Imaging lens and imaging device

Abstract

To provide an imaging lens which is miniaturized regardless of a wide angle and has excellent optical performance and an imaging apparatus including the imaging lens.SOLUTION: The imaging lens comprises a front group, a diaphragm, and a rear group having positive refractive power in order from an object side to an image side. The imaging lens satisfies a predetermined conditional expression.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] BACKGROUND ART Conventionally, lens systems described in Patent Documents 1 and 2 below, for example, have been known as imaging lenses used in imaging devices such as digital cameras. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-129022 [Patent Document 2] Japanese Patent Publication No. 2021-047384 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for imaging lenses that are wide-angle, compact, and have good optical performance.

[0005] The present disclosure provides an imaging lens that has a wide angle, yet is compact and has good optical performance, and an imaging device that includes this imaging lens. [Means for solving the problem]

[0006] A first aspect of the present disclosure is an imaging lens comprising, in order from the object side to the image side, a front group, a stop, and a rear group having positive refractive power, wherein when the lens is focused on an object at infinity, the height from the optical axis of a chief ray of a maximum image height in a plane perpendicular to the optical axis passing through the intersection of the lens surface closest to the object and the optical axis is H; when the lens is focused on an object at infinity, the focal length of the entire system is f; when the lens is focused on an object at infinity, the sum of the distance on the optical axis from the lens surface closest to the object to the lens surface closest to the image and the back focus in air equivalent distance is TL; when the lens is focused on an object at infinity, the maximum half angle of view of the entire system is ωm, and ωm is in degrees, 1 <H / (f×tanωm)<1.8 (1) 3.1 <TL / (f×tanωm)<5.2 (2) 52<ωm<74 (3) The conditions (1), (2), and (3) are satisfied.

[0007] In the first aspect, at least a portion of the front group may move during focusing, and the rear group may be fixed relative to the image plane.

[0008] In the first aspect, when the focal length of the front group is ff and the focal length of the rear group is fr, 0.2 <ff / fr<2 (4) It is preferable to satisfy conditional expression (4) below.

[0009] In the first aspect, at least a portion of the rear group may move during focusing, and the front group may be fixed relative to the image plane.

[0010] The first aspect may include a first lens that is disposed closest to the object and is a negative meniscus lens with a convex surface facing the object side, and a second lens that is disposed adjacent to the image side of the first lens and is a negative meniscus lens with a convex surface facing the object side.

[0011] In the first aspect, if the radius of curvature of the object-side surface of the first lens is R1f and the radius of curvature of the image-side surface of the first lens is R1r, then: 1.3<(R1f+R1r) / (R1f-R1r)<4.2 (5) It is preferable to satisfy conditional expression (5) below.

[0012] The first aspect described above may include a third lens arranged adjacent to the image side of the second lens, and the third lens may be a negative meniscus lens with a convex surface facing the object side, or a plano-concave lens with a flat surface facing the object side.

[0013] In the first aspect, if the radius of curvature of the image-side surface of the second lens is R2r and the radius of curvature of the object-side surface of the third lens is R3f, then: -1<(R2r-R3f) / (R2r+R3f)<0.3 (6) It is preferable to satisfy conditional expression (6) below.

[0014] In the first aspect, the front group may be made up of five or more and seven or less lenses.

[0015] In the first aspect, the rear group may be made up of five or more and seven or less lenses.

[0016] In the first aspect, if the focal length of the rear group when focused on an object at infinity is fr, then: 1 <f / fr<7 (7) It is preferable to satisfy conditional expression (7) below.

[0017] In the first aspect, the front group includes an Lfp lens having positive refractive power, and when the Abbe number of the Lfp lens based on the d-line is νfp, 16<νfp<42 (8) It is preferable to satisfy conditional expression (8) below.

[0018] In the first aspect, the rear group includes an Lrp1 lens having positive refractive power, and when the partial dispersion ratio between the g-line and the F-line of the Lrp1 lens is θgFrp1 and the Abbe number of the Lrp1 lens based on the d-line is νrp1, 0.01<θgFrp1+0.001618×νrp1-0.6415<0.1 (9) It is preferable to satisfy conditional expression (9) below.

[0019] In the first aspect, the rear group includes an Lrp2 lens having positive refractive power that is arranged closer to the image side than the Lrp1 lens, and when the partial dispersion ratio between the g-line and the F-line of the Lrp2 lens is θgFrp2 and the Abbe number of the Lrp2 lens based on the d-line is νrp2, 0.01<θgFrp2+0.001618×νrp2-0.6415<0.1 (10) It is preferable to satisfy conditional expression (10) below.

[0020] In the first aspect, the rear group includes an Lrn1 lens having negative refractive power, and when the refractive index of the Lrn1 lens at the d-line is Nrn1, 1.75 <Nrn1<2.2 (11) It is preferable to satisfy conditional expression (11) below.

[0021] In the first aspect, the rear group includes an Lrn2 lens having negative refractive power that is disposed closer to the image side than the Lrn1 lens, and when the refractive index of the Lrn2 lens at the d-line is Nrn2, 1.8 <Nrn2<2.2 (12) It is preferable to satisfy conditional expression (12) below.

[0022] In the first aspect, if the distance on the optical axis from the lens surface closest to the object side to the diaphragm is Ds, then 1.2 <Ds / (f×tanωm)<2.8 (13) It is preferable to satisfy conditional expression (13) below.

[0023] In the first aspect, if the focal length of the lens group that moves during focusing is fa, then: 1 <f / |fa|<20 (14) It is preferable to satisfy conditional expression (14) below.

[0024] In the first aspect, when the lens is focused on an object at infinity, if the distance on the optical axis from the lens surface closest to the object to the aperture stop is Ds, then: 0.3 <Ds / TL<0.6 (15) It is preferable to satisfy conditional expression (15) below.

[0025] A second aspect of the present disclosure is an imaging device including the imaging lens according to 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, the components may also include lenses that have substantially no refractive power, optical elements other than lenses such as apertures, filters, and cover glasses, as well as 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. The "front group" and "rear group" are not limited to being configured with a plurality of lenses, and may be configured with only one lens. "A lens having positive refractive power" and "positive lens" are synonymous. "A lens having negative refractive power" and "negative lens" are synonymous. "Negative meniscus lens" and "meniscus-shaped lens having negative refractive power" are synonymous.

[0028] A "single lens" refers to a single lens that is not cemented. However, a compound aspherical lens (i.e., a lens that is composed of a spherical lens and an aspherical film formed on the spherical lens, and functions as a single aspherical lens as a whole) is not considered a cemented lens, but is treated as a single lens. Unless otherwise specified, the sign of the refractive power and surface shape of lenses that include aspherical surfaces are those in the paraxial region.

