Image capturing lens and image capturing device

Abstract

To provide an image capturing lens which is compactly configured and offers good optical performance, and an image capturing device having the same.SOLUTION: An image capturing lens is provided, consisting of a first lens group and a positive second lens group arranged in order from the object side to the image side. While focusing, the first lens group moves along an optical axis and the second lens group is stationary relative to an image plane. A lens on the most object side in the first lens group is a negative lens. The imaging optical system satisfies predefined conditional expressions.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, a lens system described in Patent Document 1 below is known as an imaging lens used in cameras and the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-033004 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for imaging lenses that are compact and have good optical performance, and the level of these requirements is increasing year by year.

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

[0006] An imaging lens according to one aspect of the techniques of the present disclosure includes, in order from the object side to the image side, a first lens group and a second lens group, wherein, during focusing, the first lens group moves along an optical axis, the second lens group is fixed with respect to an image plane, and the lens of the first lens group closest to the object side is a negative lens; 1.3 <TL / (f×tanω)<2.1 (1) Conditional expression (1) expressed as follows is satisfied. Here, TL is the sum of the distance on the optical axis from the lens surface in the first lens group closest to the object to the lens surface in the second lens group closest to the image when focused on an object at infinity, and the back focal length in terms of the air-equivalent distance of the entire system. f is the focal length of the entire system when focused on an object at infinity. ω is the maximum half angle of view when focused on an object at infinity.

[0007] The number of lenses included in the entire system is preferably 7 or more and 11 or less.

[0008] When the back focus of the entire system in an air-equivalent distance in a state where the lens is focused on an object at infinity is Bf, the imaging lens of the above aspect has the following characteristics: 0.08 <Bf / f<0.3 (2) It is preferable to satisfy conditional expression (2) below.

[0009] When the maximum F-number when focused on an object at infinity is FNo, the imaging lens of the above aspect has the following characteristics: 4.3 <FNo×(TL / f)<6.4 (3) It is preferable to satisfy conditional expression (3) below.

[0010] When the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the first lens group closest to the image side is dG1, the imaging lens of the above aspect satisfies the following conditions: 0.45 <dG1 / (f×tanω)<1 (4) It is preferable to satisfy conditional expression (4) below.

[0011] When the distance on the optical axis from the lens surface of the first lens group closest to the image side to the lens surface of the second lens group closest to the object side in a state where the lens is focused on an object at infinity is dF, the imaging lens of the above aspect satisfies the following conditions: 0.05 <dF / (f×tanω)<0.32 (5) It is preferable to satisfy conditional expression (5) below.

[0012] In a configuration in which the first lens group is composed of, in order from the object side to the image side, a front subgroup, a stop, and a rear subgroup, if the focal length of the front subgroup is fG1f and the focal length of the first lens group is fG1, the imaging lens of the above aspect has the following characteristics: 1.8 <fG1f / fG1<8 (6) In this case, the imaging lens of the above aspect further satisfies the following condition: 1.3 <fG1f / f<5 (7) It is preferable to satisfy conditional expression (7) below.

[0013] When the focal length of the second lens group is fG2, the imaging lens of the above aspect has the following characteristics: -2.5 <fG2 / f<-0.4 (8) It is preferable to satisfy conditional expression (8) below.

[0014] When the focal length of the first lens group is fG1, the imaging lens of the above aspect has the following characteristics: 0.4 <fG1 / f<0.95 (9) It is preferable to satisfy conditional expression (9) below.

[0015] If the lateral magnification of the first lens group when focused on an object at infinity is βG1 and the lateral magnification of the second lens group when focused on an object at infinity is βG2, the imaging lens of the above aspect has the following properties: 1.4<(1-βG1 2 )×βG2 2 <3.2 (10) It is preferable to satisfy conditional expression (10) below.

[0016] In a configuration in which the first lens group is made up of, in order from the object side to the image side, a front subgroup, a stop, and a rear subgroup, when the average value of the refractive index for the d-line of all positive lenses included in the rear subgroup is denoted as NG1rpa, the average value of the Abbe numbers based on the d-line of all positive lenses included in the rear subgroup is denoted as νG1rpa, and the average value of the partial dispersion ratios between the g-line and the F-line of all positive lenses included in the rear subgroup is denoted as θG1rpa, the imaging lens of the above aspect satisfies the following: 1.6 <NG1rpa<1.86 (11) 0.65<θG1rpa+0.0025×νG1rpa<0.72 (12) It is preferable to satisfy the following conditional expressions (11) and (12):

[0017] In a configuration in which the second lens group includes only one positive lens, if the focal length of the positive lens in the second lens group is fG2p and the focal length of the second lens group is fG2, the imaging lens of the above aspect has the following characteristics: -4 <fG2p / fG2<-1 (13) It is preferable to satisfy conditional expression (13) below.

[0018] In a configuration in which the second lens group includes only one positive lens, when the refractive index of the positive lens in the second lens group with respect to the d-line is denoted as NG2p, the Abbe number of the positive lens in the second lens group with respect to the d-line is denoted as νG2p, and the partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group is denoted as θG2p, the imaging lens of the above aspect has the following properties: 1.88 <NG2p<1.96 (14) 0.67<θG2p+0.0025×νG2p<0.705 (15) It is preferable to satisfy the following conditions (14) and (15):

[0019] It is preferable that the lens arranged closest to the image side in the first lens group is a first aspherical lens having positive refractive power.

[0020] In a configuration in which the second lens group includes a second aspherical lens, the height from the optical axis of the position of the maximum effective diameter on the image-side surface of the second aspherical lens is defined as hE2, an arbitrary height from the optical axis is defined as h, the amount of sag at each point on the image-side surface of the second aspherical lens at height h is defined as Sg2(h), and the second-order differential of Sg2(h) with respect to h is defined as d 2 Sg2(h) / dh 2 In this case, in the range of 0.5×hE2≦h≦hE2 on the image side surface of the second aspherical lens, |d 2 Sg2(h) / dh 2 |>2×|d2 Sg2(h / 2) / dh 2 | (16) It is preferable that there exists a point that satisfies conditional expression (16) expressed as follows:

[0021] It is preferable that the object-side surface of the negative lens closest to the object side in the first lens group is a concave surface.

[0022] The first lens group preferably includes a stop and a single lens having positive refractive power arranged adjacent to the image side of the stop.

[0023] It is preferable that the second lens group consists of, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens.

[0024] Another aspect of the present disclosure is an imaging device including the imaging lens of the above aspect.

[0025] 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.

[0026] 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.

[0027] In this specification, a "single lens" refers to a single lens that is not cemented. Note that a compound aspherical lens (a lens in which a lens (e.g., a spherical lens) and an aspherical film formed on the lens are integrally configured to function 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 the surface shape of a lens including an aspherical surface are those in the paraxial region.

