Imaging lens and imaging apparatus

Abstract

To provide an imaging lens which has a small F number, is configured to be more compact, and in which aberration is satisfactorily corrected, and an imaging apparatus including the imaging lens.SOLUTION: The imaging lens consists of, in order from the object side to the image side, a first lens group, a second lens group, and a third lens group. During focusing, the first lens group and the third lens group are fixed with respect to an image plane, and the second lens group moves along an optical axis. A stop that is fixed with respect to an image plane during focusing is disposed on the object side of the second lens group. The first lens group includes, at a position closest to the object side, a first negative lens having a concave surface facing the 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 Lens systems described in Patent Documents 1 and 2 below are known as imaging lenses used in digital cameras and the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-148887 [Patent Document 2] Japanese Patent Application Publication No. 2020-177110 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for imaging lenses that have a small F-number, are more compact, and have well-corrected aberrations.

[0005] The present disclosure provides an imaging lens that has a small F-number, is configured to be more compact, and has well-corrected aberrations, 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 comprises, in order from the object side to the image side, a first lens group, a second lens group, and a third lens group, wherein, during focusing, the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group moves along the optical axis, and an aperture that is fixed with respect to the image plane during focusing is disposed closer to the object than the second lens group, and the first lens group includes a first negative lens whose image-side surface is concave, closest to the object, and the imaging lens comprises: 2 <TL / (f×tanωm)<5.5 (1) 4 <TL×FNo / f<7.5 (2) The conditional expressions (1) and (2) expressed as follows are 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 third lens group closest to the image when focused on an object at infinity, and the back focus of the entire system in air equivalent distance when focused on an object at infinity. f is the focal length of the entire system when focused on an object at infinity. ωm is the maximum half angle of view when focused on an object at infinity. FNo is the maximum F-number when focused on an object at infinity.

[0007] When the focal length of the second lens group is f2, the imaging lens of the above aspect has the following characteristics: 0.2 <f / |f2|<3 (3) It is preferable to satisfy conditional expression (3) below.

[0008] When the distance on the optical axis from the lens surface closest to the object side of the imaging lens to the paraxial entrance pupil position in a state where the imaging lens is focused on an object at infinity is denoted as Enp, the imaging lens of the above aspect satisfies the following conditions: 1.5 <f / Enp<6 (4) It is preferable to satisfy conditional expression (4) below.

[0009] In a configuration in which at least one of the first negative lens in the first lens group and the lens arranged adjacent to the image side of the first negative lens includes an aspheric surface, when the air gap on the optical axis between the first negative lens in the first lens group and the lens arranged adjacent to the image side of the first negative lens is set to DL12, the imaging lens of the above aspect has the following characteristics: 0.015 <DL12 / TL<0.25 (5) It is preferable to satisfy conditional expression (5) below.

[0010] In a configuration in which a positive lens is disposed adjacent to the object side of the aperture stop, when the refractive index of the positive lens disposed adjacent to the object side of the aperture stop with respect to the d-line is Nsf, the imaging lens of the above aspect satisfies the following conditions: 1.7 <Nsf<2.2 (6) It is preferable to satisfy conditional expression (6) below.

[0011] When the lateral magnification of the second lens group when focused on an object at infinity is β2, and the lateral magnification of the third lens group when focused on an object at infinity is β3, the imaging lens of the above aspect has the following relationship: 0.8<|(1-β2 2 )×β3 2 |<5 (7) It is preferable to satisfy conditional expression (7) below.

[0012] The first lens group preferably includes at least two negative lenses and at least one positive lens.

[0013] When the average value of the refractive index for the d-line of all the negative lenses included in the first lens group is N1nave, the imaging lens of the above aspect has the following: 1.555 <N1nave<1.9 (8) It is preferable to satisfy conditional expression (8) below.

[0014] 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, the imaging lens of the above aspect has the following characteristics: 0.4 <Bf / (f×tanωm)<2.5 (9) It is preferable to satisfy conditional expression (9) below.

[0015] When the thickness of the second lens group on the optical axis is DG2, the imaging lens of the above aspect has the following characteristics: 0.01 <DG2 / TL<0.4 (10) It is preferable to satisfy conditional expression (10) below.

[0016] When the maximum value of the refractive index for the d-line of all lenses included in the imaging lens is set to Nmax, the imaging lens of the above aspect has the following properties: 1.8 <Nmax<2.2 (11) It is preferable to satisfy conditional expression (11) below.

[0017] When the average value of the refractive index for the d-line of all the positive lenses included in the imaging lens is Npave, the imaging lens of the above aspect has the following: 1.64 <Npave<1.88 (12) It is preferable to satisfy conditional expression (12) below.

[0018] When the focal length of the first negative lens in the first lens group is fL1, the imaging lens of the above aspect has the following characteristics: -2 <f / fL1<-0.45 (13) It is preferable to satisfy conditional expression (13) below.

[0019] Let Exp be the distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity, and the sign of Exp be negative when the distance from the image plane toward the object side, and positive when the distance from the object side toward the image side, with the image plane as the reference. If an optical element without refractive power is disposed between the image plane and the paraxial exit pupil position, and Exp is calculated using the air-equivalent distance for that optical element, then the imaging lens of the above aspect will be as follows: -5 <Exp / (f×tanωm)<-1.4 (14) It is preferable to satisfy conditional expression (14) below.

[0020] In a configuration in which the second lens group has positive refractive power and the third lens group has negative refractive power, when the focal length of the first lens group is f1, the imaging lens of the above aspect has the following characteristics: -1.5 <f / f1<1.5 (15) It is preferable to satisfy conditional expression (15) below.

[0021] In a configuration in which the second lens group has positive refractive power and the third lens group has negative refractive power, if the focal length of the second lens group is f2 and the focal length of the third lens group is f3, the imaging lens of the above aspect has the following characteristics: -1.1 <f2 / f3<-0.07 (16) It is preferable to satisfy conditional expression (16) below.

[0022] In a configuration in which the second lens group has positive refractive power and the third lens group has negative refractive power, when the focal length of the third lens group is f3, the imaging lens of the above aspect has the following characteristics: -1.1 <f / f3<-0.03 (17) It is preferable to satisfy conditional expression (17) below.

[0023] In a configuration in which the second lens group has negative refractive power and the third lens group has positive refractive power, when the focal length of the first lens group is f1, the imaging lens of the above aspect has the following characteristics: 1 <f / f1<3 (15A) It is preferable to satisfy conditional formula (15A) below.

[0024] In a configuration in which the second lens group has negative refractive power and the third lens group has positive refractive power, when the focal length of the third lens group is f3, the imaging lens of the above aspect has the following characteristics: 0.1 <f / f3<0.7 (17A) It is preferable to satisfy conditional formula (17A) below.

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

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

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

[0028] A hybrid aspherical lens (a lens in which a lens (e.g., a spherical lens) and an aspherical film formed on that lens are integrally constructed, functioning as a single aspherical lens overall) is not considered a cemented lens, but is treated as a single lens. Unless otherwise specified, the radius of curvature, sign of refractive power, and surface shape of lenses including aspherical surfaces are those in the paraxial region. The sign of the radius of curvature 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.

[0029] In this specification, "total system" refers to "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.

