Imaging lens and imaging apparatus

Abstract

To provide an imaging lens which has a small F number, is compact, and holds excellent optical performance, and to provide an imaging apparatus including the imaging lens.SOLUTION: The imaging lens consists of, in order from the object side to the image side, a first lens group, a stop, and a second lens group. During focusing, the entire imaging lens moves, or the first lens group, the stop, and a part of the second lens group move. Assuming that a focal distance of the imaging lens in a state where an object at infinity is in focus is f, and a focal distance of the first lens group is f1, the imaging lens satisfies a condition of 0.1 <f / f1 <1.5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology of the present disclosure relates to an imaging lens and an imaging device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an imaging optical system described in Patent Document 1 below is known as an imaging lens that can be used in imaging devices such as digital cameras. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 034040 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for imaging lenses that have a small F-number, are compact, and maintain good optical performance, and these requirements are becoming higher every year.

[0005] The present disclosure provides an imaging lens that has a small F-number, is compact, and maintains good optical performance, and an imaging device that includes this imaging lens. [Means for solving the problem]

[0006] One aspect of the technology of the present disclosure is an imaging lens that includes, in order from the object side to the image side, a first lens group, an aperture, and a second lens group, and when focusing, the entire imaging lens moves, or the first lens group, the aperture, and a part of the second lens group move, and when the focal length of the imaging lens is in a state where it is focused on an object at infinity, is defined as f and the focal length of the first lens group is defined as f1, 0.1 <f / f1<1.5 (1) The conditional expression (1) expressed as follows is satisfied.

[0007] The first lens group includes at least one positive lens, and when the focal length of the positive lens with the strongest refractive power among the positive lenses included in the first lens group is taken as fp1, the imaging lens of the above aspect has the following characteristics: 0.1 <f / fp1<4 (2) It is preferable to satisfy conditional expression (2) below.

[0008] The first lens group includes at least one positive lens and at least one negative lens, and when the focal length of the positive lens closest to the object among the positive lenses included in the first lens group is fp1F, and the focal length of the negative lens with the strongest refractive power among the negative lenses included in the first lens group is fn1, the imaging lens of the above aspect has the following characteristics: 0.3 <fp1F / |fn1|<6 (3) It is preferable to satisfy conditional expression (3) below.

[0009] The second lens group includes at least one negative lens, and when the focal length of the negative lens with the strongest refractive power among the negative lenses included in the second lens group is denoted by fn2, the imaging lens of the above aspect has the following characteristics: 0.3 <f / |fn2|<6 (4) It is preferable to satisfy conditional expression (4) below.

[0010] The first lens group includes at least one positive lens and at least one negative lens, and when the focal length of the positive lens with the strongest refractive power among the positive lenses included in the first lens group is defined as fp1, and the focal length of the negative lens with the strongest refractive power among the negative lenses included in the first lens group is defined as fn1, the imaging lens of the above aspect has the following characteristics: 0.15 <fp1 / |fn1|<6 (5) It is preferable to satisfy conditional expression (5) below.

[0011] The first lens group includes at least one positive lens, and when the radius of curvature of the object-side surface of the positive lens with the strongest refractive power among the positive lenses included in the first lens group is Rf and the radius of curvature of the image-side surface of the positive lens with the strongest refractive power among the positive lenses included in the first lens group is Rr, the imaging lens of the above aspect has the following characteristics: 0.05<(Rr+Rf) / (Rr-Rf)<6 (6) It is preferable to satisfy conditional expression (6) below.

[0012] The first lens group includes at least one positive lens, and when the focal length of the positive lens with the strongest refractive power among the positive lenses included in the first lens group is taken as fp1, the imaging lens of the above aspect has the following characteristics: 0.3 <f1 / fp1<4.5 (7) It is preferable to satisfy conditional expression (7) below.

[0013] The first lens group includes at least one negative lens, the second lens group includes at least one negative lens, and, assuming that the focal length of the negative lens with the strongest refractive power among the negative lenses included in the first lens group is fn1 and the focal length of the negative lens with the strongest refractive power among the negative lenses included in the second lens group is fn2, the imaging lens of the above aspect has the following characteristics: 0.1 <fn1 / fn2<6 (8) It is preferable to satisfy conditional expression (8) below.

[0014] The first lens group includes at least one negative lens, and when the focal length of the negative lens with the strongest refractive power among the negative lenses included in the first lens group is taken as fn1, the imaging lens of the above aspect has the following characteristics: 0.2 <f / |fn1|<5 (9) It is preferable to satisfy conditional expression (9) below.

[0015] It is preferable that the lens surface of the first lens group closest to the image side is a concave surface, and the lens surface of the second lens group closest to the object side is a concave surface.

[0016] It is preferable that the first lens group includes two or more positive lenses.

[0017] It is preferable that a positive meniscus lens with a convex surface facing the object side be disposed closest to the object side in the first lens group.

[0018] The first lens group includes at least one positive lens, and when the refractive index of the positive lens closest to the object side among the positive lenses included in the first lens group is Np1F for the d-line, the imaging lens of the above aspect has the following refractive index: 1.5 <Np1F<2.03 (10) It is preferable to satisfy conditional expression (10) below.

[0019] The second lens group preferably includes at least one lens surface having a polar point, the polar point being a point on the lens surface other than on the optical axis, and the tangent plane of the lens surface at the polar point intersecting the optical axis perpendicularly.

[0020] The second lens group is composed of, in order from the object side to the image side, a front subgroup and a rear subgroup, During focusing, the first lens group, the aperture, and the front subgroup may move together, and the rear subgroup may be fixed relative to the image plane.

[0021] The rear subgroup preferably includes one or more lenses having at least one lens surface with a pole point, the pole point being a point on a lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole point intersects the optical axis perpendicularly.

[0022] The rear subgroup preferably includes two or more lenses each including at least one lens surface having a pole point.

[0023] When the sum of air gaps on the optical axis within the rear subgroup is D2Rair, and the distance on the optical axis from the lens surface of the rear subgroup closest to the object to the lens surface of the rear subgroup closest to the image is D2R, the imaging lens of the above aspect satisfies the following equation: 0≦D2Rair / D2R<0.45 (11) It is preferable to satisfy conditional expression (11) below.

[0024] When the distance on the optical axis from the lens surface of the first lens group closest to the object to the lens surface of the rear subgroup closest to the image when focused on an object at infinity is defined as DT, the imaging lens of the above aspect satisfies the following conditions: 0.05 <D2R / DT<0.5 (12) It is preferable to satisfy conditional expression (12) below.

[0025] Another aspect of the present disclosure is an imaging device including the imaging lens of the above aspect.

[0026] In this specification, the terms "consisting of" and "consisting of" are intended to mean that, in addition to the listed components, other components may also be included, such as lenses that have substantially no refractive power, optical elements other than lenses, such as apertures, filters, and cover glasses, and mechanical parts, such as lens flanges, lens barrels, image sensors, and image stabilization mechanisms.

[0027] In this specification, a "group having positive refractive power" means that the group as a whole has positive refractive power. Similarly, a "group having negative refractive power" means that the group as a whole has negative refractive power. A "lens having positive refractive power" and a "positive lens" are synonymous. A "lens having negative refractive power" and a "negative lens" are synonymous. In this specification, a "group" is not limited to a configuration consisting of multiple lenses, and may be a configuration consisting of only one lens.

[0028] The "focal length" used in the conditional expressions is the paraxial focal length. The "distance on the optical axis" used in the conditional expressions is the geometric distance unless otherwise specified. The values ​​used in the conditional expressions are values ​​based on the d-line when focused on an object at infinity, unless otherwise specified.

[0029] Unless otherwise specified, the radius of curvature, sign of refractive power, and surface shape of lenses including aspherical surfaces are those in the paraxial region. The sign of the radius of curvature is positive for surfaces with a convex shape facing the object side, and negative for surfaces with a convex shape facing the image side.