[0029] In this specification, "total system" refers to an imaging lens. The "focal length" used in the conditional expressions is the paraxial focal length. The "back focus in air equivalent distance" is the air equivalent distance on the optical axis from the lens surface closest to the image side of the total system to the image plane. Regarding the sign of the radius of curvature, the sign of the radius of curvature of a surface with a convex surface facing the object side is positive, and the sign of the radius of curvature of a surface with a convex surface facing the image side is negative.

[0030] In this specification, values ​​used in conditional expressions, except for the partial dispersion ratio, are values ​​based on the d-line. The partial dispersion ratio θgF between the g-line and F-line of a lens is defined as θgF = (Ng - NF) / (NF - NC), where Ng, NF, and NC are the refractive indices of the lens for the g-line, F-line, and C-line, respectively. The "d-line," "C-line," "F-line," and "g-line" used in this specification are emission lines. The wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line as 656.27 nm (nanometers), the wavelength of the F-line as 486.13 nm (nanometers), and the wavelength of the g-line as 435.84 nm (nanometers). [Effects of the Invention]

[0031] According to the above aspect, the imaging lens and imaging device of the present disclosure have a wide angle, yet are compact and have good optical performance. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view showing the configuration of an imaging lens and a light beam according to an embodiment. [Figure 2] 1 is a cross-sectional view showing the configuration of an imaging lens according to a first embodiment. [Figure 3] 3A to 3C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging lens of Example 1. [Figure 4] 3A to 3C are diagrams showing lateral aberration of the imaging lens of Example 1. [Figure 5] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a second embodiment. [Figure 6]10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging lens of Example 2. [Figure 7] 10A to 10C are diagrams showing lateral aberration 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 spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging lens of Example 3. [Figure 10] 10A to 10C are diagrams showing lateral aberration of the imaging lens of Example 3. [Figure 11] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fourth embodiment. [Figure 12] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging lens of Example 4. [Figure 13] 10A to 10C are diagrams showing lateral aberration of the imaging lens of Example 4. [Figure 14] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fifth embodiment. [Figure 15] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging lens of Example 5. [Figure 16] 10A to 10C are diagrams showing lateral aberration of the imaging lens of Example 5. [Figure 17] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a sixth embodiment. [Figure 18] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging lens of Example 6. [Figure 19] 13A to 13C are diagrams showing lateral aberration of the imaging lens of Example 6. [Figure 20] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a seventh embodiment. [Figure 21] 10A to 10C are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration of magnification of the imaging lens of Example 7. [Figure 22] 13A to 13C are diagrams showing lateral aberration of the imaging lens of Example 7. [Figure 23] 1 is a perspective view of the front side of an imaging device according to an embodiment. [Figure 24]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 and light beams of an imaging lens according to an embodiment of the present disclosure when focused on an object at infinity. In this specification, an object whose object distance (the distance on the optical axis from the object to the lens surface closest to the object) is infinite is referred to as an infinitely far object. In FIG. 1, an axial light beam 2 and a light beam 3 with a maximum half angle of view ωm are shown as light beams. In FIG. 1, the left side is the object side and the right side is the image side. The example shown in FIG. 1 corresponds to the imaging lens of Example 1, which will be described later.

[0035] FIG. 1 shows an example in which a parallel-plate-shaped optical member PP is arranged between the imaging lens and the image plane Sim, assuming that the imaging lens is applied to an imaging device. The optical member PP is a member that is assumed to include various filters and / or cover glass, etc. The various filters are low-pass filters, infrared cut filters, and / or filters that cut off specific wavelength ranges, etc. The optical member PP is a member that does not have refractive power. It is also possible to configure an imaging device without the optical member PP.

[0036] The imaging lens of this embodiment is composed of, in order from the object side to the image side along the optical axis Z, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. By having lenses on the object side and the image side of the aperture stop St, it becomes easier to correct various aberrations. As an example, in the example of FIG. 1, the front group Gf is composed of six lenses, lenses L11 to L16, and the rear group Gr is composed of five lenses, lenses L21 to L25. Note that the aperture stop St in FIG. 1 does not indicate its size or shape, but its position in the direction of the optical axis.

[0037] Furthermore, in the imaging lens of this embodiment, when the height from the optical axis Z of the chief ray of the maximum image height in a plane perpendicular to the optical axis Z passing through the intersection of the lens surface closest to the object and the optical axis Z when focused on an object at infinity is H, the focal length of the entire system when focused on an object at infinity is f, and the maximum half angle of view of the entire system is ωm, it is preferable that the imaging lens of this embodiment satisfy the following conditional expression (1): As an example, H and ωm are shown in FIG. 1 . By ensuring that the corresponding value of conditional expression (1) is not below the lower limit, light rays at each image height are appropriately separated in the front group Gf, which is advantageous for correcting coma aberration. By ensuring that the corresponding value of conditional expression (1) is not above the upper limit, the height from the optical axis Z of light rays at a peripheral angle of view when passing through the lens surface closest to the object can be reduced, which is advantageous for reducing the filter diameter. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (1-1), and it is even more preferable to satisfy the following conditional expression (1-2): 1 <H / (f×tanωm)<1.8 (1) 1.03 <H / (f×tanωm)<1.65 (1-1) 1.05 <H / (f×tanωm)<1.35 (1-2)

[0038] Furthermore, the imaging lens of this embodiment preferably satisfies the following conditional expression (2), where TL is the sum of the distance on the optical axis Z from the lens surface closest to the object to the lens surface closest to the image when focused on an object at infinity and the back focus in terms of the air equivalent distance, f is the focal length of the entire system when focused on an object at infinity, and ωm is the maximum half angle of view of the entire system. Ensuring that the corresponding value of conditional expression (2) is not equal to or less than the lower limit is advantageous for ensuring good optical performance. Ensuring that the corresponding value of conditional expression (2) is not equal to or greater than the upper limit can enable the imaging lens to be made smaller and lighter. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (2-1), and it is even more preferable to satisfy the following conditional expression (2-2). 3.1 <TL / (f×tanωm)<5.2 (2) 3.3 <TL / (f×tanωm)<5 (2-1) 3.5 <TL / (f×tanωm)<4.8 (2-2)

[0039] Furthermore, it is preferable that the imaging lens of this embodiment satisfies the following conditional expression (3), where ωm is the maximum half angle of view of the entire system and ωm is in degrees. By ensuring that the corresponding value of conditional expression (3) is not below the lower limit, it is possible to improve the added value of an ultra-wide-angle lens, which has been in demand in recent years. By ensuring that the corresponding value of conditional expression (3) is not above the upper limit, the angle of view does not become too large, which is advantageous for reducing the filter diameter and ensuring good optical performance. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (3-1), and it is even more preferable to satisfy the following conditional expression (3-2). 52<ωm<74 (3) 54<ωm<70 (3-1) 56<ωm<67 (3-2)

[0040] In the imaging lens of this embodiment, at least a portion of the front group Gf may move during focusing, while the rear group Gr may be fixed relative to the image plane. "At least a portion of the front group Gf" means at least one lens included in the front group Gf. With this configuration, it is possible to make the group that moves during focusing smaller and lighter than in a configuration in which the entire lens system moves during focusing. Hereinafter, in this specification, the group that moves during focusing will be referred to as the "focus group." Focusing is performed by moving the focus group. Examples 1 to 4, which will be described later, correspond to this configuration.