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

[0031] According to the present disclosure, it is possible to provide an imaging lens that has a small F-number, is configured to be more compact, and has aberrations corrected well, and an imaging device that includes this imaging lens. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view showing the configuration of an imaging lens according to one embodiment, corresponding to the imaging lens of Example 1. FIG. [Figure 2] 2A to 2C are cross-sectional views showing the configuration and light beams in each state of the imaging lens of FIG. 1. [Figure 3] FIG. 10 is a diagram for explaining symbols in a conditional expression. [Figure 4] 3A to 3C are diagrams showing various aberrations 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 various aberrations of the imaging lens of Example 2. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a third embodiment. [Figure 8] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 3. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fourth embodiment. [Figure 10] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 4. [Figure 11] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fifth embodiment. [Figure 12] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 5. [Figure 13] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a sixth embodiment. [Figure 14] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 6. [Figure 15] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a seventh embodiment. [Figure 16] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 7. [Figure 17] FIG. 13 is a cross-sectional view showing the configuration of an imaging lens according to an eighth embodiment. [Figure 18] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 8. [Figure 19] FIG. 13 is a cross-sectional view showing the configuration of an imaging lens according to a ninth embodiment. [Figure 20] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 9. [Figure 21] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to a tenth embodiment. [Figure 22] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 10. [Figure 23] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to an eleventh embodiment. [Figure 24] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 11. [Figure 25] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to a twelfth embodiment. [Figure 26] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 12. [Figure 27] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens of Example 13. [Figure 28] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 13. [Figure 29] 1 is a perspective view of the front side of an imaging device according to an embodiment. [Figure 30] 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 technology of the present disclosure will be described with reference to the drawings.

[0034] FIG. 1 shows a cross-sectional view of the configuration of an imaging lens according to an embodiment of the present disclosure when focused on an object at infinity. FIG. 2 shows cross-sectional views of the configuration and light beams in each focus state of the imaging lens of FIG. 1. In FIG. 2, the upper row labeled "infinity" shows the state when focused on an object at infinity, and the lower row labeled "close" shows the state when focused on a close object. FIG. 2 shows the axial light beam 2 and the light beam 3 at the maximum half angle of view ωm when focused on an object at infinity, as well as the axial light beam and the light beam at the maximum half angle of view ωm when focused on a close object. In FIGS. 1 and 2, the left side is the object side, and the right side is the image side. The example shown in FIGS. 1 and 2 corresponds to the imaging lens of Example 1, which will be described later. The following description will mainly refer to FIG. 1.

[0035] FIG. 1 shows an example in which a parallel-plate 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. The various filters are low-pass filters, infrared cut filters, and / or filters that cut off specific wavelength ranges. 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 the present disclosure comprises, in order from the object side to the image side along the optical axis Z, a first lens group G1, a second lens group G2, and a third lens group G3. During focusing, the second lens group G2 moves along the optical axis Z, while the first lens group G1 and the third lens group G3 are fixed relative to the image plane Sim. By fixing the first lens group G1 during focusing, the overall length does not change even during focusing, which prevents the lens from getting too close to the subject during close-up photography, resulting in a highly convenient lens system. Furthermore, fixing the first lens group G1 and the third lens group G3 during focusing is advantageous for a dustproof and drip-proof structure.

[0037] As an example, each group of the imaging lens in FIG. 1 is configured as follows: The first lens group G1 consists, in order from the object side to the image side, of lenses L11 to L13, an aperture stop St, and a lens L14. The second lens group G2 consists, in order from the object side to the image side, of five lenses, lenses L21 to L25. The third lens group G3 consists of a single lens, lens L31. Note that the aperture stop St in FIG. 1 does not indicate its size or shape, but its position along the optical axis.

[0038] In this specification, a group that moves along the optical axis Z during focusing is referred to as the "focusing group." In the imaging lens of the present disclosure, the focusing group consists solely of the second lens group G2. In FIG. 1, a horizontal arrow is shown below the focusing group to indicate the direction in which the second lens group G2 moves during focusing from an object at infinity to a close object. The parentheses and left-pointing arrow below the second lens group G2 in FIG. 1 indicate that the second lens group G2 is the focusing group and that the second lens group G2 moves toward the object during focusing from an object at infinity to a close object.

[0039] In the imaging lens of the present disclosure, an aperture stop that is fixed relative to the image plane Sim during focusing is located closer to the object than the second lens group G2. By configuring the focusing group so that it does not include an aperture stop, the focusing group can be made lighter, which is advantageous for faster focusing and for reducing the size of the entire lens apparatus. In the example of Figure 1, an aperture stop St is located in the first lens group G1 as an aperture stop.

[0040] In the imaging lens of the present disclosure, the first lens group G1 includes a first negative lens whose image-side surface is concave and closest to the object. This configuration makes it possible to suppress the occurrence of astigmatism. In the example of Figure 1, the lens L11 corresponds to the first negative lens.

[0041] It is preferable that the object-side surface of the first negative lens is a convex surface, which is advantageous for correcting astigmatism, which tends to occur when the angle of view is widened.

[0042] It is preferable that at least one of the first negative lens and the lens disposed adjacent to the image side of the first negative lens includes an aspheric surface, which is advantageous for correcting field curvature.

[0043] The air lens closest to the object side of the imaging lens preferably has a biconvex shape. For example, in the case of a single lens in which the first negative lens is not cemented as in the example of Figure 1, the air gap between the image-side surface of the first negative lens and the object-side surface of the lens arranged adjacent to the image side of the first negative lens preferably has a biconvex shape. This is advantageous for correcting distortion and field curvature.

[0044] It is preferable that the first lens group G1 includes at least two negative lenses and at least one positive lens, which is advantageous for correcting chromatic aberration of magnification and reducing the F-number.

[0045] The first lens group G1 may be configured to include seven or fewer lenses. This is advantageous for effectively correcting lateral chromatic aberration without increasing the size of the lens system. If it is desired to further suppress an increase in the size of the lens system, the first lens group G1 preferably includes six or fewer lenses, more preferably five or fewer lenses, and even more preferably four or fewer lenses.

[0046] It is preferable that the second lens group G2 includes at least one negative lens, which is advantageous for correcting spherical aberration.

[0047] If the second lens group G2 has negative refractive power and the third lens group G3 has positive refractive power, the second lens group G2 may be configured to consist of a single negative lens, which is advantageous for increasing the focusing speed because it allows the focusing group to be lighter.

[0048] The second lens group G2 may be configured to include seven or fewer lenses. This is advantageous for suppressing aberration fluctuations during focusing without increasing the size of the lens system. If it is desired to further suppress an increase in the size of the lens system, the second lens group G2 preferably includes six or fewer lenses, more preferably five or fewer lenses, and even more preferably four or fewer lenses.

[0049] The third lens group G3 may be configured to include four or fewer lenses. This is advantageous for reducing weight because it allows for a reduction in the number of lenses that are close to the image plane Sim and have a relatively large outer diameter. To achieve even greater weight reduction, it is more preferable that the third lens group G3 include three or fewer lenses, and even more preferably two or fewer lenses.

[0050] At least one of the second lens group G2 and the third lens group G3 may be configured to include an aspherical lens surface having an inflection point where the concave-convex shape changes midway from the optical axis toward the periphery. In this way, locating an aspherical surface at a position where an off-axis light beam is separated and further providing this aspherical surface with an inflection point is advantageous for correcting astigmatism.

[0051] The "inflection point" is the point where the surface shape changes from convex to concave or from concave to convex, i.e., the point where the sign of the radius of curvature changes. Having an inflection point on a lens surface is advantageous for aberration correction because it allows the refractive power of the peripheral part of the lens to be determined independently of the refractive power of the paraxial region.

[0052] The imaging lens may be configured so that the total number of lenses included is seven or more. This is advantageous for good correction of chromatic aberration of magnification and spherical aberration. To obtain better characteristics, the total number of lenses included in the imaging lens is more preferably eight or more, and even more preferably nine or more.

[0053] The imaging lens may be configured so that the number of lenses included in the entire system is 13 or less. This is advantageous in preventing the entire lens system from becoming too large. To further prevent the entire lens system from becoming too large, the imaging lens should preferably have 12 or less lenses, and even more preferably have 11 or less lenses.

[0054] Below, a description is given of a preferred configuration of the imaging lens of the present disclosure with respect to the conditional expressions. In the following description 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."

