Imaging lens and imaging device

Abstract

To provide an imaging lens that is constituted compactly and holds excellent optical performance, and to provide an imaging device having the imaging lens.SOLUTION: An imaging lens comprises a front group, a diaphragm, and a rear group in order from an object side to an image side. The rear group includes at least one aspherical lens that points a concave surface to an image side in a paraxial area, and has an inflection point in which a recessed and projecting shape is changed in the middle as it goes toward a peripheral section from an optical axis on a lens surface in the image side. The imaging lens satisfies a conditional expression of 0.3<Bf / (f×tanωm)<1.5, where BF, f, and ωm indicate the back focus of the entire system, the focal length of the entire system, and the maximum half-viewing angle, respectively. The imaging lens has at least one lens that satisfies a conditional expression regarding a temperature coefficient (dN / dT)×10-6 of the refractive index of a lens, namely 0<|dN / dT|<15.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, as an imaging lens that can be used in an imaging device such as a digital camera, the imaging optical system described in Patent Document 1 below is known.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for an imaging lens that is configured to be small and retains good optical performance. These required levels are increasing year by year.

[0005] An object of the present disclosure is to provide an imaging lens that is configured to be small and retains good optical performance, and an imaging device including this imaging lens.

Means for Solving the Problems

[0006] A first aspect of the present disclosure is an imaging lens including, in order from the object side to the image side, a front group including one or more lenses, a diaphragm, and a rear group including a plurality of lenses. The rear group includes at least one first aspherical lens having a concave surface facing the image side in the paraxial region and having an inflection point on the lens surface on the image side where the concavo-convex shape changes midway from the optical axis to the peripheral portion. The imaging lens satisfies the conditional expression (1) represented by: 0.3 < Bf / (f×tanωm) < 1.5 (1) and satisfies the conditional expression (2) represented by: 0 < |dN / dT| < 15 (2) It includes at least one lens that satisfies the conditional expression (2) represented by Here, the back focus at the air equivalent distance of the entire system in the state of focusing on an infinite object is defined as Bf. The focal length of the entire system in the state of focusing on an infinite object is defined as f. The maximum half angle in the state of focusing on an infinite object is defined as ωm. The temperature coefficient of the refractive index with respect to the d-line at 25 °C of the lenses included in the entire system is (dN / dT)×10 -6 is used. The unit of dN / dT is °C -1 is used.

[0007] In the second aspect of the present disclosure, in the imaging lens of the first aspect, when the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf in the state of focusing on an infinite object is defined as TL, 1.1 < TL / f < 3.5 (3) it satisfies the conditional expression (3) represented by

[0008] In the third aspect of the present disclosure, in the imaging lens of the second aspect, 1.2 < TL / f < 3 (3-1) it satisfies the conditional expression (3-1) represented by

[0009] In the fourth aspect of the present disclosure, in the imaging lens of the first aspect, 0.36 < Bf / (f×tanωm) < 1.2 (1-1) it satisfies the conditional expression (1-1) represented by

[0010] In the fifth aspect of the present disclosure, in the imaging lens of the first aspect, when the open F number in the state of focusing on an infinite object is defined as Fno, 1.6 < Fno / tanωm < 5 (4) it satisfies the conditional expression (4) represented by

[0011] In the sixth aspect of the present disclosure, in the imaging lens of the fifth aspect, 2 < Fno / tanωm < 3.2 (4-1) it satisfies the conditional expression (4-1) represented by

[0012] The seventh aspect of the present disclosure is that in the imaging lens of the first aspect, 0 < dFSt / TL < 0.8 (5) 0 < dStR / TL < 0.8 (6) The conditional expressions (5) and (6) represented by the following are satisfied. Here, the minimum value of the distance on the optical axis from the most image-side lens surface of the front group to the aperture is defined as dFSt. The sign of dFSt is positive if the aperture is on the image side with respect to the most image-side lens surface of the front group, and negative if the aperture is on the object side with respect to the most image-side lens surface of the front group. The minimum value of the distance on the optical axis from the aperture to the most object-side lens surface of the rear group is defined as dStR. The sign of dStR is positive if the most object-side lens surface of the rear group is on the image side with respect to the aperture, and negative if the most object-side lens surface of the rear group is on the object side with respect to the aperture. TL is the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf in the state of focusing on an infinite object.

[0013] The eighth aspect of the present disclosure is that in the imaging lens of the first aspect, 0.67 < dSt / TL < 0.93 (7) The conditional expression (7) represented by the following is satisfied. Here, dSt is the sum of the distance on the optical axis from the aperture to the most image-side lens surface of the rear group and Bf in the state of focusing on an infinite object. TL is the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf in the state of focusing on an infinite object.

[0014] The ninth aspect of the present disclosure is that in the imaging lens of the first aspect, when the paraxial curvature radius of the object-side surface of the most object-side lens of the front group is RL1f and the paraxial curvature radius of the image-side surface of the most object-side lens of the front group is RL1r, -3 < (RL1r - RL1f) / (RL1r + RL1f) < 0 (8) The conditional expression (8) represented by the following is satisfied.

[0015] The tenth aspect of the present disclosure is that in the imaging lens of the first aspect, 0.02 < dA1 / TL < 0.6 (9) satisfies the conditional expression (9) represented by Here, in the state of focusing on an infinite object, among the first aspherical lenses included in the rear group, the sum of the distance on the optical axis from the image-side surface of the first aspherical lens closest to the image side to the image-side lens surface of the rear group and Bf is defined as dA1. In the state of focusing on an infinite object, the sum of the distance on the optical axis from the object-side lens surface of the front group closest to the object side to the image-side lens surface of the rear group and Bf is defined as TL.

[0016] The eleventh aspect of the present disclosure is that in the imaging lens of the tenth aspect, 0.08 < dA1 / TL < 0.35 (9-1) satisfies the conditional expression (9-1) represented by

[0017] The twelfth aspect of the present disclosure is that in the imaging lens of the first aspect, the front group includes at least one lens that satisfies the conditional expression (2).

[0018] The thirteenth aspect of the present disclosure is that in the imaging lens of the twelfth aspect, the lens on the object side of the front group closest to the object side satisfies the conditional expression (2).

[0019] The fourteenth aspect of the present disclosure is that in the imaging lens of the thirteenth aspect, the rear group includes at least one lens that satisfies the conditional expression (2).

[0020] The fifteenth aspect of the present disclosure is that in the imaging lens of the first aspect, when the sum of the distance on the optical axis from the object-side lens surface of the front group closest to the object side to the image-side lens surface of the rear group and Bf in the state of focusing on an infinite object is defined as TL, 1.2 < TL / (f × tanωm) < 3 (10) satisfies the conditional expression (10) represented by

[0021] The sixteenth aspect of the present disclosure is that in the imaging lens of the fifteenth aspect, 1.7 < TL / (f × tan ωm) < 2.5 (10-1) satisfies the conditional expression (10-1) represented by

[0022] In the 17th aspect of the present disclosure, in the imaging lens of the 16th aspect, 1.2 < TL / f < 3 (3-1) satisfies the conditional expression (3-1) represented by

[0023] In the 18th aspect of the present disclosure, in the imaging lens of the 17th aspect, when the open F-number in the state of focusing on an infinite object is Fno, 2 < Fno / tan ωm < 3.2 (4-1) satisfies the conditional expression (4-1) represented by

[0024] In the 19th aspect of the present disclosure, in the imaging lens of the 18th aspect, 0.36 < Bf / (f × tan ωm) < 1.2 (1-1) satisfies the conditional expression (1-1) represented by

[0025] In the 20th aspect of the present disclosure, in the imaging lens of the 19th aspect, when the paraxial curvature radius of the object-side surface of the most object-side lens in the front group is RL1f and the paraxial curvature radius of the image-side surface of the most object-side lens in the front group is RL1r, -1 < (RL1r - RL1f) / (RL1r + RL1f) < -0.07 (8-1) satisfies the conditional expression (8-1) represented by

[0026] In the 21st aspect of the present disclosure, in the imaging lens of the 18th aspect, when the sum of the distance on the optical axis from the diaphragm to the most image-side lens surface of the rear group and Bf in the state of focusing on an infinite object is dSt, 0.67 < dSt / TL < 0.93 (7) satisfies the conditional expression (7) represented by

[0027] In the 22nd aspect of the present disclosure, in the imaging lens of the 21st aspect, when the sum of the distance on the optical axis from the image-side surface of the first aspherical lens closest to the image side among the first aspherical lenses included in the rear group to the most image-side lens surface of the rear group in the state of being focused on an infinite object is defined as dA1 and Bf, 0.08 < dA1 / TL < 0.35 (9-1) the conditional expression (9-1) represented by the following is satisfied.