[0041] In a configuration in which at least a portion of the front group Gf is a focusing group, where the focal length of the front group Gf when focused on an object at infinity is ff and the focal length of the rear group Gr is fr, it is preferable to satisfy the following conditional expression (4). Ensuring that the corresponding value of conditional expression (4) is not below the lower limit makes it easy to ensure the back focus. Ensuring that the corresponding value of conditional expression (4) is not above the upper limit is advantageous for suppressing barrel distortion. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (4-1), even more preferable to satisfy the following conditional expression (4-2), and even more preferable to satisfy the following conditional expression (4-3). 0.2 <ff / fr<2 (4) 0.5 <ff / fr<2 (4-1) 0.65 <ff / fr<1.85 (4-2) 0.7 <ff / fr<1.75 (4-3)

[0042] In the imaging lens of this embodiment, at least a part of the rear group Gr may move during focusing, while the front group Gf may be fixed relative to the image plane. "At least a part of the rear group Gr" means at least one lens included in the rear group Gr. In other words, the imaging lens of this embodiment is not limited to a configuration in which at least a part of the front group Gf is the focus group, but may also be a configuration in which at least a part of the rear group Gr is the focus group. This configuration also makes it possible to reduce the size and weight of the focus unit compared to a configuration in which the entire lens system moves during focusing. Examples 5 and 6, which will be described later, correspond to this configuration.

[0043] The imaging lens of this embodiment preferably includes a first lens, which is a negative meniscus lens with a convex surface facing the object side and is located closest to the object, and a second lens, which is a negative meniscus lens with a convex surface facing the object side and is located adjacent to the image side of the first lens. By making the lens closest to the object and the second lens from the object side negative lenses, the entrance pupil can be brought closer to the object side, which is advantageous for ensuring peripheral light intensity. Furthermore, by making the lens closest to the object and the second lens from the object side negative meniscus lenses with a convex surface facing the object side, which is advantageous for suppressing astigmatism and distortion. In the example of FIG. 1, lens L11 corresponds to the first lens, and lens L12 corresponds to the second lens.

[0044] Assuming that the radius of curvature of the object-side surface of the first lens is R1f and the radius of curvature of the image-side surface of the first lens is R1r, it is preferable to satisfy the following conditional expression (5). Ensuring that the corresponding value of conditional expression (5) is not below the lower limit is advantageous for suppressing astigmatism and distortion. Ensuring that the corresponding value of conditional expression (5) is not above the upper limit prevents the absolute value of the radius of curvature of the object-side surface of the first lens from becoming too small, which is advantageous for reducing the filter diameter. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (5-1), and even more preferable to satisfy the following conditional expression (5-2). 1.3<(R1f+R1r) / (R1f-R1r)<4.2 (5) 1.4<(R1f+R1r) / (R1f-R1r)<4 (5-1) 1.5<(R1f+R1r) / (R1f-R1r)<3.8 (5-2)

[0045] The imaging lens of this embodiment preferably includes a third lens disposed adjacent to the image side of the second lens. The third lens is a negative meniscus lens with a convex surface facing the object side, or a plano-concave lens with a flat surface on the object side. By making the third lens from the object side a negative lens, the entrance pupil can be brought closer to the object side, which is advantageous for ensuring peripheral light intensity. Furthermore, by making the third lens from the object side a negative meniscus lens with a convex surface facing the object side, or a plano-concave lens with a flat surface on the object side, it is advantageous for suppressing astigmatism and distortion. In the example of FIG. 1, lens L13 corresponds to the third lens.

[0046] Assuming that the radius of curvature of the image-side surface of the second lens is R2r and the radius of curvature of the object-side surface of the third lens is R3f, it is preferable to satisfy the following conditional expression (6). Ensuring that the corresponding value of conditional expression (6) is not equal to or less than the lower limit thereof is advantageous for suppressing astigmatism. Ensuring that the corresponding value of conditional expression (6) is not equal to or greater than the upper limit thereof is advantageous for ensuring sufficient peripheral light intensity. In order to obtain even better characteristics, it is more preferable to satisfy the following conditional expression (6-1), and it is even more preferable to satisfy the following conditional expression (6-2). -1<(R2r-R3f) / (R2r+R3f)<0.3 (6) -0.9<(R2r-R3f) / (R2r+R3f)<0.2 (6-1) -0.8<(R2r-R3f) / (R2r+R3f)<0.1 (6-2)

[0047] The front group Gf preferably consists of five to seven lens elements. This configuration is advantageous for achieving both a lightweight lens system and good optical performance. The rear group Gr preferably consists of five to seven lens elements. This configuration is advantageous for achieving both a lightweight lens system and good optical performance.