[0055] It is preferable that the imaging lens satisfy the following conditional expression (1). Here, TL is the sum of 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 third lens group G3 closest to the image when the lens is focused on an object at infinity, and the back focus of the entire system in terms of air equivalent distance. f is the focal length of the entire system when the lens is focused on an object at infinity. ωm is the maximum half angle of view when the lens is focused on an object at infinity. ωm is measured in degrees. As an example, Figure 2 shows the above maximum half angle of view ωm. Ensuring that the value corresponding to conditional expression (1) does not become equal to or smaller than the lower limit is advantageous for maintaining high optical performance. Ensuring that the value corresponding to conditional expression (1) does not become equal to or larger than the upper limit is advantageous for shortening the overall length of the lens system. 2 <TL / (f×tanωm)<5.5 (1)

[0056] In order to obtain better characteristics, the lower limit of conditional formula (1) is more preferably 2.2, even more preferably 2.3, even more preferably 2.4, and even more preferably 2.5.In order to obtain better characteristics, the upper limit of conditional formula (1) is more preferably 5, even more preferably 4, even more preferably 3.6, and even more preferably 3.5.

[0057] 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 (2). By ensuring that the corresponding value of conditional expression (2) is not below the lower limit, it becomes easy to arrange the optimum number of lenses to correct various aberrations, and therefore it becomes easy to obtain higher imaging performance. By ensuring that the corresponding value of conditional expression (2) is not above the upper limit, it is advantageous to prevent the entire lens system from becoming large, and also advantageous to reduce the F-number. 4 <TL×FNo / f<7.5 (2)

[0058] In order to obtain better characteristics, the lower limit of conditional expression (2) should preferably be set to 4.3, more preferably 4.6, and even more preferably 4.8.In order to obtain better characteristics, the upper limit of conditional expression (2) should preferably be set to 7, more preferably 6.5, and even more preferably 6.

[0059] When the focal length of the second lens group G2 is f2, it is preferable that the imaging lens satisfy the following conditional expression (3). By ensuring that the corresponding value of conditional expression (3) is not below the lower limit, the amount of movement of the second lens group G2 during focusing can be shortened, which is advantageous for shortening the overall length of the lens system. By ensuring that the corresponding value of conditional expression (3) is not above the upper limit, fluctuations in spherical aberration and field curvature during focusing can be suppressed. 0.2 <f / |f2|<3 (3)

[0060] In order to obtain better characteristics, the lower limit of conditional expression (3) is more preferably 0.25, even more preferably 0.3, even more preferably 0.4, even more preferably 0.45, and even more preferably 0.5. In order to obtain better characteristics, the upper limit of conditional expression (3) is more preferably 2.5, even more preferably 2, even more preferably 1.8, even more preferably 1.5, and even more preferably 1.3.

[0061] It is preferable that the imaging lens satisfy the following conditional expression (4). Here, Enp is the distance on the optical axis from the lens surface closest to the object to the paraxial entrance pupil position when the imaging lens is focused on an object at infinity. FIG. 3 shows the imaging lens of FIG. 1 when focused on an object at infinity, and shows the above-mentioned distance Enp as an example. Ensuring that the value corresponding to conditional expression (4) is not equal to or smaller than the lower limit is advantageous for reducing the diameter of the object-side components in the lens system. Ensuring that the value corresponding to conditional expression (4) is not equal to or larger than the upper limit facilitates separation of axial rays and off-axial rays in the object-side lens in the lens system, which is advantageous for correcting various aberrations related to off-axial rays. 1.5 <f / Enp<6 (4)

[0062] In order to obtain better characteristics, the lower limit of conditional expression (4) should preferably be 1.8, more preferably 2, even more preferably 2.2, even more preferably 2.5, and even more preferably 2.6. In order to obtain better characteristics, the upper limit of conditional expression (4) should preferably be 5, even more preferably 4.5, even more preferably 4, even more preferably 3.8, and even more preferably 3.6.

[0063] In a configuration in which at least one of the first negative lens in the first lens group G1 and the lens arranged adjacent to the image side of the first negative lens includes an aspheric surface, it is preferable that the imaging lens satisfy the following conditional expression (5). Here, the air distance on the optical axis between the first negative lens in the first lens group G1 and the lens arranged adjacent to the image side of the first negative lens is designated DL12. As an example, FIG. 3 shows the above air distance DL12. Ensuring that the corresponding value of conditional expression (5) is not equal to or less than the lower limit is advantageous for correcting distortion. Ensuring that the corresponding value of conditional expression (5) is not equal to or greater than the upper limit is advantageous for preventing the diameter of the object-side lens in the lens system from becoming large. 0.015 <DL12 / TL<0.25 (5)

[0064] In order to obtain better characteristics, the lower limit of conditional expression (5) should preferably be set to 0.02, more preferably 0.03, even more preferably 0.04, and even more preferably 0.05.In order to obtain better characteristics, the upper limit of conditional expression (5) should preferably be set to 0.2, more preferably 0.15, even more preferably 0.12, and even more preferably 0.1.

[0065] In a configuration in which a positive lens is disposed adjacent to the object side of the aperture stop St, it is preferable that the imaging lens satisfy the following conditional expression (6). Here, the refractive index for the d-line of the positive lens disposed adjacent to the object side of the aperture stop St is Nsf. Ensuring that the corresponding value of conditional expression (6) is not equal to or less than the lower limit thereof is advantageous for shortening the overall length. Ensuring that the corresponding value of conditional expression (6) is not equal to or greater than the upper limit thereof is advantageous for correcting spherical aberration. 1.7 <Nsf<2.2 (6)

[0066] In order to obtain better characteristics, the lower limit of conditional expression (6) should preferably be set to 1.73, more preferably 1.75, and even more preferably 1.78.In order to obtain better characteristics, the upper limit of conditional expression (6) should preferably be set to 2.15, more preferably 2.1, and even more preferably 2.06.

[0067] It is preferable that the imaging lens satisfy the following conditional expression (7). Here, the lateral magnification of the second lens group G2 when focused on an object at infinity is defined as β2. The lateral magnification of the third lens group G3 when focused on an object at infinity is defined as β3. By ensuring that the corresponding value of conditional expression (7) is not equal to or less than the lower limit, the amount of movement of the second lens group G2 during focusing can be shortened, which is advantageous for shortening the overall length of the lens system. By ensuring that the corresponding value of conditional expression (7) is not equal to or greater than the upper limit, fluctuations in spherical aberration and field curvature during focusing can be suppressed. 0.8<|(1-β2 2 )×β3 2 |<5 (7)

[0068] In order to obtain better characteristics, the lower limit of conditional expression (7) should preferably be set to 0.85, more preferably 0.9, even more preferably 0.93, even more preferably 0.95, and even more preferably 0.98. In order to obtain better characteristics, the upper limit of conditional expression (7) should preferably be set to 4.5, even more preferably 4.3, even more preferably 4, even more preferably 3.5, and even more preferably 3.3.

[0069] When the average value of the refractive index for the d-line of all negative lenses included in the first lens group G1 is N1nave, it is preferable that the imaging lens satisfy the following conditional expression (8). Making sure that the corresponding value of conditional expression (8) is not equal to or smaller than the lower limit value is advantageous for correcting spherical aberration. Making sure that the corresponding value of conditional expression (8) is not equal to or larger than the upper limit value is advantageous for correcting field curvature. 1.555 <N1nave<1.9 (8)

[0070] In order to obtain better characteristics, the lower limit of conditional expression (8) should preferably be set to 1.56, more preferably 1.565, and even more preferably 1.57.In order to obtain better characteristics, the upper limit of conditional expression (8) should preferably be set to 1.88, more preferably 1.86, and even more preferably 1.84.

[0071] If the back focal length of the entire system at the air-equivalent distance when focused on an object at infinity is Bf, it is preferable that the imaging lens satisfy the following conditional expression (9). Ensuring that the corresponding value of conditional expression (9) is not equal to or less than the lower limit thereof is advantageous in preventing the diameter of the lens located on the image side of the lens system from increasing. Ensuring that the corresponding value of conditional expression (9) is not equal to or greater than the upper limit thereof is advantageous in shortening the overall length of the lens system. 0.4 <Bf / (f×tanωm)<2.5 (9)

[0072] In order to obtain better characteristics, the lower limit of conditional expression (9) should preferably be set to 0.45, more preferably 0.48, even more preferably 0.5, even more preferably 0.52, and even more preferably 0.54.In order to obtain better characteristics, the upper limit of conditional expression (9) should preferably be set to 2, more preferably 1.8, even more preferably 1.5, even more preferably 1.2, and even more preferably 1.1.