[0030] The terms "d-line," "C-line," and "F-line" used in this specification are emission lines, and the wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line as 656.27 nm (nanometers), and the wavelength of the F-line as 486.13 nm (nanometers). [Effects of the Invention]

[0031] According to the present disclosure, it is possible to provide an imaging lens that has a small F-number, is compact, and maintains good optical performance, and an imaging device that includes this imaging lens. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view showing the configuration of an imaging lens according to one embodiment, corresponding to the imaging lens of Example 1. FIG. [Figure 2] 2A to 2C are cross-sectional views showing the configuration and light beams in each state of the imaging lens of FIG. 1. [Figure 3] FIG. 10 is a diagram for explaining a pole point. [Figure 4] FIG. 2 is a diagram for explaining the position of the maximum effective diameter. [Figure 5] 3A to 3C are diagrams showing various aberrations of the imaging lens of Example 1. [Figure 6] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a second embodiment. [Figure 7] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 2. [Figure 8] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a third embodiment. [Figure 9] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 3. [Figure 10] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fourth embodiment. [Figure 11] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 4. [Figure 12] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fifth embodiment. [Figure 13] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 5. [Figure 14] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a sixth embodiment. [Figure 15] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 6. [Figure 16] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a seventh embodiment. [Figure 17]13A to 13C are diagrams showing various aberrations of the imaging lens of Example 7. [Figure 18] FIG. 13 is a cross-sectional view showing the configuration of an imaging lens according to an eighth embodiment. [Figure 19] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 8. [Figure 20] FIG. 13 is a cross-sectional view showing the configuration of an imaging lens according to a ninth embodiment. [Figure 21] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 9. [Figure 22] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to a tenth embodiment. [Figure 23] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 10. [Figure 24] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to an eleventh embodiment. [Figure 25] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 11. [Figure 26] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to a twelfth embodiment. [Figure 27] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 12. [Figure 28] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to a thirteenth embodiment. [Figure 29] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 13. [Figure 30] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens of Example 14. [Figure 31] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 14. [Figure 32] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens of Example 15. [Figure 33] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 15. [Figure 34] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to a sixteenth embodiment. [Figure 35] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 16. [Figure 36] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to a seventeenth embodiment. [Figure 37] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 17. [Figure 38]FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to an eighteenth embodiment. [Figure 39] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 18. [Figure 40] 1 is a perspective view of the front side of an imaging device according to an embodiment. [Figure 41] FIG. 2 is a perspective view of the rear side of the imaging device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0034] FIG. 1 shows a cross-sectional view of the configuration of an imaging lens according to an embodiment of the present disclosure. FIG. 2 shows a cross-sectional view of the configuration of the imaging lens of FIG. 1 and a light beam. In FIG. 2, the upper row labeled "infinity" shows a state in which the lens is focused on an object at infinity, and the lower row labeled "close distance" shows a state in which the lens is focused on an object at close distance. The state in the lower row of FIG. 2 is a state in which the absolute value of the imaging magnification is 0.15. In FIG. 2, the light beams shown are the on-axis light beam and the light beam at the maximum half angle of view in the state in which the lens is focused on an object at infinity, and the on-axis light beam and the light beam at the maximum half angle of view in the state in which the lens is focused on an object at close distance. In FIGS. 1 and 2, the left side is the object side, and the right side is the image side. The example shown in FIGS. 1 and 2 corresponds to the imaging lens of Example 1, which will be described later. The following description will mainly refer to FIG. 1.

[0035] The imaging lens of the present disclosure is a fixed-focus optical system and comprises, in order from the object side to the image side along the optical axis Z, a first lens group G1, an aperture stop St, and a second lens group G2. When focusing, either the entire imaging lens moves, or the first lens group G1, the aperture stop St, and a portion of the second lens group G2 move, with the remainder of the second lens group G2 being fixed relative to the image plane Sim. By using such a focusing mechanism, the overall optical length can be shortened.

[0036] As an example, each group of the imaging lens in FIG. 1 is configured as follows: The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of five lenses, L21 to L25, in order from the object side to the image side. The aperture diaphragm St in FIG. 1 does not indicate its size or shape, but rather its position in the optical axis direction. This method of illustrating the aperture diaphragm St is also used in other cross-sectional views.

[0037] In the example of Figure 1, the entire imaging lens moves as a unit during focusing. In this specification, "moving as a unit" means moving simultaneously in the same direction by the same amount. The brackets and arrows below the imaging lens in Figure 1 indicate the lens and its direction of movement during focusing from an object at infinity to a close object.

[0038] It is preferable that the first lens group G1 includes two or more positive lenses, which is advantageous for correcting spherical aberration.

[0039] It is preferable that a positive meniscus lens with its convex surface facing the object be located closest to the object in the first lens group G1, which is advantageous for correcting spherical aberration.

[0040] It is preferable that the lens surface closest to the image in the first lens group G1 is a concave surface, and the lens surface closest to the object in the second lens group G2 is a concave surface, which improves the symmetry of the optical system with respect to the aperture stop St, and is advantageous for optimal correction of various aberrations.

[0041] It is preferable that the second lens group G2 includes at least one lens surface that has a polar point, which makes it easier to achieve a significant reduction in the size of the optical system while still providing good correction for various aberrations.

[0042] In this specification, the term "lens surface" is not limited to an air-contact surface, but also includes a surface that is not in contact with air and is an interface between lenses made of different materials, such as the cemented surface of a cemented lens. Furthermore, in this specification, the term "lens surface" refers to a lens surface through which light rays used for imaging pass.

[0043] In this specification, a "pole point" refers to a point on a lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole point intersects the optical axis Z perpendicularly. FIG. 3 shows an enlarged view of the aperture stop St and second lens group G2 of the imaging lens of FIG. 1, taken along a cross section including the optical axis Z. As an example, FIG. 3 shows a pole point P on the image-side lens surface of lens L23, and the tangent plane Tp of this lens surface at pole point P is indicated by a dashed line. The tangent plane Tp intersects the optical axis Z perpendicularly. Note that the second lens group G2 in FIG. 3 has other pole points in addition to the pole point P shown in the figure, but the reference numerals for the other pole points have been omitted.

[0044] The imaging lens of the present disclosure preferably includes at least one of the following first to fourth aspherical lenses as lenses having a polar point.

[0045] The first aspherical lens is a lens that has at least one lens surface that faces the object side in the paraxial region and has a polar point. The first aspherical lens makes it easy to achieve a compact optical system while correcting off-axis aberrations without worsening spherical aberration.

[0046] The second aspherical lens is a lens having at least one lens surface that faces the object side in the paraxial region and has a polar point. The second aspherical lens is advantageous in reducing the angle of incidence of off-axis chief rays onto the image plane Sim while suppressing field curvature.

[0047] The third aspherical lens is a lens that has a convex shape facing the image side in the paraxial region and has at least one lens surface with a pole point. The third aspherical lens is advantageous for achieving a compact optical system while correcting various off-axis aberrations.

[0048] The fourth aspherical lens is a lens having at least one lens surface that has a concave shape facing the image side in the paraxial region and has a pole point. The fourth aspherical lens facilitates correction of astigmatism.

[0049] Next, a preferred configuration of the imaging lens of the present disclosure regarding the conditional expressions will be described. In the following explanation of the conditional expressions, to avoid redundancy, the same symbols are used for elements with the same definitions, and duplicate explanations of the symbols will be omitted. Also, to avoid redundancy, hereinafter, "the imaging lens of the present disclosure" will also be referred to simply as "the imaging lens."

[0050] In this specification, the terms "positive lens" and "negative lens" refer to a single lens element. For example, in the following description, if the first lens group G1 includes a cemented lens and the cemented lens includes a positive lens, the "positive lens included in the first lens group G1" does not refer to the cemented lens, but rather to a single positive lens in the cemented lens. Similarly, if the first lens group G1 includes a cemented lens and the cemented lens includes a negative lens, the "negative lens included in the first lens group G1" does not refer to the cemented lens, but rather to a single negative lens in the cemented lens. The same applies when the first lens group G1 is read as the second lens group G2.

[0051] It is preferable that the imaging lens satisfy the following conditional expression (1). Here, f is the focal length of the imaging lens when focused on an object at infinity. f1 is the focal length of the first lens group G1. By ensuring that the corresponding value of conditional expression (1) is not equal to or less than the lower limit, it is possible to ensure positive refractive power of the first lens group G1, which is advantageous for shortening the overall lens length. By ensuring that the corresponding value of conditional expression (1) is not equal to or greater than the upper limit, the positive refractive power of the first lens group G1 does not become too strong, making it easy to suppress spherical aberration and astigmatism. By making it easy to suppress spherical aberration, it becomes easy to reduce the F-number. 0.1 <f / f1<1.5 (1)

[0052] In order to obtain better characteristics, the lower limit of conditional expression (1) is more preferably set to 0.19, even more preferably 0.24, even more preferably 0.29, even more preferably 0.34, even more preferably 0.37, and even more preferably 0.39. In order to obtain better characteristics, the upper limit of conditional expression (1) is more preferably set to 1, even more preferably 0.75, even more preferably 0.65, even more preferably 0.62, even more preferably 0.59, and even more preferably 0.56. For example, it is more preferable that the imaging lens satisfy the following conditional expression (1-1). 0.29 <f / f1<0.65 (1-1)

[0053] In a configuration in which the first lens group G1 includes at least one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (2). Here, the focal length of the positive lens with the strongest refractive power among the positive lenses included in the first lens group G1 is set to fp1. By ensuring that the corresponding value of conditional expression (2) is not equal to or smaller than the lower limit, it becomes easy to make the optical system compact. By ensuring that the corresponding value of conditional expression (2) is not equal to or larger than the upper limit, it becomes easy to correct spherical aberration. 0.1 <f / fp1<4 (2)

[0054] In order to obtain better characteristics, the lower limit of conditional expression (2) is more preferably set to 0.4, even more preferably to 0.6, even more preferably to 0.8, even more preferably to 0.9, even more preferably to 0.95, and even more preferably to 1. In order to obtain better characteristics, the upper limit of conditional expression (2) is more preferably set to 2, even more preferably to 1.7, even more preferably to 1.4, even more preferably to 1.3, even more preferably to 1.27, and even more preferably to 1.25. For example, it is more preferable that the imaging lens satisfy the following conditional expression (2-1). 0.9 <f / fp1<1.3 (2-1)