[0048] If the focal length of the entire system when focused on an object at infinity is f and the focal length of the rear group Gr when focused on an object at infinity is fr, it is preferable to satisfy the following conditional expression (7). By ensuring that the corresponding value of conditional expression (7) is not below the lower limit, the refractive power of the rear group Gr will not become too weak, which is advantageous for correcting curvature of field. By ensuring that the corresponding value of conditional expression (7) is not above the upper limit, the refractive power of the rear group Gr will not become too strong, which is advantageous for correcting distortion. In order to obtain even better characteristics, it is more preferable to satisfy the following conditional expression (7-1), and it is even more preferable to satisfy the following conditional expression (7-2). 1 <f / fr<7 (7) 1.2 <f / fr<5 (7-1) 1.4 <f / fr<4 (7-2)

[0049] It is preferable that the front group Gf includes an Lfp lens having positive refractive power, and when the Abbe number of the Lfp lens based on the d-line is νfp, it satisfies the following conditional expression (8): Ensuring that the corresponding value of conditional expression (8) is not equal to or less than the lower limit thereof is advantageous for correcting longitudinal chromatic aberration. Ensuring that the corresponding value of conditional expression (8) is not equal to or greater than the upper limit thereof is advantageous for correcting lateral chromatic aberration. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (8-1), it is even more preferable to satisfy the following conditional expression (8-2), it is even more preferable to satisfy the following conditional expression (8-3), and it is even more preferable to satisfy the following conditional expression (8-4). In the example of FIG. 1, lens L14 corresponds to the Lfp lens. 16<νfp<42 (8) 16<νfp<40 (8-1) 16<νfp<37 (8-2) 17<νfp<35 (8-3) 18<νfp<33 (8-4)

[0050] The rear group Gr includes an Lrp1 lens having positive refractive power, and when the partial dispersion ratio between the g-line and the F-line of the Lrp1 lens is θgFrp1 and the Abbe number of the Lrp1 lens based on the d-line is νrp1, it is preferable that the following conditional expression (9) be satisfied. Conditional expression (9) relates to the anomalous dispersion of the lens material. Satisfying conditional expression (9) makes it easier to correct the secondary spectrum of chromatic aberration. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (9-1), and even more preferable to satisfy the following conditional expression (9-2). In the example of FIG. 1, lens L23 corresponds to the Lrp1 lens. 0.01<θgFrp1+0.001618×νrp1-0.6415<0.1 (9) 0.015<θgFrp1+0.001618×νrp1-0.6415<0.07 (9-1) 0.02<θgFrp1+0.001618×νrp1-0.6415<0.04 (9-2)

[0051] The rear group Gr includes an Lrp2 lens having positive refractive power and located closer to the image side than the Lrp1 lens. When the partial dispersion ratio between the g-line and the F-line of the Lrp2 lens is θgFrp2 and the Abbe number of the Lrp2 lens based on the d-line is νrp2, it is preferable that the following conditional expression (10) be satisfied. Conditional expression (10) relates to the anomalous dispersion of the lens material. Satisfying conditional expression (10) facilitates correction of the secondary spectrum of chromatic aberration. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (10-1), and even more preferable to satisfy the following conditional expression (10-2). In the example of FIG. 1, lens L25 corresponds to the Lrp2 lens. 0.01<θgFrp2+0.001618×νrp2-0.6415<0.1 (10) 0.015<θgFrp2+0.001618×νrp2-0.6415<0.07 (10-1) 0.02<θgFrp2+0.001618×νrp2-0.6415<0.04 (10-2)

[0052] The rear group Gr includes an Lrn1 lens having negative refractive power. When the refractive index of the Lrn1 lens at the d-line is Nrn1, it is preferable to satisfy the following conditional expression (11): By ensuring that the value corresponding to conditional expression (11) is not below its lower limit, the refractive power of the Lrn1 lens does not become too weak, which is advantageous for correcting distortion. By ensuring that the value corresponding to conditional expression (11) is not above its upper limit, it is possible to select a material for the Lrn1 lens that does not have an excessively large dispersion, which is advantageous for correcting chromatic aberration. Furthermore, since materials with large dispersion generally have a high specific gravity, ensuring that the value corresponding to conditional expression (11) is not above its upper limit allows a material for the Lrn1 lens that does not have an excessively large specific gravity to be selected, which is advantageous for reducing weight. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (11-1), and it is even more preferable to satisfy the following conditional expression (11-2). In the example of FIG. 1, lens L21 corresponds to the Lrn1 lens. 1.75 <Nrn1<2.2 (11) 1.8 <Nrn1<2.1 (11-1) 1.85 <Nrn1<2 (11-2)

[0053] The rear group Gr includes an Lrn2 lens having negative refractive power and located closer to the image side than the Lrn1 lens. When the refractive index of the Lrn2 lens at the d-line is Nrn2, it is preferable to satisfy the following conditional expression (12): By ensuring that the value corresponding to conditional expression (12) is not below the lower limit, the refractive power of the Lrn2 lens does not become too weak, which is advantageous for correcting distortion. By ensuring that the value corresponding to conditional expression (12) is not above the upper limit, it is possible to select a material for the Lrn2 lens that does not have an excessively large dispersion, which is advantageous for correcting chromatic aberration. Furthermore, since materials with large dispersion generally have a high specific gravity, ensuring that the value corresponding to conditional expression (12) is not above the upper limit allows a material for the Lrn2 lens that does not have an excessively large specific gravity to be selected, which is advantageous for reducing weight. To obtain better characteristics, it is more preferable to satisfy the following conditional expression (12-1), and it is even more preferable to satisfy the following conditional expression (12-2). In the example of FIG. 1, lens L24 corresponds to the Lrn2 lens. 1.8 <Nrn2<2.2 (12) 1.85 <Nrn2<2.1 (12-1) 1.9 <Nrn2<2 (12-2)

[0054] If the distance on the optical axis from the lens surface closest to the object to the aperture stop St is Ds, the focal length of the entire system when focused on an object at infinity is f, and the maximum half angle of view of the entire system is ωm, it is preferable to satisfy the following conditional expression (13). Ensuring that the corresponding value of conditional expression (13) is not equal to or smaller than the lower limit is advantageous for correcting off-axial aberrations, particularly coma. Ensuring that the corresponding value of conditional expression (13) is not equal to or larger than the upper limit is advantageous for shortening the overall length of the lens system. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (13-1), and it is even more preferable to satisfy the following conditional expression (13-2). 1.2 <Ds / (f×tanωm)<2.8 (13) 1.35 <Ds / (f×tanωm)<2.5 (13-1) 1.5 <Ds / (f×tanωm)<2.2 (13-2)

[0055] If the focal length of the entire system when focused on an object at infinity is f and the focal length of the lens group that moves during focusing (i.e., the focus group) is fa, it is preferable to satisfy the following conditional expression (14). By ensuring that the corresponding value of conditional expression (14) is not below the lower limit, the amount of movement of the focus group during focusing can be prevented from becoming too long, which is advantageous for shortening the overall length of the lens system. By ensuring that the corresponding value of conditional expression (14) is not above the upper limit, the refractive power of the focus group does not become too strong, which is advantageous for suppressing aberration fluctuations that accompany changes in object distance. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (14-1), and it is even more preferable to satisfy the following conditional expression (14-2). 1 <f / |fa|<20 (14) 1.5 <f / |fa|<17 (14-1) 1.8 <f / |fa|<15 (14-2)