[0028] In this specification, "total system" refers to the imaging lens. 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] The terms "d-line," "C-line," "F-line," and "g-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), 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]

[0030] According to the present disclosure, it is possible to provide an imaging lens that is compact and has good optical performance, and an imaging device that includes this imaging lens. [Brief explanation of the drawings]

[0031] [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] FIG. 2 is a cross-sectional view showing the configuration of the imaging lens and light beams in FIG. 1, and is also a diagram for explaining symbols in conditional expressions. [Figure 3] FIG. 2 is a diagram for explaining the position of the maximum effective diameter. [Figure 4] 5A and 5B are diagrams for explaining the amount of sag of the first aspherical lens, etc. FIG. [Figure 5] 5A and 5B are diagrams for explaining the amount of sag of the second aspherical lens, etc. FIG. [Figure 6] 3A to 3C are diagrams showing various aberrations of the imaging lens of Example 1. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a second embodiment. [Figure 8] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 2. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a third embodiment. [Figure 10] 10A to 10C are diagrams showing various aberrations 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 various aberrations of the imaging lens of Example 4. [Figure 13] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fifth embodiment. [Figure 14] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 5. [Figure 15] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a sixth embodiment. [Figure 16] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 6. [Figure 17] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a seventh embodiment. [Figure 18] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 7. [Figure 19] 1 is a perspective view of the front side of an imaging device according to an embodiment. [Figure 20] FIG. 20 is a perspective view of the rear side of the imaging device of FIG. 19. [Figure 21] FIG. 10 is a perspective view of the front side of an imaging device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, embodiments of the technology of the present disclosure will be described with reference to the drawings.

[0033] 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 ray bundle. FIGS. 1 and 2 show a state in which the imaging lens is focused on an object at infinity. In FIGS. 1 and 2, the left side is the object side and the right side is the image side. In FIG. 2, the ray bundles shown are an axial ray bundle 2 and a ray bundle 3 at the maximum half angle of view ω. 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.

[0034] The imaging lens of the present disclosure comprises, in order from the object side to the image side along the optical axis Z, a first lens group G1 and a second lens group G2. During focusing, the first lens group G1 moves along the optical axis Z, while the second lens group G2 is fixed relative to the image plane Sim. In this way, focusing is performed by changing the spacing between two groups that have different degrees of separation between on-axis and off-axis light beams, which is advantageous for suppressing aberration fluctuations.

[0035] 1 is composed of, in order from the object side to the image side, a first lens group G1 with positive refractive power and a second lens group G2 with negative refractive power. This configuration is advantageous for miniaturization.

[0036] As an example, each group in the imaging lens in FIG. 1 is configured as follows: The first lens group G1 is composed of, from the object side to the image side, a front subgroup G1f, an aperture stop St, and a rear subgroup G1r. The front subgroup G1f is composed of, from the object side to the image side, two lenses, L11 and L12. The rear subgroup G1r is composed of, from the object side to the image side, five lenses, L13 to L17. The second lens group G2 is composed of, from the object side to the image side, three lenses, L21 to L23. Note that the aperture stop St in FIG. 1 does not indicate its size or shape, but its position in the optical axis direction. The parentheses and left-pointing arrow below the first lens group G1 in FIG. 1 indicate that the first lens group G1 is a focusing group that moves during focusing, and that it moves toward the object side when focusing from an object at infinity to a close object.

[0037] In the imaging lens of the present disclosure, the lens closest to the object in the first lens group G1 is configured as a negative lens, which is advantageous for correcting spherical aberration.

[0038] The object-side surface of the negative lens closest to the object in the first lens group G1 may be configured to be concave, which is advantageous for correcting spherical aberration.

[0039] When the first lens group G1 is composed of, in order from the object side to the image side, a front subgroup G1f, an aperture stop St, and a rear subgroup G1r, the front subgroup G1f may be composed only of a cemented lens in which, in order from the object side to the image side, a negative lens and a positive lens are cemented together, which is advantageous for correcting axial chromatic aberration and chromatic aberration of magnification while maintaining a compact configuration.

[0040] It is preferable that the first lens group G1 includes a cemented lens, in which a negative lens and a positive lens are cemented together, on both the object side of the aperture stop St and the image side of the aperture stop St. This is advantageous for correcting axial chromatic aberration and chromatic aberration of magnification.

[0041] The first lens group G1 may be configured to include an aperture stop St and a single lens having positive refractive power arranged adjacent to the image side of the aperture stop St. This is advantageous for correcting spherical aberration and axial chromatic aberration while maintaining a compact configuration. Furthermore, if the first lens group G1 includes a single lens having positive refractive power arranged adjacent to the image side of the aperture stop St, it is preferable that this single lens have a biconvex shape. This is advantageous for compactness and correction of spherical aberration.

[0042] The first lens group G1 may be configured so that a single lens having positive refractive power is located closest to the image side, and a single lens having negative refractive power is located adjacent to this single lens on the object side, which is advantageous for correcting chromatic aberration of magnification.

[0043] The lens disposed on the most image side of the first lens group G1 is preferably an aspherical lens having a positive refractive power. By disposing a positive lens on the most image side of the first lens group G1, it is advantageous for correcting spherical aberration. Also, on the most image side of the first lens group G1, since the on-axis light beam and the off-axis light beam around the screen are separated, disposing an aspherical lens here is advantageous for correcting field curvature. Hereinafter, the aspherical lens having a positive refractive power disposed on the most image side of the first lens group G1 is referred to as the first aspherical lens.

[0044] The first aspherical lens preferably has the configuration described below. Hereinafter, the height from the optical axis Z at the position of the maximum effective diameter on the image side surface of the first aspherical lens is denoted as hE1, an arbitrary height from the optical axis Z is denoted as h, and the sag amount of each point on the image side surface of the first aspherical lens at height h is denoted as Sg1(h). Sg1(h) is a function of h. When the second derivative of Sg1(h) with respect to h is d 2 Sg1(h) / dh 2 in the range of 0 < h ≤ hE1 on the image side surface of the first aspherical lens, it is preferably configured such that the sign of d 2 Sg1(h) / dh 2 is constant. In this case, it is advantageous for correcting field curvature.

[0045] Here, the "position of the maximum effective diameter" in this specification will be described while referring to FIG. 3. FIG. 3 is an explanatory diagram. In FIG. 3, the left side is the object side and the right side is the image side. FIG. 3 shows the on-axis light beam Xa and the off-axis light beam Xb passing through the lens Lx. In the example of FIG. 3, the light ray Xb1, which is the upper light ray of the off-axis light beam Xb, is the light ray passing through the outermost side. The "outer side" here refers to the radially outer side centered on the optical axis Z, that is, the side away from the optical axis Z. The position of the intersection of this light ray passing through the outermost side and the lens surface is the position Px of the maximum effective diameter. Note that the height from the optical axis Z at the position Px of the maximum effective diameter is the effective radius Er of the object side surface of the lens Lx. In the example of FIG. 3, the upper light ray of the off-axis light beam Xb is the light ray passing through the outermost side, but which light ray becomes the light ray passing through the outermost side depends on the lens system.

