped first negative lens L11 having a convex surface facing the object side, and a meniscus-shaped second negative lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of a biconvex first positive lens L13, a biconcave third negative lens L14, and a biconvex second positive lens L15. That is, the first lens group G1 is composed of five lenses. The second negative lens L12 has an aspherical lens surface on the image side.

The second lens group G2 includes a meniscus-shaped first negative lens L21 having a convex surface facing the image side, and a meniscus-shaped first positive lens L22 having a convex surface facing the image side, arranged in order from the object side. A biconvex second positive lens L23, a biconvex third positive lens L24, a meniscus-shaped second negative lens L25 with a convex surface facing the object side, and a meniscus with a convex surface facing the image side. It is composed of a third negative lens L26 having a shape. That is, the second lens group G2 is composed of six lenses. The first positive lens L22 has an aspherical lens surface on the image side. The third positive lens L24 has an aspherical lens surface on the image side.

The image plane I is arranged on the image side of the second lens group G2. In order to cut a spatial frequency equal to or higher than the limit resolution of an image sensor (for example, CCD, CMOS, etc.) arranged on the image plane I in the vicinity of the image plane I between the second lens group G2 and the image plane I. Low-pass filter FL is arranged. In the optical system WL (4) according to the fourth embodiment, the first lens group G1 is fixed and the second lens group G2 is on the object side along the optical axis when focusing on a short-range object from infinity. The distance between the first lens group G1 and the second lens group G2 is changed (reduced) by moving to. Further, at the time of focusing, the aperture diaphragm S is configured to move along the optical axis together with the second lens group G2.

Table 4 below lists the specifications of the optical system according to the fourth embodiment.

(Table 4)
[Overall specifications]
f = 24.09
FNO = 1.65
2ω = 85.0
Y = 21.60
Bf = 16.091 (air equivalent length)
TL = 98.489 (air equivalent length)
φ1b = 27.94
X2 = -3.837
[Lens specifications]
Surface number RD nd νd
1 331.20889 2.200 1.58913 61.2
2 20.26007 7.099
3 28.21954 1.000 1.69680 55.5
4 * 23.24760 6.765
5 54.21538 5.983 1.95375 32.3
6 -135.86729 2.821
7 -43.70270 1.000 1.74077 27.7
8 75.22383 0.100
9 49.75549 6.465 1.75500 52.3
10 -39.38857 D10 (variable)
11 ∞ 9.687 (Aperture S)
12 -17.89127 1.000 1.84666 23.8
13 -82.98744 0.100
14 -115.72126 4.350 1.92286 20.9
15 * -32.43919 0.200
16 158.09926 5.968 1.75500 52.3
17 -26.81826 0.100
18 58.04640 5.240 1.58913 61.2
19 * -39.44565 0.100
20 165.11070 4.567 1.80518 25.4
21 22.03164 4.040
22 ∞ 0.931 (virtual surface)
23 -114.80353 3.000 1.48749 70.3
24-190.00000 D24 (variable)
25 ∞ 1.500 1.51680 64.2
26 ∞ 0.100
[Aspherical data]
Side 4 κ = -2.74100E-01
A4 = 8.68813E-06, A6 = -5.16406E-10, A8 = 3.46658E-12, A10 = -4.26743E-15
Surface 15 κ = -2.79540E + 00
A4 = 9.40408E-06, A6 = 2.07357E-08, A8 = -4.24422E-11, A10 = 4.51553E-14
Surface 19 κ = -1.16990E + 00
A4 = -2.05004E-07, A6 = 3.48317E-08, A8 = -9.42820E-11, A10 = 1.27866E-13
[Lens group data]
Focal length
G1 1 71.87
G2 12 42.25
[Variable interval data]
Infinity in-focus state Short-distance in-focus state f = 24.09 β = -0.1463
D0 ∞ 151.00
D10 9.681 5.843
D24 15.002 18.840
Bf (air) 16.091 19.929
TL (air) 98.489 98.489
[Conditional expression correspondence value]
Conditional expression (1) (R22 + R21) / (R22-R21) = 1.55
Conditional expression (2) f / TL = 0.24
Conditional expression (3) f2 / TL = 0.43
Conditional expression (4) Bf / f = 0.67
Conditional expression (5) f / f1 = 0.34
Conditional expression (6) DG1 / DG2 = 1.13
Conditional expression (7) R1b / φ1b = -1.41
Conditional expression (8) Y / BL = 0.262
Conditional expression (9) | X2 | / f = 0.16
Conditional expression (10) Y × f / TL = 5.26

FIG. 8A is an aberration diagram at infinity focusing of the optical system according to the fourth embodiment. FIG. 8B is a diagram of various aberrations at the time of short-distance (close-distance) focusing of the optical system according to the fourth embodiment. From each aberration diagram, it can be seen that the optical system according to the fourth embodiment satisfactorily corrects various aberrations and has excellent imaging performance.

