Imaging lens and imaging device

Abstract

To provide an imaging lens that achieves shortening a lens system entire length and has an excellent optical performance, and also to provide an imaging device that includes the imaging lens.SOLUTION: An imaging lens is composed of, in order from an object side to an imaging side: a first lens group having positive refractive power; a second lens group; and a third lens group. Upon focusing, the second lens group moves. A lens closest to the object side is a negative meniscus lens, and at least one of a second lens from the object side and a third lens from the object side is a lens other than a negative meniscus lens. A stop is arranged on a side closer to the imaging side than the second lens from the object side, and the imaging lens satisfies a predetermined condition.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] Japanese Patent Publication No. 2023-045839 [Patent Document 2] Japanese Patent Publication No. 2023-019073 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for imaging lenses that have a shorter overall lens system length and good optical performance, and these requirements are becoming higher every year.

[0005] An object of the present disclosure is to provide an imaging lens that has a reduced overall length of the lens system and good optical performance, and an imaging device that includes this imaging lens. [Means for solving the problem]

[0006] An imaging lens according to one aspect of the techniques of the present disclosure includes, in order from the object side to the image side, a first lens group having positive refractive power, 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, the second lens group moves along an optical axis, the lens closest to the object side is a negative meniscus lens, at least one of the second lens from the object side and the third lens from the object side is a lens other than a negative meniscus lens, and an aperture is located closer to the image side than the second lens from the object side; 1 <TL / Y<4.5 (1) -0.18<(Yf×tanωm) / (f×tanωm)<-0.02 (2) 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 and the back focal length of the entire system in terms of the air equivalent distance, Y is the maximum image height, f is the focal length of the entire system when focused on an object at infinity, and ωm is the maximum half angle of view when focused on an object at infinity.

[0007] In a cross section including the optical axis, the radius of a circle that passes through three points, namely a point on the optical axis and two points at the outermost edge of the effective diameter of the lens surface, is defined as Rc of the lens surface, and the sign of Rc is positive if the point on the optical axis is closer to the object than the center of the circle, and negative if the point on the optical axis is closer to the image than the center of the circle. It is preferable that the number of lenses included in the third lens group whose object-side lens surface is aspherical and whose object-side lens surface has a negative Rc sign is one or two.

[0008] The number of lenses included in the imaging lens is preferably 5 or more and 10 or less.

[0009] When the unit of ωm is degrees, the imaging lens of the above embodiment has the following: 47<ωm<60 (3) It is preferable to satisfy conditional expression (3) below.

[0010] When the focal length of the first lens group is fG1, the imaging lens of the above aspect has the following characteristics: 0.01 <f / fG1<1.6 (4) It is preferable to satisfy conditional expression (4) below.

[0011] When the distance on the optical axis from the lens surface of the first lens group closest to the object to the diaphragm in a state where the lens is focused on an object at infinity is dL1St, the imaging lens of the above aspect satisfies the following conditions: 0.1 <dL1St / Y<2.1 (5) It is preferable to satisfy conditional expression (5) below.

[0012] When the angle between the chief ray of the maximum image height incident on the image plane in a state where an object at infinity is focused and an axis line parallel to the optical axis is defined as CRA, and the unit of CRA is degrees, the imaging lens of the above aspect has the following characteristics: 16<|CRA|<69 (6) It is preferable to satisfy conditional expression (6) below.

[0013] When the back focus of the entire system in terms of air equivalent distance is Bf, the imaging lens of the above embodiment has the following characteristics: 0.06 <Bf / TL<0.3 (7) It is preferable to satisfy conditional expression (7) below.

[0014] When the unit of f is millimeters and the maximum F-number when focused on an object at infinity is Fno, the imaging lens of the above embodiment has the following characteristics: 1.7 <f / Fno<4.1 (8) It is preferable to satisfy conditional expression (8) below.

[0015] When the focal length of the second lens group is fG2, the imaging lens of the above aspect has the following characteristics: 0.24<|f / fG2|<2.4 (9) It is preferable to satisfy conditional expression (9) below.

[0016] It is preferable that one or two single lenses having negative refractive power and one or two single lenses having positive refractive power are arranged on the object side of the aperture stop, and the number of lenses arranged on the object side of the aperture stop is four or less.

[0017] When a positive lens is disposed adjacent to the image side of the aperture stop, and the Abbe number of the positive lens disposed adjacent to the image side of the aperture stop with respect to the d-line is νrp, the imaging lens of the above aspect satisfies the following equation: 34<νrp<87 (10) It is preferable to satisfy conditional expression (10) below.

[0018] When a positive lens is disposed adjacent to the object side of the aperture stop, and the Abbe number of the positive lens disposed adjacent to the object side of the aperture stop based on the d-line is νfp, the imaging lens of the above aspect satisfies the following conditions: 23<νfp<61 (11) It is preferable to satisfy conditional expression (11) below.

[0019] When a positive lens is disposed adjacent to the object side of the aperture stop, and an Lffn lens having negative refractive power is disposed adjacent to the object side of the positive lens, and the Abbe number of the Lffn lens based on the d-line is vffn, the imaging lens of the above aspect has the following characteristics: 16<νffn<100 (12) It is preferable to satisfy conditional expression (12) below.

[0020] In a cross section including the optical axis, the radius of a circle passing through three points consisting of a point on the optical axis and two points at the outermost end of the effective diameter of the lens surface is defined as Rc of the lens surface, and the sign of Rc is positive if the point on the optical axis is closer to the object than the center of the circle, and negative if the point on the optical axis is closer to the image than the center of the circle, then the first lens group comprises, in order from closest to the object side to the image side, a negative subgroup and one positive lens, and the negative subgroup consists of one or two negative lenses whose object-side lens surface Rc and whose image-side lens surface Rc have the same sign, and it is preferable that at least one lens surface included in the negative subgroup has an aspherical shape, and the imaging lens of the above aspect is 1.45 <N1nave<2.3 (13) 16<ν1nave<85 (14) It is preferable to satisfy conditional expressions (13) and (14) expressed as follows: Here, the average value of the refractive index for the d-line of all lenses included in the negative subgroup is defined as N1nave, and the average value of the Abbe numbers based on the d-line of all lenses included in the negative subgroup is defined as ν1nave.

[0021] When the composite focal length of all lenses on the object side of the aperture stop when focused on an object at infinity is fGf, and the composite focal length of all lenses on the image side of the aperture stop when focused on an object at infinity is fGr, the imaging lens of the above aspect satisfies the following conditions: -10 <fGf / fGr<31 (15) It is preferable to satisfy conditional expression (15) below.

[0022] It is preferable that the lens surface of the second lens group closest to the image side has a convex shape.

[0023] The imaging lens includes at least one lens surface having an inflection point, and when the distance on the optical axis from the lens surface of the first lens group closest to the object to the lens surface of the third lens group closest to the image is taken as DL, it is preferable that, in a state focused on an object at infinity, at least one of the points of intersection between the lens surface having the inflection point and the optical axis be a specific intersection point within a range of 0.3 × DL from the point of intersection between the lens surface of the first lens group closest to the object and the optical axis, or within a range of 0.3 × DL from the point of intersection between the lens surface of the third lens group closest to the image and the optical axis.

[0024] When the refractive power of the lens surface having the specific intersection is φa and the refractive power of the imaging lens in a state where the imaging lens is focused on an object at infinity is φ, at least one of the lens surfaces having the specific intersection is -2<φa / φ<3 (16) It is preferable to satisfy conditional expression (16) below.

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

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

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

[0028] A compound aspherical lens (a lens in which a lens (e.g., a spherical lens) and an aspherical film formed on the lens are integrated to function as a single aspherical lens as a whole) is not considered a cemented lens, but is treated as a single lens. Unless otherwise specified, the sign of the refractive power and surface shape of lenses including aspherical surfaces are those in the paraxial region.

[0029] In this specification, "total system" refers to the imaging lens. The "focal length" used in the conditional expressions is the paraxial focal length. The "distance on the optical axis" used in the conditional expressions is the geometric distance unless otherwise specified. The values used in the conditional expressions are values based on the d-line when focused on an object at infinity, unless otherwise specified.

[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 reduced overall length of the lens system and good optical performance, and an imaging device that includes this imaging lens. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view showing the configuration of an imaging lens according to one embodiment, corresponding to the imaging lens of Example 1. FIG. [Figure 2] 2A to 2C are cross-sectional views showing the configuration and light beams in each state of the imaging lens of FIG. 1. [Figure 3] FIG. 10 is a diagram for explaining Rc. [Figure 4] FIG. 10 is a diagram for explaining symbols in a conditional expression. [Figure 5] FIG. 10 is a diagram for explaining symbols in a conditional expression. [Figure 6] 3A to 3C are diagrams showing various aberrations of the imaging lens of Example 1. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a second embodiment. [Figure 8] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 2. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a third embodiment. [Figure 10] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 3. [Figure 11] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fourth embodiment. [Figure 12] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 4. [Figure 13] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a fifth embodiment. [Figure 14] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 5. [Figure 15] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a sixth embodiment. [Figure 16] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 6. [Figure 17] FIG. 10 is a cross-sectional view showing the configuration of an imaging lens according to a seventh embodiment. [Figure 18] 10A to 10C are diagrams showing various aberrations of the imaging lens of Example 7. [Figure 19] FIG. 13 is a cross-sectional view showing the configuration of an imaging lens according to an eighth embodiment. [Figure 20] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 8. [Figure 21] FIG. 13 is a cross-sectional view showing the configuration of an imaging lens according to a ninth embodiment. [Figure 22] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 9. [Figure 23] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to a tenth embodiment. [Figure 24] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 10. [Figure 25] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to an eleventh embodiment. [Figure 26] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 11. [Figure 27] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to a twelfth embodiment. [Figure 28] 13A to 13C are diagrams showing various aberrations of the imaging lens of Example 12. [Figure 29] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to a thirteenth embodiment. [Figure 30] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 13. [Figure 31] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens of Example 14. [Figure 32] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 14. [Figure 33] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens of Example 15. [Figure 34] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 15. [Figure 35] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to a sixteenth embodiment. [Figure 36] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 16. [Figure 37] FIG. 20 is a cross-sectional view showing the configuration of an imaging lens according to a seventeenth embodiment. [Figure 38] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 17. [Figure 39]FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to an eighteenth embodiment. [Figure 40] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 18. [Figure 41] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens of Example 19. [Figure 42] 20A to 20C are diagrams showing various aberrations of the imaging lens of Example 19. [Figure 43] FIG. 26 is a cross-sectional view showing the configuration of an imaging lens according to a twentieth embodiment. [Figure 44] 23A to 23C are diagrams showing various aberrations of the imaging lens of Example 20. [Figure 45] FIG. 23 is a cross-sectional view showing the configuration of an imaging lens of Example 21. [Figure 46] 23A to 23C are diagrams showing various aberrations of the imaging lens of Example 21. [Figure 47] FIG. 22 is a cross-sectional view showing the configuration of an imaging lens according to a twenty-second embodiment. [Figure 48] 23A to 23C are diagrams showing various aberrations of the imaging lens of Example 22. [Figure 49] FIG. 23 is a cross-sectional view showing the configuration of an imaging lens according to a twenty-third embodiment. [Figure 50] 23A to 23C are diagrams showing various aberrations of the imaging lens of Example 23. [Figure 51] FIG. 26 is a cross-sectional view showing the configuration of an imaging lens of Example 24. [Figure 52] 23A to 23C are diagrams showing various aberrations of the imaging lens of Example 24. [Figure 53] FIG. 25 is a cross-sectional view showing the configuration of an imaging lens of Example 25. [Figure 54] 23A to 23C are diagrams showing various aberrations of the imaging lens of Example 25. [Figure 55] 1 is a perspective view of the front side of an imaging device according to an embodiment. [Figure 56] 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. FIG. 2 shows a cross-sectional view of the configuration of the imaging lens of FIG. 1 and light beams. In FIG. 2, the upper row labeled "infinity" shows a state in which the imaging lens is focused on an object at infinity, and the lower row labeled "0.150 m" shows a state in which the imaging lens is focused on a closest object with an object distance of 0.150 m. In this specification, the object distance refers to the distance from the lens surface of the imaging lens closest to the object to the object. In FIG. 2, the light beams shown are an axial light beam 2 and a light beam 3 with a maximum half angle of view ωm when the imaging lens is focused on an object at infinity, and an axial light beam and a light beam with a maximum half angle of view ωm when the imaging lens is focused on a closest 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 is composed of, 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, all of which have positive refractive power. By making the sign of the refractive power of the first lens group G1 positive, the light beam emerging from the first lens group G1 can be made into convergent light, which is advantageous for shortening the overall length of the lens system.