[0055] In a configuration in which the first lens group G1 includes at least one positive lens and at least one negative lens, it is preferable that the imaging lens satisfy the following conditional expression (3). Here, the focal length of the positive lens closest to the object among the positive lenses included in the first lens group G1 is set to fp1F. The focal length of the negative lens with the strongest refractive power among the negative lenses included in the first lens group G1 is set to fn1. By ensuring that the corresponding value of conditional expression (3) is not equal to or less than the lower limit, correction of spherical aberration becomes easy. By ensuring that the corresponding value of conditional expression (3) is not equal to or greater than the upper limit, miniaturization of the optical system becomes easy. 0.3 <fp1F / |fn1|<6 (3)

[0056] In order to obtain better characteristics, the lower limit of conditional expression (3) is more preferably set to 0.8, even more preferably to 1.3, even more preferably to 1.9, even more preferably to 2.2, even more preferably to 2.3, even more preferably to 2.4, and even more preferably to 2.5. In order to obtain better characteristics, the upper limit of conditional expression (3) is more preferably set to 5, even more preferably to 4.5, even more preferably to 4.1, even more preferably to 3.7, even more preferably to 3.4, even more preferably to 3.2, and even more preferably to 3. For example, it is more preferable that the imaging lens satisfy the following conditional expression (3-1). 2.2 <fp1F / |fn1|<3.7 (3-1)

[0057] In a configuration in which the second lens group G2 includes at least one negative lens, it is preferable that the imaging lens satisfy the following conditional expression (4). Here, the focal length of the negative lens with the strongest refractive power among the negative lenses included in the second lens group G2 is set to fn2. By ensuring that the corresponding value of conditional expression (4) is not equal to or less than the lower limit, it becomes easy to make the optical system compact. By ensuring that the corresponding value of conditional expression (4) is not equal to or greater than the upper limit, it becomes easy to correct chromatic aberration of magnification. 0.3 <f / |fn2|<6 (4)

[0058] In order to obtain better characteristics, the lower limit of conditional expression (4) is more preferably set to 0.7, even more preferably to 1.05, even more preferably to 1.3, even more preferably to 1.55, even more preferably to 1.8, even more preferably to 2, and even more preferably to 2.2. In order to obtain better characteristics, the upper limit of conditional expression (4) is more preferably set to 5, even more preferably to 4, even more preferably to 3.3, even more preferably to 3.1, even more preferably to 3, even more preferably to 2.9, and even more preferably to 2.8. For example, it is more preferable that the imaging lens satisfy the following conditional expression (4-1): 1.55 <f / |fn2|<3.1 (4-1)

[0059] In a configuration in which the first lens group G1 includes at least one positive lens and at least one negative lens, it is preferable that the imaging lens satisfy the following conditional expression (5). By ensuring that the corresponding value of conditional expression (5) is not equal to or smaller than the lower limit, correction of spherical aberration becomes easy. By ensuring that the corresponding value of conditional expression (5) is not equal to or larger than the upper limit, miniaturization of the optical system becomes easy. 0.15 <fp1 / |fn1|<6 (5)

[0060] In order to obtain better characteristics, the lower limit of conditional expression (5) is more preferably set to 0.35, even more preferably 0.75, even more preferably 1, even more preferably 1.3, even more preferably 1.6, even more preferably 1.7, and even more preferably 1.75. In order to obtain better characteristics, the upper limit of conditional expression (5) is more preferably set to 5, even more preferably 4.5, even more preferably 4, even more preferably 3.35, even more preferably 3.5, even more preferably 3, and even more preferably 2.6. For example, it is more preferable that the imaging lens satisfy the following conditional expression (5-1): 1.6 <fp1 / |fn1|<3.5 (5-1)

[0061] In a configuration in which the first lens group G1 includes at least one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (6). Here, Rf is the radius of curvature of the object-side surface of the positive lens with the strongest refractive power among the positive lenses included in the first lens group G1. Rr is the radius of curvature of the image-side surface of the positive lens with the strongest refractive power among the positive lenses included in the first lens group G1. By ensuring that the corresponding value of conditional expression (6) is not equal to or less than the lower limit, off-axis aberrations can be easily corrected. By ensuring that the corresponding value of conditional expression (6) is not equal to or greater than the upper limit, the positive refractive power of the positive lens with the strongest refractive power among the positive lenses included in the first lens group G1 can be made sufficiently strong, making it easier to miniaturize the optical system. 0.05<(Rr+Rf) / (Rr-Rf)<6 (6)

[0062] In order to obtain better characteristics, the lower limit of conditional expression (6) is more preferably set to 0.2, even more preferably to 0.35, even more preferably to 0.5, even more preferably to 0.65, even more preferably to 0.8, even more preferably to 0.9, and even more preferably to 1. In order to obtain better characteristics, the upper limit of conditional expression (6) is more preferably set to 4, even more preferably to 3, even more preferably to 2.5, even more preferably to 2.2, even more preferably to 2, even more preferably to 1.9, and even more preferably to 1.8. For example, it is more preferable that the imaging lens satisfy the following conditional expression (6-1). 0.5<(Rr+Rf) / (Rr-Rf)<2.5 (6-1)

[0063] In a configuration in which the first lens group G1 includes at least one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (7): By ensuring that the corresponding value of conditional expression (7) is not equal to or smaller than the lower limit, it becomes easy to make the optical system compact. By ensuring that the corresponding value of conditional expression (7) is not equal to or larger than the upper limit, it becomes easy to correct spherical aberration. 0.3 <f1 / fp1<4.5 (7)

[0064] In order to obtain better characteristics, the lower limit of conditional expression (7) should more preferably be 0.5, even more preferably 0.7, even more preferably 0.8, even more preferably 0.9, even more preferably 1, even more preferably 1.1, and even more preferably 1.2. In order to obtain better characteristics, the upper limit of conditional expression (7) should more preferably be 3.8, even more preferably 3.1, even more preferably 2.8, even more preferably 2.7, even more preferably 2.6, even more preferably 2.5, and even more preferably 2.45.

[0065] In a configuration in which the first lens group G1 includes at least one negative lens and the second lens group G2 includes at least one negative lens, it is preferable that the imaging lens satisfy the following conditional expression (8). By ensuring that the corresponding value of conditional expression (8) is not equal to or smaller than the lower limit, correction of spherical aberration and curvature of field becomes easy. By ensuring that the corresponding value of conditional expression (8) is not equal to or larger than the upper limit, correction of longitudinal chromatic aberration becomes easy. 0.1 <fn1 / fn2<6 (8)

[0066] In order to obtain better characteristics, the lower limit of conditional expression (8) is more preferably 0.15, even more preferably 0.2, even more preferably 0.35, even more preferably 0.4, even more preferably 0.45, even more preferably 0.5, and even more preferably 0.55. In order to obtain better characteristics, the upper limit of conditional expression (8) is more preferably 4, even more preferably 2, even more preferably 1.7, even more preferably 1.5, even more preferably 1.3, even more preferably 1.1, and even more preferably 1.

[0067] In a configuration in which the first lens group G1 includes at least one negative lens, it is preferable that the imaging lens satisfy the following conditional expression (9): By ensuring that the corresponding value of conditional expression (9) is not equal to or smaller than the lower limit, correction of longitudinal chromatic aberration becomes easy. By ensuring that the corresponding value of conditional expression (9) is not equal to or larger than the upper limit, correction of spherical aberration becomes easy. 0.2 <f / |fn1|<5 (9)

[0068] In order to obtain better characteristics, the lower limit of conditional expression (9) is more preferably 0.5, even more preferably 0.8, even more preferably 1.1, even more preferably 1.4, even more preferably 1.7, even more preferably 1.9, and even more preferably 2.1. In order to obtain better characteristics, the upper limit of conditional expression (9) is more preferably 4, even more preferably 3.7, even more preferably 3.5, even more preferably 3.3, even more preferably 3.2, even more preferably 3.1, and even more preferably 3.

[0069] In a configuration in which the first lens group G1 includes at least one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (10). Here, the refractive index at the d-line of the positive lens closest to the object among the positive lenses included in the first lens group G1 is set to Np1F. Ensuring that the corresponding value of conditional expression (10) is not equal to or less than the lower limit thereof is advantageous for miniaturizing the optical system. Ensuring that the corresponding value of conditional expression (10) is not equal to or greater than the upper limit thereof can prevent the lens from becoming too heavy. 1.5 <Np1F<2.03 (10)

[0070] In order to obtain better characteristics, the lower limit of conditional expression (10) should preferably be set to 1.6, more preferably 1.7, even more preferably 1.74, and even more preferably 1.78.In order to obtain better characteristics, the upper limit of conditional expression (10) should preferably be set to 1.98, more preferably 1.94, even more preferably 1.92, and even more preferably 1.9.

[0071] If the focal length of the second lens group G2 when focused on an object at infinity is f2, it is preferable that the imaging lens satisfy the following conditional expression (14). By ensuring that the corresponding value of conditional expression (14) is not equal to or less than the lower limit, the positive refractive power of the second lens group G2 can be ensured, which is advantageous for shortening the overall lens length. By ensuring that the corresponding value of conditional expression (14) is not equal to or greater than the upper limit, the positive refractive power of the second lens group G2 does not become too strong, which makes it easy to suppress spherical aberration and / or astigmatism. 0.4 <f / f2<2.5 (14)

[0072] In order to obtain better characteristics, the lower limit of conditional expression (14) should preferably be set to 0.6, more preferably to 0.75, and even more preferably to 0.9.In order to obtain better characteristics, the upper limit of conditional expression (14) should preferably be set to 2, more preferably to 1.6, and even more preferably to 1.2.