[0028] In the 23rd aspect of the present disclosure, in the imaging lens of the 22nd aspect, the front group includes at least one lens that satisfies the conditional expression (2).

[0029] In the 24th aspect of the present disclosure, in the imaging lens of the 23rd aspect, the lens closest to the object side in the front group satisfies the conditional expression (2).

[0030] In the 25th aspect of the present disclosure, in the imaging lens of the 1st aspect, when the refractive index with respect to the d-line and the Abbe number based on the d-line of the lenses included in the entire system are defined as Nd and νd, respectively, 1.6 < Nd + 0.01×νd < 2.6 (11) the front group includes at least one lens that satisfies the conditional expression (11) represented by the following.

[0031] In the 26th aspect of the present disclosure, in the imaging lens of the 25th aspect, the lens closest to the object side in the front group satisfies the conditional expression (11).

[0032] In the 27th aspect of the present disclosure, in the imaging lens of the 1st aspect, when the focal length of the lens closest to the object side in the front group is defined as fL1, -1.5 < f / fL1 < 0 (12) the conditional expression (12) represented by the following is satisfied.

[0033] In the 28th aspect of the present disclosure, in the imaging lens of the 1st aspect, among the 1st aspherical lenses included in the rear group, taking the paraxial curvature radius of the image-side surface of the 1st aspherical lens closest to the image side as RA1c, and taking the curvature radius at the position of the maximum effective diameter of the image-side surface of the 1st aspherical lens closest to the image side among the 1st aspherical lenses included in the rear group as RA1y, -100 < RA1y / RA1c < 0 (13) The conditional expression (13) represented by this satisfies.

[0034] In the 29th aspect of the present disclosure, in the imaging lens of the 1st aspect, among the 1st aspherical lenses included in the rear group, taking the refractive index with respect to the d-line and the Abbe number based on the d-line of the 1st aspherical lens closest to the image side as NdA1 and νdA1 respectively, 1.8 < NdA1 + 0.01×νdA1 < 2.14 (14) The conditional expression (14) represented by this satisfies.

[0035] In the 30th aspect of the present disclosure, in the imaging lens of the 1st aspect, the rear group includes at least one 2nd aspherical lens having an image-side lens surface that is convex toward the image side in the paraxial region and whose refractive power at the position of the maximum effective diameter is shifted in the negative direction compared to the refractive power in the paraxial region.

[0036] In the 31st aspect of the present disclosure, in the imaging lens of the 30th aspect, taking the paraxial curvature radius of the image-side surface of the 2nd aspherical lens as RA2c, and taking the curvature radius at the position of the maximum effective diameter of the image-side surface of the 2nd aspherical lens as RA2y, -1 < RA2c / RA2y < 1 (15) All the 2nd aspherical lenses included in the rear group satisfy the conditional expression (15) represented by this.

[0037] In the 32nd aspect of the present disclosure, in the imaging lens of the 30th aspect, 0.2 < dA2 / TL < 0.6 (16) The conditional expression (16) represented by this satisfies. Here, in the state of focusing on an infinitely distant object, the sum of the distance on the optical axis from the image-side surface of the second aspherical lens closest to the image side among the second aspherical lenses included in the rear group to the image-side lens surface of the rear group and Bf is defined as dA2. In the state of focusing on an infinitely distant object, the sum of the distance on the optical axis from the object-side lens surface of the front group to the image-side lens surface of the rear group and Bf is defined as TL.

[0038] The 33rd aspect of the present disclosure is that in the imaging lens of the 32nd aspect, the second lens from the image side of the rear group is the second aspherical lens closest to the image side among the second aspherical lenses included in the rear group.

[0039] The 34th aspect of the present disclosure is that in the imaging lens of the 33rd aspect, the second lens from the image side of the rear group has an inflection point on the image-side lens surface where the concavo-convex shape changes midway from the optical axis toward the peripheral part.

[0040] The 35th aspect of the present disclosure is that in the imaging lens of the 1st aspect, the lens closest to the image side of the rear group is the first aspherical lens.

[0041] The 36th aspect of the present disclosure is that in the imaging lens of the 35th aspect, the lens closest to the image side of the rear group faces a convex surface toward the object side in the paraxial region and has an inflection point on the object-side lens surface where the concavo-convex shape changes midway from the optical axis toward the peripheral part.

[0042] The 37th aspect of the present disclosure is that in the imaging lens of the 1st aspect, the rear group includes two first aspherical lenses.

[0043] The 38th aspect of the present disclosure is that in the imaging lens of the 30th aspect, the rear group includes two second aspherical lenses.

[0044] The 39th aspect of the present disclosure is that in the imaging lens of the 1st aspect, it includes at least one cemented lens.

[0045] The 40th aspect of the present disclosure is that in the imaging lens of the first aspect, the lens on the most object side of the front group satisfies the conditional expression (2), 1.2 < TL / f < 1.6 (3-2) 2.5 < Fno / tanωm < 4 (4-2) 0.67 < dSt / TL < 0.93 (7) 0.08 < dA1 / TL < 0.35 (9-1) and satisfies the conditional expressions (3-2), (4-2), (7), and (9-1) represented by Here, TL is the sum of the distance on the optical axis from the lens surface on the most object side of the front group to the lens surface on the most image side of the rear group and Bf in the state of focusing on an infinite object. Fno is the open F-number in the state of focusing on an infinite object. dSt is the sum of the distance on the optical axis from the diaphragm to the lens surface on the most image side of the rear group and Bf in the state of focusing on an infinite object. dA1 is the sum of the distance on the optical axis from the image-side surface of the first aspherical lens included in the rear group, which is the most image-side first aspherical lens, to the lens surface on the most image side of the rear group and Bf in the state of focusing on an infinite object.

[0046] The 41st aspect of the present disclosure is an imaging device including the imaging lens according to any one of the first to 40th aspects.

[0047] Note that the "consisting of" and "comprising" in this specification are intended to include lenses having substantially no refractive power, optical elements other than lenses such as diaphragms, filters, and cover glasses, and mechanical parts such as lens flanges, lens barrels, imaging elements, and shake correction mechanisms, etc., in addition to the listed components.

[0048] Regarding the radius of curvature, sign of refractive power, and surface shape of a lens including an aspherical surface, those in the paraxial region are used unless otherwise specified. The sign of the radius of curvature is positive for the radius of curvature of a surface convex toward the object side and negative for the radius of curvature of a surface convex toward the image side.

[0049] "Entire system" in this specification means an 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 the values based on the d-line in the state of focusing on an infinitely distant object unless otherwise specified. The "~ group" in this specification is not limited to a configuration consisting of a plurality of lenses, and may also be a configuration consisting of only one lens. A "single lens" means one lens that is not joined.

[0050] The "d-line", "C-line", and "F-line" described in this specification are spectral lines, and the wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line is treated as 656.27 nm (nanometers), and the wavelength of the F-line is treated as 486.13 nm (nanometers).

Advantages of the Invention

[0051] According to the present disclosure, it is possible to provide an imaging lens that is configured to be small and retains good optical performance, and an imaging device including this imaging lens.