[0037] During focusing, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane Sim, and the second lens group G2 moves along the optical axis Z. Hereinafter, the lens group that moves during focusing will be referred to as the focus group. Focusing is achieved by the movement of the focus group. In the imaging lens of the present disclosure, the focus group consists of the second lens group G2. By using the second lens group G2 as the focus group, the weight of the focus group can be reduced compared to a configuration in which the entire lens system moves during focusing, enabling high-speed focusing.

[0038] As an example, each group in the imaging lens in FIG. 1 is configured as follows: The first lens group G1 consists of, in order from the object side to the image side, four lenses, L11 to L14, and an aperture stop St. The second lens group G2 consists of, in order from the object side to the image side, four lenses, L21 to L24. 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 in the optical axis direction. The parentheses and left-pointing arrow below the second lens group G2 in FIG. 1 indicate that the second lens group G2 is a focus group that moves toward the object side when focusing from an object at infinity to a closest object.

[0039] In this specification, a "lens group" is a component of an imaging lens that includes at least one lens and is separated by an air gap that changes during focusing. During focusing, each lens group is moved or fixed, and the mutual spacing between lenses within each lens group does not change. In other words, in this specification, a group in which the spacing between adjacent groups changes during focusing, but the total spacing between adjacent lenses within itself does not change, is defined as one lens group.

[0040] In the imaging lens of the present disclosure, the number of lenses included in the first lens group G1 may be configured to be between 1 and 7. This is advantageous for shortening the overall length of the lens system.

[0041] The second lens group G2 may be a lens group having a positive refractive power, or may be a lens group having a negative refractive power.

[0042] The number of lenses included in the second lens group G2 may be set to be between 1 and 4. This is advantageous for shortening the overall length of the lens system.

[0043] It is preferable that the lens surface of the second lens group G2 closest to the image side has a convex shape, which reduces the exit angle of light rays emerging from this lens surface, thereby suppressing the occurrence of aberrations, particularly curvature of field.

[0044] The third lens group G3 may be a lens group having positive refractive power, or may be a lens group having negative refractive power.

[0045] The number of lenses included in the third lens group G3 may be set to be between 1 and 4. This is advantageous for shortening the overall length of the lens system.

[0046] The number of lenses included in the imaging lens may be between 5 and 10. Having 5 or more lenses is advantageous for achieving compactness while maintaining high performance. Having 10 or fewer lenses is advantageous for shortening the overall length of the lens system.

[0047] The imaging lens may be configured so that the number of cemented lenses included is 0 or 1. In this case, the degree of freedom increases by reducing the number of cemented surfaces, and therefore the aberration correction effect can be improved even with a small number of lenses, thereby enabling high performance.

[0048] In the imaging lens of the present disclosure, the lens closest to the object is a negative meniscus lens, and at least one of the second lens from the object side and the third lens from the object side is a lens other than a negative meniscus lens. Using a negative meniscus lens as the lens closest to the object side is advantageous for achieving a wider angle of view. Using a lens other than a negative meniscus lens as at least one of the second lens from the object side and the third lens from the object side can effectively correct astigmatic difference that is overcorrected by the negative meniscus lens. Note that in this specification, "negative meniscus lens" refers to a meniscus lens with negative refractive power.

[0049] In the example of FIG. 1, the above-mentioned "lens closest to the object," "second lens from the object," and "third lens from the object" correspond to lens L11, lens L12, and lens L13, respectively. However, the above-mentioned "second lens from the object" does not necessarily mean the second lens from the object side in the first lens group G1, but rather the second lens from the object side in the imaging lens. Similarly, the above-mentioned "third lens from the object side" also means the third lens from the object side in the imaging lens. For example, unlike the example of FIG. 1, in an imaging lens in which the first lens group G1 is composed of two lenses, the above-mentioned "third lens from the object side" refers to the lens closest to the object side in the second lens group G2.

[0050] In the imaging lens of the present disclosure, the aperture stop St is located closer to the image side than the second lens from the object side. This configuration is advantageous for making the entire lens system compact.

[0051] It is preferable that one or two single lenses having negative refractive power and one or two single lenses having positive refractive power are arranged on the object side of the aperture stop St. It is also preferable that the number of lenses arranged on the object side of the aperture stop St be four or less. Arranging a negative lens on the object side of the aperture stop St is advantageous for achieving a wider angle of view. Furthermore, placing a positive lens on the object side of the aperture stop St is advantageous for correcting chromatic aberration. Using single lenses as described above increases the degree of freedom, which is advantageous for more effective aberration correction, particularly correction of field curvature. Restricting the number of lenses on the object side of the aperture stop St to four or less is advantageous for shortening the overall length of the lens system.

[0052] It is preferable to place a positive lens adjacent to the object side of the aperture stop St. This is advantageous for effectively correcting astigmatism that occurs in the lens closest to the object side.

[0053] When a positive lens is arranged adjacent to the object side of the aperture stop St, it is preferable to arrange an Lffn lens having negative refractive power adjacent to the object side of the positive lens arranged adjacent to the object side of the aperture stop St. That is, it is preferable to arrange an Lffn lens having negative refractive power, a positive lens, and the aperture stop St in succession from the object side to the image side. Arranging a negative lens adjacent to the positive lens arranged adjacent to the object side of the aperture stop St is advantageous for effectively correcting axial chromatic aberration and lateral chromatic aberration. In the example of FIG. 1, the Lffn lens corresponds to lens L13.

[0054] It is preferable to locate a positive lens adjacent to the image side of the aperture stop St. This is advantageous for effectively correcting residual astigmatism that occurs in all lens groups located on the object side of the aperture stop St.

[0055] It is preferable that one to three negative lenses and two to four positive lenses are arranged on the image side of the aperture stop St, and that the number of lenses arranged on the image side of the aperture stop St is seven or less. In this case, the number of positive lenses and negative lenses is balanced, making it easier to balance the correction of field curvature and chromatic aberration, which is advantageous for maintaining high performance. Furthermore, keeping the number of lenses on the image side of the aperture stop St to seven or less is advantageous for shortening the overall length of the lens system.

[0056] The imaging lens of the present disclosure may be configured to include an aspherical lens. In the technology of the present disclosure, the radius of a circle passing through three points on the lens surface, including a point on the optical axis and two points at the outermost ends of the effective diameter, in a cross section including the optical axis Z, is defined as Rc of that lens surface. For a spherical lens surface, the radius of curvature of that lens surface is Rc. For an aspherical lens surface, the approximate radius of curvature, described below, is Rc.

[0057] The approximate radius of curvature will be described with reference to Figure 3. Figure 3 is an explanatory diagram showing a cross section including the optical axis Z. The lens surface Sa on the right side of the lens Lex shown in Figure 3 has an aspheric shape. Figure 3 shows three points: point Pa on the optical axis of lens surface Sa, point Pe1 at the outermost end of the effective diameter of lens surface Sa on the upper side in the figure, and point Pe2 at the outermost end of the effective diameter of lens surface Sa on the lower side in the figure, and a circle C passing through these three points is shown by a two-dot chain line.

[0058] In the technology disclosed herein, the radius of a circle C that passes through the above three points is the approximate radius of curvature of the lens surface Sa, and is shown as radius Rc in Fig. 3. The sign of radius Rc is positive if point Pa on the optical axis of circle C is closer to the object than center O, and negative if point Pa on the optical axis of circle C is closer to the image than center O. Similarly, the sign of Rc for a spherical lens surface is positive if the point on the optical axis of the lens surface is closer to the object than center O of the circle that passes through the above three points, and negative if it is closer to the image.

[0059] The "outermost point of the effective diameter" of a lens surface refers to the intersection of the outermost ray of light used in imaging on that lens surface with that lens surface. Here, "outside" refers to the radially outward direction centered on the optical axis Z, i.e., the side away from the optical axis Z. For example, in the lens surface closest to the object in the upper diagram of Figure 2, if lower ray 3b is the outermost ray, the intersection of lower ray 3b and this lens surface is the outermost point of the effective diameter. The height of the outermost point of the effective diameter from the optical axis Z is the effective radius, and twice the effective radius is the effective diameter.

[0060] It is preferable that the third lens group G3 includes an aspherical lens. In this case, it is preferable that the number of aspherical lenses included in the third lens group G3 whose object-side lens surface is aspherical and whose object-side lens surface has a negative Rc sign is one or two. This is advantageous for achieving both a wide angle and compactness. Furthermore, the use of an aspherical lens makes it easier to optimize the distortion curve.