[0073] If the axial thickness of the second lens group G2 is DG2, it is preferable that the imaging lens satisfy the following conditional expression (10). Note that the axial thickness of a certain group refers to the axial distance from the surface of that group closest to the object to the surface of that group closest to the image. As an example, FIG. 3 shows the above thickness DG2. By ensuring that the corresponding value of conditional expression (10) is not equal to or less than the lower limit, it is possible to suppress fluctuations in spherical aberration and field curvature during focusing. By ensuring that the corresponding value of conditional expression (10) is not equal to or greater than the upper limit, it is advantageous for shortening the overall length and reducing the weight. 0.01 <DG2 / TL<0.4 (10)

[0074] In order to obtain better characteristics, the lower limit of conditional expression (10) should preferably be set to 0.012, more preferably 0.014, and even more preferably 0.015.In order to obtain better characteristics, the upper limit of conditional expression (10) should preferably be set to 0.36, more preferably 0.34, and even more preferably 0.32.

[0075] When the maximum value of the refractive index for the d-line of all lenses included in the imaging lens is Nmax, it is preferable that the imaging lens satisfy the following conditional expression (11). Ensuring that the corresponding value of conditional expression (11) is not equal to or smaller than the lower limit thereof is advantageous for suppressing field curvature. Ensuring that the corresponding value of conditional expression (11) is not equal to or larger than the upper limit thereof is advantageous for suppressing error sensitivity of the surface shape. 1.8 <Nmax<2.2 (11)

[0076] In order to obtain better characteristics, the lower limit of conditional expression (11) should preferably be set to 1.82, more preferably 1.84, and even more preferably 1.85.In order to obtain better characteristics, the upper limit of conditional expression (11) should preferably be set to 2.1, more preferably 2.08, and even more preferably 2.06.

[0077] If the average value of the refractive indexes for the d-line of all positive lenses included in the imaging lens is Npave, it is preferable that the imaging lens satisfy the following conditional expression (12). By ensuring that the corresponding value of conditional expression (12) is not equal to or less than the lower limit, it becomes easy to reduce the absolute value of the Petzval sum of the entire lens system, which is advantageous for correcting field curvature. By ensuring that the corresponding value of conditional expression (12) is not equal to or greater than the upper limit, it becomes easy to reduce dispersion, which is advantageous for correcting axial chromatic aberration. 1.64 <Npave<1.88 (12)

[0078] In order to obtain better characteristics, the lower limit of conditional expression (12) should preferably be set to 1.65, more preferably 1.66, even more preferably 1.68, and even more preferably 1.7.In order to obtain better characteristics, the upper limit of conditional expression (12) should preferably be set to 1.85, more preferably 1.83, even more preferably 1.81, and even more preferably 1.8.

[0079] When the focal length of the first negative lens in the first lens group G1 is fL1, it is preferable that the imaging lens satisfy the following conditional expression (13). By ensuring that the corresponding value of conditional expression (13) is not equal to or less than the lower limit, the refractive power of the first negative lens does not become too strong, which is advantageous for correcting astigmatism. By ensuring that the corresponding value of conditional expression (13) is not equal to or greater than the upper limit, the refractive power of the first negative lens does not become too weak, which is advantageous for reducing the lens diameter. -2 <f / fL1<-0.45 (13)

[0080] In order to obtain better characteristics, the lower limit of conditional expression (13) should preferably be set to -1.5, more preferably to -1.3, and even more preferably to -1.25.In order to obtain better characteristics, the upper limit of conditional expression (13) should preferably be set to -0.48, more preferably to -0.5, and even more preferably to -0.52.

[0081] When the distance on the optical axis from the image plane Sim to the paraxial exit pupil position when focused on an object at infinity is Exp, the imaging lens preferably satisfies the following conditional expression (14). Note that the sign of Exp, with the image plane Sim as the reference, is negative for the distance from the image plane Sim toward the object side, and positive for the distance from the object side toward the image side. Furthermore, if an optical element without refractive power is disposed between the image plane Sim and the paraxial exit pupil position, Exp is calculated using the air-equivalent distance for that optical element. As an example, FIG. 3 schematically shows the distance Exp. In FIG. 3, a parallel-plate-like optical element without refractive power that should be calculated using the air-equivalent distance is indicated by a dashed line. Ensuring that the value corresponding to conditional expression (14) is not less than its lower limit is advantageous for shortening the overall length of the lens system. Ensuring that the value corresponding to conditional expression (14) is not less than its upper limit is advantageous for ensuring sufficient peripheral illumination. -5 <Exp / (f×tanωm)<-1.4 (14)

[0082] In order to obtain better characteristics, the lower limit of conditional expression (14) should preferably be set to -4.5, more preferably to -4.4, even more preferably to -4.2, and even more preferably to -4.1.In order to obtain better characteristics, the upper limit of conditional expression (14) should preferably be set to -1.5, even more preferably to -1.6, even more preferably to -1.7, and even more preferably to -1.8.

[0083] In a configuration in which the second lens group G2 has positive refractive power and the third lens group G3 has negative refractive power, it is preferable that the imaging lens satisfy the following conditional expression (15). Here, the focal length of the first lens group G1 is set to f1. Ensuring that the corresponding value of conditional expression (15) is not equal to or less than the lower limit thereof is advantageous for shortening the overall length of the lens system. Ensuring that the corresponding value of conditional expression (15) is not equal to or greater than the upper limit thereof is advantageous for widening the angle of view. -1.5 <f / f1<1.5 (15)

[0084] In order to obtain better characteristics, the lower limit of conditional expression (15) should preferably be set to -1.2, more preferably to -0.8, even more preferably to -0.7, even more preferably to -0.65, and even more preferably to -0.63.In order to obtain better characteristics, the upper limit of conditional expression (15) should preferably be set to 1.2, more preferably to 1, even more preferably to 0.8, even more preferably to 0.7, and even more preferably to 0.67.

[0085] In a configuration in which the second lens group G2 has positive refractive power and the third lens group G3 has negative refractive power, it is preferable that the imaging lens satisfy the following conditional expression (16). Here, the focal length of the second lens group G2 is f2. The focal length of the third lens group G3 is f3. By ensuring that the corresponding value of conditional expression (16) is not equal to or less than the lower limit, it becomes easy to prevent over-correction of field curvature. By ensuring that the corresponding value of conditional expression (16) is not equal to or greater than the upper limit, it becomes easy to prevent under-correction of field curvature. -1.1 <f2 / f3<-0.07 (16)

[0086] In order to obtain better characteristics, the lower limit of conditional expression (16) should preferably be set to -1, more preferably -0.95, even more preferably -0.9, even more preferably -0.85, and even more preferably -0.8.In order to obtain better characteristics, the upper limit of conditional expression (16) should preferably be set to -0.08, more preferably -0.09, even more preferably -0.1, even more preferably -0.11, and even more preferably -0.12.

[0087] In a configuration in which the second lens group G2 has positive refractive power and the third lens group G3 has negative refractive power, it is preferable that the imaging lens satisfy the following conditional expression (17). Ensuring that the corresponding value of conditional expression (17) 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 (17) is not equal to or larger than the upper limit thereof is advantageous for shortening the overall length of the lens system. -1.1 <f / f3<-0.03 (17)

[0088] In order to obtain better characteristics, the lower limit of conditional expression (17) should preferably be set to -1, more preferably -0.9, even more preferably -0.8, even more preferably -0.7, and even more preferably -0.6.In order to obtain better characteristics, the upper limit of conditional expression (17) should preferably be set to -0.05, more preferably -0.1, even more preferably -0.11, even more preferably -0.13, and even more preferably -0.15.