[0073] When the radius of curvature of the lens surface closest to the object in the second lens group G2 is R21f, it is preferable that the imaging lens satisfy the following conditional expression (16). By ensuring that the corresponding value of conditional expression (16) is not equal to or smaller than the lower limit, it is possible to prevent spherical aberration from being overcorrected. By ensuring that the corresponding value of conditional expression (16) is not equal to or larger than the upper limit, it is possible to prevent spherical aberration from being undercorrected. -2 <R21f / f2<-0.1 (16)

[0074] In order to obtain better characteristics, the lower limit of conditional expression (16) should preferably be set to -1.6, more preferably to -1.2, and even more preferably to -0.8.In order to obtain better characteristics, the upper limit of conditional expression (16) should preferably be set to -0.2, more preferably to -0.25, and even more preferably to -0.3.

[0075] If the back focus in air equivalent distance of the imaging lens when focused on an object at infinity is Bf, it is preferable that the imaging lens satisfy the following conditional expression (17). The back focus in air equivalent distance is the air equivalent distance on the optical axis from the lens surface of the imaging lens closest to the image side to the image plane Sim. By ensuring that the corresponding value of conditional expression (17) is not equal to or smaller than the lower limit, it is easy to ensure the back focus required for an interchangeable lens for a camera. By ensuring that the corresponding value of conditional expression (17) is not equal to or larger than the upper limit, it is possible to prevent an increase in the overall lens length. 0.05 <Bf / f<0.7 (17)

[0076] In order to obtain better characteristics, the lower limit of conditional expression (17) should preferably be set to 0.1, more preferably to 0.15, and even more preferably to 0.2.In order to obtain better characteristics, the upper limit of conditional expression (17) should preferably be set to 0.6, more preferably to 0.5, and even more preferably to 0.45.

[0077] It is preferable that the imaging lens satisfy the following conditional expression (18). Here, the Abbe number based on the d-line of the positive lens with the strongest refractive power among the positive lenses included in the first lens group G1 is set to νp1. By ensuring that the corresponding value of conditional expression (18) is not equal to or smaller than the lower limit, correction of longitudinal chromatic aberration becomes easy. By ensuring that the corresponding value of conditional expression (18) is not equal to or larger than the upper limit, the refractive index of the positive lens with the strongest refractive power among the positive lenses included in the first lens group G1 does not become too low, making it easy to ensure the positive refractive power of this positive lens. 38<νp1<96 (18)

[0078] In order to obtain better characteristics, it is more preferable that the lower limit of conditional formula (18) be set to 48, even more preferably to 58, even more preferably to 64, and even more preferably to 70. In order to obtain better characteristics, it is more preferable that the upper limit of conditional formula (18) be set to 90, even more preferably to 86, even more preferably to 84, and even more preferably to 82.

[0079] In a configuration in which the imaging lens includes a first aspherical lens, it is preferable that at least one first aspherical lens satisfies the following conditional expression (20). Here, the radius of curvature of the object-side surface of the first aspherical lens at the position of the maximum effective diameter is defined as Ra1y. The paraxial radius of curvature of the object-side surface of the first aspherical lens is defined as Ra1c. By ensuring that the corresponding value of conditional expression (20) is not equal to or less than the lower limit, the negative refractive power at the periphery of the lens does not become too weak, making it easy to correct off-axis aberrations. By ensuring that the corresponding value of conditional expression (20) is not equal to or greater than the upper limit, the positive refractive power in the paraxial region does not become too weak, making it easy to correct spherical aberrations. -10 <Ra1y / Ra1c<0 (20)

[0080] In order to obtain better characteristics, the lower limit of conditional expression (20) should preferably be set to -5, more preferably to -3, even more preferably to -1, and even more preferably to -0.8.In order to obtain better characteristics, the upper limit of conditional expression (20) should preferably be set to -0.05, more preferably to -0.1, even more preferably to -0.15, and even more preferably to -0.2.

[0081] Here, the "position of the maximum effective diameter" in this specification will be explained with reference to FIG. 4. FIG. 4 is an explanatory diagram showing the configuration in a cross section including the optical axis Z. In FIG. 4, the left side is the object side and the right side is the image side. FIG. 4 shows an on-axis ray Xa and an off-axis ray Xb passing through the lens Lx. In the example of FIG. 4, ray Xb1, which is the upper ray of the off-axis ray Xb, is the outermost ray. Here, "outside" refers to the radially outward direction centered on the optical axis Z, i.e., the side away from the optical axis Z. In this specification, the position of intersection between this outermost ray and the lens surface is the position of the maximum effective diameter Px. Furthermore, twice the distance from the position of the maximum effective diameter Px to the optical axis Z is the effective diameter ED of the object-side surface of the lens Lx. Note that in the example of FIG. 4, the upper ray of the off-axis ray Xb is the outermost ray, but which ray is the outermost ray varies depending on the optical system.

[0082] In a configuration in which the imaging lens includes a second aspherical lens, it is preferable that at least one second aspherical lens satisfies the following conditional expression (21). Here, the radius of curvature of the object-side surface of the second aspherical lens at the position of the maximum effective diameter is defined as Ra2y. The paraxial radius of curvature of the object-side surface of the second aspherical lens is defined as Ra2c. By ensuring that the corresponding value of conditional expression (21) is not equal to or less than the lower limit, the positive refractive power at the peripheral part of the lens does not become too weak, which is advantageous for reducing the angle of incidence of the off-axial chief ray on the image plane Sim. By ensuring that the corresponding value of conditional expression (21) is not equal to or greater than the upper limit, the negative refractive power in the paraxial region does not become too weak, which makes it easy to prevent over-correction of spherical aberration. -10 <Ra2y / Ra2c<0 (21)

[0083] In order to obtain better characteristics, the lower limit of conditional expression (21) should preferably be set to -5, more preferably to -3, even more preferably to -1, and even more preferably to -0.8.In order to obtain better characteristics, the upper limit of conditional expression (21) should preferably be set to -0.05, more preferably to -0.1, even more preferably to -0.15, and even more preferably to -0.2.

[0084] In a configuration in which the imaging lens includes a third aspherical lens, it is preferable that at least one third aspherical lens satisfies the following conditional expression (22). Here, the radius of curvature of the image-side surface of the third aspherical lens at the position of the maximum effective diameter is defined as Ra3y. The paraxial radius of curvature of the image-side surface of the third aspherical lens is defined as Ra3c. By ensuring that the corresponding value of conditional expression (22) is not equal to or less than the lower limit, the negative refractive power at the periphery of the lens does not become too weak, making it easy to correct off-axis aberrations. By ensuring that the corresponding value of conditional expression (22) is not equal to or greater than the upper limit, the positive refractive power in the paraxial region does not become too weak, making it easy to correct spherical aberrations. -10 <Ra3y / Ra3c<0 (22)

[0085] In order to obtain better characteristics, the lower limit of conditional expression (22) should preferably be set to -5, more preferably to -3, even more preferably to -1, and even more preferably to -0.8.In order to obtain better characteristics, the upper limit of conditional expression (22) should preferably be set to -0.05, more preferably to -0.1, even more preferably to -0.15, and even more preferably to -0.2.

[0086] In a configuration in which the imaging lens includes a fourth aspherical lens, it is preferable that at least one fourth aspherical lens satisfies the following conditional expression (23). Here, the radius of curvature of the image-side surface of the fourth aspherical lens at the position of the maximum effective diameter is defined as Ra4y. The paraxial radius of curvature of the image-side surface of the fourth aspherical lens is defined as Ra4c. By ensuring that the corresponding value of conditional expression (23) is not equal to or less than the lower limit, the positive refractive power at the peripheral part of the lens does not become too weak, which is advantageous for reducing the angle of incidence of the off-axial chief ray on the image surface Sim. By ensuring that the corresponding value of conditional expression (23) is not equal to or greater than the upper limit, the negative refractive power in the paraxial region does not become too weak, which makes it easy to prevent over-correction of spherical aberration. -10 <Ra4y / Ra4c<0 (23)

[0087] In order to obtain better characteristics, the lower limit of conditional expression (23) should preferably be set to -5, more preferably to -3, even more preferably to -1, and even more preferably to -0.6.In order to obtain better characteristics, the upper limit of conditional expression (23) should preferably be set to -0.05, more preferably to -0.1, even more preferably to -0.15, and even more preferably to -0.2.

[0088] 1 is merely an example, and various modifications of the imaging lens of the present disclosure are possible without departing from the spirit and scope of the present disclosure. For example, the number of lenses included in each lens group may be different from that in the example of FIG.

[0089] In the imaging lens of the present disclosure, as shown in Example 3 (see FIG. 8) described later, the second lens group G2 may be configured to include, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. During focusing, the first lens group G1, aperture stop St, and front subgroup G2F may move integrally along the optical axis Z, while the rear subgroup G2R may be fixed relative to the image plane Sim. Fixing the rear subgroup G2R during focusing is advantageous for simplifying the mechanism. The rear subgroup G2R may be a group having positive refractive power or a group having negative refractive power.