[0061] The first lens group G1 preferably includes, in order from the object side to the image side, a negative subgroup G1n and one positive lens. The negative subgroup G1n is composed of one or two negative lenses in which the Rc of the object-side lens surface and the Rc of the image-side lens surface have the same sign. Furthermore, at least one lens surface included in the negative subgroup G1n has an aspherical shape. This configuration is advantageous for correcting distortion and chromatic aberration of magnification.

[0062] As an example, the negative subgroup G1n of the imaging lens in Fig. 1 is composed of a single lens, the negative meniscus lens L11, whose object-side and image-side surfaces both have positive Rc values, and whose object-side and image-side surfaces are both aspherical.

[0063] The imaging lens of the present disclosure preferably includes at least one lens surface having an inflection point. An inflection point is a point where the surface shape changes from a convex shape to a concave shape or from a concave shape to a convex shape, i.e., a point where the sign of the radius of curvature changes. By having an inflection point on the lens surface, the refractive power of the peripheral part of the lens can be determined independently of the refractive power of the paraxial region.

[0064] The imaging lens preferably includes a lens surface having an inflection point, and at least one of the intersections of the lens surface having the inflection point and the optical axis Z is a specific intersection point described below. Here, DL is the distance on the optical axis from the lens surface of the first lens group G1 closest to the object to the lens surface of the third lens group G3 closest to the image. The specific intersection point is a point where the lens surface having the inflection point intersects with the optical axis Z, and is located within a range of 0.3×DL from the intersection of the lens surface of the first lens group G1 closest to the object and the optical axis Z toward the image side, or within a range of 0.3×DL from the intersection of the lens surface of the third lens group G3 closest to the image side and the optical axis Z toward the object side, when focused on an object at infinity. Note that in this specification, the phrase "in the range from" means a range that includes the "to" part. At the lens surface closer to the object side and the lens surface closer to the image side, the light beams at each angle of view are separated. Therefore, by providing inflection points on these surfaces, it becomes easy to effectively correct aberrations such as field curvature while satisfactorily correcting spherical aberration.

[0065] As an example, Fig. 4 shows a cross-sectional view of the imaging lens of Fig. 1 and indicates the distance DL for this imaging lens. Fig. 4 also shows a range of 0.3 × DL extending from the intersection of the lens surface of the first lens group G1 closest to the object with the optical axis Z toward the image side, and a range of 0.3 × DL extending from the intersection of the lens surface of the third lens group G3 closest to the image with the optical axis Z toward the object side. In the example of Fig. 4, the object-side surface of lens L11, the image-side surface of lens L21, the object-side surface of lens L24, the image-side surface of lens L24, and the image-side surface of lens L31 have inflection points. Of these, the intersections of the optical axis Z with four surfaces—the object-side surface of lens L11, the object-side surface of lens L24, the image-side surface of lens L24, and the image-side surface of lens L31—are specific intersection points P1, P2, P3, and P4. The intersection between the image-side surface of the lens L21 and the optical axis Z is outside the above range, and is therefore not a specific intersection.

[0066] 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."

[0067] 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 in the first lens group G1 closest to the object to the lens surface in the third lens group G3 closest to the image, and the back focus of the entire system in air equivalent distance. Y is the maximum image height. As an example, Figure 2 shows the maximum image height Y. Ensuring that the corresponding value of conditional expression (1) does not fall below the lower limit is advantageous for ensuring the number of lenses required for aberration correction. Ensuring that the corresponding value of conditional expression (1) does not fall above the upper limit facilitates compactness. 1 <TL / Y<4.5 (1)

[0068] In order to obtain better characteristics, the lower limit of conditional expression (1) should preferably be 1.1, more preferably 1.2, and even more preferably 1.3. In order to obtain better characteristics, the upper limit of conditional expression (1) should preferably be 4.3, more preferably 4.2, and even more preferably 4.1.

[0069] It is preferable that the imaging lens satisfy the following conditional expression (2). Here, 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. As an example, FIG. 2 shows the above maximum half angle of view ωm, where tan is the tangent. By ensuring that the corresponding value of conditional expression (2) is not equal to or less than the lower limit, barrel distortion can be reduced. This makes it easy to keep image quality degradation after image processing correction at an acceptable level when image processing is performed on an image captured with the imaging lens. By ensuring that the corresponding value of conditional expression (2) is not equal to or greater than the upper limit, the image height position relative to the angle of incidence is lowered, allowing the lens diameter to be reduced, which is advantageous for reducing the size of the entire optical system. -0.18<(Yf×tanωm) / (f×tanωm)<-0.02 (2)

[0070] In order to obtain better characteristics, the lower limit of conditional expression (2) should preferably be set to -0.175, more preferably -0.16, even more preferably -0.145, and even more preferably -0.14.In order to obtain better characteristics, the upper limit of conditional expression (2) should preferably be set to -0.03, even more preferably -0.04, even more preferably -0.05, and even more preferably -0.06.

[0071] It is preferable that the imaging lens satisfy the following conditional expression (3). Here, the unit of ωm is degrees. By ensuring that the corresponding value of conditional expression (3) is not equal to or smaller than the lower limit, the added value of the ultra-wide-angle lens system is increased. By ensuring that the corresponding value of conditional expression (3) is not equal to or larger than the upper limit, it becomes easy to achieve both a small filter diameter and good optical performance. 47<ωm<60 (3)

[0072] In order to obtain better characteristics, the lower limit of conditional expression (3) should preferably be set to 48, more preferably to 49, even more preferably to 50, and even more preferably to 51. In order to obtain better characteristics, the upper limit of conditional expression (3) should preferably be set to 59, more preferably to 58, even more preferably to 57, and even more preferably to 56.

[0073] When the focal length of the first lens group G1 is fG1, it is preferable that the imaging lens satisfy the following conditional expression (4). By ensuring that the corresponding value of conditional expression (4) is not equal to or less than the lower limit, it becomes easy to shorten the overall length of the lens system, which is advantageous for miniaturization. By ensuring that the corresponding value of conditional expression (4) is not equal to or greater than the upper limit, it becomes easy to achieve a wide angle. 0.01 <f / fG1<1.6 (4)

[0074] In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (4) be set to 1.55, and even more preferable that it be set to 1.5.

[0075] It is preferable that the imaging lens satisfy the following conditional expression (5). Here, dL1St is the distance on the optical axis from the lens surface in the first lens group G1 closest to the object to the aperture stop St when focused on an object at infinity. As an example, FIG. 4 shows the above distance dL1St. Ensuring that the value corresponding to conditional expression (5) is not equal to or less than the lower limit thereof is advantageous for reducing the angle of incidence of off-axial chief rays on the image plane Sim. Ensuring that the value corresponding to conditional expression (5) is not equal to or greater than the upper limit thereof is advantageous for shortening the overall length of the lens system. 0.1 <dL1St / Y<2.1 (5)

[0076] In order to obtain better characteristics, the lower limit of conditional expression (5) should preferably be set to 0.2, and more preferably to 0.3.In order to obtain better characteristics, the upper limit of conditional expression (5) should preferably be set to 1.9, and more preferably to 1.7.

[0077] It is preferable that the imaging lens satisfy the following conditional expression (6). Here, CRA is the angle between the chief ray at the maximum image height incident on the image plane Sim when focused on an object at infinity and an axis parallel to the optical axis Z. The unit of CRA is degrees. FIG. 5 shows an enlarged partial view of the imaging lens shown in FIG. 1, including the lens L31, optical member PP, and the upper part of the image plane Sim, illustrating the above-mentioned angle CRA as an example. In FIG. 5, the chief ray 3c incident on the image plane Sim at the maximum half angle of view ωm is indicated by a solid line, and the axis Zp passing through the intersection of the chief ray 3c and the image plane Sim and parallel to the optical axis Z is indicated by a dashed line. The chief ray 3c at the maximum half angle of view ωm corresponds to the chief ray at the maximum image height. By ensuring that the value corresponding to conditional expression (6) is not less than the lower limit, the distance from the aperture stop St to the image plane Sim can be shortened, which is advantageous for shortening the overall length of the lens system. By ensuring that the corresponding value of conditional expression (6) is not equal to or greater than the upper limit, the back focus can be lengthened, making it easier to insert various filters such as an infrared cut filter. 16<|CRA|<69 (6)

[0078] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (6) be set to 18, and even more preferable that it be set to 20. In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (6) be set to 67, and even more preferable that it be set to 65.

[0079] If the back focus of the entire system in terms of air equivalent distance is Bf, it is preferable that the imaging lens satisfy the following conditional expression (7). The back focus Bf of the entire system in terms of air equivalent distance is the air equivalent distance on the optical axis from the lens surface of the imaging lens closest to the image plane Sim. By ensuring that the value corresponding to conditional expression (7) is not equal to or smaller than the lower limit, it becomes easy to insert various filters such as an infrared cut filter. By ensuring that the value corresponding to conditional expression (7) is not equal to or larger than the upper limit, it is advantageous to ensure the number of lenses required for aberration correction. 0.06 <Bf / TL<0.3 (7)

[0080] In order to obtain better characteristics, the lower limit of conditional expression (7) should preferably be set to 0.08, and more preferably to 0.1.In order to obtain better characteristics, the upper limit of conditional expression (7) should preferably be set to 0.28, and more preferably to 0.26.

[0081] It is preferable that the imaging lens satisfy the following conditional expression (8). Here, the unit of f is mm (millimeters). Fno is the maximum F-number of the imaging lens when focused on an object at infinity. By ensuring that the corresponding value of conditional expression (8) is not equal to or less than the lower limit, it is possible to ensure brightness that allows marketability to be maintained. By ensuring that the corresponding value of conditional expression (8) is not equal to or greater than the upper limit, it is advantageous to maintain high performance while ensuring the required brightness. 1.7 <f / Fno<4.1 (8)

[0082] In order to obtain better characteristics, the lower limit of conditional expression (8) should preferably be set to 1.8, and more preferably to 1.9.In order to obtain better characteristics, the upper limit of conditional expression (8) should preferably be set to 3.9, and more preferably to 3.7.

[0083] When the focal length of the second lens group G2 is fG2, it is preferable that the imaging lens satisfy the following conditional expression (9). By ensuring that the corresponding value of conditional expression (9) is not below the lower limit, the desired refractive power of the second lens group G2 can be ensured, and the amount of movement during focusing can be reduced. This is advantageous for making the lens system more compact. By ensuring that the corresponding value of conditional expression (9) is not above the upper limit, aberration fluctuations during focusing can be suppressed, and this can also suppress fluctuations in optical performance when the object distance changes. 0.24<|f / fG2|<2.4 (9)

[0084] In order to obtain better characteristics, the lower limit of conditional expression (9) should preferably be set to 0.26, and more preferably to 0.28.In order to obtain better characteristics, the upper limit of conditional expression (9) should preferably be set to 2.2, and more preferably to 2.