[0089] In a configuration in which the second lens group G2 has negative refractive power and the third lens group G3 has positive refractive power, it is preferable that the imaging lens satisfy the following conditional expression (15A). Here, the focal length of the first lens group G1 is set to f1. By ensuring that the corresponding value of conditional expression (15A) is not below the lower limit, the refractive power of the first lens group G1 does not become too weak, which is advantageous for shortening the overall length of the lens system. By ensuring that the corresponding value of conditional expression (15A) is not above the upper limit, the refractive power of the first lens group G1 does not become too strong, which is advantageous for suppressing aberration fluctuations during focusing. 1 <f / f1<3 (15A)

[0090] In order to obtain better characteristics, it is more preferable that the lower limit of conditional formula (15A) be set to 1.3, even more preferably to 1.5, and even more preferably to 1.7.In order to obtain better characteristics, it is more preferable that the upper limit of conditional formula (15A) be set to 2.5, even more preferably to 2.2, and even more preferably to 2.

[0091] In a configuration in which the second lens group G2 has negative refractive power and the third lens group G3 has positive refractive power, it is preferable that the imaging lens satisfy the following conditional expression (17A). Here, the focal length of the third lens group G3 is f3. Ensuring that the corresponding value of conditional expression (17A) is not equal to or less than the lower limit thereof is advantageous for shortening the overall length of the lens system. Ensuring that the corresponding value of conditional expression (17A) is not equal to or greater than the upper limit thereof is advantageous for correcting field curvature. 0.1 <f / f3<0.7 (17A)

[0092] In order to obtain better characteristics, the lower limit of conditional formula (17A) should preferably be set to 0.13, more preferably 0.135, even more preferably 0.14, even more preferably 0.145, and even more preferably 0.15. In order to obtain better characteristics, the upper limit of conditional formula (17A) should preferably be set to 0.6, more preferably 0.55, even more preferably 0.5, even more preferably 0.45, and even more preferably 0.42.

[0093] If the axial thickness of the first lens group G1 is DG1, it is preferable that the imaging lens satisfy the following conditional expression (18). As an example, the above thickness DG1 is shown in FIG. 3. Ensuring that the value corresponding to conditional expression (18) is not equal to or smaller than the lower limit thereof is advantageous for correcting lateral chromatic aberration and distortion. Ensuring that the value corresponding to conditional expression (18) is not equal to or larger than the upper limit thereof is advantageous for shortening the overall length and reducing the weight. 0.1 <DG1 / TL<0.55 (18)

[0094] In order to obtain better characteristics, the lower limit of conditional expression (18) should preferably be set to 0.11, more preferably 0.115, even more preferably 0.12, even more preferably 0.125, and even more preferably 0.13. In order to obtain better characteristics, the upper limit of conditional expression (18) should preferably be set to 0.5, more preferably 0.4, even more preferably 0.3, even more preferably 0.2, and even more preferably 0.17.

[0095] If the axial thickness of the third lens group G3 is DG3, it is preferable that the imaging lens satisfy the following conditional expression (19). As an example, the above thickness DG3 is shown in FIG. 3. Ensuring that the value corresponding to conditional expression (19) is not equal to or smaller than the lower limit thereof is advantageous for correcting field curvature. Ensuring that the value corresponding to conditional expression (19) is not equal to or larger than the upper limit thereof is advantageous for shortening the overall length and reducing the weight. 0.01 <DG3 / TL<0.25 (19)

[0096] In order to obtain better characteristics, the lower limit of conditional expression (19) should preferably be set to 0.013, more preferably to 0.015, and even more preferably to 0.02.In order to obtain better characteristics, the upper limit of conditional expression (19) should preferably be set to 0.2, more preferably to 0.15, and even more preferably to 0.12.

[0097] When the composite focal length of the first lens group G1 and the second lens group G2 when focused on an object at infinity is f12, it is preferable that the imaging lens satisfy the following conditional expression (20). By ensuring that the corresponding value of conditional expression (20) is not equal to or less than the lower limit, the composite refractive power of the first lens group G1 and the second lens group G2 does not become too weak, which is advantageous for shortening the overall length. By ensuring that the corresponding value of conditional expression (20) is not equal to or greater than the upper limit, the composite refractive power of the first lens group G1 and the second lens group G2 does not become too strong, which is advantageous for suppressing spherical aberration. 0.5 <f / f12<2.5 (20)

[0098] In order to obtain better characteristics, the lower limit of conditional expression (20) should preferably be set to 0.6, more preferably 0.65, even more preferably 0.68, and even more preferably 0.7.In order to obtain better characteristics, the upper limit of conditional expression (20) should preferably be set to 2, more preferably 1.8, even more preferably 1.5, and even more preferably 1.4.

[0099] Note that the example shown in Fig. 1 is merely an example, and various modifications are possible without departing from the spirit of the technology of the present disclosure. For example, the number of lenses included in each group may be different from that in the example of Fig. 1. Furthermore, the configuration of lenses included in each lens group may also be different from that in the example of Fig. 1.

[0100] The above-described preferred and possible configurations, including those relating to the conditional expressions, can be arbitrarily combined, and are preferably selectively adopted as appropriate according to the required specifications.

[0101] As an example, an imaging lens according to a preferred embodiment of the present disclosure comprises, in order from the object side to the image side, a first lens group G1, a second lens group G2, and a third lens group G3; during focusing, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane Sim, the second lens group G2 moves along the optical axis Z, an aperture that is fixed with respect to the image plane Sim with respect to focusing is disposed closer to the object than the second lens group G2, the first lens group G1 includes a first negative lens whose image-side surface is concave, closest to the object, and the imaging lens satisfies the above conditional expressions (1) and (2).

[0102] 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.

[0103] [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 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The focusing group is composed only of the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object along the optical axis Z.

[0104] For the imaging lens of Example 1, basic lens data is shown in Table 1, specifications are shown in Table 2, variable surface spacing is shown in Table 3, and aspherical coefficients are shown in Table 4.

[0105] 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 towards 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 the d-line of each component element. The "νd" column shows the Abbe number for each component element based on the d-line.

[0106] 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 surface number and the phrase (St) are entered in the column for the surface number corresponding to the aperture stop St. The basic lens data table also shows the optical element PP. The value in the bottom column of the D column in the table is the distance between the surface closest to the image side in the table and the image plane Sim. The symbol DD[ ] is used to indicate the variable surface distance during focusing, and the surface number on the object side of this distance is entered in the [ ] in the surface distance column.

[0107] Table 2 shows the focal length (f) of the imaging lens, the back focal length (Bf) in air equivalent distance, the maximum F-number (FNo.), and the maximum full-field angle (2ωm) based on the d-line. The [°] in the maximum full-field angle column indicates that the unit is degrees. Table 2 shows the values ​​when focused on an object at infinity.

[0108] In Table 3, the "Variable Surface Distance" column shows the symbols for the variable surface distances used in Table 1. The "Infinity" column shows the variable surface distances when focused on an object at infinity. The "Closest" column shows the variable surface distances when focused on a close object. The "Closest" column shows the object distance of the closest object in parentheses. "Object distance" is the distance on the optical axis from the object to the lens surface closest to the object. For example, in Example 1, this object distance is 86.716 mm (millimeters).

[0109] In the basic lens data, the surface numbers of aspherical surfaces are marked with an *, and the numerical value of the paraxial radius of curvature is entered in the column for the radius of curvature of the aspherical surface. In Table 4, 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 first surface in Example 1, m = 3, 4, 5, ..., 16. The numerical values ​​of the aspherical coefficients in Table 4, "E±n" (n: integer), are expressed as "×10 ±n KA and Am are aspherical coefficients in the aspherical formula given below. Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m however, Zd: Aspheric depth (length of the perpendicular line drawn from a point on the aspheric surface at height h to a plane perpendicular to the optical axis Z where the vertex of the aspheric surface is in contact) h: Height (distance from optical axis Z to lens surface) C: Reciprocal of paraxial curvature radius KA, Am: aspherical coefficients In the aspherical formula, Σ means the summation over m.