[0046] Furthermore, in this specification, the "amount of sag" of each point on a surface at height h is expressed as the distance between each point on the surface at height h and a plane perpendicular to the optical axis Z that passes through the intersection of that surface with the optical axis Z. In the imaging lens of FIG. 1, lens L17 corresponds to the first aspherical lens. FIG. 4 shows this lens L17, with a dashed line indicating a plane perpendicular to the optical axis Z that passes through the intersection of the image-side surface of lens L17 with the optical axis Z. As an example, FIG. 4 also shows the height hE1 from the optical axis Z at the position of the maximum effective diameter on the image-side surface of lens L17, a certain height ha, and the amount of sag Sg1(ha) at height ha.

[0047] The second lens group G2 may be configured to include only one positive lens, which is advantageous for size reduction.

[0048] The lens closest to the image side in the second lens group G2 may be a positive lens, which is advantageous for achieving compactness while reducing the angle of incidence of off-axis chief rays onto the image plane Sim.

[0049] The second lens group G2 may be configured to consist of, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens, which is advantageous for correcting chromatic aberration of magnification and for achieving compactness while reducing the angle of incidence of off-axis chief rays on the image plane Sim.

[0050] The second lens group G2 may be configured to include an aspherical lens. Since the second lens group G2 separates the on-axis light beam from the off-axis light beam at the periphery of the image, including an aspherical lens in the second lens group G2 is advantageous for correcting field curvature. Hereinafter, the aspherical lens included in the second lens group G2 will be referred to as the second aspherical lens.

[0051] The second aspherical lens is preferably positioned closest to the object in the second lens group G2, which allows the diameter of the aspherical lens to be reduced, which is advantageous in terms of cost and also makes it easier to process with high precision.

[0052] The second aspherical lens preferably has the following configuration. In the following, the height from the optical axis Z at the position of the maximum effective diameter on the image-side surface of the second aspherical lens is defined as hE2, an arbitrary height from the optical axis Z is defined as h, and the sag amount of each point on the image-side surface of the second aspherical lens at height h is defined as Sg2(h). Sg2(h) is a function of h. The second-order differential of Sg2(h) with respect to h is defined as d 2 Sg2(h) / dh 2 In this case, it is preferable that there exists a point on the image-side surface of the second aspherical lens within the range of 0.5×hE2≦h≦hE2 that satisfies the following conditional expression (16): In this case, an aspherical surface with a large amount of sag can be obtained in the peripheral portion of the lens, which is advantageous for correcting field curvature. |d 2 Sg2(h) / dh 2 |>2×|d 2 Sg2(h / 2) / dh 2 | (16)

[0053] In the imaging lens of Fig. 1, lens L21 corresponds to the second aspherical lens. Fig. 5 shows this lens L21, with the dashed line indicating a plane perpendicular to optical axis Z that passes through the intersection of the image-side surface of lens L21 and the optical axis Z. As an example, Fig. 5 also shows the height hE2 from the optical axis Z at the position of the maximum effective diameter on the image-side surface of lens L21, the height that is 0.5 × hE2 from the optical axis Z, a certain height hb, and the sag Sg2(hb) at height hb.

[0054] The number of lenses included in the entire system is preferably 7 to 11. This makes it easier to balance compactness and aberration correction. To obtain better characteristics, the number of lenses included in the entire system is preferably 9 to 11.

[0055] Furthermore, it is preferable that the imaging lens of the present disclosure satisfy at least one of the following conditional expressions. 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 are omitted. Also, to avoid redundancy, hereinafter, "the imaging lens of the present disclosure" will also be referred to simply as "the imaging lens."

[0056] It is preferable that the imaging lens satisfy the following conditional expression (1). Here, TL is the sum of the axial distance from the lens surface of the first lens group G1 closest to the object to the lens surface of the second lens group G2 closest to the image when the lens is focused on an object at infinity, and the back focus in terms of the air-equivalent distance of the entire system when the lens is focused on an object at infinity. f is the focal length of the entire system when the lens is focused on an object at infinity. ω is the maximum half angle of view when the lens is focused on an object at infinity. TL is the total optical length when the lens is focused on an object at infinity. As an example, Figure 2 shows the above-mentioned total optical length TL and maximum half angle of view ω. Ensuring that the corresponding value of conditional expression (1) is not equal to or less than the lower limit is advantageous for correcting spherical aberration and field curvature. Ensuring that the corresponding value of conditional expression (1) is not equal to or greater than the upper limit is advantageous for compactness. 1.3 <TL / (f×tanω)<2.1 (1)

[0057] In order to obtain better characteristics, the lower limit of conditional expression (1) is more preferably 1.37, even more preferably 1.44, even more preferably 1.51, even more preferably 1.58, and even more preferably 1.64.In order to obtain better characteristics, the upper limit of conditional expression (1) is more preferably 2.05, even more preferably 2, even more preferably 1.9, even more preferably 1.8, and even more preferably 1.72.

[0058] If the back focus in air-equivalent distance of the entire system when focused on an object at infinity is Bf, it is preferable that the imaging lens satisfy the following conditional expression (2). 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. As an example, Figure 2 shows the above back focus Bf. Ensuring that the corresponding value of conditional expression (2) is not equal to or less than the lower limit is advantageous for ensuring the amount of peripheral light. Ensuring that the corresponding value of conditional expression (2) is not equal to or greater than the upper limit is advantageous for miniaturization. 0.08 <Bf / f<0.3 (2)

[0059] In order to obtain better characteristics, the lower limit of conditional expression (2) should preferably be set to 0.11, more preferably 0.14, and even more preferably 0.17.In order to obtain better characteristics, the upper limit of conditional expression (2) should preferably be set to 0.27, more preferably 0.24, and even more preferably 0.21.

[0060] If the maximum F-number when focused on an object at infinity is FNo, it is preferable that the imaging lens satisfy the following conditional expression (3). Ensuring that the corresponding value of conditional expression (3) is not equal to or less than the lower limit thereof is advantageous for correcting various aberrations. Ensuring that the corresponding value of conditional expression (3) is not equal to or greater than the upper limit thereof is advantageous for reducing the F-number and the overall length. 4.3 <FNo×(TL / f)<6.4 (3)

[0061] In order to obtain better characteristics, the lower limit of conditional expression (3) should preferably be set to 4.8, more preferably to 5.2, and even more preferably to 5.3.In order to obtain better characteristics, the upper limit of conditional expression (3) should preferably be set to 6.3, more preferably to 6.2, and even more preferably to 6.1.