[0085] In a configuration in which a positive lens is arranged adjacent to the image side of the aperture stop St, it is preferable that the imaging lens satisfy the following conditional expression (10). Here, the Abbe number based on the d-line of the positive lens arranged adjacent to the image side of the aperture stop St is defined as νrp. Satisfying conditional expression (10) makes it easy to correct lateral chromatic aberration and axial chromatic aberration. 34<νrp<87 (10)

[0086] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (10) be set to 36, and even more preferable that it be set to 38. In order to obtain even better characteristics, it is more preferable that the upper limit of conditional expression (10) be set to 85, and even more preferable that it be set to 83.

[0087] In a configuration in which a positive lens is arranged adjacent to the object side of the aperture stop St, it is preferable that the imaging lens satisfy the following conditional expression (11). Here, the Abbe number based on the d-line of the positive lens arranged adjacent to the object side of the aperture stop St is defined as νfp. Satisfying conditional expression (11) makes it easy to correct lateral chromatic aberration and axial chromatic aberration. 23<νfp<61 (11)

[0088] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (11) be set to 25, and even more preferable that it be set to 27. In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (11) be set to 59, and even more preferable that it be set to 57.

[0089] In a configuration in which a positive lens is disposed adjacent to the object side of aperture stop St, and an Lffn lens having negative refractive power is disposed adjacent to the object side of this positive lens, it is preferable that the imaging lens satisfy the following conditional expression (12). Here, the Abbe number of the Lffn lens based on the d-line is defined as vffn. Satisfying conditional expression (12) makes it easy to correct lateral chromatic aberration and axial chromatic aberration. 16<νffn<100 (12)

[0090] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (12) be set to 17, even more preferably to 18, and even more preferably to 35. In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (12) be set to 98, even more preferably to 96, and even more preferably to 45.

[0091] In a configuration in which the first lens group G1 includes, in order from the object side to the image side, the above-mentioned negative subgroup G1n and one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (13). Here, the average value of the refractive index at the d-line of all lenses included in the negative subgroup G1n is defined as N1nave. By ensuring that the corresponding value of conditional expression (13) is not equal to or less than the lower limit, it becomes easy to obtain the desired refractive power without reducing the absolute value of the radius of curvature of the image-side lens surface of the lens included in the negative subgroup G1n. Therefore, the absolute value of the radius of curvature of the image-side lens surface can be increased, thereby improving workability. By ensuring that the corresponding value of conditional expression (13) is not equal to or greater than the upper limit, it is possible to suppress a decrease in transmittance. 1.45 <N1nave<2.3 (13)

[0092] In order to obtain better characteristics, the lower limit of conditional expression (13) should preferably be set to 1.5, and more preferably to 1.55.In order to obtain better characteristics, the upper limit of conditional expression (13) should preferably be set to 2.2, and more preferably to 2.1.

[0093] In a configuration in which the first lens group G1 includes, in order from the object side to the image side, the above-mentioned negative subgroup G1n and one positive lens, it is preferable that the imaging lens satisfy the following conditional expression (14). Here, the average value of the Abbe numbers based on the d-line of all the lenses included in the negative subgroup G1n is defined as ν1nave. By ensuring that the corresponding value of conditional expression (14) is not equal to or less than the lower limit, correction of lateral chromatic aberration becomes easy. By ensuring that the corresponding value of conditional expression (14) is not equal to or greater than the upper limit, the use of soft materials that are easily scratched can be suppressed, which is advantageous for improving the quality of the appearance. 16<ν1nave<85 (14)

[0094] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (14) be set to 17, even more preferably to 18, and even more preferably to 25. In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (14) be set to 82, even more preferably to 72, and even more preferably to 35.

[0095] In a configuration in which the first lens group G1 includes, in succession from the object side to the image side, the above-mentioned negative sub group G1n and one positive lens, it is more preferable that the imaging lens simultaneously satisfy conditional expressions (13) and (14).

[0096] It is preferable that the imaging lens satisfy the following conditional expression (15). Here, the composite focal length of all lenses on the object side of the aperture stop St when focused on an object at infinity is defined as fGf. The composite focal length of all lenses on the image side of the aperture stop St when focused on an object at infinity is defined as fGr. By ensuring that the corresponding value of conditional expression (15) is not equal to or less than the lower limit, it is advantageous to achieve a good balance between the object-side refractive power of the aperture stop St and the image-side refractive power of the aperture stop St, and it also becomes easier to ensure back focus. By ensuring that the corresponding value of conditional expression (15) is not equal to or greater than the upper limit, it is advantageous to achieve a good balance between the object-side refractive power of the aperture stop St and the image-side refractive power of the aperture stop St, and it also becomes easier to correct barrel distortion. -10 <fGf / fGr<31 (15)

[0097] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (15) be set to -8, even more preferably to -6, and even more preferably to 1.7.In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (15) be set to 29, even more preferably to 27, and even more preferably to 6.

[0098] In the configuration having the specific intersection point described above, it is preferable that at least one of the lens surfaces having the specific intersection point satisfy the following conditional expression (16). Note that a "lens surface having a specific intersection point" refers to a lens surface whose intersection point with the optical axis Z is the specific intersection point. Here, the refractive power of the lens surface having the specific intersection point is φa. The refractive power of the imaging lens when focused on an object at infinity is φ. φ=1 / f. Satisfying conditional expression (16) prevents the refractive power of the lens surfaces having the specific intersection point and inflection point from becoming too strong, thereby preventing excessive processing sensitivity and assembly sensitivity. This is also advantageous for effectively correcting spherical aberration, field curvature, and the like. -2<φa / φ<3 (16)

[0099] The refractive power φa of a lens surface is expressed as φa=(Nout-Nin) / R, where Nin is the refractive index of the medium on the incident side of the lens surface, Nout is the refractive index of the medium on the exit side of the lens surface, and R is the radius of curvature of the lens surface.

[0100] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (16) be set to -1, and even more preferable that it be set to -0.8.In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (16) be set to 2.5, and even more preferable that it be set to 2.2.

[0101] In the configuration having the specific intersection point described above, it is preferable that at least one of the lens surfaces having the specific intersection point satisfy the following conditional expression (17). Here, for each lens surface, the height of the inflection point from the optical axis Z is Hinf, and the height of the point at the outermost end of the effective diameter from the optical axis Z is He. Hinf and He are assumed to be positive values. As described above, He corresponds to the effective radius. Note that when one lens surface has multiple inflection points, it is sufficient that at least one of the inflection points satisfies conditional expression (17). As an example, FIG. 4 shows the inflection point Pinf, the height Hinf, the point at the outermost end of the effective diameter Pe, and the height He for the object-side lens surface of lens L11. By ensuring that the corresponding value of conditional expression (17) is not less than the lower limit, the inflection point can be located at a position away from the optical axis Z, which is advantageous for effectively correcting field curvature while satisfactorily correcting spherical aberration. By making sure that the corresponding value of conditional expression (17) is not equal to or greater than the upper limit, it is advantageous for correcting curvature of field. 0.3 <Hinf / He<0.99 (17)

[0102] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (17) be set to 0.4, and even more preferable that it be set to 0.55.In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (17) be set to 0.98.

[0103] It is preferable that the imaging lens satisfy the following conditional expression (18). By ensuring that the corresponding value of conditional expression (18) is not equal to or smaller than the lower limit, it is advantageous to ensure the number of lenses required for aberration correction. By ensuring that the corresponding value of conditional expression (18) is not equal to or larger than the upper limit, it becomes easier to achieve compactness. 1 <TL / f<6 (18)

[0104] In order to obtain better characteristics, the lower limit of conditional expression (18) should preferably be set to 1.25, and more preferably to 1.5.In order to obtain better characteristics, the upper limit of conditional expression (18) should preferably be set to 5.5, and more preferably to 5.1.

[0105] It is preferable that the imaging lens satisfy the following conditional expression (19): Satisfying conditional expression (19) is advantageous for suppressing the occurrence of aberrations and for reducing the angle of incidence of off-axis chief rays onto the image plane Sim. -1.1 <f / fGf<1.3 (19)

[0106] In order to obtain better characteristics, the lower limit of conditional expression (19) should preferably be set to -0.9, and more preferably to -0.7.In order to obtain better characteristics, the upper limit of conditional expression (19) should preferably be set to 1.1, and more preferably to 0.9.

[0107] It is preferable that the imaging lens satisfy the following conditional expression (20): Satisfying conditional expression (20) is advantageous for suppressing the occurrence of aberrations and for reducing the angle of incidence of off-axis chief rays onto the image plane Sim. -0.4 <f / fGr<1.4 (20)

[0108] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (20) be set to −0.2, and even more preferable that it be set to 0. In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (20) be set to 1.2, and even more preferable that it be set to 1.

[0109] It is preferable that the imaging lens satisfy the following conditional expression (21). Here, the average value of the Abbe numbers based on the d-line of all negative lenses located on the object side of the aperture stop St is defined as νGfaven. The average value of the Abbe numbers based on the d-line of all positive lenses located on the object side of the aperture stop St is defined as νGfavep. Conditional expression (21) is a conditional expression for effectively correcting chromatic aberration over the entire wavelength range of the visible range. By ensuring that the corresponding value of conditional expression (21) is not equal to or smaller than the lower limit, it is possible to improve the correction effect of residual secondary spectrum. By ensuring that the corresponding value of conditional expression (21) is not equal to or larger than the upper limit, it is possible to improve the correction effect of primary chromatic aberration. 0.6<|νGfaven-νGfavep|<47 (21)

[0110] In order to obtain better characteristics, the lower limit of conditional expression (21) should preferably be set to 0.8, more preferably to 1, and even more preferably to 6. In order to obtain better characteristics, the upper limit of conditional expression (21) should preferably be set to 45, more preferably to 43, and even more preferably to 30.