[0056] If the distance on the optical axis from the lens surface closest to the object to the aperture stop St when focused on an object at infinity is Ds, and the sum of the distance on the optical axis Z from the lens surface closest to the object to the lens surface closest to the image when focused on an object at infinity to the back focus in air equivalent distance is TL, it is preferable to satisfy the following conditional expression (15). By ensuring that the corresponding value of conditional expression (15) is not below the lower limit, it is possible to prevent the overall length of the front group Gf from becoming too short relative to the overall length of the lens system, which is advantageous for correcting off-axial aberrations, especially coma. By ensuring that the corresponding value of conditional expression (15) is not above the upper limit, it is possible to prevent the overall length of the front group Gf from becoming too long relative to the overall length of the lens system, which is advantageous for reducing the diameter of the lens system. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (15-1), and it is even more preferable to satisfy the following conditional expression (15-2). 0.3 <Ds / TL<0.6 (15) 0.35 <Ds / TL<0.55 (15-1) 0.4 <Ds / TL<0.5 (15-2)

[0057] In the imaging lens of this embodiment, it is preferable that the lens closest to the object side is a spherical lens and the second lens from the object side is an aspherical lens. Placing an aspherical lens in the second position from the object side is advantageous for correcting various aberrations, particularly coma aberration, while using a spherical lens as the lens closest to the object side, which has a large outer diameter, is advantageous for reducing costs. If the lens closest to the object side were an aspherical lens, the large outer diameter would increase costs. In the example of FIG. 1, the lens L11 closest to the object side is a spherical lens, and the lens L12 second from the object side is an aspherical lens.

[0058] If the back focal length in air equivalent of the entire system when focused on an object at infinity is Bf, the focal length of the entire system when focused on an object at infinity is f, and the maximum half angle of view of the entire system is ωm, it is preferable to satisfy the following conditional expression (16). By ensuring that the corresponding value of conditional expression (16) is not below the lower limit, the back focal length does not become too short relative to the image circle, which is advantageous for making the diameter of the rear group Gr smaller. By ensuring that the corresponding value of conditional expression (16) is not above the upper limit, the back focal length does not become too long relative to the image circle, which is advantageous for shortening the overall length of the lens system. In order to obtain better characteristics, it is more preferable to satisfy the following conditional expression (16-1), even more preferable to satisfy the following conditional expression (16-2), even more preferable to satisfy the following conditional expression (16-3), and even more preferable to satisfy the following conditional expression (16-4). 0.70 <Bf / (f×tanωm)<1.4 (16) 0.72 <Bf / (f×tanωm)<1.4 (16-1) 0.74 <Bf / (f×tanωm)<1.3 (16-2) 0.77 <Bf / (f×tanωm)<1.3 (16-3) 0.82 <Bf / (f×tanωm)<1.25 (16-4)

[0059] In a configuration in which at least a part of the front group Gf is a focus group, it is preferable that the focus group consists of a single lens. This configuration is advantageous for making the focus unit more compact. Examples 1 to 4, which will be described later, correspond to this configuration.

[0060] The above-described preferred and possible configurations, including configurations related to the conditional expressions, can be combined in any desired manner, and are preferably selectively adopted as appropriate according to the required specifications. Note that the conditional expressions that the imaging lens of the present disclosure preferably satisfies are not limited to conditional expressions written in the form of an expression, and include all conditional expressions obtained by arbitrarily combining lower limits and upper limits from among the preferred, more preferred, and even more preferred conditional expressions.

[0061] As an example, a preferred embodiment of the imaging lens of the present disclosure is an imaging lens that comprises, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power, and that satisfies the above conditional expressions (1), (2), and (3).

[0062] Next, examples of the imaging lens of the present disclosure will be described with reference to the drawings. The reference symbols assigned to the lenses in the cross-sectional views of each example are used independently for each example to avoid cluttering the explanation and the 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.

[0063] [Example 1] FIG. 2 shows a cross-sectional view of the configuration of the imaging lens of Example 1. The basic illustration method of FIG. 2 is the same as that of FIG. 1, so some overlapping explanations will be omitted here. The imaging lens of Example 1 comprises, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. The front group Gf comprises, in order from the object side to the image side, lenses L11 to L16. The rear group Gr comprises lenses L21 to L25. When focusing from an object at infinity to an object at a close distance, lens L14 moves toward the image side, and the other lenses are fixed with respect to the image plane Sim. The right-pointing arrow below lens L14 in FIG. 2 indicates that lens L14 moves toward the image side when focusing from an object at infinity to an object at a close distance (i.e., lens L14 is a focus group).

[0064] For the imaging lens of Example 1, basic lens data is shown in Table 1, specifications in Table 2, and aspherical coefficients in Table 3. Table 1 is written as follows: The Sn column indicates the surface number, with the surface closest to the object being surface 1 and the numbers increasing by one toward the image side. The R column indicates the radius of curvature of each surface. The D column indicates the surface spacing on the optical axis between each surface and its adjacent surface on the image side. The Nd column indicates the refractive index of each component with respect to the d-line. The νd column indicates the Abbe number of each component based on the d-line. The θgF column indicates the partial dispersion ratio between the g-line and the F-line of each component. The ΔθgF column indicates the anomalous dispersion of each component. In this specification, when the Abbe number based on the d-line is νd and the partial dispersion ratio between the g-line and the F-line of each component is θgF, the anomalous dispersion ΔθgF is defined by the following equation: ΔθgF=θgF+0.001618×νd-0.6415

[0065] In Table 1, the sign of the radius of curvature of surfaces with a convex surface facing the object side is positive, and the sign of the radius of curvature of surfaces with a convex surface facing the image side is negative. Table 1 also shows the aperture stop St and optical member PP, and the column for the surface number of the surface corresponding to the aperture stop St contains the surface number and the term (St). The value in the bottom column of D is the distance between the surface in the table closest to the image and the image plane Sim.

[0066] Table 2 shows the focal length f of the entire system, the back focal length Bf in air equivalent distance of the entire system, the F-number FNo., and the maximum full angle of view 2ωm. The [°] in the 2ωm column indicates that the unit is degrees. The values ​​shown in Table 2 are based on the d-line when focused on an object at infinity.

[0067] In Table 1, the aspherical surface numbers are marked with an *, and the paraxial radius of curvature is listed in the aspherical radius of curvature column. In Table 3, the Sn row shows the aspherical surface numbers, and the KA and Am (m is an integer of 3 or more) rows show the numerical values ​​of the aspherical coefficients for each aspherical surface. 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 where the vertex of the aspheric surface touches) h: Height (distance from the optical axis to the lens surface) C: Reciprocal of paraxial curvature radius KA, Am: aspherical coefficients In the aspherical formula, Σ means the summation over m.