[0110] In the data in each table, degrees are used as the unit of angle and millimeters as the unit of length, but since the optical system can be used with proportional magnification or reduction, other appropriate units can also be used. Also, in each table below, values ​​are listed rounded to a predetermined number of decimal places.

[0111] [Table 1]

[0112] [Table 2]

[0113] [Table 3]

[0114] [Table 4]

[0115] FIG. 4 shows aberration diagrams of the imaging lens of Example 1. From left to right, FIG. 4 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration. In FIG. 4, the upper row labeled "Infinity" shows aberration diagrams of the imaging lens focused on an object at infinity, and the lower row labeled "Close" shows aberration diagrams of the imaging lens focused on a close object, which corresponds to the object distance shown in the variable surface spacing table. In the spherical aberration diagrams, aberrations at the d-line, C-line, and F-line are shown by solid lines, long-dashed lines, and short-dashed lines, respectively. In the astigmatism diagrams, aberrations at the d-line in the sagittal direction are shown by solid lines, and aberrations at the d-line in the tangential direction are shown by short-dashed lines. In the distortion diagrams, aberrations at the d-line are shown by solid lines. In the lateral chromatic aberration diagrams, aberrations at the C-line and F-line are shown by long-dashed lines and short-dashed lines, respectively. In the spherical aberration diagram, the maximum F-number is shown after "FNo.=". In the other aberration diagrams, the maximum half angle of view is shown after "ω=". The FNo. and ω in the upper diagram correspond to the FNo and ωm in the conditional expression mentioned above, respectively.

[0116] 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.

[0117] [Example 2] FIG. 5 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, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L13, an aperture stop St, and a lens L14. The second lens group G2 comprises, in order from the object side to the image side, five lenses, lenses L21 to L25. The third lens group G3 comprises a single lens, lens L31. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0118] For the imaging lens of Example 2, basic lens data is shown in Table 5, specifications are shown in Table 6, variable surface spacing is shown in Table 7, aspherical coefficients are shown in Table 8, and each aberration diagram is shown in FIG.

[0119] [Table 5]

[0120] [Table 6]

[0121] [Table 7]

[0122] [Table 8]

[0123] [Example 3] FIG. 7 shows a cross-sectional view of the configuration of the imaging lens of Example 3. The imaging lens of Example 3 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L13, an aperture stop St, and a lens L14. The second lens group G2 comprises, in order from the object side to the image side, five lenses, lenses L21 to L25. The third lens group G3 comprises a single lens, lens L31. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0124] For the imaging lens of Example 3, basic lens data is shown in Table 9, specifications are shown in Table 10, variable surface spacings are shown in Table 11, aspherical coefficients are shown in Table 12, and aberration diagrams are shown in FIG. [Table 9]

[0125] [Table 10]

[0126] [Table 11]

[0127] [Table 12]

[0128] [Example 4] FIG. 9 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, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L14, an aperture stop St, and a lens L15. The second lens group G2 comprises, in order from the object side to the image side, four lenses, lenses L21 to L24. The third lens group G3 comprises a single lens, lens L31. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0129] In Example 4, optical members PP1 and PP2 are arranged between the imaging lens and the image plane Sim. The optical members PP1 and PP2 are parallel plate-shaped members that have no refractive power. The optical member PP2 has the same function as the optical member PP in Example 1. When the lens closest to the image side of the imaging lens is a plastic lens, the optical member PP1 may be arranged as a protective filter as in Example 4.

[0130] For the imaging lens of Example 4, basic lens data is shown in Table 13, specifications are shown in Table 14, variable surface spacings are shown in Table 15, aspherical coefficients are shown in Table 16, and each aberration diagram is shown in FIG.

[0131] [Table 13]

[0132] [Table 14]

[0133] [Table 15]

[0134] [Table 16]

[0135] [Example 5] FIG. 11 shows a cross-sectional view of the configuration of the imaging lens of Example 5. The imaging lens of Example 5 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L14, an aperture stop St, and a lens L15. The second lens group G2 comprises, in order from the object side to the image side, four lenses, lenses L21 to L24. The third lens group G3 comprises a single lens, lens L31. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0136] In the fifth embodiment, optical members PP1 and PP2 are disposed between the imaging lens and the image plane Sim. The optical members PP1 and PP2 in the fifth embodiment have the same functions as the optical members PP1 and PP2 in the fourth embodiment, respectively.

[0137] For the imaging lens of Example 5, basic lens data is shown in Table 17, specifications are shown in Table 18, variable surface spacing is shown in Table 19, aspherical coefficients are shown in Table 20, and each aberration diagram is shown in FIG.

[0138] [Table 17]

[0139] [Table 18]

[0140] [Table 19]

[0141] [Table 20]

[0142] [Example 6] FIG. 13 shows a cross-sectional view of the configuration of the imaging lens of Example 6. The imaging lens of Example 6 comprises, in order from the object side to the image side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L13 and an aperture stop St. The second lens group G2 comprises, in order from the object side to the image side, six lenses, lenses L21 to L26. The third lens group G3 comprises, in order from the object side to the image side, two lenses, lenses L31 and L32. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0143] For the imaging lens of Example 6, basic lens data is shown in Table 21, specifications are shown in Table 22, variable surface spacing is shown in Table 23, aspherical coefficients are shown in Table 24, and each aberration diagram is shown in FIG.

[0144] [Table 21]

[0145] [Table 22]

[0146] [Table 23]

[0147] [Table 24]

[0148] [Example 7] FIG. 15 shows a cross-sectional view of the configuration of the imaging lens of Example 7. The imaging lens of Example 7 comprises, in order from the object side to the image side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L13 and an aperture stop St. The second lens group G2 comprises, in order from the object side to the image side, six lenses, lenses L21 to L26. The third lens group G3 comprises, in order from the object side to the image side, two lenses, lenses L31 and L32. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0149] For the imaging lens of Example 7, basic lens data is shown in Table 25, specifications in Table 26, variable surface spacing in Table 27, aspherical coefficients in Table 28, and each aberration diagram is shown in FIG.

[0150] [Table 25]

[0151] [Table 26]

[0152] [Table 27]

[0153] [Table 28]

[0154] [Example 8] FIG. 17 shows a cross-sectional view of the configuration of the imaging lens of Example 8. The imaging lens of Example 8 comprises, in order from the object side to the image side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L13 and an aperture stop St. The second lens group G2 comprises, in order from the object side to the image side, six lenses, lenses L21 to L26. The third lens group G3 comprises, in order from the object side to the image side, two lenses, lenses L31 and L32. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0155] For the imaging lens of Example 8, basic lens data is shown in Table 29, specifications are shown in Table 30, variable surface spacing is shown in Table 31, aspherical coefficients are shown in Table 32, and each aberration diagram is shown in FIG.

[0156] [Table 29]

[0157] [Table 30]

[0158] [Table 31]

[0159] [Table 32]

[0160] [Example 9] FIG. 19 shows a cross-sectional view of the configuration of the imaging lens of Example 9. The imaging lens of Example 9 comprises, in order from the object side to the image side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L13 and an aperture stop St. The second lens group G2 comprises, in order from the object side to the image side, six lenses, lenses L21 to L26. The third lens group G3 comprises, in order from the object side to the image side, two lenses, lenses L31 and L32. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the object side along the optical axis Z.

[0161] For the imaging lens of Example 9, basic lens data is shown in Table 33, specifications are shown in Table 34, variable surface spacing is shown in Table 35, aspherical coefficients are shown in Table 36, and each aberration diagram is shown in FIG.