[0090] The rear subgroup G2R preferably includes one or more lenses that include at least one lens surface with a pole point. In this case, it becomes easier to suppress aberration fluctuations that accompany focusing. To further enhance this effect, it is more preferable that the rear subgroup G2R include two or more lenses that include at least one lens surface with a pole point.

[0091] In a configuration in which the second lens group G2 is composed of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R, the rear subgroup G2R including one or more lenses including at least one lens surface with a polar point, and in which the rear subgroup G2R is fixed with respect to the image plane Sim while the other groups and the aperture stop St move integrally during focusing, it is preferable that the imaging lens satisfy the following conditional expression (11). Here, the sum of air spaces on the optical axis within the rear subgroup G2R is defined as D2Rair. The distance on the optical axis from the lens surface of the rear subgroup G2R closest to the object to the lens surface of the rear subgroup G2R closest to the image is defined as D2R. Satisfying conditional expression (11) is advantageous for suppressing various aberrations. 0≦D2Rair / D2R<0.45 (11)

[0092] In order to obtain better characteristics, the lower limit of conditional expression (11) should preferably be set to 0.01, more preferably 0.015, even more preferably 0.02, and even more preferably 0.025.In order to obtain better characteristics, the upper limit of conditional expression (11) should preferably be set to 0.4, more preferably 0.36, even more preferably 0.32, and even more preferably 0.29.

[0093] In a configuration in which the second lens group G2 is composed of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R, the rear subgroup G2R including one or more lenses including at least one lens surface with a polar point, and the rear subgroup G2R is fixed with respect to the image plane Sim while the other groups and the aperture stop St move integrally during focusing, it is preferable that the imaging lens satisfy the following conditional expression (12). Here, DT is the distance on the optical axis from the lens surface of the first lens group G1 closest to the object to the lens surface of the rear subgroup G2R closest to the image when focused on an object at infinity. By ensuring that the corresponding value of conditional expression (12) is not less than the lower limit, it becomes easy to ensure an optical path length for correcting various aberrations within the rear subgroup G2R while achieving a significant reduction in the size of the optical system. By ensuring that the corresponding value of conditional expression (12) is not equal to or greater than the upper limit, the thickness of the rear subgroup G2R in the optical axis direction does not become too large, which is advantageous for shortening the overall optical length. 0.05 <D2R / DT<0.5 (12)

[0094] In order to obtain better characteristics, the lower limit of conditional expression (12) should preferably be set to 0.12, more preferably 0.18, and even more preferably 0.22. In order to obtain better characteristics, the upper limit of conditional expression (12) should preferably be set to 0.45, more preferably 0.4, and even more preferably 0.36. For example, it is more preferable that the imaging lens satisfy the following conditional expression (12-1). 0.22 <D2R / DT<0.36 (12-1)

[0095] In a configuration in which the second lens group G2 is composed of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R, and in which, during focusing, the rear subgroup G2R is fixed with respect to the image plane Sim, while the other groups and the aperture stop St move integrally, it is preferable that the rear subgroup G2R include at least one lens that satisfies the following conditional expression (13). Here, the refractive index of the lens included in the rear subgroup G2R at the d-line is denoted as N2R. The Abbe number of the lens included in the rear subgroup G2R based on the d-line is denoted as ν2R. By ensuring that the corresponding value of conditional expression (13) is not less than the lower limit, materials other than those with low refractive indexes and low Abbe numbers can be selected, making it easier to correct lateral chromatic aberration. By ensuring that the corresponding value of conditional expression (13) is not less than the upper limit, materials other than those with high refractive indexes and high Abbe numbers can be selected, making it easier to select materials with a low specific gravity, making it easier to reduce weight. 1.8 <N2R+0.01×ν2R<2.14 (13)

[0096] In order to obtain better characteristics, the lower limit of conditional expression (13) should preferably be set to 1.85, more preferably 1.9, and even more preferably 1.95.In order to obtain better characteristics, the upper limit of conditional expression (13) should preferably be set to 2.13, more preferably 2.12, and even more preferably 2.11.

[0097] In a configuration in which the second lens group G2 is composed of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R, and during focusing, the rear subgroup G2R is fixed with respect to the image plane Sim, while the other groups and the aperture stop St move integrally, it is preferable that the imaging lens satisfy the following conditional expression (15). Here, the focal length of the rear subgroup G2R is f2R. By satisfying conditional expression (15), the absolute value of the Petzval sum can be made close to zero, thereby preventing an increase in field curvature. Furthermore, by satisfying conditional expression (15), fluctuations in various aberrations can be suppressed when focusing from an object at infinity to an object at a close distance. 0.05<|f / f2R|<1.5 (15)

[0098] In order to obtain better characteristics, the lower limit of conditional expression (15) should preferably be set to 0.15, more preferably 0.25, and even more preferably 0.3.In order to obtain better characteristics, the upper limit of conditional expression (15) should preferably be set to 1.2, more preferably 0.9, and even more preferably 0.75.

[0099] The imaging lens of the present disclosure may include a triplet cemented lens in which a first positive lens, a second positive lens, and a negative lens are cemented together in this order, as shown in Example 10 (see FIG. 22) described later. This triplet cemented lens may be formed by cementing, in order from the object side to the image side, a first positive lens, a second positive lens, and a negative lens, or may be formed by cementing, in order from the image side to the object side, a first positive lens, a second positive lens, and a negative lens. Such a triplet cemented lens is advantageous for suppressing chromatic aberration.

[0100] When the imaging lens has a configuration including a triplet cemented lens in which a first positive lens, a second positive lens, and a negative lens are cemented together in this order, it is preferable that the imaging lens satisfy the following conditional expression (19). Here, the Abbe number based on the d-line of the first positive lens in the triplet cemented lens is denoted as νcp1. The Abbe number based on the d-line of the second positive lens in the triplet cemented lens is denoted as νcp2. By ensuring that the corresponding value of conditional expression (19) is not equal to or smaller than the lower limit, correction of lateral chromatic aberration becomes easier. By ensuring that the corresponding value of conditional expression (19) is not equal to or larger than the upper limit, the refractive index of the first positive lens does not become too low, which is advantageous for correction of spherical aberration. 16<νcp1-νcp2<83 (19)

[0101] In order to obtain better characteristics, the lower limit of conditional expression (19) should preferably be set to 17.5, and more preferably to 18.5.In order to obtain better characteristics, the upper limit of conditional expression (19) should preferably be set to 78, and more preferably to 75.

[0102] The above-described preferred and possible configurations can be arbitrarily combined within a range that does not cause a contradiction, and it is preferable that they be selectively adopted as appropriate according to the required specifications.

[0103] As an example, a preferred embodiment of the imaging lens of the present disclosure is an imaging lens consisting of, in order from the object side to the image side, a first lens group G1, an aperture stop St, and a second lens group G2, and when focusing, the entire imaging lens moves, or alternatively, parts of the first lens group G1, the aperture stop St, and the second lens group G2 move, and the above conditional formula (1) is satisfied.

[0104] Next, examples of the imaging lens of the present disclosure will be described with reference to the drawings. The reference symbols assigned to the groups and lenses in the cross-sectional views of each example are used independently for each example to avoid cluttering the explanations and drawings due to an increase in the number of digits in the reference symbols. Therefore, even if common reference symbols are assigned in drawings of different examples, this does not necessarily mean that the configuration is the same.

[0105] [Example 1] A cross-sectional view of the configuration of the imaging lens of Example 1 is shown in Figure 1, and since the illustration method and configuration are as described above, some redundant explanation will be omitted here. The imaging lens of Example 1 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. When focusing from an object at infinity to an object at a close distance, the entire imaging lens moves integrally toward the object side along the optical axis Z.

[0106] For the imaging lens of Example 1, basic lens data is shown in Table 1, specifications and variable surface spacing are shown in Table 2, and aspherical coefficients are shown in Table 3.

[0107] The table of basic lens data is written as follows. The "Sn" column shows the surface number, with the surface closest to the object being surface 1 and the numbers increasing by one as you move toward the image side. The "R" column shows the radius of curvature of each surface. The "D" column shows the surface spacing on the optical axis between each surface and its adjacent surface on the image side. The "Nd" column shows the refractive index of each lens relative to the d-line. The "νd" column shows the Abbe number of each lens based on the d-line.

[0108] The "Material" column in the table of basic lens data is written as follows: In the "Material" column, lenses made of resin are marked "plastic," while lenses made of a material other than resin are marked with the material name and the name of the manufacturer with a period between them. In the table, the names of manufacturers are shown generally as follows: "CDGM" stands for Chengdu Guangming Optoelectronics Co., Ltd. "OHARA" stands for Ohara Corporation. "HOYA" stands for Hoya Corporation.

[0109] The "ED" column shows the effective diameter of each surface, and to the left of the "Sn" column, the rows of lenses corresponding to the first aspherical lens, the second aspherical lens, the third aspherical lens, and the fourth aspherical lens are labeled "La1," "La2," "La3," and "La4," respectively.