[0111] It is preferable that the imaging lens satisfy the following conditional expression (22). Here, the average value of the Abbe numbers based on the d-line of all negative lenses located on the image side of the aperture stop St is designated as νGraven. The average value of the Abbe numbers based on the d-line of all positive lenses located on the image side of the aperture stop St is designated as νGravep. Conditional expression (22) is a conditional expression for effectively correcting chromatic aberration over the entire wavelength range of the visible range. By ensuring that the corresponding value of conditional expression (22) is not equal to or smaller than the lower limit, it is possible to improve the correction effect of residual secondary spectrum. By ensuring that the corresponding value of conditional expression (22) is not equal to or larger than the upper limit, it is possible to improve the correction effect of primary chromatic aberration. 4<|νGraven-νGravep|<52 (22)

[0112] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (22) be set to 6, even more preferably to 8, and even more preferably to 30. In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (22) be set to 50, even more preferably to 49, and even more preferably to 48.

[0113] It is preferable that the imaging lens satisfy the following conditional expression (23). By ensuring that the corresponding value of conditional expression (23) is not below the lower limit, it becomes easy to maintain high performance and also to make the lens compact. By ensuring that the corresponding value of conditional expression (23) is not above the upper limit, it becomes easy to ensure both a small F-number and a wide angle. 0.8 <Fno / tanωm<3.2 (23)

[0114] In order to obtain better characteristics, it is more preferable that the lower limit of conditional expression (23) be set to 1, and even more preferable that it be set to 1.2. In order to obtain better characteristics, it is more preferable that the upper limit of conditional expression (23) be set to 3, and even more preferable that it be set to 2.8.

[0115] When the focal length of the third lens group G3 is fG3, it is preferable that the imaging lens satisfy the following conditional expression (24). By ensuring that the corresponding value of conditional expression (24) is not equal to or smaller than the lower limit, the angle of incidence of the off-axial chief ray on the image plane Sim can be reduced, thereby suppressing peripheral light falloff. By ensuring that the corresponding value of conditional expression (24) is not equal to or larger than the upper limit, it becomes easy to suppress distortion. -2.4 <f / fG3<1 (24)

[0116] In order to obtain even better characteristics, the lower limit of conditional expression (24) should preferably be set to −2.2, and even more preferably to −2. In order to obtain even better characteristics, the upper limit of conditional expression (24) should preferably be set to 0.8, and even more preferably to 0.6.

[0117] It is preferable that the imaging lens satisfy the following conditional expression (25). Conditional expression (25) relates to the second lens group G2 constituting the focus group. Here, the lateral magnification of the second lens group G2 when focused on an object at infinity is defined as βfoc. The lateral magnification of the third lens group G3 when focused on an object at infinity is defined as βfocR. By ensuring that the corresponding value of conditional expression (25) is not below its lower limit, the amount of movement of the image plane Sim relative to the amount of movement of the second lens group G2 in the optical axis direction can be increased, thereby reducing the amount of movement of the second lens group G2 during focusing, which is advantageous for shortening the overall length of the lens system. By ensuring that the corresponding value of conditional expression (25) is not above its upper limit, the amount of movement of the image plane Sim relative to the amount of movement of the second lens group G2 in the optical axis direction can be reduced, which facilitates control during focusing and is advantageous for accurate focusing. 0.4<|(1-βfoc 2 )×βfocR 2 |<3.8 (25)

[0118] In order to obtain better characteristics, the lower limit of conditional expression (25) should preferably be set to 0.45, and more preferably to 0.5.In order to obtain better characteristics, the upper limit of conditional expression (25) should preferably be set to 3.6, and more preferably to 3.4.

[0119] It is preferable that the imaging lens satisfy the following conditional expression (26). Here, the unit of Y is mm (millimeters). By ensuring that the corresponding value of conditional expression (26) is not equal to or smaller than the lower limit, it becomes easy to ensure that the number of pixels of the imaging element used in combination with the imaging lens is sufficient to achieve high resolution. By ensuring that the corresponding value of conditional expression (26) is not equal to or larger than the upper limit, it becomes easy to reduce the size. 2 <Y<17 (26)

[0120] In order to obtain better characteristics, it is more preferable that the lower limit of conditional formula (26) be set to 3, even more preferably to 4, and even more preferably to 5. In order to obtain better characteristics, it is more preferable that the upper limit of conditional formula (26) be set to 16, even more preferably to 15, and even more preferably to 8.

[0121] 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 lens group may be different from that in the example of FIG. 1. The signs of the refractive powers of the second lens group G2 and the third lens group G3 may be different from those in the example of FIG. 1.

[0122] 1 is composed of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. This refractive power arrangement makes the lens a telephoto type, which is advantageous for size reduction.

[0123] As will be shown in the examples described later, the imaging lens of the present disclosure may be configured to include, 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 negative refractive power. This configuration also results in a telephoto type lens system, which is advantageous for miniaturization.

[0124] As shown in another embodiment described later, the imaging lens of the present disclosure may be configured to include, 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. By making the second lens group G2, which is the focus group, the only group having negative refractive power, it is possible to impart a relatively strong refractive power to the second lens group G2, which makes it easy to reduce the amount of movement of the focus group during focusing.

[0125] As will be shown in yet another embodiment described later, the imaging lens of the present disclosure may be configured to include, 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 positive refractive power. Having all lens groups have positive refractive power is advantageous for miniaturization.

[0126] In the imaging lens of the present disclosure, the lens surface to be aspherical may be a surface different from the example shown in FIG. 1. The aspherical shape may be formed by grinding or molding. A hybrid aspherical lens may also be used as the lens having an aspherical shape. The lens material may be glass or resin.

[0127] In the imaging lens of the present disclosure, in order to correct chromatic aberration, any of the lens groups may be configured to have a gradient index lens such as a GRIN (Gradient Index Lens) lens, or a diffractive optical element.

[0128] In the imaging lens of the present disclosure, an anti-reflection coating may be applied to the lens to maintain transmittance over a wide wavelength range. The anti-reflection coating may suppress reflection over the entire wavelength range used, or may suppress reflection only over several selected wavelength ranges used. The anti-reflection coating may be a special coating configured to suppress reflection by forming nano-level structures in a moth-eye shape on the lens surface.

[0129] The above-described preferred and possible configurations can be arbitrarily combined within a range that does not cause a contradiction, and it is preferable that they be selectively adopted as appropriate according to the required specifications.

[0130] As an example, one preferred embodiment of the imaging lens of the present disclosure comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, 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, the lens closest to the object side is a negative meniscus lens, at least one of the second lens from the object side and the third lens from the object side is a lens other than a negative meniscus lens, an aperture stop St is positioned closer to the image side than the second lens from the object side, and the above conditional expressions (1) and (2) are satisfied.

[0131] 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.

[0132] [Example 1] A cross-sectional view of the configuration of the imaging lens of Example 1 is shown in Figure 1, and since the illustration method and configuration are as described above, some redundant explanation will be omitted here. The imaging lens of Example 1 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0133] For the imaging lens of Example 1, basic lens data is shown in Table 1, specifications are shown in Table 2, variable surface spacing during focusing is shown in Table 3, and aspherical coefficients are shown in Tables 4A and 4B.

[0134] The basic lens data table is structured as follows: The "Sn" column lists the surface numbers, with the surface closest to the object designated as surface 1 and the numbers increasing by one as you move toward the image. The "R" column lists the radius of curvature of each surface. The "D" column lists the on-axis surface spacing between each surface and its adjacent image-side surface. The "Nd" column lists the refractive index of each lens relative to the d-line. The "νd" column lists the Abbe number of each lens relative to the d-line. The "ED" column lists the effective diameter of each surface. Half of the effective diameter corresponds to the height He of the outermost point of the clear diameter from the optical axis Z. For surfaces with inflection points, the "Hinf" column lists the height of each inflection point from the optical axis Z. For surfaces with multiple inflection points, the values for each inflection point are listed, separated by a " / ". For surfaces with inflection points but no specific intersection, the values are listed in parentheses for reference.

[0135] 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.

[0136] Table 2 shows the focal length (f) of the entire system, the back focal length (Bf) in air equivalent distance, the maximum F-number (Fno), and the maximum full angle of view (2ωm) based on the d-line. The [°] in the maximum full angle of view column indicates that the unit is degrees. Table 2 shows the values when focused on an object at infinity.

[0137] In Table 3, the "Infinity" column shows the variable surface distance when focused on an object at infinity. The top row on the far right shows the object distance of the closest object, and the row below that shows the variable surface distance when focused on the closest object. For example, in Example 1, the object distance of the closest object is 0.150 m (meters).

[0138] In the basic lens data, the aspherical surface numbers are marked with an *, and the paraxial radius of curvature is listed in the aspherical radius of curvature column. In Tables 4A and 4B, the Sn row shows the aspherical surface numbers, and the KA and Am (m = 3, 4, 5, ..., 20) rows show the numerical values of the aspherical coefficients for each aspherical surface. The "E±n" (n: integer) of the numerical values of the aspherical coefficients in Tables 4A and 4B is 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.

[0139] In the data in each table, degrees are used as the unit of angle, and mm (millimeters) are used as the unit of length other than the object distance, but since the optical system can be used with proportional enlargement or reduction, other appropriate units can also be used. Also, in each table shown below, values are rounded to a predetermined number of digits.

[0140] [Table 1]

[0141] [Table 2]

[0142] [Table 3]

[0143] [Table 4A]

[0144] [Table 4B]

[0145] FIG. 6 shows aberration diagrams of the imaging lens of Example 1. From left to right, FIG. 6 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration. In FIG. 6, the upper row labeled "Infinity" shows aberration diagrams focused on an object at infinity, while the lower row labeled "0.150 m" shows aberration diagrams focused on a closest object. In the spherical aberration diagrams, aberrations at the d-line, C-line, and F-line are shown by solid lines, long-dashed lines, and short-dashed lines, respectively. In the astigmatism diagrams, aberrations at the d-line in the sagittal direction are shown by solid lines, and aberrations at the d-line in the tangential direction are shown by short-dashed lines. In the distortion diagrams, aberrations at the d-line are shown by solid lines. In the lateral chromatic aberration diagrams, aberrations at the C-line and F-line are shown by long-dashed lines and short-dashed lines, respectively. In the spherical aberration diagrams, the maximum F-number is indicated after "FNo.=". In other aberration diagrams, the value of the maximum half angle of view is shown after "ω=". The FNo. and ω in the upper diagram correspond to Fno and ωm in the conditional expression mentioned above, respectively.

[0146] The symbols, meanings, notation methods, and illustration methods of each data item related to the first embodiment are basically the same in the following embodiments unless otherwise specified, and therefore, redundant explanations will be omitted below. Note that in the cross-sectional views of the second and subsequent embodiments, the symbols of the negative subgroup G1n are omitted.