Brief Description of the Drawings

[0052]

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Embodiments for Carrying Out the Invention

[0053] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0054] FIG. 1 shows a cross-sectional view of the configuration of an imaging lens according to an embodiment of the present disclosure. FIG. 2 shows a cross-sectional view of the configuration of the imaging lens of FIG. 1 and a light beam. In FIG. 2, the upper part marked "infinity" shows the state of focusing on an infinite object, and the lower part marked "close distance" shows the state of focusing on a close-distance object. The state of the lower part of FIG. 2 is a state where the absolute value of the imaging magnification is 0.11 times. In FIG. 2, as the light beams, the on-axis light beam and the light beam with the maximum semi-aperture angle ωm in the state of focusing on an infinite object, and the on-axis light beam and the light beam with the maximum semi-aperture angle in the state of focusing on a close-distance object are shown. In FIGS. 1 and 2, the left side is the object side and the right side is the image side. The examples shown in FIGS. 1 and 2 correspond to the imaging lens of Example 1 described later. Hereinafter, the description will be mainly made with reference to FIG. 1.

[0055] The imaging lens of the present disclosure includes, in order from the object side to the image side along the optical axis Z, a front group GF including one or more lenses, an aperture stop St, and a rear group GR including a plurality of lenses. In this way, by not arranging the aperture stop St on either the most object side or the most image side of the lens system, it is advantageous for correcting various aberrations.

[0056] As an example, each group of the imaging lens of FIG. 1 is configured as follows. The front group GF consists of one lens, lens L11. The rear group GR consists of five lenses, lenses L21 to L25, in order from the object side to the image side. The aperture stop St in FIG. 1 indicates the position in the optical axis direction, not the size or shape. This method of illustrating the aperture stop St is the same in other cross-sectional views.

[0057] The rear group GR includes at least one first aspherical lens LA1. The first aspherical lens LA1 has a shape with a concave surface facing the image side in the paraxial region. Here, "having a shape with a concave surface facing the image side in the paraxial region" means that the lens surface on the image side is concave in the paraxial region. The first aspherical lens LA1 further has an inflection point on the lens surface on the image side where the concavo-convex shape changes midway from the optical axis to the peripheral portion. An inflection point is a point where the surface shape switches from a convex shape to a concave shape, or from a concave shape to a convex shape, that is, a point where the sign of the radius of curvature changes. Since the lens surface has an inflection point, the refractive power of the peripheral portion of the lens can be determined without depending on the refractive power of the paraxial region, which is advantageous for controlling the field curvature and the incident angle of light rays on the image plane Sim. From the above, the first aspherical lens LA1 makes it easy to miniaturize the lens system while simultaneously correcting the field curvature and preventing the incident angle of the chief ray on the image plane Sim from becoming too large. Although a lens having a shape like the first aspherical lens LA1 has been required in optical design, it has been difficult to manufacture. In recent years, due to the further increase in the demand for miniaturization and the improvement of manufacturing technology, it is becoming practical to use a lens of such a shape for an imaging lens.

[0058] In the example of FIG. 1, the lens L25 corresponds to the first aspherical lens LA1. In the example of FIG. 1, there is only one first aspherical lens LA1 included in the rear group GR, but in the imaging lens of the present disclosure, the rear group GR may be configured to include two first aspherical lenses LA1. In this case, it is more advantageous for correcting the field curvature.

[0059] When configured such that the lens closest to the image side of the rear group GR is the first aspherical lens LA1 as in the example of FIG. 1, it becomes easy to correct the field curvature and prevent the incident angle of the chief ray on the image plane Sim from becoming too large.

[0060] The most image-side lens of the rear group GR may be configured to have a shape with a convex surface facing the object side in the paraxial region and to have an inflection point on the object-side lens surface where the concavo-convex shape changes midway from the optical axis toward the peripheral portion. Here, "having a shape with a convex surface facing the object side in the paraxial region" means that the lens surface on the object side is convex in the paraxial region. When the most image-side lens of the rear group GR has the above configuration, it is advantageous for shortening the overall optical length.

[0061] The rear group GR preferably includes at least one second aspherical lens LA2. The second aspherical lens LA2 has a shape with a convex surface facing the image side in the paraxial region. Here, "having a shape with a convex surface facing the image side in the paraxial region" means that the lens surface on the image side is convex in the paraxial region. The lens surface on the image side of the second aspherical lens LA2 further has a shape in which the refractive power at the position of the maximum effective diameter is shifted in the negative direction compared to the refractive power in the paraxial region. The second aspherical lens LA2 having the above shape is advantageous for correcting various aberrations while suppressing the increase in the overall optical length.

[0062] Note that "the refractive power at the position of the maximum effective diameter is shifted in the negative direction compared to the refractive power in the paraxial region" in this specification has the following meaning based on the sign of the refractive power. When the surface has a negative refractive power at both the paraxial region and the position of the maximum effective diameter, it means having a stronger negative refractive power at the position of the maximum effective diameter than in the paraxial region. When the surface has a positive refractive power at both the paraxial region and the position of the maximum effective diameter, it means having a weaker positive refractive power at the position of the maximum effective diameter than in the paraxial region. When the surface has refractive powers with different signs at the paraxial region and the position of the maximum effective diameter, it means having a positive refractive power in the paraxial region and a negative refractive power at the position of the maximum effective diameter.

[0063] In the example of FIG. 1, the lens L24 corresponds to the second aspherical lens LA2. In the example of FIG. 1, there is only one second aspherical lens LA2 included in the rear group GR. However, in the imaging lens of the present disclosure, the rear group GR may be configured to include two second aspherical lenses LA2. In such a case, it is advantageous to correct various aberrations while suppressing an increase in the overall optical length.

[0064] The second lens from the image side of the rear group GR may be configured to be the second aspherical lens LA2 closest to the image side among the second aspherical lenses LA2 included in the rear group GR. In such a case, it is advantageous to correct various aberrations while suppressing an increase in the overall optical length.

[0065] The second lens from the image side of the rear group GR may be configured to have an inflection point on the image-side lens surface where the concavo-convex shape changes midway from the optical axis to the peripheral portion. In such a case, it becomes easy to correct spherical aberration and field curvature while miniaturizing the lens system.

[0066] At least one of the aspherical lenses included in the imaging lens may be a composite aspherical lens in which a resin with an aspherical air contact surface is formed on the spherical surface of a glass lens. In such a case, since an aspherical surface can be added to the lens surface while suppressing the manufacturing cost, it is possible to achieve both cost reduction and good correction of various aberrations. Note that in this specification, the composite aspherical lens is not regarded as a cemented lens, but is treated as a single lens that is not cemented, that is, a single lens.

[0067] The imaging lens preferably includes at least one cemented lens. In such a case, it is advantageous for correcting chromatic aberration.

[0068] Next, a preferred configuration of the imaging lens of the present disclosure regarding conditional expressions will be described. In the following description of the conditional expressions, to avoid redundancy, the same symbols are used for those with the same definitions, and the duplicate description of the symbols is omitted. Also, hereinafter, to avoid redundancy, the "imaging lens of the present disclosure" is also simply referred to as the "imaging lens".

[0069] The imaging lens preferably satisfies the following conditional expression (1). Here, the back focus at the air equivalent distance of the entire system in the state of focusing on an infinite object is defined as Bf. The focal length of the entire system in the state of focusing on an infinite object is defined as f. Tan is the tangent. The maximum semi-field angle in the state of focusing on an infinite object is defined as ωm. The back focus Bf at the air equivalent distance of the entire system is the air equivalent distance on the optical axis from the most image-side lens surface of the imaging lens to the image plane Sim. As an example, the back focus Bf is shown in FIG. 3. FIG. 3 is a diagram showing symbols and the like used in the conditional expression in the cross-sectional view of the imaging lens of FIG. 1. In FIG. 3, the description of the symbols of some lenses is omitted. By ensuring that the corresponding value of the conditional expression (1) does not fall below the lower limit value, the back focus Bf defined above does not become too short, making it easier to attach the mount exchange mechanism. By ensuring that the corresponding value of the conditional expression (1) does not exceed the upper limit value, the back focus Bf defined above does not become too long, facilitating miniaturization. 0.3 < Bf / (f × tan ωm) < 1.5 (1)

[0070] To obtain better characteristics, the lower limit value of the conditional expression (1) is more preferably 0.32, still more preferably 0.34, still more preferably 0.36, still more preferably 0.38, and still more preferably 0.4. To obtain better characteristics, the upper limit value of the conditional expression (1) is more preferably 1.4, still more preferably 1.3, still more preferably 1.2, still more preferably 1.1, and still more preferably 0.9. For example, the imaging lens more preferably satisfies the following conditional expression (1-1). 0.36 < Bf / (f × tan ωm) < 1.2 (1-1)

[0071] The imaging lens preferably includes at least one lens that satisfies the following conditional expression (2). Here, the temperature coefficient of the refractive index with respect to the d-line at 25 °C of the lens included in the imaging lens is (dN / dT) × 10 -6is used. The unit of dN / dT is °C -1 is set. Regarding the lower limit of the conditional expression (2), since |dN / dT| is an absolute value, 0 < |dN / dT|. By ensuring that the corresponding value of the conditional expression (2) does not exceed the upper limit value, it becomes easier to suppress the fluctuation of the focusing position of the imaging lens during temperature changes. 0 < |dN / dT| < 15 (2)

[0072] The front group GF preferably includes at least one lens that satisfies the conditional expression (2). More specifically, it is preferable that the lens on the object side of the front group GF satisfies the conditional expression (2). Also, the rear group GR preferably includes at least one lens that satisfies the conditional expression (2).