[0068] 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.

[0069] [Table 1]

[0070] [Table 2]

[0071] [Table 3]

[0072] 3 and 4 show aberration diagrams of the imaging lens of Example 1 when focused on an object at infinity. In FIG. 3, spherical aberration, astigmatism, distortion, and lateral chromatic aberration are shown, from left to right. In the spherical aberration diagram, aberrations at the d-line, C-line, F-line, and g-line are shown with a solid line, a long-dashed line, a short-dashed line, and a two-dot chain line, respectively. In the astigmatism diagram, aberrations at the d-line in the sagittal direction are shown with a solid line, and aberrations at the d-line in the tangential direction are shown with a short-dashed line. In the distortion diagram, aberrations at the d-line are shown with a solid line. In the lateral chromatic aberration diagram, aberrations at the C-line, F-line, and g-line are shown with a long-dashed line, a short-dashed line, and a two-dot chain line, respectively. In the spherical aberration diagram, the F-number value is shown after "FNo.=". In the other aberration diagrams, the value of the half angle of view corresponding to the top of the vertical axis is shown after "ω=".

[0073] Figure 4 shows lateral aberration diagrams for each angle of view. In Figure 4, the left column shows lateral aberration in the tangential direction, and the right column shows lateral aberration in the sagittal direction. In Figure 4, aberrations for the d-line, C-line, and F-line are shown by solid lines, long-dashed lines, and short-dashed lines, respectively. In the lateral aberration diagrams, the value of the half angle of view is shown after "ω=".

[0074] The symbols, meanings, notation methods, and illustration methods of each data item related to the above-mentioned Example 1 are the same in the following Examples unless otherwise specified, and therefore, redundant explanations will be omitted below.

[0075] [Example 2] A cross-sectional view of the configuration of the imaging lens of Example 2 is shown in Figure 5. The imaging lens of Example 2 is composed of, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. The front group Gf is composed of, in order from the object side to the image side, lenses L11 to L16. The rear group Gr is composed of lenses L21 to L25. When focusing from an object at infinity to an object at a close distance, lens L14 moves toward the image side, and the other lenses are fixed with respect to the image plane Sim.

[0076] For the imaging lens of Example 2, basic lens data is shown in Table 4, specifications are shown in Table 5, and aspherical coefficients are shown in Table 6. Also, aberration diagrams when focused on an object at infinity are shown in FIGS.

[0077] [Table 4]

[0078] [Table 5]

[0079] [Table 6]

[0080] [Example 3] A cross-sectional view of the configuration of the imaging lens of Example 3 is shown in Figure 8. The imaging lens of Example 3 is composed of, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. The front group Gf is composed of, in order from the object side to the image side, lenses L11 to L16. The rear group Gr is composed of lenses L21 to L25. When focusing from an object at infinity to an object at a close distance, lens L14 moves toward the image side, and the other lenses are fixed with respect to the image plane Sim.

[0081] For the imaging lens of Example 3, basic lens data is shown in Table 7, specifications are shown in Table 8, and aspherical coefficients are shown in Table 9. Also, aberration diagrams when focused on an object at infinity are shown in Figs.

[0082] [Table 7]

[0083] [Table 8]

[0084] [Table 9]

[0085] [Example 4] A cross-sectional view of the configuration of the imaging lens of Example 4 is shown in Figure 11. The imaging lens of Example 4 is composed of, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. The front group Gf is composed of, in order from the object side to the image side, lenses L11 to L16. The rear group Gr is composed of lenses L21 to L25. When focusing from an object at infinity to an object at a close distance, lens L14 moves toward the image side, and the other lenses are fixed with respect to the image plane Sim.

[0086] For the imaging lens of Example 4, basic lens data is shown in Table 10, specifications are shown in Table 11, and aspherical coefficients are shown in Table 12. Also, aberration diagrams when focused on an object at infinity are shown in FIGS.

[0087] [Table 10]

[0088] [Table 11]

[0089] [Table 12]

[0090] [Example 5] A cross-sectional view of the configuration of the imaging lens of Example 5 is shown in Figure 14. The imaging lens of Example 5 comprises, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. The front group Gf comprises, in order from the object side to the image side, lenses L11 to L16. The rear group Gr comprises lenses L21 to L25. When focusing from an object at infinity to an object at a close distance, the lenses L21 to L25 of the rear group Gr move integrally toward the object side, and the front group Gf is fixed with respect to the image plane Sim. In this specification, "moving integrally" means moving simultaneously in the same direction by the same amount.

[0091] For the imaging lens of Example 5, basic lens data is shown in Table 13, specifications are shown in Table 14, and aspherical coefficients are shown in Table 15. Also, aberration diagrams when focused on an object at infinity are shown in Figs.

[0092] [Table 13]

[0093] [Table 14]

[0094] [Table 15]

[0095] [Example 6] 17 shows a cross-sectional view of the configuration of the imaging lens of Example 6. The imaging lens of Example 6 is composed of, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. The front group Gf is composed of, in order from the object side to the image side, lenses L11 to L15. The rear group Gr is composed of lenses L21 to L25. When focusing from an object at infinity to an object at a close distance, the lenses L21 to L25 of the rear group Gr move integrally toward the object side, and the front group Gf is fixed with respect to the image plane Sim.

[0096] For the imaging lens of Example 6, basic lens data is shown in Table 16, specifications are shown in Table 17, and aspherical coefficients are shown in Table 18. Also, aberration diagrams when focused on an object at infinity are shown in Figs.

[0097] [Table 16]

[0098] [Table 17]

[0099] [Table 18]

[0100] [Example 7] A cross-sectional view of the configuration of the imaging lens of Example 7 is shown in Figure 20. The imaging lens of Example 7 is composed of, in order from the object side to the image side, a front group Gf, an aperture stop St, and a rear group Gr having positive refractive power. The front group Gf is composed of, in order from the object side to the image side, lenses L11 to L17. The rear group Gr is composed of lenses L21 to L25. When focusing from an object at infinity to an object at a close distance, lens L15 moves toward the image side, and the other lenses are fixed with respect to the image plane Sim.

[0101] For the imaging lens of Example 7, basic lens data is shown in Table 19, specifications are shown in Table 20, and aspherical coefficients are shown in Table 21. Also, aberration diagrams when focused on an object at infinity are shown in Figs.

[0102] [Table 19]

[0103] [Table 20]

[0104] [Table 21]

[0105] Table 22 shows the corresponding values ​​of conditional expressions (1) to (16) for the imaging lenses of Examples 1 to 7.