[0147] [Example 2] 7 shows a cross-sectional view of the configuration of the imaging lens of Example 2. The imaging lens of Example 2 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0148] The first lens group G1 consists of, in order from the object side to the image side, four lenses, L11 to L14, and an aperture stop St. The second lens group G2 consists of, in order from the object side to the image side, four lenses, L21 to L24. The third lens group G3 consists of a single lens, lens L31.

[0149] 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 Tables 8A and 8B, and aberration diagrams are shown in FIG.

[0150] [Table 5]

[0151] [Table 6]

[0152] [Table 7]

[0153] [Table 8A]

[0154] [Table 8B]

[0155] [Example 3] 9 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 focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0156] The first lens group G1 consists of, in order from the object side to the image side, four lenses, L11 to L14, and an aperture stop St. The second lens group G2 consists of, in order from the object side to the image side, four lenses, L21 to L24. The third lens group G3 consists of a single lens, lens L31.

[0157] For the imaging lens of Example 3, basic lens data is shown in Table 9, specifications are shown in Table 10, variable surface spacing is shown in Table 11, aspherical coefficients are shown in Tables 12A and 12B, and aberration diagrams are shown in FIG.

[0158] [Table 9]

[0159] [Table 10]

[0160] [Table 11]

[0161] [Table 12A]

[0162] [Table 12B]

[0163] [Example 4] 11 shows a cross-sectional view of the configuration of the imaging lens of Example 4. The imaging lens of Example 4 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the image side along the optical axis Z.

[0164] The first lens group G1 consists, in order from the object side to the image side, of lenses L11-L14, an aperture stop St, and a lens L15. The second lens group G2 consists, in order from the object side to the image side, of two lenses, lenses L21-L22. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31-L32.

[0165] For the imaging lens of Example 4, basic lens data is shown in Table 13, specifications are shown in Table 14, variable surface spacing is shown in Table 15, aspherical coefficients are shown in Tables 16A and 16B, and each aberration diagram is shown in FIG.

[0166] [Table 13]

[0167] [Table 14]

[0168] [Table 15]

[0169] [Table 16A]

[0170] [Table 16B]

[0171] [Example 5] 13 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 focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0172] The first lens group G1 consists of, in order from the object side to the image side, four lenses, L11 to L14, and an aperture stop St. The second lens group G2 consists of, in order from the object side to the image side, four lenses, L21 to L24. The third lens group G3 consists of a single lens, lens L31.

[0173] 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 Tables 20A and 20B, and aberration diagrams are shown in FIG.

[0174] [Table 17]

[0175] [Table 18]

[0176] [Table 19]

[0177] [Table 20A]

[0178] [Table 20B]

[0179] [Example 6] 15 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 positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the image side along the optical axis Z.

[0180] 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 lenses L14 to L16. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0181] For the imaging lens of Example 6, basic lens data is shown in Table 21, specifications in Table 22, variable surface spacing in Table 23, aspherical coefficients in Table 24, and each aberration diagram is shown in FIG.

[0182] [Table 21]

[0183] [Table 22]

[0184] [Table 23]

[0185] [Table 24]

[0186] [Example 7] 17 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 positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the image side along the optical axis Z.

[0187] 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 lenses L14 and L15. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0188] 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.

[0189] [Table 25]

[0190] [Table 26]

[0191] [Table 27]

[0192] [Table 28]

[0193] [Example 8] 19 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 positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the image side along the optical axis Z.

[0194] 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 lenses L14 to L15. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of three lenses, lenses L31 to L33.

[0195] 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.

[0196] [Table 29]

[0197] [Table 30]

[0198] [Table 31]

[0199] [Table 32]

[0200] [Example 9] 21 shows a cross-sectional view of the configuration of the imaging lens of Example 9. The imaging lens of Example 9 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the image side along the optical axis Z.

[0201] 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 lenses L14 to L15. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of three lenses, lenses L31 to L33.

[0202] For the imaging lens of Example 9, basic lens data is shown in Table 33, specifications in Table 34, variable surface spacing in Table 35, aspherical coefficients in Table 36, and each aberration diagram is shown in FIG.

[0203] [Table 33]

[0204] [Table 34]

[0205] [Table 35]

[0206] [Table 36]

[0207] [Example 10] 23 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 positive refractive power, and a third lens group G3 having positive refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0208] 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 lenses L14 to L17. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0209] For the imaging lens of Example 10, basic lens data is shown in Table 37, specifications are shown in Table 38, variable surface spacing is shown in Table 39, aspherical coefficients are shown in Tables 40A and 40B, and each aberration diagram is shown in FIG.

[0210] [Table 37]

[0211] [Table 38]

[0212] [Table 39]

[0213] [Table 40A]

[0214] [Table 40B]

[0215] [Example 11] 25 shows a cross-sectional view of the configuration of the imaging lens of Example 11. The imaging lens of Example 11 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 focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0216] 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 lenses L14 to L17. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0217] 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 Tables 44A and 44B, and each aberration diagram is shown in FIG.

[0218] [Table 41]

[0219] [Table 42]

[0220] [Table 43]

[0221] [Table 44A]

[0222] [Table 44B]

[0223] [Example 12] 27 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 positive refractive power, and a third lens group G3 having negative refractive power. The focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0224] The first lens group G1 consists of, in order from the object side to the image side, four lenses, L11 to L14, and an aperture stop St. The second lens group G2 consists of, in order from the object side to the image side, three lenses, L21 to L23. The third lens group G3 consists of a single lens, lens L31.

[0225] For the imaging lens of Example 12, basic lens data is shown in Table 45, specifications are shown in Table 46, variable surface spacing is shown in Table 47, aspherical coefficients are shown in Tables 48A and 48B, and each aberration diagram is shown in FIG.

[0226] [Table 45]

[0227] [Table 46]

[0228] [Table 47]

[0229] [Table 48A]

[0230] [Table 48B]

[0231] [Example 13] 29 shows a cross-sectional view of the configuration of the imaging lens of Example 13. The imaging lens of Example 13 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 focus group comprises the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0232] The first lens group G1 consists of, in order from the object side to the image side, three lenses, L11 to L13, and an aperture stop St. The second lens group G2 consists of, in order from the object side to the image side, three lenses, L21 to L23. The third lens group G3 consists of a single lens, lens L31.

[0233] For the imaging lens of Example 13, basic lens data is shown in Table 49, specifications are shown in Table 50, variable surface spacing is shown in Table 51, aspherical coefficients are shown in Tables 52A and 52B, and each aberration diagram is shown in FIG.

[0234] [Table 49]

[0235] [Table 50]

[0236] [Table 51]

[0237] [Table 52A]

[0238] [Table 52B]

[0239] [Example 14] A cross-sectional view of the configuration of the imaging lens of Example 14 is shown in Figure 31. The imaging lens of Example 14 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0240] The first lens group G1 consists, in order from the object side to the image side, of two lenses, lenses L11 and L12, and an aperture stop St. The second lens group G2 consists, in order from the object side to the image side, of three lenses, lenses L21 to L23. The third lens group G3 consists of a single lens, lens L31.

[0241] For the imaging lens of Example 14, basic lens data is shown in Table 53, specifications are shown in Table 54, variable surface spacing is shown in Table 55, aspherical coefficients are shown in Tables 56A and 56B, and each aberration diagram is shown in FIG.

[0242] [Table 53]

[0243] [Table 54]

[0244] [Table 55]

[0245] [Table 56A]

[0246] [Table 56B]

[0247] [Example 15] A cross-sectional view of the configuration of the imaging lens of Example 15 is shown in Figure 33. The imaging lens of Example 15 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0248] The first lens group G1 consists, in order from the object side to the image side, of two lenses, lenses L11 and L12, and an aperture stop St. The second lens group G2 consists, in order from the object side to the image side, of two lenses, lenses L21 and L22. The third lens group G3 consists of a single lens, lens L31.

[0249] For the imaging lens of Example 15, basic lens data is shown in Table 57, specifications are shown in Table 58, variable surface spacing is shown in Table 59, aspherical coefficients are shown in Tables 60A and 60B, and each aberration diagram is shown in FIG.

[0250] [Table 57]

[0251] [Table 58]

[0252] [Table 59]

[0253] Table 60A

[0254] [Table 60B]

[0255] [Example 16] A cross-sectional view of the configuration of the imaging lens of Example 16 is shown in Figure 35. The imaging lens of Example 16 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the image side along the optical axis Z.

[0256] The first lens group G1 consists, in order from the object side to the image side, of lenses L11-L14, an aperture stop St, and a lens L15. The second lens group G2 consists, in order from the object side to the image side, of two lenses, lenses L21-L22. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31-L32.

[0257] For the imaging lens of Example 16, basic lens data is shown in Table 61, specifications are shown in Table 62, variable surface spacing is shown in Table 63, aspherical coefficients are shown in Tables 64A and 64B, and each aberration diagram is shown in FIG.

[0258] [Table 61]

[0259] [Table 62]

[0260] [Table 63]

[0261] [Table 64A]

[0262] [Table 64B]

[0263] [Example 17] A cross-sectional view of the configuration of the imaging lens of Example 17 is shown in Figure 37. The imaging lens of Example 17 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0264] 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 lenses L14 to L16. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0265] For the imaging lens of Example 17, basic lens data is shown in Table 65, specifications are shown in Table 66, variable surface spacing is shown in Table 67, aspherical coefficients are shown in Tables 68A and 68B, and each aberration diagram is shown in FIG.

[0266] [Table 65]

[0267] [Table 66]

[0268] [Table 67]

[0269] [Table 68A]

[0270] [Table 68B]

[0271] [Example 18] A cross-sectional view of the configuration of the imaging lens of Example 18 is shown in Figure 39. The imaging lens of Example 18 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0272] 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 lenses L14 to L16. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0273] For the imaging lens of Example 18, basic lens data is shown in Table 69, specifications are shown in Table 70, variable surface spacing is shown in Table 71, aspherical coefficients are shown in Tables 72A and 72B, and each aberration diagram is shown in FIG.

[0274] [Table 69]

[0275] [Table 70]

[0276] [Table 71]

[0277] [Table 72A]

[0278] [Table 72B]

[0279] [Example 19] A cross-sectional view of the configuration of the imaging lens of Example 19 is shown in Figure 41. The imaging lens of Example 19 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 positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0280] The first lens group G1 consists, in order from the object side to the image side, of lenses L11 and L12, an aperture stop St, and lenses L13 to L15. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0281] For the imaging lens of Example 19, basic lens data is shown in Table 73, specifications are shown in Table 74, variable surface spacing is shown in Table 75, aspherical coefficients are shown in Tables 76A and 76B, and each aberration diagram is shown in FIG.