[0062] It is preferable that the imaging lens satisfy the following conditional expression (4). Here, 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 first lens group G1 closest to the image is defined as dG1. As an example, the above distance dG1 is shown in FIG. 2. Ensuring that the value corresponding to conditional expression (4) is not equal to or smaller than the lower limit is advantageous for correcting spherical aberration. Ensuring that the value corresponding to conditional expression (4) is not equal to or larger than the upper limit is advantageous for miniaturization. 0.45 <dG1 / (f×tanω)<1 (4)

[0063] In order to obtain better characteristics, the lower limit of conditional expression (4) should preferably be set to 0.53, more preferably to 0.61, and even more preferably to 0.7.In order to obtain better characteristics, the upper limit of conditional expression (4) should preferably be set to 0.9, more preferably to 0.85, and even more preferably to 0.8.

[0064] It is preferable that the imaging lens satisfy the following conditional expression (5). Here, dF is the distance on the optical axis from the lens surface of the first lens group G1 closest to the image to the lens surface of the second lens group G2 closest to the object when focused on an object at infinity. As an example, FIG. 2 shows the above distance dF. Ensuring that the value corresponding to conditional expression (5) is not equal to or smaller than the lower limit is advantageous for correcting field curvature. Ensuring that the value corresponding to conditional expression (5) is not equal to or larger than the upper limit is advantageous for compactness. 0.05 <dF / (f×tanω)<0.32 (5)

[0065] In order to obtain better characteristics, the lower limit of conditional expression (5) should preferably be set to 0.1, more preferably to 0.15, and even more preferably to 0.156.In order to obtain better characteristics, the upper limit of conditional expression (5) should preferably be set to 0.28, more preferably to 0.24, and even more preferably to 0.2.

[0066] When the first lens group G1 is configured to include, in order from the object side to the image side, a front subgroup G1f, an aperture stop St, and a rear subgroup G1r, it is preferable that the imaging lens satisfy the following conditional expression (6). Here, the focal length of the front subgroup G1f is defined as fG1f. The focal length of the first lens group G1 is defined as fG1. Ensuring that the corresponding value of conditional expression (6) falls within the range defined by conditional expression (6) is advantageous for correction of spherical aberration. 1.8 <fG1f / fG1<8 (6)

[0067] In order to obtain better characteristics, the lower limit of conditional expression (6) should preferably be set to 2.1, more preferably 2.5, and even more preferably 3.8.In order to obtain better characteristics, the upper limit of conditional expression (6) should preferably be set to 7, more preferably 6, and even more preferably 5.3.

[0068] In a configuration in which the first lens group G1 is composed of, in order from the object side to the image side, a front subgroup G1f, an aperture stop St, and a rear subgroup G1r, it is preferable that the imaging lens satisfy the following conditional expression (7): By ensuring that the corresponding value of conditional expression (7) falls within the range of conditional expression (7), it is advantageous for correction of spherical aberration. 1.3 <fG1f / f<5 (7)

[0069] In order to obtain better characteristics, the lower limit of conditional expression (7) should preferably be set to 1.5, more preferably 1.8, and even more preferably 2.5.In order to obtain better characteristics, the upper limit of conditional expression (7) should preferably be set to 4.2, more preferably 3.4, and even more preferably 2.8.

[0070] When the focal length of the second lens group G2 is fG2, it is preferable that the imaging lens satisfy the following conditional expression (8). Ensuring that the corresponding value of conditional expression (8) is not equal to or smaller than the lower limit thereof is advantageous for correcting field curvature. Ensuring that the corresponding value of conditional expression (8) is not equal to or larger than the upper limit thereof is advantageous for miniaturization. -2.5 <fG2 / f<-0.4 (8)

[0071] In order to obtain better characteristics, the lower limit of conditional expression (8) should preferably be set to -2, more preferably to -1.5, and even more preferably to -1.2.In order to obtain better characteristics, the upper limit of conditional expression (8) should preferably be set to -0.6, more preferably to -0.8, and even more preferably to -0.85.

[0072] 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 less than the lower limit, it is advantageous for correction of spherical aberration. By ensuring that the corresponding value of conditional expression (9) is not equal to or greater than the upper limit, it is advantageous for miniaturization. 0.4 <fG1 / f<0.95 (9)

[0073] In order to obtain better characteristics, the lower limit of conditional expression (9) should preferably be set to 0.5, more preferably to 0.6, and even more preferably to 0.62.In order to obtain better characteristics, the upper limit of conditional expression (9) should preferably be set to 0.8, more preferably to 0.7, and even more preferably to 0.69.

[0074] It is preferable that the imaging lens satisfy the following conditional expression (10). Here, the lateral magnification of the first lens group G1 when focused on an object at infinity is defined as βG1. The lateral magnification of the second lens group G2 when focused on an object at infinity is defined as βG2. Ensuring that the corresponding value of conditional expression (10) is not equal to or smaller than the lower limit thereof is advantageous for achieving compactness. Ensuring that the corresponding value of conditional expression (10) is not equal to or larger than the upper limit thereof is advantageous for suppressing changes in optical performance when the subject distance changes. 1.4<(1-βG1 2 )×βG2 2 <3.2 (10)

[0075] In order to obtain better characteristics, the lower limit of conditional expression (10) should preferably be set to 1.7, more preferably to 2, and even more preferably to 2.1. In order to obtain better characteristics, the upper limit of conditional expression (10) should preferably be set to 3, more preferably to 2.8, and even more preferably to 2.6.

[0076] When the first lens group G1 is configured to include, in order from the object side to the image side, a front subgroup G1f, an aperture stop St, and a rear subgroup G1r, it is preferable that the imaging lens satisfy the following conditional expression (11). Here, the average value of the refractive index for the d-line of all the positive lenses included in the rear subgroup G1r is defined as NG1rpa. Ensuring that the corresponding value of conditional expression (11) falls within the range of conditional expression (11) is advantageous for correction of spherical aberration. 1.6 <NG1rpa<1.86 (11)

[0077] In order to obtain better characteristics, the lower limit of conditional expression (11) should preferably be set to 1.65, and more preferably to 1.68.In order to obtain better characteristics, the upper limit of conditional expression (11) should preferably be set to 1.8, and more preferably to 1.75.