[0073] To obtain better characteristics, the upper limit value of the conditional expression (2) is more preferably 14, still more preferably 13, still more preferably 12, still more preferably 11, still more preferably 10.

[0074] The imaging lens preferably satisfies the following conditional expression (3). Here, the sum of the distance on the optical axis from the lens surface on the object side of the front group GF to the lens surface on the image side of the rear group GR in the state of focusing on an infinite object and the above back focus Bf is defined as TL. TL is the overall length in the state of focusing on an infinite object. As an example, the overall length TL is shown in FIG. 3. By ensuring that the corresponding value of the conditional expression (3) does not fall below the lower limit value, it is advantageous for suppressing various aberrations. By ensuring that the corresponding value of the conditional expression (3) does not exceed the upper limit value, it is advantageous for miniaturizing the entire lens system. 1.1 < TL / f < 3.5 (3)

[0075] To obtain better characteristics, the lower limit value of conditional expression (3) is more preferably 1.2, even more preferably 1.21, even more preferably 1.22, even more preferably 1.23, even more preferably 1.24, even more preferably 1.25, even more preferably 1.3, even more preferably 1.4, even more preferably 1.5, even more preferably 1.6, even more preferably 1.7, even more preferably 1.8, even more preferably 1.9. To obtain better characteristics, the upper limit value of conditional expression (3) is more preferably 3, even more preferably 2.9, even more preferably 2.85, even more preferably 2.8, even more preferably 2.75, even more preferably 2.7, even more preferably 2.65, even more preferably 2.6, even more preferably 1.6, even more preferably 1.55, even more preferably 1.5, even more preferably 1.48, even more preferably 1.46, even more preferably 1.45. For example, it is more preferable for the imaging lens to satisfy the following conditional expression (3-1), and even more preferable to satisfy the following conditional expression (3-2). 1.2 < TL / f < 3 (3-1) 1.2 < TL / f < 1.6 (3-2)

[0076] It is preferable for the imaging lens to satisfy the following conditional expression (4). Here, the open F-number in the state of focusing on an infinite object is defined as Fno. By preventing the corresponding value of conditional expression (4) from falling below the lower limit value, it is advantageous for suppressing the increase in the number of lens elements and the enlargement of the lens system while obtaining good optical performance. By preventing the corresponding value of conditional expression (4) from exceeding the upper limit value, it becomes easier to reduce the open F-number while widening the angle of view. 1.6 < Fno / tanωm < 5 (4)

[0077] In order to obtain better characteristics, the lower limit value of conditional expression (4) is more preferably 1.7, even more preferably 1.8, still more preferably 1.9, even more preferably 2, still more preferably 2.1, even more preferably 2.5, and still more preferably 2.8. In order to obtain better characteristics, the upper limit value of conditional expression (4) is more preferably 4, even more preferably 3.5, still more preferably 3.3, even more preferably 3.2, and still more preferably 3.1. For example, it is more preferable that the imaging lens satisfies the following conditional expression (4-1), and even more preferably satisfies the following conditional expression (4-2). 2 < Fno / tanωm < 3.2 (4-1) 2.5 < Fno / tanωm < 4 (4-2)

[0078] It is preferable that the imaging lens simultaneously satisfies the following conditional expressions (5) and (6). Here, the minimum value of the distance on the optical axis from the most image-side lens surface of the front group GF to the aperture stop St is defined as dFSt. The minimum value of the distance on the optical axis from the aperture stop St to the most object-side lens surface of the rear group GR is defined as dStR. That is, dFSt is the minimum distance between the front group GF and the aperture stop St, and dStR is the minimum distance between the aperture stop St and the rear group GR. Note that the "minimum" here means the minimum in the focusing state from the state of focusing on an infinite object to the state of focusing on the closest object. The sign of dFSt is positive if the aperture stop St is on the image side with respect to the most image-side lens surface of the front group GF, and negative if the aperture stop St is on the object side with respect to the most image-side lens surface of the front group GF. The sign of dStR is positive if the most object-side lens surface of the rear group GR is on the image side with respect to the aperture stop St, and negative if the most object-side lens surface of the rear group GR is on the object side with respect to the aperture stop St. As an example, FIG. 3 shows the above minimum distance dFSt and minimum distance dStR. By ensuring that any corresponding values of conditional expressions (5) and (6) do not fall below the lower limit value, it becomes easy to provide a mechanism for changing the aperture diameter of the aperture stop St to an arbitrary value. By ensuring that any corresponding values of conditional expressions (5) and (6) do not exceed the upper limit value, it is advantageous for miniaturization of the lens system. 0 < dFSt / TL < 0.8 (5) 0 < dStR / TL < 0.8 (6)

[0079] In order to obtain better characteristics, the lower limit value of conditional expression (5) is more preferably 0.001, still more preferably 0.003, and even more preferably 0.005. In order to obtain better characteristics, the upper limit value of conditional expression (5) is more preferably 0.5, still more preferably 0.35, and even more preferably 0.3.

[0080] In order to obtain better characteristics, the lower limit value of conditional expression (6) is more preferably 0.001, still more preferably 0.003, and even more preferably 0.005. In order to obtain better characteristics, the upper limit value of conditional expression (6) is more preferably 0.5, still more preferably 0.35, and even more preferably 0.3.

[0081] The imaging lens preferably satisfies the following conditional expression (7). Here, in a state of being focused on an infinite object, the sum of the distance on the optical axis from the aperture stop St to the most image-side lens surface of the rear group GR and the above-mentioned back focus Bf is defined as dSt. As an example, FIG. 3 shows the above-mentioned distance dSt. By preventing the corresponding value of conditional expression (7) from falling below the lower limit value, it becomes easy to prevent the incident angle of the chief ray on the image plane Sim from becoming too large. By preventing the corresponding value of conditional expression (7) from exceeding the upper limit value, it is advantageous for correcting distortion favorably. 0.67 < dSt / TL < 0.93 (7)

[0082] In order to obtain better characteristics, the lower limit value of conditional expression (7) is more preferably 0.68, still more preferably 0.69, even more preferably 0.7, and even more preferably 0.71. In order to obtain better characteristics, the upper limit value of conditional expression (7) is more preferably 0.89, still more preferably 0.85, even more preferably 0.84, and even more preferably 0.83.