(Fifth Example)
A fifth embodiment will be described with reference to FIGS. 9 to 10 and Table 5. FIG. 9 is a diagram showing a lens configuration of an optical system according to a fifth embodiment of the present embodiment. The optical system WL (5) according to the fifth embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power arranged in order from the object side. .. Further, an aperture diaphragm S is arranged between the first lens group G1 and the second lens group G2.

The first lens group G1 includes a meniscus-shaped first negative lens L11 having a convex surface facing the object side, and a meniscus-shaped first positive lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of a biconcave second negative lens L13 and a biconvex second positive lens L14. That is, the first lens group G1 is composed of four lenses. The second positive lens L14 has an aspherical lens surface on the image side.

The second lens group G2 includes a meniscus-shaped first negative lens L21 arranged in order from the object side and having a convex surface facing the image side, a biconvex first positive lens L22, and a biconcave second lens. A junction lens composed of a negative lens L23, a biconvex second positive lens L24, a biconcave third negative lens L25, a biconcave fourth negative lens L26, and a biconvex third. It is composed of a bonded lens made of the positive lens L27 of That is, the second lens group G2 is composed of seven lenses. The lens surface of the second positive lens L24 on the image side is aspherical. The third positive lens L27 has an aspherical lens surface on the image side.

The image plane I is arranged on the image side of the second lens group G2. In order to cut a spatial frequency equal to or higher than the limit resolution of an image sensor (for example, CCD, CMOS, etc.) arranged on the image plane I in the vicinity of the image plane I between the second lens group G2 and the image plane I. Low-pass filter FL is arranged. In the optical system WL (5) according to the fifth embodiment, the first lens group G1 is fixed and the second lens group G2 is on the object side along the optical axis when focusing on a short-range object from infinity. The distance between the first lens group G1 and the second lens group G2 is changed (reduced) by moving to. Further, at the time of focusing, the aperture diaphragm S is configured to be fixed together with the first lens group G1.

Table 5 below lists the specifications of the optical system according to the fifth embodiment.

(Table 5)
[Overall specifications]
f = 24.88
FNO = 1.85
2ω = 85.0
Y = 21.60
Bf = 16.084 (air equivalent length)
TL = 98.489 (air equivalent length)
φ1b = 26.32
X2 = -4.162
[Lens specifications]
Surface number RD nd νd
1 259.93798 1.800 1.61800 63.3
2 23.21609 17.645
3 57.64328 3.617 1.85026 32.4
4 825.22838 10.110
5 -34.47703 1.000 1.80518 25.4
6 537.21533 0.500
7 87.30361 5.646 1.85108 40.1
8 * -33.94300 2.539
9 ∞ D9 (variable) (aperture S)
10 -51.86043 2.000 1.63980 34.5
11 -625.30255 0.100
12 25.00000 11.041 1.61800 63.3
13 -27.39159 1.000 1.62588 35.7
14 27.16911 0.782
15 24.68610 5.040 1.88202 37.2
16 * -127.35739 3.526
17 -866.88526 1.000 1.64769 33.7
18 37.60165 3.974
19 -29.83312 1.000 1.69895 30.1
20 108.02024 3.000 1.82098 42.5
21 * -34.70573 D21 (variable)
22 ∞ 1.500 1.51680 63.9
23 ∞ 0.100
[Aspherical data]
Side 8 κ = 4.89200E-01
A4 = 8.32980E-07, A6 = 1.36681E-09, A8 = 2.95579E-12, A10 = -9.22667E-15
16th surface κ = -1.97822E + 01
A4 = 1.34043E-05, A6 = -1.68712E-08, A8 = -6.06266E-11, A10 = 1.67715E-13
Side 21 κ = 1.03830E + 00
A4 = 2.78128E-05, A6 = 1.14967E-08, A8 = 6.40144E-10, A10 = -8.79238E-13
[Lens group data]
Focal length
G1 1 73.76
G2 10 52.78
[Variable interval data]
Infinity focusing state Short range focusing state f = 24.88 β = -0.1525
D0 ∞ 150.00
D9 7.119 2.916
D21 14.995 19.198
Bf (air) 16.084 20.287
TL (air) 98.489 98.489
[Conditional expression correspondence value]
Conditional expression (1) (R22 + R21) / (R22-R21) = 1.18
Conditional expression (2) f / TL = 0.31
Conditional expression (3) f2 / TL = 0.66
Conditional expression (4) Bf / f = 0.65
Conditional expression (5) f / f1 = 0.34
Conditional expression (6) DG1 / DG2 = 1.24
Conditional expression (7) R1b / φ1b = -1.31
Conditional expression (8) Y / BL = 0.262
Conditional expression (9) | X2 | / f = 0.17
Conditional expression (10) Y × f / TL = 6.72