[0282] [Table 73]

[0283] [Table 74]

[0284] [Table 75]

[0285] [Table 76A]

[0286] [Table 76B]

[0287] [Example 20] A cross-sectional view of the configuration of the imaging lens of Example 20 is shown in Figure 43. The imaging lens of Example 20 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 positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0288] The first lens group G1 consists, in order from the object side to the image side, of lenses L11 and L12, an aperture stop St, and lenses L13 to L15. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of three lenses, lenses L31 to L33.

[0289] For the imaging lens of Example 20, basic lens data is shown in Table 77, specifications are shown in Table 78, variable surface spacing is shown in Table 79, aspherical coefficients are shown in Tables 80A and 80B, and each aberration diagram is shown in FIG.

[0290] [Table 77]

[0291] [Table 78]

[0292] [Table 79]

[0293] [Table 80A]

[0294] [Table 80B]

[0295] [Example 21] A cross-sectional view of the configuration of the imaging lens of Example 21 is shown in Figure 45. The imaging lens of Example 21 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 positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0296] The first lens group G1 consists, in order from the object side to the image side, of lenses L11 and L12, an aperture stop St, and lenses L13 to L15. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of three lenses, lenses L31 to L33.

[0297] For the imaging lens of Example 21, basic lens data is shown in Table 81, specifications are shown in Table 82, variable surface spacing is shown in Table 83, aspherical coefficients are shown in Tables 84A and 84B, and each aberration diagram is shown in FIG.

[0298] [Table 81]

[0299] [Table 82]

[0300] [Table 83]

[0301] [Table 84A]

[0302] [Table 84B]

[0303] [Example 22] A cross-sectional view of the configuration of the imaging lens of Example 22 is shown in Figure 47. The imaging lens of Example 22 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 positive refractive power, and a third lens group G3 having positive refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0304] 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 of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of four lenses, lenses L31 to L34.

[0305] For the imaging lens of Example 22, basic lens data is shown in Table 85, specifications in Table 86, variable surface spacing in Table 87, aspherical coefficients in Tables 88A and 88B, and aberration diagrams in FIG.

[0306] [Table 85]

[0307] [Table 86]

[0308] [Table 87]

[0309] [Table 88A]

[0310] [Table 88B]

[0311] [Example 23] A cross-sectional view of the configuration of the imaging lens of Example 23 is shown in Figure 49. The imaging lens of Example 23 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 positive refractive power, and a third lens group G3 having positive refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0312] 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 lenses L14 to L16. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0313] For the imaging lens of Example 23, basic lens data is shown in Table 89, specifications are shown in Table 90, variable surface spacing is shown in Table 91, aspherical coefficients are shown in Tables 92A and 92B, and each aberration diagram is shown in FIG.

[0314] [Table 89]

[0315] [Table 90]

[0316] [Table 91]

[0317] [Table 92A]

[0318] [Table 92B]

[0319] [Example 24] A cross-sectional view of the configuration of the imaging lens of Example 24 is shown in Figure 51. The imaging lens of Example 24 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 positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0320] 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 lenses L14 to L16. The second lens group G2 consists of one lens, lens L21. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0321] For the imaging lens of Example 24, basic lens data is shown in Table 93, specifications in Table 94, variable surface spacing in Table 95, aspherical coefficients in Tables 96A and 96B, and aberration diagrams in FIG.

[0322] [Table 93]

[0323] [Table 94]

[0324] [Table 95]

[0325] [Table 96A]

[0326] [Table 96B]

[0327] [Example 25] A cross-sectional view of the configuration of the imaging lens of Example 25 is shown in Figure 53. The imaging lens of Example 25 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 positive refractive power, and a third lens group G3 having negative refractive power. The focus group consists of the second lens group G2, and when focusing from an object at infinity to a closest object, the focus group moves toward the object along the optical axis Z.

[0328] The first lens group G1 consists, in order from the object side to the image side, of lenses L11 and L12, an aperture stop St, and lenses L13 to L15. The second lens group G2 consists, in order from the object side to the image side, of two lenses, lenses L21 and L22. The third lens group G3 consists, in order from the object side to the image side, of two lenses, lenses L31 and L32.

[0329] For the imaging lens of Example 25, basic lens data is shown in Table 97, specifications in Table 98, variable surface spacing in Table 99, aspherical coefficients in Tables 100A and 100B, and aberration diagrams are shown in FIG.

[0330] [Table 97]

[0331] [Table 98]

[0332] [Table 99]

[0333] [Table 100A]

[0334] [Table 100B]

[0335] Tables 101 to 109 show the corresponding values of conditional expressions (1) to (26) for the imaging lenses of Examples 1 to 25. In the column for the corresponding values of conditional expressions (16) and (17), the surface number of a surface having a specific intersection is preceded by an "S" in parentheses, and for surfaces having multiple inflection points, the corresponding values are separated by a " / ". However, in the column for the corresponding values of conditional expressions (16) and (17), the corresponding values that do not satisfy the respective conditional expressions are omitted, and for surfaces that do not have a corresponding value that satisfies the respective conditional expressions, "none" is written after the surface number. The corresponding values of the examples shown in Tables 101 to 109 may be used as the upper or lower limits of the conditional expressions to set preferred ranges for the conditional expressions.

[0336] [Table 101]

[0337] [Table 102]

[0338] [Table 103]

[0339] [Table 104]

[0340] [Table 105]

[0341] [Table 106]

[0342] [Table 107]

[0343] [Table 108]

[0344] [Table 109]

[0345] The imaging lenses of Examples 1 to 25 are all compact, yet are configured to have a wide angle, with a maximum total angle of view of 100 degrees or more when focused on an object at infinity. In addition, some Examples have an F-number of less than 2. The imaging lenses of Examples 1 to 25 all have excellent correction of various aberrations and maintain high optical performance.

[0346] Next, an imaging device according to an embodiment of the present disclosure will be described. Fig. 55 and Fig. 56 show external views of camera 30, which is an imaging device according to an embodiment of the present disclosure. Fig. 55 shows a perspective view of camera 30 as seen from the front side, and Fig. 56 shows a perspective view of camera 30 as seen from the rear side. Camera 30 is a so-called mirrorless type digital camera, and is configured to include an imaging lens 1 according to an embodiment of the present disclosure housed in a lens barrel.

[0347] 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.

[0348] An imaging element 38 is provided within the camera body 31. The imaging element 38 outputs an imaging signal corresponding to the subject image formed by the imaging lens 1. For example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) is used as the imaging element 38. A signal processing circuit (not shown) and a recording medium (not shown) are provided within the camera body 31. The signal processing circuit processes the imaging signal output from the imaging element 38 to generate an image. The recording medium is for recording the generated image. With the camera 30, it is possible to take still images or videos by pressing the shutter button 32, and the image data obtained by this shooting is recorded on the recording medium.

[0349] 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.

[0350] Although the aberration diagrams in the above examples show the d-line, C-line, and F-line, the technology of the present disclosure is not limited to this wavelength range and can also be applied to imaging lenses with expanded or contracted wavelength ranges. Therefore, the imaging device of the present disclosure is not limited to cameras compatible with the visible range. The technology of the present disclosure can also be applied to, for example, visible range cameras, SWIR (Short Wave Infra-Red) range cameras, multispectral cameras, hyperspectral cameras, thermography cameras, etc.

[0351] 55 shows a fixed-lens camera in which the imaging lens is fixed to the camera body, but the imaging device of the present disclosure may also be an interchangeable-lens camera in which the imaging lens can be detachably attached to the camera body. Also, the imaging device of the present disclosure may take various forms, such as a camera other than a mirrorless type, a film camera, a video camera, a camera for FA (Factory Automation), a camera for MV (Machine Vision), a surveillance camera, an in-vehicle camera, and a cinema camera.