[0078] When the first lens group G1 is configured to include, in order from the object side to the image side, a front subgroup G1f, an aperture stop St, and a rear subgroup G1r, it is preferable that the imaging lens satisfy the following conditional expression (12). Here, the average value of the Abbe numbers based on the d-line of all the positive lenses included in the rear subgroup G1r is defined as νG1rpa. The average value of the partial dispersion ratios between the g-line and the F-line of all the positive lenses included in the rear subgroup G1r is defined as θG1rpa. Ensuring that the corresponding value of conditional expression (12) falls within the range defined by conditional expression (12) is advantageous for correcting longitudinal chromatic aberration. 0.65<θG1rpa+0.0025×νG1rpa<0.72 (12)

[0079] In order to obtain better characteristics, the lower limit of conditional expression (12) should preferably be set to 0.665, and more preferably to 0.68.In order to obtain better characteristics, the upper limit of conditional expression (12) should preferably be set to 0.705, and more preferably to 0.695.

[0080] If the refractive indices of a lens for the g-line, F-line, and C-line are Ng, NF, and NC, respectively, and the partial dispersion ratio between the g-line and F-line of that lens is θg,F, then θg,F is defined by the following equation. θg,F=(Ng-NF) / (NF-NC)

[0081] In a configuration in which the first lens group G1 is composed of, in order from the object side to the image side, a front subgroup G1f, an aperture stop St, and a rear subgroup G1r, it is preferable that the imaging lens simultaneously satisfy conditional expressions (11) and (12).

[0082] In a configuration in which the second lens group G2 includes only one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (13). Here, the focal length of the positive lens in the second lens group G2 is fG2p. The focal length of the second lens group G2 is fG2. Ensuring that the corresponding value of conditional expression (13) is not equal to or smaller than the lower limit thereof is advantageous for correcting curvature of field. Ensuring that the corresponding value of conditional expression (13) is not equal to or larger than the upper limit thereof is advantageous for correcting distortion. -4 <fG2p / fG2<-1 (13)

[0083] In order to obtain better characteristics, the lower limit of conditional expression (13) should preferably be set to -3.8, more preferably to -3.5, and even more preferably to -3.2.In order to obtain better characteristics, the upper limit of conditional expression (13) should preferably be set to -1.25, more preferably to -1.5, and even more preferably to -2.2.

[0084] In a configuration in which the second lens group G2 includes only one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (14). Here, the refractive index of the positive lens in the second lens group G2 at the d-line is defined as NG2p. Ensuring that the corresponding value of conditional expression (14) falls within the range of conditional expression (14) is advantageous for correcting field curvature. 1.88 <NG2p<1.96 (14)

[0085] In order to obtain better characteristics, the lower limit of conditional expression (14) should preferably be set to 1.91, and more preferably to 1.92. In order to obtain better characteristics, the upper limit of conditional expression (14) should preferably be set to 1.93, and more preferably to 1.925.

[0086] In a configuration in which the second lens group G2 includes only one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (15). Here, the Abbe number of the positive lens in the second lens group G2 based on the d-line is denoted as νG2p. The partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group G2 is denoted as θG2p. Ensuring that the corresponding value of conditional expression (15) falls within the range of conditional expression (15) is advantageous for correcting chromatic aberration of magnification. 0.67<θG2p+0.0025×νG2p<0.705 (15)

[0087] In order to obtain better characteristics, the lower limit of conditional expression (15) should preferably be set to 0.674, and more preferably to 0.678.In order to obtain better characteristics, the upper limit of conditional expression (15) should preferably be set to 0.695, and more preferably to 0.693.

[0088] In a configuration in which the second lens group G2 includes only one positive lens, it is preferable that the imaging lens simultaneously satisfy conditional expressions (14) and (15).

[0089] It is preferable that the imaging lens satisfy the following conditional expression (17). By ensuring that the corresponding value of conditional expression (17) is not equal to or less than the lower limit, it is advantageous for correcting various aberrations. By ensuring that the corresponding value of conditional expression (17) is not equal to or greater than the upper limit, it is advantageous for reducing the overall length. 1.2 <TL / f<1.6 (17)

[0090] In order to obtain better characteristics, the lower limit of conditional expression (17) should preferably be set to 1.3, and more preferably to 1.4.In order to obtain better characteristics, the upper limit of conditional expression (17) should preferably be set to 1.55, and more preferably to 1.5.

[0091] 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.

[0092] As an example, one preferred embodiment of the imaging lens of the present disclosure comprises, in order from the object side to the image side, a first lens group G1 and a second lens group G2, wherein, during focusing, the first lens group G1 moves along the optical axis Z, the second lens group G2 is fixed with respect to the image plane Sim, the lens in the first lens group G1 closest to the object side is a negative lens, and satisfies the above conditional expression (1).

[0093] Next, examples of the imaging lens of the present disclosure will be described with reference to the drawings. The reference symbols assigned to the lens 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.

[0094] [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 overlapping explanations 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 and a second lens group G2 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, a front subgroup G1f having positive refractive power, an aperture stop St, and a rear subgroup G1r having positive refractive power. When focusing from an object at infinity to a close-up object, the first lens group G1 moves toward the object along the optical axis Z, and the second lens group G2 is fixed with respect to the image plane Sim.

[0095] For the imaging lens of Example 1, basic lens data is shown in Table 1, specifications are shown in Table 2, and aspherical coefficients are shown in Table 3.

[0096] 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 for each lens with respect to the d-line. The "νd" column shows the Abbe number of each lens based on the d-line. The "θg,F" column shows the partial dispersion ratio between the g-line and F-line of each lens.

[0097] 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 contains the surface number and the term (St). The value at the bottom of the D column in the table is the distance between the surface closest to the image side and the image plane Sim.

[0098] Table 2 shows the focal length (f) of the entire system, the back focal length (Bf) in air equivalent distance, the maximum F-number (FNo.), and the maximum full angle of view (2ω) based on the d-line. In the maximum full angle of view column, [°] indicates that the unit is degrees. The specifications table shows the values ​​when focused on an object at infinity.

[0099] In the basic lens data, the surface numbers of aspherical surfaces are marked with an *, and the value of the paraxial radius of curvature is listed 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 12th surface in Example 1, m = 4, 6, 8, 10, ..., 20. 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 (the distance between a plane perpendicular to the optical axis Z that passes through the intersection of the aspheric surface and the optical axis Z and a point on the aspheric surface at height h) h: Height (distance from optical axis Z to lens surface) C: Reciprocal of paraxial curvature radius KA, Am: aspherical coefficients In the aspherical formula, Σ means the summation over m.

[0100] 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.

[0101] [Table 1]

[0102] [Table 2]

[0103] [Table 3]

[0104] FIG. 6 shows aberration diagrams of the imaging lens of Example 1 when focused on an object at infinity. From left to right, FIG. 6 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration. In the spherical aberration diagram, 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 diagram, 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 diagram, aberrations at the d-line are shown by solid lines. In the lateral chromatic aberration diagram, aberrations at the C-line, F-line, and g-line are shown by long-dashed lines, short-dashed lines, and dash-dot lines, respectively. In the spherical aberration diagram, the maximum F-number is shown after "FNo.=". In the other aberration diagrams, the maximum half angle of view is shown after "ω=".