[0110] In the basic lens data table, the sign of the radius of curvature of a surface with a convex shape facing the object side is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image side is negative. The column for the surface number of the surface corresponding to the aperture stop St is entered with the surface number and the phrase (St). The value in the bottom column of the D column in the table is the distance between the surface in the table closest to the image side and the image plane Sim. The symbol DD[ ] is used to indicate the variable surface distance during focusing, and the surface number of this distance on the object side is entered in the [ ] in the surface distance column.

[0111] Table 2 shows the focal length, back focal length, maximum F-number, maximum full-field angle, and variable surface spacing of imaging lenses, based on the d-line. In the maximum full-field angle column, [°] indicates that the unit is degrees. In Table 2, the "Infinity" column shows the values ​​when focused on an object at infinity, and the "Close Distance" column shows the values ​​when focused on an object at close range. However, only the focal length value when focused on an object at infinity is shown. The "Close Distance" column shows the absolute value of the shooting magnification when focused on an object at close range, followed by "times."

[0112] In the basic lens data, the surface numbers of aspherical surfaces are marked with an *, and the numerical value of the paraxial radius of curvature is entered in the column for the radius of curvature of the aspherical surface. In Table 3, the Sn row shows the surface numbers of aspherical surfaces, and the KA and Am rows show the numerical values ​​of the aspherical coefficients for each aspherical surface. Note that m in Am is an integer of 3 or more, and varies depending on the surface. For example, for the 10th surface of Example 1, m = 4, 6, 8, 10, 12, 14, 16, 18. The numerical values ​​of the aspherical coefficients in Table 3, "E±n" (n: integer), are expressed as "×10 ±n KA and Am are aspherical coefficients in the aspherical formula given below. Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m however, Zd: Aspheric depth (length of the perpendicular line drawn from a point on the aspheric surface at height h to a plane perpendicular to the optical axis Z where the vertex of the aspheric surface is in contact) h: Height (distance from optical axis Z to lens surface) C: Reciprocal of paraxial radius of curvature KA, Am: aspherical coefficients In the aspherical formula, Σ means the summation over m.

[0113] In the data in each table, the angle unit is degrees and the length unit is mm (millimeters), but since the optical system can be used with proportional enlargement or reduction, other appropriate units can also be used. Also, in each table below, the values ​​are rounded to a predetermined number of decimal places.

[0114] [Table 1]

[0115] [Table 2]

[0116] [Table 3]

[0117] FIG. 5 shows aberration diagrams of the imaging lens of Example 1. From left to right, FIG. 5 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration. In FIG. 5, the upper row labeled "Infinity" shows aberration diagrams in a state focused on an object at infinity, while the lower row labeled "Close" shows aberration diagrams in a state focused on an object at close range. In the spherical aberration diagrams, aberrations at the d-line, C-line, and F-line are shown by solid lines, long-dashed lines, and short-dashed lines, respectively. In the astigmatism diagrams, aberrations at the d-line in the sagittal direction are shown by solid lines, and aberrations at the d-line in the tangential direction are shown by short-dashed lines. In the distortion diagrams, aberrations at the d-line are shown by solid lines. In the lateral chromatic aberration diagrams, aberrations at the C-line and F-line are shown by long-dashed lines and short-dashed lines, respectively. In the spherical aberration diagrams, the maximum F-number is indicated after "FNo.=". In other aberration diagrams, the value of the maximum half angle of view is shown after "ω=".

[0118] The symbols, meanings, notation methods, and illustration methods of each data item related to the above-mentioned Example 1 are basically the same in the following Examples unless otherwise specified, and therefore, redundant explanations will be omitted below.

[0119] [Example 2] A cross-sectional view of the configuration of the imaging lens of Example 2 is shown in Figure 6. The imaging lens of Example 2 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of, in order from the object side to the image side, three lenses, lenses L11 to L13. The second lens group G2 consists of, in order from the object side to the image side, four lenses, lenses L21 to L24. When focusing from an object at infinity to a close-up object, the entire imaging lens moves integrally toward the object side along the optical axis Z.

[0120] For the imaging lens of Example 2, basic lens data is shown in Table 4, specifications and variable surface spacings are shown in Table 5, aspherical coefficients are shown in Table 6, and aberration diagrams are shown in FIG.

[0121] [Table 4]

[0122] [Table 5]

[0123] [Table 6]

[0124] [Example 3] FIG. 8 shows a cross-sectional view of the configuration of the imaging lens of Example 3. The imaging lens of Example 3 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 comprises, in order from the object side to the image side, three lenses, L11 to L13. The second lens group G2 comprises, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F comprises, in order from the object side to the image side, four lenses, L21 to L24. The rear subgroup G2R comprises a single lens, lens L25. When focusing from an object at infinity to a close-up object, the first lens group G1, aperture stop St, and front subgroup G2F move together toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0125] For the imaging lens of Example 3, basic lens data is shown in Table 7, specifications and variable surface spacings are shown in Table 8, aspherical coefficients are shown in Table 9, and each aberration diagram is shown in FIG.

[0126] [Table 7]

[0127] [Table 8]

[0128] [Table 9]

[0129] [Example 4] A cross-sectional view of the configuration of the imaging lens of Example 4 is shown in Figure 10. The imaging lens of Example 4 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, lenses L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of one lens, lens L25. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0130] For the imaging lens of Example 4, basic lens data is shown in Table 10, specifications and variable surface spacings are shown in Table 11, aspherical coefficients are shown in Table 12, and aberration diagrams are shown in FIG.

[0131] [Table 10]

[0132] [Table 11]

[0133] [Table 12]

[0134] [Example 5] A cross-sectional view of the configuration of the imaging lens of Example 5 is shown in Figure 12. The imaging lens of Example 5 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, lenses L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of one lens, lens L25. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0135] For the imaging lens of Example 5, basic lens data is shown in Table 13, specifications and variable surface spacings are shown in Table 14, aspherical coefficients are shown in Table 15, and each aberration diagram is shown in FIG.

[0136] [Table 13]

[0137] [Table 14]

[0138] [Table 15]

[0139] [Example 6] A cross-sectional view of the configuration of the imaging lens of Example 6 is shown in Figure 14. The imaging lens of Example 6 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, lenses L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of two lenses, lenses L25 to L26, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0140] For the imaging lens of Example 6, basic lens data is shown in Table 16, specifications and variable surface spacings are shown in Table 17, aspherical coefficients are shown in Table 18, and each aberration diagram is shown in FIG.

[0141] [Table 16]

[0142] [Table 17]

[0143] [Table 18]

[0144] [Example 7] A cross-sectional view of the configuration of the imaging lens of Example 7 is shown in Figure 16. The imaging lens of Example 7 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, lenses L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of two lenses, lenses L25 to L26, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0145] For the imaging lens of Example 7, basic lens data is shown in Table 19, specifications and variable surface spacings are shown in Table 20, aspherical coefficients are shown in Table 21, and various aberration diagrams are shown in FIG.

[0146] [Table 19]

[0147] [Table 20]

[0148] [Table 21]

[0149] [Example 8] A cross-sectional view of the configuration of the imaging lens of Example 8 is shown in Figure 18. The imaging lens of Example 8 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of three lenses, lenses L21 to L23, in order from the object side to the image side. The rear subgroup G2R consists of two lenses, lenses L24 to L25, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0150] For the imaging lens of Example 8, basic lens data is shown in Table 22, specifications and variable surface spacing are shown in Table 23, aspherical coefficients are shown in Table 24, and each aberration diagram is shown in FIG.

[0151] [Table 22]

[0152] [Table 23]

[0153] [Table 24]

[0154] [Example 9] 20 shows a cross-sectional view of the configuration of the imaging lens of Example 9. The imaging lens of Example 9 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 comprises, in order from the object side to the image side, three lenses, lenses L11 to L13. The second lens group G2 comprises, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F comprises, in order from the object side to the image side, three lenses, lenses L21 to L23. The rear subgroup G2R comprises, in order from the object side to the image side, two lenses, lenses L24 to L25. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0155] For the imaging lens of Example 9, basic lens data is shown in Table 25, specifications and variable surface spacing are shown in Table 26, aspherical coefficients are shown in Table 27, and various aberration diagrams are shown in FIG.

[0156] [Table 25]

[0157] [Table 26]

[0158] [Table 27]

[0159] [Example 10] A cross-sectional view of the configuration of the imaging lens of Example 10 is shown in Figure 22. The imaging lens of Example 10 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of five lenses, lenses L21 to L25, in order from the object side to the image side. The rear subgroup G2R consists of two lenses, lenses L26 to L27, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0160] For the imaging lens of Example 10, basic lens data is shown in Table 28, specifications and variable surface spacings are shown in Table 29, aspherical coefficients are shown in Table 30, and various aberration diagrams are shown in FIG.

[0161] [Table 28]

[0162] [Table 29]

[0163] [Table 30]

[0164] [Example 11] A cross-sectional view of the configuration of the imaging lens of Example 11 is shown in Figure 24. The imaging lens of Example 11 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, lenses L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of three lenses, lenses L25 to L27, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0165] For the imaging lens of Example 11, basic lens data is shown in Table 31, specifications and variable surface spacings are shown in Table 32, aspherical coefficients are shown in Table 33, and various aberration diagrams are shown in FIG.