[0162] [Table 33]

[0163] [Table 34]

[0164] [Table 35]

[0165] [Table 36]

[0166] [Example 10] FIG. 21 shows a cross-sectional view of the configuration of the imaging lens of Example 10. The imaging lens of Example 10 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The first lens group G1 consists of, in order from the object side to the image side, lenses L11 to L13, an aperture stop St, and lenses L14 to L17. The second lens group G2 consists of a single lens, lens L21. The third lens group G3 consists of a single lens, lens L31. The focusing group consists only of the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the image side along the optical axis Z.

[0167] For the imaging lens of Example 10, basic lens data is shown in Table 37, specifications in Table 38, variable surface spacing in Table 39, aspherical coefficients in Table 40, and each aberration diagram is shown in FIG.

[0168] [Table 37]

[0169] [Table 38]

[0170] [Table 39]

[0171] [Table 40]

[0172] [Example 11] A cross-sectional view of the configuration of the imaging lens of Example 11 is shown in Figure 23. The imaging lens of Example 11 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The first lens group G1 consists of, in order from the object side to the image side, lenses L11 to L13, an aperture stop St, and lenses L14 to L17. The second lens group G2 consists of a single lens, lens L21. The third lens group G3 consists of a single lens, lens L31. The focusing group consists only of the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the image side along the optical axis Z.

[0173] For the imaging lens of Example 11, basic lens data is shown in Table 41, specifications are shown in Table 42, variable surface spacing is shown in Table 43, aspherical coefficients are shown in Table 44, and each aberration diagram is shown in FIG.

[0174] [Table 41]

[0175] [Table 42]

[0176] [Table 43]

[0177] [Table 44]

[0178] [Example 12] FIG. 25 shows a cross-sectional view of the configuration of the imaging lens of Example 12. The imaging lens of Example 12 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The first lens group G1 comprises, in order from the object side to the image side, lenses L11 to L13, an aperture stop St, and lenses L14 to L17. The second lens group G2 comprises one lens, lens L21. The third lens group G3 comprises, in order from the object side to the image side, lenses L31 and L32. The focusing group comprises only the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the image side along the optical axis Z.

[0179] For the imaging lens of Example 12, basic lens data is shown in Table 45, specifications in Table 46, variable surface spacing in Table 47, aspherical coefficients in Table 48, and various aberration diagrams are shown in FIG.

[0180] [Table 45]

[0181] [Table 46]

[0182] [Table 47]

[0183] [Table 48]

[0184] [Example 13] A cross-sectional view of the configuration of the imaging lens of Example 13 is shown in Figure 27. The imaging lens of Example 13 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The first lens group G1 consists of, in order from the object side to the image side, lenses L11 to L13, an aperture stop St, and lenses L14 to L17. The second lens group G2 consists of a single lens, lens L21. The third lens group G3 consists of a single lens, lens L31. The focusing group consists only of the second lens group G2. When focusing from an object at infinity to a close object, the focusing group moves toward the image side along the optical axis Z.

[0185] For the imaging lens of Example 13, basic lens data is shown in Table 49, specifications in Table 50, variable surface spacing in Table 51, aspherical coefficients in Table 52, and each aberration diagram is shown in FIG.

[0186] [Table 49]

[0187] [Table 50]

[0188] [Table 51]

[0189] [Table 52]

[0190] Tables 53 to 55 show values ​​corresponding to conditional formulas (1) to (20), (15A), and (17A) for the imaging lenses of Examples 1 to 13. The values ​​corresponding to the Examples shown in Tables 53 to 55 may be used as upper or lower limits for the conditional formulas to set preferred ranges for the conditional formulas.

[0191] [Table 53]

[0192] [Table 54]

[0193] [Table 55]

[0194] The imaging lenses of Examples 1 to 13 are constructed to be small in size, yet have an F-number smaller than 2.1, and maintain high optical performance with various aberrations well corrected.

[0195] Next, an imaging device according to an embodiment of the present disclosure will be described. Fig. 29 and Fig. 30 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure. Fig. 29 shows a perspective view of the camera 30 as seen from the front side, and Fig. 30 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.

[0196] The camera 30 includes a camera body 31. A shutter button 32 and a power button 33 are provided on the top surface of the camera body 31. An operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back surface of the camera body 31. The display unit 36 ​​can display a captured image and an image within the angle of view before the image was captured.

[0197] A photographic opening through which light from a subject enters is provided in the center of the front surface of camera body 31. A mount 37 is provided at a position corresponding to the photographic opening, and interchangeable lens 20 is attached to camera body 31 via mount 37.

[0198] An imaging element 38 is provided within the camera body 31. The imaging element 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. For example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) is used as the imaging element 38. A signal processing circuit (not shown) and a recording medium (not shown) are provided within the camera body 31. The signal processing circuit processes the imaging signal output from the imaging element 38 to generate an image. The recording medium is for recording the generated image. With the camera 30, it is possible to take still images or videos by pressing the shutter button 32, and the image data obtained by this shooting is recorded on the recording medium.

[0199] 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.

[0200] 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.

[0201] 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, a second lens group, and a third lens group, During focusing, the first lens group and the third lens group are fixed with respect to an image plane, and the second lens group moves along an optical axis; a stop that is fixed with respect to the image plane during focusing is disposed on the object side of the second lens group, the first lens group includes a first negative lens element having a concave image-side surface closest to the object, 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 third lens group closest to the image when focused on an object at infinity, and the back focus of the entire system in air equivalent distance; The focal length of the entire system when focused on an object at infinity is f. The maximum half angle of view when focused on an object at infinity is ωm. If the open F-number when focused on an object at infinity is FNo, 2 <TL / (f×tanωm)<5.5 (1) 4 <TL×FNo / f<7.5 (2) An imaging lens that satisfies conditional expressions (1) and (2) expressed as follows: [Appendix 2] If the focal length of the second lens group is f2, then 0.2 <f / |f2|<3 (3) The imaging lens according to claim 1, which satisfies conditional expression (3) expressed as follows: [Appendix 3] When the distance on the optical axis from the lens surface of the imaging lens closest to the object to the paraxial entrance pupil position in a state where the lens is focused on an object at infinity is denoted as Enp, 1.5 <f / Enp<6 (4) The imaging lens according to claim 1 or 2, which satisfies conditional expression (4) expressed by: [Appendix 4] at least one of the first negative lens in the first lens group and a lens disposed adjacent to the first negative lens on the image side includes an aspheric surface, When the air gap on the optical axis between the first negative lens of the first lens group and a lens disposed adjacent to the first negative lens on the image side is DL12, 0.015 <DL12 / TL<0.25 (5) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 3, which satisfies conditional expression (5) expressed as follows: [Appendix 5] a positive lens is disposed adjacent to the object side of the aperture; When the refractive index of the positive lens arranged adjacent to the aperture stop on the object side is Nsf for the d-line, 1.7 <Nsf<2.2 (6) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 4, which satisfies conditional expression (6) expressed as follows: [Appendix 6] The lateral magnification of the second lens group when focused on an object at infinity is β2, When the lateral magnification of the third lens group in a state where the lens is focused on an object at infinity is β3, 0.8<|(1-β2 2 )×β3 2 |<5 (7) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 5, which satisfies conditional expression (7) shown below. [Appendix 7] The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 6, wherein the first lens group includes at least two negative lenses and at least one positive lens. [Appendix 8] When the average value of the refractive index for the d-line of all the negative lenses included in the first lens group is N1nave, 1.555 <N1nave<1.9 (8) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 7, which satisfies conditional expression (8) shown below. [Appendix 9] When the back focus of the entire system in air equivalent distance in a state where it is focused on an object at infinity is Bf, 0.4 <Bf / (f×tanωm)<2.5 (9) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 8, which satisfies conditional expression (9) shown below. [Appendix 10] When the thickness of the second lens group on the optical axis is DG2, 0.01 <DG2 / TL<0.4 (10) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 9, which satisfies conditional expression (10) shown below. [Appendix 11] When the maximum value of the refractive index for the d-line of all lenses included in the imaging lens is Nmax, 1.8 <Nmax<2.2 (11) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 10, which satisfies conditional expression (11) shown below. [Appendix 12] When the average value of the refractive index for the d-line of all the positive lenses included in the imaging lens is Npave, 1.64 <Npave<1.88 (12) 12. The imaging lens according to claim 1, which satisfies conditional expression (12) below. [Appendix 13] When the focal length of the first negative lens in the first lens group is fL1, -2 <f / fL1<-0.45 (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 distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity is Exp. The sign of Exp is determined based on the image plane, with the distance from the image plane toward the object side being negative and the distance from the object side toward the image side being positive. When an optical element having no refractive power is disposed between the image plane and the paraxial exit pupil position, when calculating Exp for the optical element using an air-equivalent distance, -5 <Exp / (f×tanωm)<-1.4 (14) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 13, which satisfies conditional expression (14) represented by the following: [Appendix 15] the second lens group has positive refractive power, the third lens group has negative refractive power, If the focal length of the first lens group is f1, then -1.5 <f / f1<1.5 (15) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 14, which satisfies conditional expression (15) shown below. [Appendix 16] the second lens group has positive refractive power, the third lens group has negative refractive power, The focal length of the second lens group is f2, If the focal length of the third lens group is f3, -1.1 <f2 / f3<-0.07 (16) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 15, which satisfies conditional expression (16) shown below. [Appendix 17] the second lens group has positive refractive power, the third lens group has negative refractive power, If the focal length of the third lens group is f3, -1.1 <f / f3<-0.03 (17) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 16, which satisfies conditional expression (17) shown below. [Appendix 18] the second lens group has negative refractive power, the third lens group has positive refractive power, If the focal length of the first lens group is f1, then 1 <f / f1<3 (15A) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 14, which satisfies conditional formula (15A) represented by the following formula: [Appendix 19] the second lens group has negative refractive power, the third lens group has positive refractive power, If the focal length of the third lens group is f3, 0.1 <f / f3<0.7 (17A) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 14 and Supplementary Note 18, which satisfies conditional formula (17A) represented by the following formula: [Appendix 20] An imaging device comprising the imaging lens according to any one of Supplementary Note 1 to Supplementary Note 19. [Explanation of symbols]