[0105] 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.

[0106] [Example 2] FIG. 7 shows a cross-sectional view of the configuration of the imaging lens of Example 2. The imaging lens of Example 2 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power and a second lens group G2 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, a front subgroup G1f having positive refractive power, an aperture stop St, and a rear subgroup G1r having positive refractive power. The front subgroup G1f comprises, in order from the object side to the image side, two lenses, lenses L11 and L12. The rear subgroup G1r comprises, in order from the object side to the image side, five lenses, lenses L13 to L17. The second lens group G2 comprises, in order from the object side to the image side, three lenses, lenses L21 to L23. When focusing from an object at infinity to an object at a close distance, the first lens group G1 moves along the optical axis Z toward the object side, and the second lens group G2 is fixed relative to the image plane Sim.

[0107] For the imaging lens of Example 2, basic lens data is shown in Table 4, specifications are shown in Table 5, aspherical coefficients are shown in Table 6, and aberration diagrams are shown in FIG.

[0108] [Table 4]

[0109] [Table 5]

[0110] [Table 6]

[0111] [Example 3] A cross-sectional view of the configuration of the imaging lens of Example 3 is shown in Figure 9. The imaging lens of Example 3 consists of, from the object side to the image side, a first lens group G1 having positive refractive power and a second lens group G2 having negative refractive power. The first lens group G1 consists of, from the object side to the image side, a front subgroup G1f having positive refractive power, an aperture stop St, and a rear subgroup G1r having positive refractive power. The front subgroup G1f consists of, from the object side to the image side, two lenses, lenses L11 and L12. The rear subgroup G1r consists of, from the object side to the image side, five lenses, lenses L13 to L17. The second lens group G2 consists of, from the object side to the image side, three lenses, lenses L21 to L23. When focusing from an object at infinity to an object at a close distance, the first lens group G1 moves along the optical axis Z toward the object side, and the second lens group G2 is fixed relative to the image plane Sim.

[0112] 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 aberration diagrams are shown in FIG.

[0113] [Table 7]

[0114] [Table 8]

[0115] [Table 9]

[0116] [Example 4] FIG. 11 shows a cross-sectional view of the configuration of the imaging lens of Example 4. The imaging lens of Example 4 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power and a second lens group G2 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, a front subgroup G1f having positive refractive power, an aperture stop St, and a rear subgroup G1r having positive refractive power. The front subgroup G1f comprises, in order from the object side to the image side, two lenses, lenses L11 and L12. The rear subgroup G1r comprises, in order from the object side to the image side, five lenses, lenses L13 to L17. The second lens group G2 comprises, in order from the object side to the image side, three lenses, lenses L21 to L23. When focusing from an object at infinity to an object at a close distance, the first lens group G1 moves along the optical axis Z toward the object side, and the second lens group G2 is fixed relative to the image plane Sim.

[0117] 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 each aberration diagram is shown in FIG.

[0118] [Table 10]

[0119] [Table 11]

[0120] [Table 12]

[0121] [Example 5] A cross-sectional view of the configuration of the imaging lens of Example 5 is shown in Figure 13. The imaging lens of Example 5 consists of, from the object side to the image side, a first lens group G1 having positive refractive power and a second lens group G2 having negative refractive power. The first lens group G1 consists, from the object side to the image side, of a front subgroup G1f having positive refractive power, an aperture stop St, and a rear subgroup G1r having positive refractive power. The front subgroup G1f consists, from the object side to the image side, of two lenses, lenses L11 and L12. The rear subgroup G1r consists, from the object side to the image side, of five lenses, lenses L13 to L17. The second lens group G2 consists, from the object side to the image side, of three lenses, lenses L21 to L23. When focusing from an object at infinity to an object at a close distance, the first lens group G1 moves along the optical axis Z toward the object side, and the second lens group G2 is fixed relative to the image plane Sim.

[0122] For the imaging lens of Example 5, basic lens data is shown in Table 13, specifications and variable surface spacing are shown in Table 14, aspherical coefficients are shown in Table 15, and each aberration diagram is shown in FIG.

[0123] [Table 13]

[0124] [Table 14]

[0125] [Table 15]

[0126] [Example 6] A cross-sectional view of the configuration of the imaging lens of Example 6 is shown in Figure 15. The imaging lens of Example 6 consists of, from the object side to the image side, a first lens group G1 having positive refractive power and a second lens group G2 having negative refractive power. The first lens group G1 consists, from the object side to the image side, of a front subgroup G1f having positive refractive power, an aperture stop St, and a rear subgroup G1r having positive refractive power. The front subgroup G1f consists, from the object side to the image side, of two lenses, lenses L11 and L12. The rear subgroup G1r consists, from the object side to the image side, of four lenses, lenses L13 to L16. The second lens group G2 consists, from the object side to the image side, of three lenses, lenses L21 to L23. When focusing from an object at infinity to an object at a close distance, the first lens group G1 moves along the optical axis Z toward the object side, and the second lens group G2 is fixed relative to the image plane Sim.

[0127] For the imaging lens of Example 6, basic lens data is shown in Table 16, specifications and variable surface spacing are shown in Table 17, aspherical coefficients are shown in Table 18, and each aberration diagram is shown in FIG.

[0128] [Table 16]

[0129] [Table 17]

[0130] [Table 18]

[0131] [Example 7] A cross-sectional view of the configuration of the imaging lens of Example 7 is shown in Figure 17. The imaging lens of Example 7 consists of, from the object side to the image side, a first lens group G1 having positive refractive power and a second lens group G2 having negative refractive power. The first lens group G1 consists, from the object side to the image side, of a front subgroup G1f having positive refractive power, an aperture stop St, and a rear subgroup G1r having positive refractive power. The front subgroup G1f consists, from the object side to the image side, of two lenses, lenses L11 and L12. The rear subgroup G1r consists, from the object side to the image side, of six lenses, lenses L13 to L18. The second lens group G2 consists, from the object side to the image side, of three lenses, lenses L21 to L23. When focusing from an object at infinity to an object at a close distance, the first lens group G1 moves along the optical axis Z toward the object side, and the second lens group G2 is fixed relative to the image plane Sim.

[0132] 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.

[0133] [Table 19]

[0134] [Table 20]

[0135] [Table 21]

[0136] Table 22 shows the corresponding values ​​of conditional expressions (1) to (15) and (17) for the imaging lenses of Examples 1 to 7. The imaging lenses of Examples 1 to 7 satisfy conditional expressions (1) to (15) and (17). The imaging lenses of Examples 1 to 7 have a feature that satisfies conditional expression (16). The corresponding values ​​of the Examples shown in Table 22 may be used as the upper or lower limits of the conditional expressions to set preferred ranges for the conditional expressions.