[0083] The imaging lens preferably satisfies the following conditional expression (8). Here, the paraxial curvature radius of the object-side surface of the most object-side lens of the front group GF is denoted as RL1f, and the paraxial curvature radius of the image-side surface of the most object-side lens of the front group GF is denoted as RL1r. The conditional expression (8) defines the shape factor of the lens. By ensuring that the corresponding value of the conditional expression (8) does not fall below the lower limit value, it becomes easier to correct the aberration well. By ensuring that the corresponding value of the conditional expression (8) does not exceed the upper limit value, it becomes easier to correct the spherical aberration well. Also, by ensuring that the corresponding value of the conditional expression (8) does not exceed the upper limit value, the refractive power of the most object-side lens of the front group GF does not become too weak, making it easier to achieve wide-angleization. -3 < (RL1r - RL1f) / (RL1r + RL1f) < 0 (8)

[0084] To obtain better characteristics, the lower limit value of the conditional expression (8) is more preferably -2, even more preferably -1.5, even more preferably -1, even more preferably -0.96, even more preferably -0.93, and even more preferably -0.9. To obtain better characteristics, the upper limit value of the conditional expression (8) is more preferably -0.04, even more preferably -0.06, even more preferably -0.07, even more preferably -0.08, even more preferably -0.09, and even more preferably -0.1. For example, the imaging lens more preferably satisfies the following conditional expression (8-1). -1 < (RL1r - RL1f) / (RL1r + RL1f) < -0.07 (8-1)

[0085] The imaging lens preferably satisfies the following conditional expression (9). Here, in the state of focusing on an infinitely distant object, among the first aspherical lenses LA1 included in the rear group GR, the distance on the optical axis from the image-side surface of the first aspherical lens LA1 closest to the image side to the image-side lens surface of the rear group GR is defined as dA1, which is the sum of the above Bf. As an example, FIG. 3 shows the above distance dA1. In the imaging lens of FIG. 3, since the first aspherical lens LA1 is arranged on the image side of the rear group GR, the above Bf is equal to the distance dA1. However, when the first aspherical lens LA1 is not arranged on the image side of the rear group GR, the above Bf and the distance dA1 are not equal. By preventing the corresponding value of the conditional expression (9) from falling below the lower limit value, it becomes easy to prevent the image-side surface of the first aspherical lens LA1 from interfering with various optical filters installed near the image plane. By preventing the corresponding value of the conditional expression (9) from exceeding the upper limit value, it becomes easy to correct distortion and field curvature. 0.02 < dA1 / TL < 0.6 (9)

[0086] To obtain better characteristics, the lower limit value of the conditional expression (9) is more preferably 0.03, even more preferably 0.04, even more preferably 0.06, even more preferably 0.07, even more preferably 0.08, even more preferably 0.09, and even more preferably 0.1. To obtain better characteristics, the upper limit value of the conditional expression (9) is more preferably 0.55, even more preferably 0.5, even more preferably 0.45, even more preferably 0.4, even more preferably 0.35, even more preferably 0.34, and even more preferably 0.33. For example, the imaging lens more preferably satisfies the following conditional expression (9-1). 0.08 < dA1 / TL < 0.35 (9-1)

[0087] The imaging lens preferably satisfies the following conditional expression (10). By preventing the corresponding value of the conditional expression (10) from falling below the lower limit value, it is advantageous for suppressing various aberrations. By preventing the corresponding value of the conditional expression (10) from exceeding the upper limit value, it is advantageous for reducing the size of the entire lens system. 1.2 < TL / (f × tan ωm) < 3 (10)

[0088] To obtain better characteristics, the lower limit value of the conditional expression (10) is more preferably 1.3, still more preferably 1.4, still more preferably 1.5, still more preferably 1.6, still more preferably 1.7, still more preferably 1.8, and still more preferably 1.85. To obtain better characteristics, the upper limit value of the conditional expression (10) is more preferably 2.9, still more preferably 2.8, still more preferably 2.7, still more preferably 2.6, still more preferably 2.5, still more preferably 2.4, and still more preferably 2.35. For example, the imaging lens more preferably satisfies the following conditional expression (10-1). 1.7 < TL / (f × tan ωm) < 2.5 (10-1)

[0089] The front group GF preferably includes at least one lens that satisfies the following conditional expression (11). In particular, it is preferable that the lens on the object side most of the front group GF satisfies the conditional expression (11). Here, the refractive index with respect to the d-line and the Abbe number based on the d-line of the lens included in the imaging lens are respectively defined as Nd and νd. By preventing the corresponding value of the conditional expression (11) from falling below the lower limit value, materials other than materials with a low refractive index and a low Abbe number can be selected, so that it becomes easy to correct the magnification chromatic aberration. By preventing the corresponding value of the conditional expression (11) from exceeding the upper limit value, materials other than materials with a high refractive index and a high Abbe number can be selected, so that a material with a small specific gravity can be selected, and it becomes easy to reduce the weight. 1.6 < Nd + 0.01 × νd < 2.6 (11)

[0090] In order to obtain better characteristics, the lower limit value of conditional expression (11) is more preferably 1.7, still more preferably 1.8, and even more preferably 1.85. In order to obtain better characteristics, the upper limit value of conditional expression (11) is more preferably 2.5, still more preferably 2.4, and even more preferably 2.35.

[0091] When the focal length of the most object-side lens of the front group GF is fL1, it is preferable that the imaging lens satisfies the following conditional expression (12). By preventing the corresponding value of conditional expression (12) from falling below the lower limit value, it becomes easier to correct distortion. By preventing the corresponding value of conditional expression (12) from exceeding the upper limit value, it becomes easier to correct field curvature. -1.5 < f / fL1 < 0 (12)

[0092] In order to obtain better characteristics, the lower limit value of conditional expression (12) is more preferably -1.3, still more preferably -1.1, even more preferably -0.9, and even more preferably -0.8. In order to obtain better characteristics, the upper limit value of conditional expression (12) is more preferably -0.2, still more preferably -0.35, even more preferably -0.45, and even more preferably -0.55.

[0093] It is preferable that the imaging lens satisfies the following conditional expression (13). Here, among the first aspherical lenses LA1 included in the rear group GR, the paraxial curvature radius of the image-side surface of the most image-side first aspherical lens LA1 is defined as RA1c. Among the first aspherical lenses LA1 included in the rear group GR, the curvature radius at the position of the maximum effective diameter of the image-side surface of the most image-side first aspherical lens LA1 is defined as RA1y. By preventing the corresponding value of conditional expression (13) from falling below the lower limit value, it becomes easier to prevent the incident angle of the chief ray on the image plane Sim from becoming too large. By preventing the corresponding value of conditional expression (13) from exceeding the upper limit value, it becomes easier to suppress the intensity of stray light caused by the light reflected by the image-side surface of the most image-side first aspherical lens LA1 included in the rear group GR. -100 < RA1y / RA1c < 0 (13)

[0094] In order to obtain better characteristics, the lower limit value of the conditional expression (13) is more preferably -10, still more preferably -6, still more preferably -5, still more preferably -4, still more preferably -3, still more preferably -2. In order to obtain better characteristics, the upper limit value of the conditional expression (13) is more preferably -0.1, still more preferably -0.2, still more preferably -0.3, still more preferably -0.4, still more preferably -0.5, still more preferably -0.6.

[0095] Here, the "position of the maximum effective diameter" in this specification will be described with reference to FIG. 4. FIG. 4 is an explanatory diagram. In FIG. 4, the left side is the object side and the right side is the image side. FIG. 4 shows an on-axis light beam Xa and an off-axis light beam Xb passing through the lens Lx. In the example of FIG. 4, the ray Xb1, which is the upper ray of the off-axis light beam Xb, is the ray passing through the outermost side. The "outer side" referred to here is the radially outer side centered on the optical axis Z, that is, the side away from the optical axis Z. In this specification, the position of the intersection of this outermost passing ray and the lens surface is the position Px of the maximum effective diameter. Also, twice the distance from the position Px of the maximum effective diameter to the optical axis Z is the effective diameter ED of the object-side surface of the lens Lx. Note that in the example of FIG. 4, the upper ray of the off-axis light beam Xb is the ray passing through the outermost side, but which ray becomes the ray passing through the outermost side depends on the lens system.

[0096] The imaging lens preferably satisfies the following conditional expression (14). Here, among the first aspherical lenses LA1 included in the rear group GR, the refractive index with respect to the d-line and the Abbe number based on the d-line of the first aspherical lens LA1 closest to the image side are denoted as NdA1 and νdA1, respectively. By preventing the corresponding value of the conditional expression (14) from falling below the lower limit value, materials other than those with a low refractive index and a low Abbe number can be selected, facilitating the correction of longitudinal chromatic aberration. By preventing the corresponding value of the conditional expression (14) from exceeding the upper limit value, materials other than those with a high refractive index and a high Abbe number can be selected, enabling the selection of materials with a low specific gravity and facilitating weight reduction. 1.8 < NdA1 + 0.01 × νdA1 < 2.14 (14)

[0097] To obtain better characteristics, the lower limit value of the conditional expression (14) is more preferably 1.85, even more preferably 1.9, and even more preferably 1.95. To obtain better characteristics, the upper limit value of the conditional expression (14) is more preferably 2.13, even more preferably 2.12, and even more preferably 2.11.