[0202] 1 Imaging lens 2 On-axis luminous flux 3 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 38 Image sensor DG1 Thickness DG2 Thickness DG3 Thickness DL12 Air Spacing Enp distance Exp distance G1 First lens group G2 Second lens group G3 Third lens group L11~L32 lenses PP optical components PP1 Optical Components PP2 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 first lens group, a second lens group, and a third lens group, During focusing, the first lens group and the third lens group are fixed with respect to an image plane, and the second lens group moves along an optical axis; a stop that is fixed with respect to the image plane during focusing is disposed on the object side of the second lens group, the first lens group includes a first negative lens element having a concave image-side surface closest to the object, 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 third lens group closest to the image when focused on an object at infinity, and the back focus of the entire system in air equivalent distance; The focal length of the entire system when focused on an object at infinity is f. The maximum half angle of view when focused on an object at infinity is ωm. When the open F-number when focused on an object at infinity is FNo, 2<TL / (f×tanωm)<5.5 (1) 4<TL×FNo / f<7.5 (2) An imaging lens that satisfies conditional expressions (1) and (2) expressed by the following formulas.

2. When the focal length of the second lens group is f2, 0.2<f / |f2|<3 (3) 2. The imaging lens according to claim 1, which satisfies conditional expression (3) expressed as follows:

3. When the distance on the optical axis from the lens surface of the imaging lens closest to the object to the paraxial entrance pupil position in a state where the lens is focused on an object at infinity is denoted by Enp, 1.5<f / Enp<6 (4) 2. The imaging lens according to claim 1, which satisfies conditional expression (4) expressed as follows:

4. at least one of the first negative lens in the first lens group and a lens disposed adjacent to the first negative lens on the image side includes an aspheric surface, When the air gap on the optical axis between the first negative lens of the first lens group and a lens disposed adjacent to the first negative lens on the image side is DL12, 0.015<DL12 / TL<0.25 (5) 2. The imaging lens according to claim 1, which satisfies conditional expression (5) expressed as follows:

5. a positive lens is disposed adjacent to the object side of the aperture; When the refractive index of the positive lens arranged adjacent to the object side of the stop with respect to the d line is Nsf, 1.7<Nsf<2.2 (6) 2. The imaging lens according to claim 1, which satisfies conditional expression (6) expressed as follows:

6. The lateral magnification of the second lens group when focused on an object at infinity is β2, When the lateral magnification of the third lens group in a state where the lens is focused on an object at infinity is β3, ０．８＜｜（１－β２ ２ ）×β３ ２ ｜＜５ （７） 2. The imaging lens according to claim 1, which satisfies conditional expression (7) expressed as follows:

7. The imaging lens according to claim 1 , wherein the first lens group includes at least two negative lenses and at least one positive lens.

8. When the average value of the refractive index for the d-line of all the negative lenses included in the first lens group is N1nave, 1.555<N1nave<1.9 (8) 2. The imaging lens according to claim 1, which satisfies conditional expression (8) expressed as follows:

9. 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, 0.4<Bf / (f×tanωm)<2.5 (9) 2. The imaging lens according to claim 1, which satisfies conditional expression (9) expressed as follows:

10. When the thickness of the second lens group on the optical axis is DG2, 0.01<DG2 / TL<0.4 (10) 2. The imaging lens according to claim 1, which satisfies conditional expression (10) expressed as follows:

11. When the maximum value of the refractive index for the d-line of all lenses included in the imaging lens is Nmax, 1.8<Nmax<2.2 (11) 2. The imaging lens according to claim 1, which satisfies conditional expression (11) expressed as follows:

12. When the average value of the refractive index for the d-line of all the positive lenses included in the imaging lens is Npave, 1.64<Npave<1.88 (12) 2. The imaging lens according to claim 1, which satisfies conditional expression (12) expressed as follows:

13. When the focal length of the first negative lens in the first lens group is fL1, -2<f / fL1<-0.45 (13) 2. The imaging lens according to claim 1, which satisfies conditional expression (13) expressed as follows:

14. Exp is the distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity, The sign of Exp is negative when the distance from the image surface toward the object side is taken as a reference, and positive when the distance from the object side toward the image side is taken as a reference. When an optical element having no refractive power is disposed between the image plane and the paraxial exit pupil position, when Exp is calculated for the optical element using an air-equivalent distance, -5<Exp / (f×tanωm)<-1.4 (14) 2. The imaging lens according to claim 1, which satisfies conditional expression (14) expressed as follows:

15. the second lens group has a positive refractive power, the third lens group has negative refractive power, When the focal length of the first lens group is f1, -1.5<f / f1<1.5 (15) 2. The imaging lens according to claim 1, which satisfies conditional expression (15) expressed as follows:

16. the second lens group has a positive refractive power, the third lens group has negative refractive power, The focal length of the second lens group is f2, When the focal length of the third lens group is f3, -1.1<f2 / f3<-0.07 (16) 2. The imaging lens according to claim 1, which satisfies conditional expression (16) expressed as follows:

17. the second lens group has a positive refractive power, the third lens group has negative refractive power, When the focal length of the third lens group is f3, -1.1<f / f3<-0.03 (17) 2. The imaging lens according to claim 1, which satisfies conditional expression (17) expressed as follows:

18. the second lens group has negative refractive power, the third lens group has a positive refractive power, When the focal length of the first lens group is f1, 1<f / f1<3 (15A) 2. The imaging lens according to claim 1, which satisfies conditional expression (15A) expressed as follows:

19. the second lens group has negative refractive power, the third lens group has a positive refractive power, When the focal length of the third lens group is f3, 0.1<f / f3<0.7 (17A) 2. The imaging lens according to claim 1, which satisfies conditional expression (17A) expressed as follows:

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

Images