[0137] [Table 22]

[0138] Next, an imaging device according to an embodiment of the present disclosure will be described. Fig. 19 and Fig. 20 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure. Fig. 19 shows a perspective view of the camera 30 as seen from the front side, and Fig. 20 shows a perspective view of the camera 30 as seen from the rear side. As an example, the camera 30 is a digital camera. The camera 30 includes an imaging lens 1 according to an embodiment of the present disclosure and a camera body 31 configured integrally with the imaging lens 1.

[0139] 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.

[0140] 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 imaging lens 1. 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.

[0141] 21 shows a perspective view of a camera 800, which is an imaging device according to another embodiment of the present disclosure. As an example, the camera 800 is a so-called mirrorless digital camera. The camera 800 includes a camera body 831 and an interchangeable lens 820 that is removably attached to the camera body 831. An imaging lens 801 according to an embodiment of the present disclosure is housed inside the interchangeable lens 820.

[0142] A shutter button 832 and a power button 833 are provided on the top surface of camera body 831. A photographic opening through which light from a subject enters is provided in the center of the front surface of camera body 831, and a mount 837 is provided at a position corresponding to the photographic opening, and interchangeable lens 820 is attached to camera body 831 via mount 837.

[0143] An imaging element 838 is provided within the camera body 831. The imaging element 838 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 820. For example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) is used as the imaging element 838. A signal processing circuit (not shown), a recording medium (not shown), and the like are provided within the camera body 831. The signal processing circuit processes the imaging signal output from the imaging element 838 to generate an image. The recording medium is for recording the generated image. With the camera 800, it is possible to take a still image or a video by pressing the shutter button 832, and the image data obtained by this shooting is recorded on the recording medium.

[0144] 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.

[0145] 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.

[0146] The following additional notes are provided regarding the above embodiments and examples. [Appendix 1] The lens comprises, in order from the object side to the image side, a first lens group and a second lens group, During focusing, the first lens group moves along the optical axis, and the second lens group is fixed relative to an image plane; the lens closest to the object side in the first lens group is a negative lens; TL is the sum of 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 second lens group closest to the image when focused on an object at infinity, and the back focus in air equivalent distance of the entire system; The focal length of the entire system when focused on an object at infinity is f. When the maximum half angle of view when focused on an object at infinity is ω, 1.3 <TL / (f×tanω)<2.1 (1) An imaging lens that satisfies conditional expression (1) expressed as follows: [Appendix 2] 10. The imaging lens according to claim 1, wherein the total number of lens elements included in the imaging lens is 7 or more and 11 or less. [Appendix 3] When the back focus of the entire system in air equivalent distance when focused on an object at infinity is Bf, 0.08 <Bf / f<0.3 (2) The imaging lens according to claim 1 or 2, which satisfies conditional expression (2) expressed by: [Appendix 4] If the open F-number when focused on an object at infinity is FNo, 4.3 <FNo×(TL / f)<6.4 (3) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 3, which satisfies conditional expression (3) expressed as follows: [Appendix 5] When the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the first lens group closest to the image side is dG1, 0.45 <dG1 / (f×tanω)<1 (4) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 4, which satisfies conditional expression (4) expressed by the following formula: [Appendix 6] When the lens surface of the first lens group closest to the image side to the lens surface of the second lens group closest to the object side is dF, 0.05 <dF / (f×tanω)<0.32 (5) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 5, which satisfies conditional expression (5) shown below. [Appendix 7] the first lens group comprises, in order from the object side to the image side, a front subgroup, a stop, and a rear subgroup; The focal length of the front subgroup is fG1f, If the focal length of the first lens group is fG1, then 1.8 <fG1f / fG1<8 (6) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 6, which satisfies conditional expression (6) shown below. [Appendix 8] 1.3 <fG1f / f<5 (7) The imaging lens according to claim 7, which satisfies conditional expression (7) shown below. [Appendix 9] If the focal length of the second lens group is fG2, then -2.5 <fG2 / f<-0.4 (8) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 8, which satisfies conditional expression (8) shown below. [Appendix 10] If the focal length of the first lens group is fG1, then 0.4 <fG1 / f<0.95 (9) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 9, which satisfies conditional expression (9) shown below. [Appendix 11] The lateral magnification of the first lens group when focused on an object at infinity is βG1, When the lateral magnification of the second lens group in a state focused on an object at infinity is βG2, 1.4<(1-βG1 2 )×βG2 2 <3.2 (10) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 10, which satisfies conditional expression (10) shown below. [Appendix 12] the first lens group comprises, in order from the object side to the image side, a front subgroup, a stop, and a rear subgroup; The average value of the refractive index for the d-line of all the positive lenses included in the rear subgroup is set to NG1rpa, The average value of the Abbe numbers based on the d-line of all the positive lenses included in the rear subgroup is νG1rpa, When the average value of the partial dispersion ratio between the g-line and the F-line of all the positive lenses included in the rear subgroup is θG1rpa, 1.6 <NG1rpa<1.86 (11) 0.65<θG1rpa+0.0025×νG1rpa<0.72 (12) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 11, which satisfies conditional expressions (11) and (12) expressed by the following formulas: [Appendix 13] the second lens group includes only one positive lens, The focal length of the positive lens in the second lens group is fG2p, If the focal length of the second lens group is fG2, then -4 <fG2p / fG2<-1 (13) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 12, which satisfies conditional expression (13) represented by the following: [Appendix 14] The refractive index of the positive lens in the second lens group with respect to the d-line is NG2p, νG2p is the Abbe number of the positive lens in the second lens group based on the d-line; When the partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group is θG2p, 1.88 <NG2p<1.96 (14) 0.67<θG2p+0.0025×νG2p<0.705 (15) The imaging lens according to claim 13, which satisfies conditional expressions (14) and (15) expressed by the following formula: [Appendix 15] The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 14, wherein the lens in the first lens group arranged closest to the image side is a first aspherical lens having positive refractive power. [Appendix 16] the second lens group includes a second aspherical lens; The height from the optical axis of the position of the maximum effective diameter on the image side surface of the second aspherical lens is hE2, Let h be an arbitrary height from the optical axis. Sg2(h) is the amount of sag at each point on the image-side surface of the second aspherical lens at a height h, The second derivative of Sg2(h) with respect to h is d 2 Sg2(h) / dh 2 In this case, In the range of 0.5×hE2≦h≦hE2 on the image-side surface of the second aspherical lens |d 2 Sg2(h) / dh 2 |>2×|d 2 Sg2(h / 2) / dh 2 | (16) 16. The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 15, wherein there exists a point that satisfies conditional expression (16) expressed as follows: [Appendix 17] The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 16, wherein the object-side surface of the negative lens closest to the object side in the first lens group is a concave surface. [Appendix 18] 18. The imaging lens according to claim 1, wherein the first lens group includes a diaphragm and a single lens having positive refractive power that is arranged adjacent to the diaphragm on the image side. [Appendix 19] The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 18, wherein the second lens group is composed of, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens. [Appendix 20] An imaging device comprising the imaging lens according to any one of Supplementary Note 1 to Supplementary Note 19. [Explanation of symbols]