[0098] In a configuration where the rear group GR includes at least one second aspherical lens LA2, it is preferable that all the second aspherical lenses LA2 included in the rear group GR satisfy the following conditional expression (15). Here, the paraxial curvature radius of the image-side surface of the second aspherical lens LA2 is denoted as RA2c. The curvature radius at the position of the maximum effective diameter of the image-side surface of the second aspherical lens LA2 is denoted as RA2y. By preventing the corresponding value of the conditional expression (15) from falling below the lower limit value, it is advantageous for suppressing spherical aberration. By preventing the corresponding value of the conditional expression (15) from exceeding the upper limit value, it becomes easier to suppress various aberrations while suppressing the increase in the overall optical length. -1 < RA2c / RA2y < 1 (15)

[0099] In order to obtain better characteristics, the lower limit value of conditional expression (15) is more preferably -0.9, even more preferably -0.8, still more preferably -0.7, even more preferably -0.6, even more preferably -0.5, even more preferably -0.4, and even more preferably -0.3. In order to obtain better characteristics, the upper limit value of conditional expression (15) is more preferably 0.9, even more preferably 0.8, still more preferably 0.7, even more preferably 0.6, even more preferably 0.5, even more preferably 0.4, and even more preferably 0.3.

[0100] In a configuration where the rear group GR includes at least one second aspherical lens LA2, it is preferable that the imaging lens satisfies the following conditional expression (16). Here, among the second aspherical lenses LA2 included in the rear group GR, the sum of the distance on the optical axis from the image-side surface of the most image-side second aspherical lens LA2 to the most image-side lens surface of the rear group GR and Bf is defined as dA2. In a state of focusing on an infinite object, the sum of the distance on the optical axis from the most object-side lens surface of the front group GF to the most image-side lens surface of the rear group GR and Bf is defined as TL. As an example, FIG. 3 shows the above distance dA2. By preventing the corresponding value of conditional expression (16) from falling below the lower limit value, it becomes easy to suppress the increase in the overall optical length while suppressing various aberrations related to the off-axis light beam. By preventing the corresponding value of conditional expression (16) from exceeding the upper limit value, it becomes easy to correct spherical aberration. 0.2 < dA2 / TL < 0.6 (16)

[0101] In order to obtain better characteristics, the lower limit value of conditional expression (16) is more preferably 0.21, even more preferably 0.22, still more preferably 0.23, even more preferably 0.24, and even more preferably 0.25. In order to obtain better characteristics, the upper limit value of conditional expression (16) is more preferably 0.58, even more preferably 0.56, still more preferably 0.54, even more preferably 0.52, and even more preferably 0.5.

[0102] The front lens group GF preferably includes at least one single lens or cemented lens that satisfies the following conditional expression (17). Here, the focal length of one single lens or one cemented lens included in the front lens group GF is defined as fLF. Hereinafter, for convenience of explanation, the single lens or cemented lens that satisfies the conditional expression (17) and is included in the front lens group GF is referred to as an LFp lens. By ensuring that the corresponding value of the conditional expression (17) does not fall below the lower limit value, the front lens group GF can include a single lens or cemented lens having a positive refractive power, which is advantageous for shortening the overall optical length and facilitating ensuring the peripheral light quantity. By ensuring that the corresponding value of the conditional expression (17) does not exceed the upper limit value, the positive refractive power of the LFp lens does not become too strong, which is advantageous for correcting distortion aberration and field curvature. 0 < f / fLF < 2 (17)

[0103] To obtain better characteristics, the lower limit value of the conditional expression (17) is more preferably 0.2. In this case, since the positive refractive power of the LFp lens does not become too weak, it is more advantageous for shortening the overall optical length and facilitating ensuring the peripheral light quantity. To obtain even better characteristics, the lower limit value of the conditional expression (17) is even more preferably 0.3, still more preferably 0.4, still more preferably 0.45, and still more preferably 0.5. To obtain better characteristics, the upper limit value of the conditional expression (17) is more preferably 1.5, still more preferably 1.3, still more preferably 1.1, still more preferably 0.95, and still more preferably 0.9.

[0104] When the focal length of the front lens group GF is fF, the imaging lens preferably satisfies the following conditional expression (18). By ensuring that the corresponding value of the conditional expression (18) does not fall below the lower limit value, the negative refractive power of the front lens group GF does not become too strong, which is advantageous for shortening the overall optical length and facilitating ensuring the peripheral light quantity. By ensuring that the corresponding value of the conditional expression (18) does not exceed the upper limit value, the positive refractive power of the front lens group GF does not become too strong, which is advantageous for correcting spherical aberration and field curvature. -1.5 < f / fF < 1.5 (18)

[0105] In order to obtain better characteristics, the lower limit value of conditional expression (18) is more preferably -1.2, still more preferably -1, still more preferably -0.9, still more preferably -0.85, and still more preferably -0.8. In order to obtain better characteristics, the upper limit value of conditional expression (18) is more preferably 1.2, still more preferably 1, still more preferably 0.9, still more preferably 0.85, and still more preferably 0.8.

[0106] When the maximum shooting magnification is β, it is preferable that the imaging lens satisfies the following conditional expression (19). The maximum shooting magnification is the shooting magnification when shooting the closest object. By preventing the corresponding value of conditional expression (19) from falling below the lower limit value, it is possible to suppress the narrowing of the shooting range of the lens system, and thus secure a suitable added value as an imaging lens. By preventing the corresponding value of conditional expression (19) from exceeding the upper limit value, it is possible to suppress the movement amount of the lens group during focusing, and thus contribute to the miniaturization of the lens system. 0.07 < |β| < 1 (19)

[0107] In order to obtain better characteristics, the lower limit value of conditional expression (19) is more preferably 0.08, still more preferably 0.09, and still more preferably 0.1. In order to obtain better characteristics, the upper limit value of conditional expression (19) is more preferably 0.6, still more preferably 0.35, and still more preferably 0.25.

[0108] The rear group GR preferably includes at least two lenses that satisfy the following conditional expression (20). Here, the specific gravity of the lenses included in the rear group GR is denoted as ρr. By ensuring that the corresponding value of the conditional expression (20) does not fall below the lower limit value, materials with high availability can be used, making it easier to achieve good correction of various aberrations. By ensuring that the corresponding value of the conditional expression (20) does not exceed the upper limit value, it is advantageous for weight reduction of the rear group GR. More preferably, the rear group GR preferably includes at least three lenses that satisfy the following conditional expression (20). 0.86 < ρr < 2.2 (20)

[0109] To obtain better characteristics, the lower limit value of the conditional expression (20) is more preferably 0.88, even more preferably 0.9, and even more preferably 0.92. To obtain better characteristics, the upper limit value of the conditional expression (20) is more preferably 2, even more preferably 1.8, and even more preferably 1.6.

[0110] The imaging lens preferably satisfies the following conditional expression (21). By ensuring that the corresponding value of the conditional expression (21) does not fall below the lower limit value, correction of various aberrations and shortening of the overall optical length become easier. By ensuring that the corresponding value of the conditional expression (21) does not exceed the upper limit value, the brightness of the lens system can be ensured. 1.2 < Fno < 3 (21)

[0111] To obtain better characteristics, the lower limit value of the conditional expression (21) is more preferably 1.3, even more preferably 1.4, and even more preferably 1.5. To obtain better characteristics, the upper limit value of the conditional expression (21) is more preferably 2.5, even more preferably 2.1, and even more preferably 1.9.