FIG. 10A is an aberration diagram at infinity focusing of the optical system according to the fifth embodiment. FIG. 10B is a diagram of various aberrations at the time of short-distance (close-distance) focusing of the optical system according to the fifth embodiment. From each aberration diagram, it can be seen that the optical system according to the fifth embodiment satisfactorily corrects various aberrations and has excellent imaging performance.

According to each of the above embodiments, it is possible to realize an optical system having a large aperture ratio, a small size, and good optical performance.

Here, each of the above examples shows a specific example of the present invention, and the present invention is not limited thereto.

The following contents can be appropriately adopted as long as the optical performance of the optical system of the present embodiment is not impaired.

As a numerical example of the optical system of the present embodiment, a two-group configuration is shown, but the present application is not limited to this, and an optical system having another group configuration (for example, three groups or the like) can also be configured. Specifically, a lens or a lens group may be added to the most object side or the most image plane side of the optical system of the present embodiment.

In the optical system of the present embodiment, not only the second lens group G2 but also a single lens group, a plurality of lens groups, or a partial lens group is moved in the optical axis direction to focus from an infinity object to a short-range object. It may be a focusing lens group. This focusing lens group can also be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like).

In addition, the lens group or partial lens group is moved so as to have a component in the direction perpendicular to the optical axis, or is rotationally moved (swinged) in the in-plane direction including the optical axis to cause image blur caused by camera shake. It may be a group of anti-vibration lenses to be corrected.

The lens surface may be formed on a spherical surface or a flat surface, or may be formed on an aspherical surface. When the lens surface is spherical or flat, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to processing and assembly adjustment errors can be prevented, which is preferable. Further, even if the image plane is deviated, the depiction performance is less deteriorated, which is preferable.

When the lens surface is aspherical, the aspherical surface is an aspherical surface formed by grinding, a glass mold aspherical surface formed by forming glass into an aspherical shape, or a composite aspherical surface formed by forming resin on the glass surface into an aspherical shape. It doesn't matter which one. Further, the lens surface may be a diffraction surface, and the lens may be a refractive index distribution type lens (GRIN lens) or a plastic lens.

The aperture diaphragm is preferably arranged between the first lens group and the second lens group, but the role may be substituted by the frame of the lens without providing the member as the aperture diaphragm.

An antireflection film having a high transmittance in a wide wavelength range may be applied to each lens surface in order to reduce flare and ghost and achieve high contrast optical performance. As a result, flare and ghost can be reduced, and high contrast and high optical performance can be achieved.

G1 1st lens group G2 2nd lens group I image plane S aperture stop

Claims (21)