[0352] 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 having positive refractive power, 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; the lens closest to the object side is a negative meniscus lens, and at least one of the second lens from the object side and the third lens from the object side is a lens other than a negative meniscus lens; a stop is disposed on the image side of the second lens from the object side, TL is the sum of the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the third lens group closest to the image side and the back focus of the entire system in air equivalent distance, The maximum image height is Y, The focal length of the entire system when focused on an object at infinity is f. When the maximum half angle of view when focused on an object at infinity is ωm, 1 <TL / Y<4.5 (1) -0.18<(Yf×tanωm) / (f×tanωm)<-0.02 (2) An imaging lens that satisfies conditional expressions (1) and (2) expressed as follows: [Appendix 2] In a cross section including the optical axis, the radius of a circle passing through three points on the lens surface, namely, a point on the optical axis and two points on the outermost ends of the effective diameter, is defined as Rc of the lens surface, The sign of Rc is positive if the point on the optical axis is closer to the object side than the center of the circle, and negative if the point on the optical axis is closer to the image side than the center of the circle. The imaging lens according to Supplementary note 1, wherein the number of lenses included in the third lens group, whose object-side lens surface is aspherical and whose object-side lens surface has a negative Rc sign, is one or two. [Appendix 3] The imaging lens according to claim 1 or 2, wherein the imaging lens includes five or more lenses and ten or less lenses. [Appendix 4] If the unit of ωm is degrees, 47<ωm<60 (3) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 3, which satisfies conditional expression (3) expressed as follows: [Appendix 5] If the focal length of the first lens group is fG1, then 0.01 <f / fG1<1.6 (4) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 4, which satisfies conditional expression (4) expressed by the following formula: [Appendix 6] When the distance on the optical axis from the lens surface of the first lens group closest to the object to the stop in a state where the lens is focused on an object at infinity is dL1St, 0.1 <dL1St / Y<2.1 (5) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 5, which satisfies conditional expression (5) shown below. [Appendix 7] CRA is the angle between the chief ray of the maximum image height incident on the image plane when focused on an object at infinity and an axis parallel to the optical axis. If the unit of CRA is a degree, 16<|CRA|<69 (6) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 6, which satisfies conditional expression (6) shown below. [Appendix 8] If the back focus of the entire system in air equivalent distance is Bf, 0.06 <Bf / TL<0.3 (7) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 7, which satisfies conditional expression (7) shown below. [Appendix 9] f in millimeters, If the open F-number when focused on an object at infinity is Fno, 1.7 <f / Fno<4.1 (8) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 8, which satisfies conditional expression (8) shown below. [Appendix 10] If the focal length of the second lens group is fG2, then 0.24<|f / fG2|<2.4 (9) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 9, which satisfies conditional expression (9) shown below. [Appendix 11] one or two single lenses having negative refractive power and one or two single lenses having positive refractive power are disposed on the object side of the aperture stop, The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 10, wherein the number of lenses arranged on the object side of the aperture stop is four or less. [Appendix 12] a positive lens is disposed adjacent to the image side of the aperture; When the Abbe number of the positive lens arranged adjacent to the image side of the aperture stop based on the d-line is νrp, 34<νrp<87 (10) 12. The imaging lens according to claim 1, which satisfies conditional expression (10) below. [Appendix 13] a positive lens is disposed adjacent to the object side of the aperture; When the Abbe number of the positive lens arranged adjacent to the aperture stop on the object side is νfp, the Abbe number based on the d-line is: 23<νfp<61 (11) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 12, which satisfies conditional expression (11) shown below. [Appendix 14] a positive lens is disposed adjacent to the object side of the aperture stop, and an Lffn lens having negative refractive power is disposed adjacent to the object side of the positive lens, When the Abbe number of the Lffn lens based on the d line is νffn, 16<νffn<100 (12) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 13, which satisfies conditional expression (12) expressed by the following formula: [Appendix 15] In a cross section including the optical axis, the radius of a circle passing through three points on the lens surface, namely, a point on the optical axis and two points on the outermost ends of the effective diameter, is defined as Rc of the lens surface, The sign of Rc is positive if the point on the optical axis is closer to the object side than the center of the circle, and negative if the point on the optical axis is closer to the image side than the center of the circle. the first lens group includes, in order from the object side to the image side, a negative subgroup and one positive lens; the negative subgroup is composed of one or two negative lenses, the Rc of which on the object side and the Rc of which on the image side are the same sign; at least one lens surface included in the negative subgroup has an aspherical shape; The average value of the refractive index for the d-line of all the lenses included in the negative subgroup is N1nave, When the average value of the Abbe numbers of all the lenses included in the negative subgroup based on the d-line is ν1nave, 1.45 <N1nave<2.3 (13) 16<ν1nave<85 (14) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 14, which satisfies conditional expressions (13) and (14) expressed by the following formulas: [Appendix 16] The composite focal length of all lenses on the object side of the aperture when focused on an object at infinity is fGf. When the composite focal length of all lenses on the image side of the aperture stop in a state where the lens is focused on an object at infinity is fGr, -10 <fGf / fGr<31 (15) The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 15, which satisfies conditional expression (15) shown below. [Appendix 17] The imaging lens according to any one of Supplementary Note 1 to Supplementary Note 16, wherein the lens surface of the second lens group closest to the image side has a convex shape. [Appendix 18] the imaging lens includes at least one lens surface having an inflection point; When the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the third lens group closest to the image side is DL, the imaging lens according to any one of Appendix 1 to Appendix 17, wherein, in a state focused on an object at infinity, at least one of the points of intersection between the lens surface having the inflection point and the optical axis is a specific intersection point within a range of 0.3 × DL from the point of intersection between the lens surface of the first lens group closest to the object and the optical axis, or within a range of 0.3 × DL from the point of intersection between the lens surface of the third lens group closest to the image and the optical axis, [Appendix 19] The refractive power of the lens surface having the specific intersection point is φa, When the refractive power of the imaging lens in a state where it is focused on an object at infinity is φ, At least one of the lens surfaces having the specific intersection point is -2<φa / φ<3 (16) 19. The imaging lens according to claim 18, which satisfies conditional expression (16) expressed as follows: [Appendix 20] An imaging device comprising the imaging lens according to any one of Supplementary Note 1 to Supplementary Note 19. [Explanation of symbols]

[0353] 1 Imaging lens 2 On-axis luminous flux 3 Luminous flux 3b Lower ray 3c chief ray 30 Camera 31 Camera Body 32 Shutter button 33 Power button 34 Control section 35 Control section 36 Display section 38 Image sensor C yen CRA angle DL distance dL1St distance G1 First lens group G1n negative subgroup G2 Second lens group G3 Third lens group He Height Hinf Height L11~L34 lenses Lex Lens O center P1 Specific intersection P2 Specific intersection P3 Specific intersection P4 Specific intersection Pa Point on the optical axis Pe: Outermost point of effective diameter Pe1: Outermost point of effective diameter Pe2: Outermost point of effective diameter Pinf inflection point PP optical components Rc radius Sa lens surface Sim image plane St aperture stop Y Maximum image height Z optical axis Zp 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 having positive refractive power, 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; the lens closest to the object side is a negative meniscus lens, and at least one of the second lens from the object side and the third lens from the object side is a lens other than a negative meniscus lens; a stop is disposed on the image side of the second lens from the object side, TL is the sum of the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the third lens group closest to the image side and the back focus of the entire system in air equivalent distance, The maximum image height is Y, The focal length of the entire system when focused on an object at infinity is f. When the maximum half angle of view in a state where the focus is on an object at infinity is ωm, 1<TL / Y<4.5 (1) -0.18<(Y-f×tanωm) / (f×tanωm)<-0.02 (2) An imaging lens that satisfies conditional expressions (1) and (2) expressed by the following formulas.

2. In a cross section including the optical axis, the radius of a circle passing through three points on the lens surface, namely, a point on the optical axis and two points on the outermost edge of the effective diameter, is defined as Rc of the lens surface, The sign of Rc is positive if the point on the optical axis is closer to the object side than the center of the circle, and negative if the point on the optical axis is closer to the image side than the center of the circle.

2. The imaging lens according to claim 1, wherein the number of lenses included in the third lens group, whose object-side lens surface is aspherical and whose object-side lens surface has a negative Rc sign, is one or two.

3. The imaging lens according to claim 1 , wherein the number of lenses included in the imaging lens is 5 or more and 10 or less.

4. If the unit of ωm is degrees, 47<ωm<60 (3) 2. The imaging lens according to claim 1, which satisfies conditional expression (3) expressed as follows:

5. When the focal length of the first lens group is fG1, 0.01<f / fG1<1.6 (4) 2. The imaging lens according to claim 1, which satisfies conditional expression (4) expressed as follows:

6. When the distance on the optical axis from the lens surface of the first lens group closest to the object side to the stop in a state where the lens is focused on an object at infinity is dL1St, 0.1<dL1St / Y<2.1 (5) 2. The imaging lens according to claim 1, which satisfies conditional expression (5) expressed as follows:

7. The angle between the chief ray of the maximum image height incident on the image plane when focused on an object at infinity and an axis parallel to the optical axis is called CRA. If the unit of CRA is degrees, 16<|CRA|<69 (6) 2. The imaging lens according to claim 1, which satisfies conditional expression (6) expressed as follows:

8. When the back focus of the entire system in air equivalent distance is Bf, 0.06<Bf / TL<0.3 (7) 2. The imaging lens according to claim 1, which satisfies conditional expression (7) expressed as follows:

9. The unit of f is millimeters. When the open F-number when focused on an object at infinity is Fno, 1.7<f / Fno<4.1 (8) 2. The imaging lens according to claim 1, which satisfies conditional expression (8) expressed as follows:

10. When the focal length of the second lens group is fG2, 0.24<|f / fG2|<2.4 (9) 2. The imaging lens according to claim 1, which satisfies conditional expression (9) expressed as follows:

11. one or two single lenses having negative refractive power and one or two single lenses having positive refractive power are disposed on the object side of the aperture stop, 2. The imaging lens according to claim 1, wherein the number of lenses arranged on the object side of the aperture stop is four or less.

12. a positive lens is disposed adjacent to the image side of the aperture; When the Abbe number of the positive lens arranged adjacent to the image side of the stop is νrp, the Abbe number based on the d-line is: 34<νrp<87 (10) 2. The imaging lens according to claim 1, which satisfies conditional expression (10) expressed as follows:

13. a positive lens is disposed adjacent to the object side of the aperture; When the Abbe number of the positive lens arranged adjacent to the aperture stop on the object side is νfp, the Abbe number based on the d-line is: 23<νfp<61 (11) 2. The imaging lens according to claim 1, which satisfies conditional expression (11) expressed as follows:

14. a positive lens is disposed adjacent to the object side of the aperture stop, and an Lffn lens having negative refractive power is disposed adjacent to the object side of the positive lens, When the Abbe number of the Lffn lens based on the d line is vffn, 16<νffn<100 (12) 2. The imaging lens according to claim 1, which satisfies conditional expression (12) expressed as follows:

15. In a cross section including the optical axis, the radius of a circle passing through three points on the lens surface, namely, a point on the optical axis and two points on the outermost edge of the effective diameter, is defined as Rc of the lens surface, The sign of Rc is positive if the point on the optical axis is closer to the object side than the center of the circle, and negative if the point on the optical axis is closer to the image side than the center of the circle. the first lens group includes, in order from the object side to the image side, a negative subgroup and one positive lens; the negative subgroup is composed of one or two negative lenses, the Rc of which on the object side and the Rc of which on the image side are the same sign; at least one lens surface included in the negative subgroup has an aspherical shape; The average value of the refractive index for the d line of all the lenses included in the negative subgroup is N1nave, When the average value of the Abbe numbers of all the lenses included in the negative subgroup based on the d-line is ν1nave, 1.45<N1nave<2.3 (13) 16<ν1nave<85 (14) 2. The imaging lens according to claim 1, which satisfies conditional expressions (13) and (14) expressed as follows:

16. The composite focal length of all lenses on the object side of the aperture when focused on an object at infinity is fGf. When the composite focal length of all the lenses on the image side of the aperture stop in a state where the lens is focused on an object at infinity is fGr, -10<fGf / fGr<31 (15) 2. The imaging lens according to claim 1, which satisfies conditional expression (15) expressed as follows:

17. 2. The imaging lens according to claim 1, wherein the lens surface of the second lens group closest to the image side has a convex shape.

18. the imaging lens includes at least one lens surface having an inflection point; When the distance on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the third lens group closest to the image side is DL, 2. The imaging lens according to claim 1, wherein, in a state focused on an object at infinity, at least one of the points of intersection between the lens surface having the inflection point and the optical axis is a specific intersection point within a range of 0.3×DL toward the image side from the point of intersection between the lens surface of the first lens group closest to the object and the optical axis, or within a range of 0.3×DL toward the object side from the point of intersection between the lens surface of the third lens group closest to the image side and the optical axis.

19. The refractive power of the lens surface having the specific intersection point is φa, When the refractive power of the imaging lens in a state where it is focused on an object at infinity is φ, At least one of the lens surfaces having the specific intersection point is -2<φa / φ<3 (16) 19. The imaging lens according to claim 18, which satisfies conditional expression (16) expressed as follows:

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

Images