[0106] [Table 22]

[0107] From the above data, it can be seen that the imaging lenses of Examples 1 to 7 are configured to have a wide maximum half angle of view exceeding 50 degrees, yet are compact and have good optical performance.

[0108] Next, an imaging device according to an embodiment of the present disclosure will be described. Fig. 23 and Fig. 24 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure. Fig. 23 shows a perspective view of the camera 30 as seen from the front side, and Fig. 24 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.

[0109] The camera 30 includes a camera body 31, and 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.

[0110] A photographic opening through which light from the subject to be photographed enters is provided in the center of the front face of the camera body 31, and a mount 37 is provided at a position corresponding to the photographic opening, and an interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0111] Inside the camera body 31 are provided an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, and a recording medium 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.

[0112] The camera 30 may also have a so-called autofocus function. Specifically, the camera body 31 may include a processor (e.g., a CPU (Central Processing Unit)), a memory, and a lens shift mechanism (e.g., an actuator such as a solenoid or a motor) for driving the focus unit. The processor executes a control program in cooperation with the memory to determine an appropriate focus position and controls the lens shift mechanism so that the focus unit moves to the focus position. That is, in the camera 30 according to this embodiment, the processor in the camera body 31 may be able to electrically control the position of the focus group when focusing. This configuration makes it easier to focus on a subject, improving convenience.

[0113] 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.

[0114] 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, and a video camera.

[0115] The following supplementary items are further disclosed regarding the above embodiments and examples. [Additional note 1] The lens comprises, in order from the object side to the image side, a front group, a stop, and a rear group having positive refractive power, When focused on an object at infinity, the height from the optical axis of the chief ray of the maximum image height on a plane perpendicular to the optical axis passing through the intersection of the lens surface closest to the object and the optical axis is H. The focal length of the entire system when focused on an object at infinity is f. TL is the sum of the distance on the optical axis from the lens surface closest to the object to the lens surface closest to the image when focused on an object at infinity and the back focus in air equivalent distance. The maximum half angle of view of the entire system is ωm. If the unit of ωm is degrees, 1 <H / (f×tanωm)<1.8 (1) 3.1 <TL / (f×tanωm)<5.2 (2) 52<ωm<74 (3) An imaging lens that satisfies conditional expressions (1), (2), and (3) expressed by the following formulas. [Additional note 2] During focusing, at least a portion of the front group moves, and the rear group is fixed relative to the image plane. Item 1. The imaging lens according to claim 1. [Additional note 3] The focal length of the front group when focused on an object at infinity is ff, If the focal length of the rear group is fr, then 0.2 <ff / fr<2 (4) The imaging lens according to supplementary item 2 satisfies conditional expression (4) shown below. [Additional note 4] During focusing, at least a portion of the rear group moves, and the front group is fixed relative to the image plane. Item 1. The imaging lens according to claim 1. [Additional note 5] a first lens element that is a negative meniscus lens element with a convex surface facing the object side and is disposed closest to the object side; a second lens which is a negative meniscus lens having a convex surface facing the object side and is disposed adjacent to the image side of the first lens; 5. The imaging lens according to claim 1, wherein: [Additional note 6] The radius of curvature of the object side surface of the first lens is R1f, When the radius of curvature of the image-side surface of the first lens is R1r, 1.3<(R1f+R1r) / (R1f-R1r)<4.2 (5) The imaging lens according to supplementary item 5, which satisfies conditional expression (5) shown below. [Additional note 7] a third lens disposed adjacent to the image side of the second lens, The third lens is a negative meniscus lens with a convex surface facing the object side, or a plano-concave lens with a flat surface facing the object side. Item 7. The imaging lens according to item 5 or 6. [Additional note 8] The radius of curvature of the image-side surface of the second lens is R2r, When the radius of curvature of the object-side surface of the third lens is R3f, -1<(R2r-R3f) / (R2r+R3f)<0.3 (6) The imaging lens according to supplementary item 7, which satisfies conditional expression (6) shown below. [Additional note 9] The front group is made up of five to seven lens elements. The imaging lens according to any one of claims 1 to 8. [Additional Note 10] The rear group is made up of five to seven lenses. The imaging lens according to any one of claims 1 to 9. [Additional Note 11] If the focal length of the rear group when focused on an object at infinity is fr, 1 <f / fr<7 (7) The imaging lens according to any one of supplementary items 1 to 10, which satisfies conditional expression (7) shown below. [Additional Note 12] the front group includes an Lfp lens having positive refractive power, When the Abbe number of the Lfp lens based on the d line is νfp, 16<νfp<42 (8) The imaging lens according to any one of supplementary items 1 to 11, which satisfies conditional expression (8) shown below. [Additional Note 13] the rear group includes an Lrp1 lens having a positive refractive power, The partial dispersion ratio between the g-line and F-line of the Lrp1 lens is θgFrp1, When the Abbe number of the Lrp1 lens based on the d line is νrp1, 0.01<θgFrp1+0.001618×νrp1-0.6415<0.1 (9) The imaging lens according to any one of supplementary items 1 to 12, which satisfies conditional expression (9) shown below. [Additional Note 14] the rear group includes an Lrp2 lens having positive refractive power that is located closer to the image side than the Lrp1 lens, The partial dispersion ratio between the g-line and F-line of the Lrp2 lens is θgFrp2, When the Abbe number of the Lrp2 lens based on the d line is νrp2, 0.01<θgFrp2+0.001618×νrp2-0.6415<0.1 (10) The imaging lens according to supplementary item 13, which satisfies conditional expression (10) shown below. [Additional Note 15] the rear group includes an Lrn1 lens having negative refractive power, When the refractive index of the Lrn1 lens at the d line is Nrn1, 1.75 <Nrn1<2.2 (11) The imaging lens according to any one of supplementary items 1 to 14, which satisfies conditional expression (11) shown below. [Additional Note 16] the rear group includes an Lrn2 lens having negative refractive power that is located closer to the image side than the Lrn1 lens, When the refractive index of the Lrn2 lens at the d line is Nrn2, 1.8 <Nrn2<2.2 (12) The imaging lens according to supplementary item 15, which satisfies conditional expression (12) shown below. [Additional Note 17] If the distance on the optical axis from the lens surface closest to the object side to the stop is Ds, 1.2 <Ds / (f×tanωm)<2.8 (13) The imaging lens according to any one of supplementary items 1 to 16, which satisfies conditional expression (13) shown below. [Additional Note 18] If the focal length of the lens group that moves during focusing is fa, then 1 <f / |fa|<20 (14) The imaging lens according to claim 2 or 4, which satisfies conditional expression (14) shown below. [Additional Note 19] When the lens is focused on an object at infinity, the distance on the optical axis from the lens surface closest to the object to the stop is Ds. 0.3 <Ds / TL<0.6 (15) The imaging lens according to any one of supplementary items 1 to 18, which satisfies conditional expression (15) shown below. [Additional Note 20] 20. An imaging device comprising the imaging lens according to any one of claims 1 to 19. [Explanation of symbols]