[0166] [Table 31]

[0167] [Table 32]

[0168] [Table 33]

[0169] [Example 12] A cross-sectional view of the configuration of the imaging lens of Example 12 is shown in Figure 26. The imaging lens of Example 12 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of four lenses, L11 to L14, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of three lenses, L25 to L27, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0170] For the imaging lens of Example 12, basic lens data is shown in Table 34, specifications and variable surface spacings are shown in Table 35, aspherical coefficients are shown in Table 36, and various aberration diagrams are shown in FIG.

[0171] [Table 34]

[0172] [Table 35]

[0173] [Table 36]

[0174] [Example 13] A cross-sectional view of the configuration of the imaging lens of Example 13 is shown in Figure 28. The imaging lens of Example 13 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, lenses L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of three lenses, lenses L25 to L27, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0175] For the imaging lens of Example 13, basic lens data is shown in Table 37, specifications and variable surface spacings are shown in Table 38, aspherical coefficients are shown in Table 39, and various aberration diagrams are shown in FIG.

[0176] [Table 37]

[0177] [Table 38]

[0178] [Table 39]

[0179] [Example 14] A cross-sectional view of the configuration of the imaging lens of Example 14 is shown in Figure 30. The imaging lens of Example 14 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of four lenses, lenses L11 to L14, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of three lenses, lenses L21 to L23, in order from the object side to the image side. The rear subgroup G2R consists of three lenses, lenses L24 to L26, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0180] For the imaging lens of Example 14, basic lens data is shown in Table 40, specifications and variable surface spacings are shown in Table 41, aspherical coefficients are shown in Table 42, and various aberration diagrams are shown in FIG.

[0181] [Table 40]

[0182] [Table 41]

[0183] [Table 42]

[0184] [Example 15] A cross-sectional view of the configuration of the imaging lens of Example 15 is shown in Figure 32. The imaging lens of Example 15 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of three lenses, lenses L11 to L13, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of three lenses, lenses L21 to L23, in order from the object side to the image side. The rear subgroup G2R consists of three lenses, lenses L24 to L26, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0185] For the imaging lens of Example 15, basic lens data is shown in Table 43, specifications and variable surface spacings are shown in Table 44, aspherical coefficients are shown in Table 45, and various aberration diagrams are shown in FIG.

[0186] [Table 43]

[0187] [Table 44]

[0188] [Table 45]

[0189] [Example 16] A cross-sectional view of the configuration of the imaging lens of Example 16 is shown in Figure 34. The imaging lens of Example 16 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of four lenses, lenses L11 to L14, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of three lenses, lenses L21 to L23, in order from the object side to the image side. The rear subgroup G2R consists of three lenses, lenses L24 to L26, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0190] For the imaging lens of Example 16, basic lens data is shown in Table 46, specifications and variable surface spacings are shown in Table 47, aspherical coefficients are shown in Table 48, and various aberration diagrams are shown in FIG.

[0191] [Table 46]

[0192] [Table 47]

[0193] [Table 48]

[0194] [Example 17] A cross-sectional view of the configuration of the imaging lens of Example 17 is shown in Figure 36. The imaging lens of Example 17 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of four lenses, L11 to L14, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of four lenses, L25 to L28, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0195] For the imaging lens of Example 17, basic lens data is shown in Table 49, specifications and variable surface spacings are shown in Table 50, aspherical coefficients are shown in Table 51, and various aberration diagrams are shown in FIG.

[0196] [Table 49]

[0197] [Table 50]

[0198] [Table 51]

[0199] [Example 18] A cross-sectional view of the configuration of the imaging lens of Example 18 is shown in Figure 38. The imaging lens of Example 18 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, an aperture stop St, and a second lens group G2 having positive refractive power. The first lens group G1 consists of four lenses, L11 to L14, in order from the object side to the image side. The second lens group G2 consists of, in order from the object side to the image side, a front subgroup G2F and a rear subgroup G2R. The front subgroup G2F consists of four lenses, L21 to L24, in order from the object side to the image side. The rear subgroup G2R consists of four lenses, L25 to L28, in order from the object side to the image side. When focusing from an object at infinity to an object at a close distance, the first lens group G1, aperture stop St, and front subgroup G2F move integrally toward the object along the optical axis Z, while the rear subgroup G2R is fixed relative to the image plane Sim.

[0200] For the imaging lens of Example 18, basic lens data is shown in Table 52, specifications and variable surface spacings are shown in Table 53, aspherical coefficients are shown in Table 54, and each aberration diagram is shown in FIG.

[0201] [Table 52]

[0202] [Table 53]

[0203] [Table 54]

[0204] Tables 55 to 58 show the corresponding values ​​of conditional formulas (1) to (23) for the imaging lenses of Examples 1 to 18. The corresponding values ​​of the Examples shown in Tables 55 to 58 may be used as the upper or lower limits of the conditional formulas to set preferred ranges for the conditional formulas.

[0205] [Table 55]

[0206] [Table 56]

[0207] [Table 57]

[0208] [Table 58]

[0209] The imaging lenses of Examples 1 to 18 all have small F-numbers. Specifically, the F-number when focused on an object at infinity is smaller than 1.5 for all of the imaging lenses of Examples 1 to 18, and even smaller than 1.3 for the imaging lenses of some Examples. Furthermore, the imaging lenses of Examples 1 to 16 are all compact, and maintain high optical performance with various aberrations well corrected.

[0210] Next, an imaging device according to an embodiment of the present disclosure will be described. Fig. 40 and Fig. 41 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure. Fig. 40 shows a perspective view of the camera 30 as seen from the front side, and Fig. 41 shows a perspective view of the camera 30 as seen from the rear side. The camera 30 is a so-called mirrorless digital camera, to which an interchangeable lens 20 can be removably attached. The interchangeable lens 20 is configured to include an imaging lens 1 according to an embodiment of the present disclosure housed in a lens barrel.

[0211] The camera 30 includes a camera body 31. A shutter button 32 and a power button 33 are provided on the top surface of the camera body 31. An operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back surface of the camera body 31. The display unit 36 ​​can display a captured image and an image within the angle of view before the image was captured.

[0212] A photographic opening through which light from a subject enters is provided in the center of the front surface of camera body 31. A mount 37 is provided at a position corresponding to the photographic opening, and interchangeable lens 20 is attached to camera body 31 via mount 37.

[0213] An imaging element 38 is provided within the camera body 31. The imaging element 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. For example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) is used as the imaging element 38. A signal processing circuit (not shown) and a recording medium (not shown) are provided within the camera body 31. The signal processing circuit processes the imaging signal output from the imaging element 38 to generate an image. The recording medium is for recording the generated image. With the camera 30, it is possible to take still images or videos by pressing the shutter button 32, and the image data obtained by this shooting is recorded on the recording medium.

[0214] Although the technology of the present disclosure has been described above using embodiments and examples, the technology of the present disclosure is not limited to the above embodiments and examples and can be modified in various ways. For example, the radius of curvature, surface spacing, refractive index, Abbe number, aspherical coefficient, etc. of each lens are not limited to the values ​​shown in the above examples and can take other values.

[0215] Furthermore, the imaging device according to the embodiment of the present disclosure is not limited to the above example, and can take various forms, such as a camera other than a mirrorless type, a film camera, a video camera, and a security camera.