[0147] 1 Imaging lens 2 On-axis luminous flux 3 Luminous flux 30 Camera 31 Camera Body 32 Shutter button 33 Power button 34 Control section 35 Control section 36 Display section 38 Image sensor 800 cameras 801 Imaging Lens 820 Interchangeable Lens 831 Camera Body 832 shutter button 833 Power button 837 Mount 838 Image sensor Bf Back Focus Er effective radius dF distance dG1 distance G1 First lens group G1f anterior subgroup G1r posterior subgroup G2 Second lens group ha height hb height hE1 Height hE2 Height L11~L23 lenses Lx Lens Px Position of maximum effective diameter Sg1(ha) Sag amount Sg2(hb) Sag amount Sim image plane St aperture stop TL optical total length Xa On-axis luminous flux Xb Off-axis luminous flux Xb1 ray Z optical axis ω Maximum half angle of view

Claims

1. The lens comprises, in order from the object side to the image side, a first lens group and a second lens group, During focusing, the first lens group moves along the optical axis, and the second lens group is fixed relative to an image plane; the lens closest to the object side in the first lens group is a negative lens; TL is the sum of 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 second lens group closest to the image when focused on an object at infinity, and the back focus in terms of the air equivalent distance of the entire system; The focal length of the entire system when focused on an object at infinity is f. When the maximum half angle of view when focused on an object at infinity is ω, 1.3<TL / (f×tanω)<2.1 (1) An imaging lens that satisfies conditional expression (1) expressed as follows.

2. 2. The imaging lens according to claim 1, wherein the total number of lenses included in the imaging lens is 7 or more and 11 or less.

3. When the back focus of the entire system in the air equivalent distance in a state where the lens is focused on an object at infinity is Bf, 0.08<Bf / f<0.3 (2) 2. The imaging lens according to claim 1, which satisfies conditional expression (2) expressed as follows:

4. When the open F-number when focused on an object at infinity is FNo, 4.3<FNo×(TL / f)<6.4 (3) 2. The imaging lens according to claim 1, which satisfies conditional expression (3) expressed as follows:

5. When the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the first lens group closest to the image side is dG1, 0.45<dG1 / (f×tanω)<1 (4) 2. The imaging lens according to claim 1, which satisfies conditional expression (4) expressed as follows:

6. When the lens surface of the first lens group closest to the image side to the lens surface of the second lens group closest to the object side is dF, 0.05<dF / (f×tanω)<0.32 (5) 2. The imaging lens according to claim 1, which satisfies conditional expression (5) expressed as follows:

7. the first lens group comprises, in order from the object side to the image side, a front subgroup, a stop, and a rear subgroup; The focal length of the front subgroup is fG1f, When the focal length of the first lens group is fG1, 1.8<fG1f / fG1<8 (6) 2. The imaging lens according to claim 1, which satisfies conditional expression (6) expressed as follows:

8. 1.3<fG1f / f<5 (7) 8. The imaging lens according to claim 7, which satisfies conditional expression (7) expressed as follows:

9. When the focal length of the second lens group is fG2, -2.5<fG2 / f<-0.4 (8) 2. The imaging lens according to claim 1, which satisfies conditional expression (8) expressed as follows:

10. When the focal length of the first lens group is fG1, 0.4<fG1 / f<0.95 (9) 2. The imaging lens according to claim 1, which satisfies conditional expression (9) expressed as follows:

11. The lateral magnification of the first lens group when focused on an object at infinity is βG1, When the lateral magnification of the second lens group in a state where the lens is focused on an object at infinity is βG2, 1.4<(1-βG1) ２ )×βG2 ２ <3.2 (10) 2. The imaging lens according to claim 1, which satisfies conditional expression (10) expressed as follows:

12. the first lens group comprises, in order from the object side to the image side, a front subgroup, a stop, and a rear subgroup; the average value of the refractive index for the d-line of all the positive lenses included in the rear subgroup is NG1rpa, The average value of the Abbe numbers based on the d-line of all the positive lenses included in the rear subgroup is νG1rpa, When the average value of the partial dispersion ratio between the g-line and the F-line of all the positive lenses included in the rear subgroup is θG1rpa, 1.6<NG1rpa<1.86 (11) 0.65<θG1rpa+0.0025×νG1rpa<0.72 (12) 2. The imaging lens according to claim 1, which satisfies conditional expressions (11) and (12) expressed as follows:

13. the second lens group includes only one positive lens, The focal length of the positive lens in the second lens group is fG2p, When the focal length of the second lens group is fG2, -4<fG2p / fG2<-1 (13) 2. The imaging lens according to claim 1, which satisfies conditional expression (13) expressed as follows:

14. The refractive index of the positive lens in the second lens group with respect to the d-line is NG2p, νG2p is the Abbe number of the positive lens in the second lens group based on the d-line; When the partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group is θG2p, 1.88<NG2p<1.96 (14) 0.67<θG2p+0.0025×νG2p<0.705 (15) 14. The imaging lens according to claim 13, which satisfies conditional expressions (14) and (15) expressed as follows:

15. 2. The imaging lens according to claim 1, wherein the lens in the first lens group arranged closest to the image side is a first aspherical lens having positive refractive power.

16. the second lens group includes a second aspherical lens; The height from the optical axis of the position of the maximum effective diameter on the image side surface of the second aspherical lens is hE2, Let h be an arbitrary height from the optical axis. The sag amount of each point on the image-side surface of the second aspherical lens at a height h is Sg2(h), The second derivative of Sg2(h) with respect to h is d ２ Sg2(h) / dh ２ In this case, In the range of 0.5×hE2≦h≦hE2 on the image side surface of the second aspherical lens |d ２ Sg2(h) / dh ２ |>2×|d ２ Sg2(h / 2) / d( ２ | (16) 2. The imaging lens according to claim 1, wherein there exists a point that satisfies conditional expression (16) expressed as follows:

17. 2. The imaging lens according to claim 1, wherein the object-side surface of the negative lens closest to the object side in the first lens group is a concave surface.

18. The imaging lens according to claim 1 , wherein the first lens group includes a stop and a single lens having positive refractive power arranged adjacent to the stop on the image side.

19. 2. The imaging lens according to claim 1, wherein the second lens group comprises, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens.

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

Images