[0112] The imaging lens preferably satisfies the following conditional expression (22). By setting the surface shape of the most object-side lens of the front group GF so as to satisfy the conditional expression (22), it becomes easier to suppress distortion aberration. -0.8 < f / RL1r < 3 (22)

[0113] In order to obtain better characteristics, the lower limit value of the conditional expression (22) is more preferably -0.5, still more preferably 0, still more preferably 0.2, still more preferably 0.4, still more preferably 0.6, still more preferably 0.8, and still more preferably 1. In order to obtain better characteristics, the upper limit value of the conditional expression (22) is more preferably 2.7, still more preferably 2.4, still more preferably 2.1, still more preferably 1.8, still more preferably 1.7, still more preferably 1.6, and still more preferably 1.5.

[0114] Note that the example shown in FIG. 1 is just an example, and various modifications are possible without departing from the gist of the technology of the present disclosure. For example, the positions where the first aspherical lens LA1 and the second aspherical lens LA2 are arranged may be different from those in the example of FIG. 1. The number of the first aspherical lens LA1 and the second aspherical lens LA2 included in the imaging lens may be different from that in the example of FIG. 1. The number of lenses included in the front group GF and the rear group GR may be different from that in the example of FIG. 1. The sign of the refractive power of the front group GF may be positive or negative. The sign of the refractive power of the rear group GR may be positive or negative.

[0115] In the example of FIG. 1, focusing is performed by the integral movement of the entire imaging lens, but in the imaging lens of the present disclosure, another focusing method may be adopted. Note that in this specification, "integrally move" means moving simultaneously in the same direction by the same amount. The parentheses described below the imaging lens in FIG. 1 indicate the lens group that moves during focusing, and the arrow attached to this parentheses indicates the moving direction during focusing from an infinite object to a near-distance object.

[0116] In the imaging lens of the present disclosure, a front focus method may be adopted. For example, the rear group GR may be composed of a first subsequent lens group and a second subsequent lens group in order from the object side to the image side. At the time of focusing, the front group GF, the aperture stop St, and the first subsequent lens group may be moved integrally, and the second subsequent lens group may be configured to be fixed with respect to the image plane Sim. In this way, when only some lenses are moved at the time of focusing, it is advantageous for speeding up the focusing compared to the case where all lenses are moved.

[0117] Alternatively, in the imaging lens of the present disclosure, an inner focus method may be adopted. For example, the rear group GR may be composed of a first subsequent lens group and a second subsequent lens group in order from the object side to the image side. At the time of focusing, only the first subsequent lens group may be configured to move. In this case, it is more advantageous for speeding up the focusing.

[0118] Or, the rear group GR may be composed of a first subsequent lens group, a second subsequent lens group, and a third subsequent lens group in order from the object side to the image side. At the time of focusing, only the second subsequent lens group may be configured to move. In this case as well, it is more advantageous for speeding up the focusing.

[0119] When the imaging lens includes only one lens group that moves at the time of focusing, it is advantageous for simplifying the drive mechanism. The imaging lens of the present disclosure may be configured to include two lens groups that move while changing the mutual distance at the time of focusing. In this case, it is advantageous for suppressing aberration variation at the time of focusing.

[0120] The above-described preferred configurations and possible configurations can be arbitrarily combined within a non-contradictory range, and it is preferable to appropriately and selectively adopt them according to the required specifications.

[0121] As an example, a preferred embodiment of the imaging lens of the present disclosure includes, in order from the object side to the image side, a front group GF including one or more lenses, an aperture stop St, and a rear group GR including a plurality of lenses. At least one first aspherical lens LA1 having a concave surface facing the image side in the paraxial region and having an inflection point on the lens surface on the image side where the concavo-convex shape changes midway from the optical axis to the peripheral portion is disposed in the rear group GR, includes at least one lens that satisfies the above conditional expression (2), and satisfies the above conditional expression (1).

[0122] Further, another preferred embodiment of the imaging lens of the present disclosure is that, in the configuration of the above preferred embodiment, the lens on the object side most of the front group GF satisfies the conditional expression (2) and satisfies the above conditional expressions (3-2), (4-2), (7), and (9-1).

[0123] Next, an embodiment of the imaging lens of the present disclosure will be described with reference to the drawings. Note that the reference numerals attached to the lenses in the cross-sectional views of the respective embodiments are used independently for each embodiment in order to avoid explanations associated with the increase in the number of digits of the reference numerals and the complication of the drawings. Therefore, even if the same reference numeral is attached in the drawings of different embodiments, it is not necessarily the same configuration.

[0124] [Embodiment 1] A cross-sectional view of the configuration of the imaging lens of Embodiment 1 is shown in FIG. 1, and the illustration method and configuration are as described above, so duplicate explanations are partially omitted here. The imaging lens of Embodiment 1 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. When focusing from an infinite object to a near object, the entire imaging lens moves integrally toward the object side.

[0125] For the imaging lens of Embodiment 1, the basic lens data is shown in Table 1, the specifications and variable surface intervals are shown in Table 2, and the aspherical coefficients are shown in Table 3.

[0126] The table of the basic lens data is described as follows. In the column of "Sn", the surface numbers are shown when the surface closest to the object side is taken as the first surface and the numbers are incremented one by one as moving toward the image side. In the column of "R", the radius of curvature of each surface is shown. In the column of "D", the axial surface interval between each surface and the surface adjacent to it on the image side is shown. In the column of "Nd", the refractive index of each lens with respect to the d-line is shown. In the column of "νd", the Abbe number of each lens based on the d-line is shown.

[0127] Including the table of the following-described embodiments, the column of "Material" in the table of the basic lens data is described as follows. For the lens whose material is resin, "Plastic" is described in the column of "Material". For the lens whose material is other than resin, the material name is shown in the upper part of the column and the manufacturing company name is shown in the lower part. In the table, the manufacturing company names are shown schematically as described below. "OHARA" indicates Ohara Corporation. "CDGM" indicates Chengdu Guangming Optoelectronic Co., Ltd. "HIKARI" indicates Hikari Glass Co., Ltd. "HOYA" indicates HOYA Corporation. Also, in the column of "Material", for the lens corresponding to the first aspherical lens LA1, "(LA1)" is entered, and for the lens corresponding to the second aspherical lens LA2, "(LA2)" is entered.

[0128] In the column of "ED", the effective diameter of each surface is shown. In the column of "Nd + 0.01×νd", the corresponding value of the conditional expression (11) of each lens is shown. In the column of "ρr", the specific gravity of each lens, that is, the corresponding value of the conditional expression (20) is shown. In the column of "(dN / dT)×10 -6 ", the temperature coefficient of the refractive index of each lens with respect to the d-line at 25°C, that is, the corresponding value of the conditional expression (2) is shown. Note that, including the table of the following-described embodiments, in the columns of "ED", "ρr", and "(dN / dT)×10 -6 ", for the surfaces and lenses not related to the conditional expressions, some descriptions are omitted.

[0129] In the table of basic lens data, the sign of the radius of curvature of the surface facing the object side with a convex shape is positive, and the sign of the radius of curvature of the surface facing the image side with a convex shape is negative. In the column of the surface number corresponding to the aperture stop St, the surface number and the phrase "(St)" are entered. The value in the bottommost column of the D column in the table is the distance between the most image-side surface in the table and the image plane Sim. Regarding the variable surface interval during focusing, the symbol DD is used, and after DD, the surface number on the object side of this interval is attached and entered in the column of the surface interval.

[0130] Table 2 shows the focal length, back focus, open F-number, maximum full angle of view, and variable surface interval based on the d-line. The [°] in the column of the maximum full angle of view indicates that the unit is degrees. In Table 2, the "Infinity" column shows each value in the state of focusing on an infinite object, and the "Close distance" column shows each value in the state of focusing on the closest object. However, the focal length shows only the value in the state of focusing on an infinite object. In the "Close distance" column, the absolute value of the maximum shooting magnification is shown with "times" attached.