[0216] The following additional notes are provided regarding the above embodiments and examples. [Appendix 1] An imaging lens comprising, in order from the object side to the image side, a first lens group, a diaphragm, and a second lens group, When focusing, the entire imaging lens moves, or the first lens group, the diaphragm, and a part of the second lens group move, The focal length of the imaging lens when focused on an object at infinity is f, If the focal length of the first lens group is f1, then 0.1 <f / f1<1.5 (1) An imaging lens that satisfies conditional expression (1) expressed as follows: [Appendix 2] the first lens group includes at least one positive lens; If the focal length of the positive lens with the strongest refractive power among the positive lenses included in the first lens group is fp1, then 0.1 <f / fp1<4 (2) The imaging lens according to claim 1, which satisfies conditional expression (2) expressed as follows: [Appendix 3] the first lens group includes at least one positive lens and at least one negative lens, Among the positive lenses included in the first lens group, the focal length of the positive lens closest to the object is fp1F, When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the first lens group is fn1, 0.3 <fp1F / |fn1|<6 (3) The imaging lens according to claim 1 or 2, which satisfies conditional expression (3) expressed by: [Appendix 4] the second lens group includes at least one negative lens; If the focal length of the negative lens having the strongest refractive power among the negative lenses included in the second lens group is fn2, then 0.3 <f / |fn2|<6 (4) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 3, which satisfies conditional expression (4) expressed by the following formula: [Appendix 5] the first lens group includes at least one positive lens and at least one negative lens, Among the positive lenses included in the first lens group, the focal length of the positive lens with the strongest refractive power is defined as fp1, When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the first lens group is fn1, 0.15 <fp1 / |fn1|<6 (5) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 4, which satisfies conditional expression (5) expressed as follows: [Appendix 6] the first lens group includes at least one positive lens; Among the positive lenses included in the first lens group, the radius of curvature of the object side surface of the positive lens having the strongest refractive power is Rf, When the radius of curvature of the image-side surface of the positive lens having the strongest refractive power among the positive lenses included in the first lens group is Rr, 0.05<(Rr+Rf) / (Rr-Rf)<6 (6) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 5, which satisfies conditional expression (6) expressed as follows: [Appendix 7] the first lens group includes at least one positive lens; If the focal length of the positive lens with the strongest refractive power among the positive lenses included in the first lens group is fp1, then 0.3 <f1 / fp1<4.5 (7) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 6, which satisfies conditional expression (7) shown below. [Appendix 8] the first lens group includes at least one negative lens; the second lens group includes at least one negative lens; Among the negative lenses included in the first lens group, the focal length of the negative lens with the strongest refractive power is defined as fn1, If the focal length of the negative lens having the strongest refractive power among the negative lenses included in the second lens group is fn2, then 0.1 <fn1 / fn2<6 (8) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 7, which satisfies conditional expression (8) shown below. [Appendix 9] the first lens group includes at least one negative lens; When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the first lens group is fn1, 0.2 <f / |fn1|<5 (9) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 8, which satisfies conditional expression (9) shown below. [Appendix 10] the lens surface of the first lens group closest to the image side is a concave surface, 10. The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 9, wherein the lens surface of the second lens group closest to the object side is a concave surface. [Appendix 11] The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 10, wherein the first lens group includes two or more positive lenses. [Appendix 12] The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 11, wherein a positive meniscus lens having a convex surface facing the object side is disposed closest to the object side in the first lens group. [Appendix 13] the first lens group includes at least one positive lens; When the refractive index of the positive lens closest to the object side among the positive lenses included in the first lens group is Np1F for the d-line, 1.5 <Np1F<2.03 (10) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 12, which satisfies conditional expression (10) expressed by the following: [Appendix 14] the second lens group includes at least one lens surface having a pole point, 14. The imaging lens according to claim 1, wherein the polar point is a point on a lens surface other than on the optical axis, and a tangent plane of the lens surface at the polar point intersects with the optical axis perpendicularly. [Appendix 15] the second lens group comprises, in order from the object side to the image side, a front subgroup and a rear subgroup, 15. The imaging lens according to claim 1, wherein, during focusing, the first lens group, the diaphragm, and the front subgroup move integrally, and the rear subgroup is fixed with respect to an image plane. [Appendix 16] the rear subgroup includes one or more lenses including at least one lens surface having a pole point, 16. The imaging lens according to claim 15, wherein the polar point is a point on a lens surface other than on the optical axis, and a tangent plane to the lens surface at the polar point intersects the optical axis perpendicularly. [Appendix 17] The imaging lens according to claim 16, wherein the rear subgroup includes two or more lenses each including at least one lens surface having the polar point. [Appendix 18] The sum of the air gaps on the optical axis within the rear sub-group is D2Rair, When the distance on the optical axis from the lens surface of the rear subunit closest to the object side to the lens surface of the rear subunit closest to the image side is denoted by D2R, 0≦D2Rair / D2R<0.45 (11) 18. The imaging lens according to any one of claims 15 to 17, which satisfies conditional expression (11) shown below. [Appendix 19] the distance on the optical axis from the lens surface of the rear subgroup closest to the object side to the lens surface of the rear subgroup closest to the image side is D2R; When the lens surface closest to the object in the first lens group is focused on an object at infinity, the distance on the optical axis from the lens surface closest to the image in the rear subgroup is defined as DT. 0.05 <D2R / DT<0.5 (12) 19. The imaging lens according to any one of claims 15 to 18, which satisfies conditional expression (12) shown below. [Appendix 20] An imaging device comprising the imaging lens according to any one of Supplementary Note 1 to Supplementary Note 19. [Explanation of symbols]

[0217] 1 Imaging lens 20 Interchangeable Lenses 30 Camera 31 Camera Body 32 Shutter button 33 Power button 34 Control section 35 Control section 36 Display section 37 Mount 38 Image sensor ED Effective Diameter G1 First lens group G2 Second lens group G2F anterior subgroup G2R posterior subgroup L11~L28 lenses Lx Lens P pole Px Position of maximum effective diameter Sim image plane St aperture stop Tp tangent plane Xa On-axis luminous flux Xb Off-axis luminous flux Xb1 ray Z optical axis

Claims

1. An imaging lens comprising, in order from the object side to the image side, a first lens group, a diaphragm, and a second lens group, When focusing, the entire imaging lens moves, or the first lens group, the diaphragm, and a part of the second lens group move, The focal length of the imaging lens when focused on an object at infinity is f, When the focal length of the first lens group is f1, 0.1<f / f1<1.5 (1) An imaging lens that satisfies conditional expression (1) expressed as follows.

2. the first lens group includes at least one positive lens; When the focal length of the positive lens having the strongest refractive power among the positive lenses included in the first lens group is fp1, 0.1<f / fp1<4 (2) 2. The imaging lens according to claim 1, which satisfies conditional expression (2) expressed as follows:

3. the first lens group includes at least one positive lens and at least one negative lens; Among the positive lenses included in the first lens group, the focal length of the positive lens closest to the object is fp1F, When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the first lens group is fn1, 0.3<fp1F / |fn1|<6 (3) 2. The imaging lens according to claim 1, which satisfies conditional expression (3) expressed as follows:

4. the second lens group includes at least one negative lens; When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the second lens group is fn2, 0.3<f / |fn2|<6 (4) 2. The imaging lens according to claim 1, which satisfies conditional expression (4) expressed as follows:

5. the first lens group includes at least one positive lens and at least one negative lens; Among the positive lenses included in the first lens group, the focal length of the positive lens having the strongest refractive power is fp1, When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the first lens group is fn1, 0.15<fp1 / |fn1|<6 (5) 2. The imaging lens according to claim 1, which satisfies conditional expression (5) expressed as follows:

6. the first lens group includes at least one positive lens; Among the positive lenses included in the first lens group, the radius of curvature of the object side surface of the positive lens having the strongest refractive power is Rf, When the radius of curvature of the image-side surface of the positive lens having the strongest refractive power among the positive lenses included in the first lens group is Rr, 0.05<(Rr+Rf) / (Rr-Rf)<6 (6) 2. The imaging lens according to claim 1, which satisfies conditional expression (6) expressed as follows:

7. the first lens group includes at least one positive lens; When the focal length of the positive lens having the strongest refractive power among the positive lenses included in the first lens group is fp1, 0.3<f1 / fp1<4.5 (7) 2. The imaging lens according to claim 1, which satisfies conditional expression (7) expressed as follows:

8. the first lens group includes at least one negative lens; the second lens group includes at least one negative lens; Among the negative lenses included in the first lens group, the focal length of the negative lens having the strongest refractive power is fn1, When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the second lens group is fn2, 0.1<fn1 / fn2<6 (8) 2. The imaging lens according to claim 1, which satisfies conditional expression (8) expressed as follows:

9. the first lens group includes at least one negative lens; When the focal length of the negative lens having the strongest refractive power among the negative lenses included in the first lens group is fn1, 0.2<f / |fn1|<5 (9) 2. The imaging lens according to claim 1, which satisfies conditional expression (9) expressed as follows:

10. the lens surface of the first lens group closest to the image side is a concave surface, 2. The imaging lens according to claim 1, wherein the lens surface of the second lens group closest to the object side is a concave surface.

11. The imaging lens according to claim 1 , wherein the first lens group includes two or more positive lenses.

12. 2. The imaging lens according to claim 1, wherein a positive meniscus lens having a convex surface facing the object side is disposed closest to the object side of the first lens group.

13. the first lens group includes at least one positive lens; When the refractive index of the positive lens closest to the object side among the positive lenses included in the first lens group is Np1F with respect to the d-line, 1.5<Np1F<2.03 (10) 2. The imaging lens according to claim 1, which satisfies conditional expression (10) expressed as follows:

14. the second lens group includes at least one lens surface having a pole point, 2. The imaging lens according to claim 1, wherein the polar point is a point on the lens surface other than on the optical axis, and a tangent plane of the lens surface at the polar point intersects the optical axis perpendicularly.

15. the second lens group comprises, in order from the object side to the image side, a front subgroup and a rear subgroup, 2. The imaging lens according to claim 1, wherein, during focusing, the first lens group, the diaphragm, and the front subgroup move together, and the rear subgroup is fixed relative to an image plane.

16. the rear subgroup includes one or more lenses including at least one lens surface having a pole point, 16. The imaging lens according to claim 15, wherein the polar point is a point on the lens surface other than on the optical axis, and a tangent plane to the lens surface at the polar point intersects the optical axis perpendicularly.

17. The imaging lens according to claim 16 , wherein the rear subgroup includes two or more lenses each including at least one lens surface having the polar point.

18. The sum of the air gaps on the optical axis within the rear sub-group is D2Rair, When the distance on the optical axis from the lens surface of the rear subunit closest to the object side to the lens surface of the rear subunit closest to the image side is D2R, 0≦D2Rair / D2R<0.45 (11) 17. The imaging lens according to claim 16, which satisfies conditional expression (11) expressed as follows:

19. When the lens surface of the first lens group closest to the object side to the lens surface of the rear subgroup closest to the image side is defined as DT, 0.05<D2R / DT<0.5 (12) 19. The imaging lens according to claim 18, which satisfies conditional expression (12) expressed as follows:

20. An imaging device comprising the imaging lens according to any one of claims 1 to 19.

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