The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.35
0.12 << | X2 | / f <0.20
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
X2: The amount of movement of the second lens group when focusing from infinity to a short-distance object,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.30
0.45 <Bf / f <0.80
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
Bf: Air conversion distance on the optical axis from the lens surface on the image side to the image surface in the optical system in the infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.30
0.95 <DG1 / DG2 <1.70
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
DG1: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the first lens group,
DG2: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the second lens group.
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
The lens surface on the image side of the lens arranged on the image side of the first lens group is a convex surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.20 <f / TL <0.30
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
f: Focal length of the optical system in an infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.50 <Bf / f <0.80
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
Bf: Air conversion distance on the optical axis from the lens surface on the image side to the image surface in the optical system in the infinity focused state,
f: Focal length of the optical system in an infinity focused state. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
The lens surface on the image side of the lens arranged on the image side of the second lens group is a convex surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.45 <Bf / f <0.80
0.10 <f / f1 <0.55
5.20 <Y × f / TL <6.80 [Unit: mm]
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
Bf: Air conversion distance on the optical axis from the lens surface on the image side to the image surface in the optical system in the infinity focused state,
f: Focal length of the optical system in an infinity focused state,
f1: Focal length of the first lens group,
Y: Radius of the image circle of the optical system,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.12 << | X2 | / f <0.20
0.10 <f / f1 <0.55
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
X2: The amount of movement of the second lens group when focusing from infinity to a short-distance object,
f: Focal length of the optical system in an infinity focused state,
f1: Focal length of the first lens group. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
The lens surface on the image side of the lens arranged on the image side of the first lens group is a convex surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.12 << | X2 | / f <0.20
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
X2: The amount of movement of the second lens group when focusing from infinity to a short-distance object,
f: Focal length of the optical system in an infinity focused state. The first lens group and the second lens group, which are arranged in order from the object side, are substantially composed of two lens groups.
When focusing on a short-range object from infinity, the first lens group is fixed, the second lens group moves toward the object along the optical axis, and the distance between adjacent lens groups changes. ,
An aperture diaphragm is arranged between the first lens group and the second lens group.
The lens arranged on the object side of the second lens group located on the image side of the aperture diaphragm is a negative lens.
The lens surface on the object side of the negative lens arranged on the most object side of the second lens group is a concave surface.
The lens surface on the image side of the lens arranged on the image side of the first lens group is a convex surface.
The lens surface on the image side of the lens arranged on the image side of the second lens group is a convex surface.
An optical system characterized by satisfying the following conditional expression.
0.10 <(R22 + R21) / (R22-R21) <3.00
0.95 <DG1 / DG2 <1.70
5.20 <Y × f / TL <6.80 [Unit: mm]
However, R21: the radius of curvature of the lens surface on the object side of the negative lens arranged on the most object side of the second lens group,
R22: Radius of curvature of the lens surface on the image side of the negative lens arranged on the most object side of the second lens group,
DG1: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the first lens group,
DG2: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the second lens group.
Y: Radius of the image circle of the optical system,
f: Focal length of the optical system in an infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The optical system according to any one of claims 5 to 9 , wherein the optical system satisfies the following conditional expression.
0.20 <f / TL <0.35
However, f: the focal length of the optical system in the infinite focus state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The optical system according to any one of claims 1, 3, 4, and 7 to 9 , wherein the optical system satisfies the following conditional expression.
0.45 <Bf / f <0.80
However, Bf: the air conversion distance on the optical axis from the lens surface on the image side to the image surface in the optical system in the infinity focused state,
f: Focal length of the optical system in an infinity focused state. The optical system according to any one of claims 1 to 5, 8, and 9 , wherein the optical system satisfies the following conditional expression.
0.10 <f / f1 <0.55
However, f: the focal length of the optical system in the infinite focus state,
f1: Focal length of the first lens group. The optical system according to any one of claims 1 and 4 to 8 , wherein the optical system satisfies the following conditional expression.
0.95 <DG1 / DG2 <1.70
However, DG1: the distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the first lens group,
DG2: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the second lens group. The optical system according to any one of claims 3, 5, and 9 , wherein the optical system satisfies the following conditional expression.
0.12 << | X2 | / f <0.20
However, X2: the amount of movement of the second lens group when focusing from infinity to a short-distance object,
f: Focal length of the optical system in an infinity focused state. The optical system according to claim 3 or 5, wherein the optical system satisfies the following conditional expression.
5.20 <Y × f / TL <6.80 [Unit: mm]
However, Y: the radius of the image circle of the optical system,
f: Focal length of the optical system in an infinity focused state,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The optical system according to claim 5, wherein the lens surface on the image side of the lens arranged on the most image side of the first lens group is a convex surface. The optical system according to any one of claims 1 to 16 , wherein the optical system satisfies the following conditional expression.
0.30 <f2 / TL <0.65
However, f2: the focal length of the second lens group,
TL: The distance on the optical axis from the lens surface on the most object side to the image plane in the optical system in the infinity focused state, and the air conversion distance from the lens surface on the image side to the image plane. The optical system according to any one of claims 1 to 17 , wherein the optical system satisfies the following conditional expression.
-12.0 <R1b / φ1b <8.0
However, R1b: the radius of curvature of the lens surface on the image side of the lens arranged on the image side of the first lens group,
φ1b: The effective diameter of the lens arranged on the image side of the first lens group on the image side. The optical system according to any one of claims 1 to 18 , wherein the optical system satisfies the following conditional expression.
0.10 <Y / BL <0.56
However, Y: the radius of the image circle of the optical system,
BL: The distance on the optical axis from the lens surface on the most object side to the lens surface on the image side in the optical system in the infinity focused state. A 1st to 5th, 7th, 8th, and 10th to 19th claims, wherein the lens surface on the image side of the lens arranged on the most image side of the second lens group is a convex surface. The optical system according to any one item. An optical device including the optical system according to any one of claims 1 to 20 .

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