[0116] 1 Imaging lens 2 On-axis luminous flux 3. Maximum half-angle luminous flux 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 Gf front group Gr rear group H Height L11~L25 lenses PP optical components Sim image plane St aperture stop Z optical axis ωm Maximum half angle of view

Claims

1. The lens comprises, in order from the object side to the image side, a front group, a stop, and a rear group having positive refractive power, When focused on an object at infinity, the height from the optical axis of the chief ray of the maximum image height on a plane perpendicular to the optical axis passing through the intersection of the lens surface closest to the object and the optical axis is H, The focal length of the entire system when focused on an object at infinity is f. TL is the sum of the distance on the optical axis from the lens surface closest to the object to the lens surface closest to the image when focused on an object at infinity and the back focus in air equivalent distance. The maximum half angle of view of the entire system is ωm. The unit of ωm is degrees, When the focal length of the rear group is in focus on an object at infinity, fr, 1<H / (f×tanωm)<1.8 (1) 3.1<TL / (f×tanωm)<5.2 (2) 52<ωm<74 (3) 1<f / fr<7 (7) An imaging lens that satisfies conditional expressions (1), (2), (3), and (7) expressed as follows:

2. The lens comprises, in order from the object side to the image side, a front group, a stop, and a rear group having positive refractive power, When focused on an object at infinity, the height from the optical axis of the chief ray of the maximum image height on a plane perpendicular to the optical axis passing through the intersection of the lens surface closest to the object and the optical axis is H, The focal length of the entire system when focused on an object at infinity is f. TL is the sum of the distance on the optical axis from the lens surface closest to the object to the lens surface closest to the image when focused on an object at infinity and the back focus in air equivalent distance. The maximum half angle of view of the entire system is ωm. The unit of ωm is degrees, If the distance on the optical axis from the lens surface closest to the object side to the stop is Ds, then 1<H / (f×tanωm)<1.8 (1) 3.1<TL / (f×tanωm)<5.2 (2) 52<ωm<74 (3) 1.2<Ds / (f×tanωm)<2.2 (13-3) An imaging lens that satisfies conditional expressions (1), (2), (3), and (13-3) expressed by the following formulas.

3. During focusing, at least a portion of the front group moves, and the rear group is fixed relative to the image plane. The imaging lens according to claim 1 or 2.

4. The focal length of the front group when focused on an object at infinity is ff, If the focal length of the rear group is fr, then 0.2<ff / fr<2 (4) 4. The imaging lens according to claim 3, which satisfies conditional expression (4) expressed as follows:

5. During focusing, at least a portion of the rear group moves, and the front group is fixed relative to the image plane. The imaging lens according to claim 1 or 2.

6. a first lens element which is a negative meniscus lens element having a convex surface facing the object side and is disposed closest to the object side; a second lens which is a negative meniscus lens having a convex surface facing the object side and is disposed adjacent to the image side of the first lens; The imaging lens according to claim 1 or 2, comprising:

7. The radius of curvature of the object side surface of the first lens is R1f, When the radius of curvature of the image-side surface of the first lens is R1r, 1.3<(R1f+R1r) / (R1f-R1r)<4.2 (5) 7. The imaging lens according to claim 6, which satisfies conditional expression (5) expressed as follows:

8. a third lens disposed adjacent to the image side of the second lens; The third lens is a negative meniscus lens with a convex surface facing the object side, or a plano-concave lens with a flat surface facing the object side. The imaging lens according to claim 6 .

9. The radius of curvature of the image-side surface of the second lens is R2r, When the radius of curvature of the object-side surface of the third lens is R3f, -1<(R2r-R3f) / (R2r+R3f)<0.3 (6) 9. The imaging lens according to claim 8, which satisfies conditional expression (6) expressed as follows:

10. The front group is made up of five to seven lenses. The imaging lens according to claim 1 or 2.

11. The rear group is made up of five to seven lenses. The imaging lens according to claim 1 or 2.

12. the front group includes an Lfp lens having positive refractive power, When the Abbe number of the Lfp lens based on the d line is νfp, 16<νfp<42 (8) 3. The imaging lens according to claim 1, wherein conditional expression (8) expressed as follows is satisfied:

13. the rear group includes an Lrp1 lens having a positive refractive power, The partial dispersion ratio between the g-line and F-line of the Lrp1 lens is θgFrp1, When the Abbe number of the Lrp1 lens based on the d line is νrp1, 0.01<θgFrp1+0.001618×νrp1-0.6415<0.1 (9) 3. The imaging lens according to claim 1, which satisfies conditional expression (9) expressed as follows:

14. the rear group includes an Lrp2 lens having positive refractive power and located closer to the image side than the Lrp1 lens, The partial dispersion ratio between the g-line and the F-line of the Lrp2 lens is θgFrp2, When the Abbe number of the Lrp2 lens based on the d line is νrp2, 0.01<θgFrp2+0.001618×νrp2-0.6415<0.1 (10) 14. The imaging lens according to claim 13, which satisfies conditional expression (10) expressed as follows:

15. the rear group includes an Lrn1 lens having negative refractive power, When the refractive index of the Lrn1 lens at the d line is Nrn1, 1.75<Nrn1<2.2 (11) 3. The imaging lens according to claim 1, which satisfies conditional expression (11) expressed as follows:

16. the rear group includes an Lrn2 lens having negative refractive power and located closer to the image side than the Lrn1 lens, When the refractive index of the Lrn2 lens at the d line is Nrn2, 1.8<Nrn2<2.2 (12) 16. The imaging lens according to claim 15, which satisfies conditional expression (12) expressed as follows:

17. When the focal length of the lens group that moves during focusing is fa, 1<f / |fa|<20 (14) 4. The imaging lens according to claim 3, which satisfies conditional expression (14) expressed as follows:

18. When the distance on the optical axis from the lens surface closest to the object to the stop in a state where the lens is focused on an object at infinity is Ds, 0.3<Ds / TL<0.6 (15) 3. The imaging lens according to claim 1, which satisfies conditional expression (15) expressed as follows:

19. An imaging device comprising the imaging lens according to claim 1 or 2.

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