[0131] In the basic lens data, an asterisk is attached to the surface number of the aspherical surface, and the numerical value of the paraxial radius of curvature is described in the column of the radius of curvature of the aspherical surface. In Table 3, the Sn row shows the surface number of the aspherical surface, and the KA and Am rows show the numerical values of the aspherical coefficients for each aspherical surface. Here, m in Am is an integer of 3 or more and varies depending on the surface. For example, in the first surface of Example 1, m = 4, 6, 8, 10. The "E±n" (n: integer) of the numerical value of the aspherical coefficient in Table 3 means "×10 ±n ". KA and Am are the aspherical coefficients in the aspherical formula represented by the following formula. Zd = C × h 2 / {1 + (1 - KA × C 2 × h 2 ) 1 / 2}+ ΣAm × h m However, Zd: Aspherical depth (the length of the perpendicular line dropped from the point on the aspherical surface with height h to the plane perpendicular to the optical axis Z where the aspherical vertex touches) h: Height (the distance from the optical axis Z to the lens surface) C: Reciprocal of the paraxial radius of curvature KA, Am: Aspherical coefficients where the aspherical Σ means the sum with respect to m.

[0132] In the data of each table, degrees are used as the unit of angle and mm (millimeter) is used as the unit of length. However, since the optical system can be used even with proportional magnification or reduction, other appropriate units can also be used. Also, in each of the tables shown below, the numerical values are rounded to a predetermined number of digits.

[0133] [Table 1]

[0134] [Table 2]

[0135] [Table 3]

[0136] Fig. 5 shows aberration diagrams of the imaging lens of Example 1. In Fig. 5, from left to right, spherical aberration, astigmatism, distortion, and lateral color aberration are shown. In Fig. 5, the upper row marked with "infinity" shows aberration diagrams in the state of focusing on an object at infinity, and the lower row marked with "close distance" shows aberration diagrams in the state of focusing on the closest object. In the spherical aberration diagram, the aberrations at the d-line, C-line, and F-line are shown by a solid line, a long dashed line, and a short dashed line, respectively. In the astigmatism diagram, the aberration at the d-line in the sagittal direction is shown by a solid line, and the aberration at the d-line in the tangential direction is shown by a short dashed line. In the distortion diagram, the aberration at the d-line is shown by a solid line. In the lateral color aberration diagram, the aberrations at the C-line and F-line are shown by a long dashed line and a short dashed line, respectively. In the spherical aberration diagram, the value of the open F-number is shown after "FNo.=". In the other aberration diagrams, the value of the maximum semi-aperture angle is shown after "ω=".

[0137] The symbols, meanings, description methods, and illustration methods of the data related to Example 1 above are basically the same in the following examples unless otherwise specified, so duplicate explanations are omitted below.

[0138] [Example 2] A cross-sectional view of the configuration of the imaging lens of Example 2 is shown in FIG. 6. The imaging lens of Example 2 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes two lenses, L11 to L12, in order from the object side to the image side. Lens L12 corresponds to the LFp lens. The rear group GR includes five lenses, L21 to L25, in order from the object side to the image side. When focusing from an infinite object to a close-distance object, the entire imaging lens moves integrally toward the object side.

[0139] Regarding the imaging lens of Example 2, the basic lens data is shown in Table 4, the specifications and variable surface intervals are shown in Table 5, the aspherical coefficients are shown in Table 6, and each aberration diagram is shown in FIG. 7.

[0140]

Table 4

[0141]

Table 5

[0142]

Table 6

[0143] [Example 3] A cross-sectional view of the configuration of the imaging lens of Example 3 is shown in FIG. 8. The imaging lens of Example 3 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes two lenses, L11 to L12, in order from the object side to the image side. Lens L12 corresponds to the LFp lens. The rear group GR includes five lenses, L21 to L25, in order from the object side to the image side. When focusing from an infinite object to a close-distance object, the entire imaging lens moves integrally toward the object side.

[0144] For the imaging lens of Example 3, the basic lens data is shown in Table 7, the specifications and variable surface intervals are shown in Table 8, the aspherical coefficients are shown in Table 9, and each aberration diagram is shown in FIG. 9.

[0145] [Table 7]

[0146] [Table 8]

[0147] [Table 9]

[0148] [Example 4] A cross-sectional view of the configuration of the imaging lens of Example 4 is shown in FIG. 10. The imaging lens of Example 4 is composed of a front group GF, a diaphragm St, and a rear group GR in order from the object side to the image side. The front group GF is composed of three lenses L11 to L13 in order from the object side to the image side. A cemented lens in which lens L12 and lens L13 are cemented corresponds to the LFp lens. The rear group GR is composed of four lenses L21 to L24 in order from the object side to the image side. When focusing from an infinite object to a close object, the entire imaging lens moves integrally toward the object side.

[0149] For the imaging lens of Example 4, the basic lens data is shown in Table 10, the specifications and variable surface intervals are shown in Table 11, the aspherical coefficients are shown in Table 12, and each aberration diagram is shown in FIG. 11.

[0150] [Table 10]

[0151] [Table 11]

[0152] [Table 12]

[0153] [Example 5] A cross-sectional view of the configuration of the imaging lens of Example 5 is shown in FIG. 12. The imaging lens of Example 5 is composed of a front group GF, an aperture stop St, and a rear group GR in order from the object side to the image side. The front group GF is composed of three lenses L11 to L13 in order from the object side to the image side. A cemented lens in which lens L12 and lens L13 are cemented corresponds to the LFp lens. The rear group GR is composed of five lenses L21 to L25 in order from the object side to the image side. When focusing from an infinite object to a close-distance object, the entire imaging lens moves integrally toward the object side.

[0154] Regarding the imaging lens of Example 5, the basic lens data is shown in Table 13, the specifications and variable surface intervals are shown in Table 14, the aspherical coefficients are shown in Table 15, and each aberration diagram is shown in FIG. 13.

[0155]

Table 13

[0156]

Table 14

[0157]

Table 15

[0158] [Example 6] A cross-sectional view of the configuration of the imaging lens of Example 6 is shown in FIG. 14. The imaging lens of Example 6 is composed of a front group GF, an aperture stop St, and a rear group GR in order from the object side to the image side. The front group GF is composed of two lenses L11 to L12 in order from the object side to the image side. Lens L12 corresponds to the LFp lens. The rear group GR is composed of five lenses L21 to L25 in order from the object side to the image side. When focusing from an infinite object to a close-distance object, the entire imaging lens moves integrally toward the object side.

[0159] For the imaging lens of Example 6, the basic lens data is shown in Table 16, the specifications and variable surface intervals are shown in Table 17, the aspherical coefficients are shown in Table 18, and each aberration diagram is shown in FIG. 15.

[0160] [Table 16]

[0161] [Table 17]

[0162] [Table 18]

[0163] [Example 7] A cross-sectional view of the configuration of the imaging lens of Example 7 is shown in FIG. 16. The imaging lens of Example 7 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes two lenses, L11 and L12, in order from the object side to the image side. Lens L12 corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes three lenses, L21 to L23, in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses, L24 to L25, in order from the object side to the image side. When focusing from an infinite object to a close object, the front group GF, the aperture stop St, and the first subsequent lens group GR1 move integrally toward the object side, and the second subsequent lens group GR2 is fixed with respect to the image plane Sim.

[0164] For the imaging lens of Example 7, the basic lens data is shown in Table 19, the specifications and variable surface intervals are shown in Table 20, the aspherical coefficients are shown in Table 21, and each aberration diagram is shown in FIG. 17.

[0165] [Table 19]

[0166]

Table 20

[0167]

Table 21

[0168] [Example 8] A cross-sectional view of the configuration of the imaging lens of Example 8 is shown in FIG. 18. The imaging lens of Example 8 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes three lenses L11 to L13 in order from the object side to the image side. The cemented lens formed by cementing lens L12 and lens L13 corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes three lenses L21 to L23 in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses L24 to L25 in order from the object side to the image side. When focusing from an infinite object to a close object, the front group GF, the aperture stop St, and the first subsequent lens group GR1 move integrally toward the object side, and the second subsequent lens group GR2 is fixed with respect to the image plane Sim.

[0169] Regarding the imaging lens of Example 8, the basic lens data is shown in Table 22, the specifications and variable surface intervals are shown in Table 23, the aspherical coefficients are shown in Table 24, and each aberration diagram is shown in FIG. 19.

[0170]

Table 22

[0171]

Table 23

[0172]

Table 24

[0173] [Example 9] A cross-sectional view of the configuration of the imaging lens of Example 9 is shown in FIG. 20. The imaging lens of Example 9 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes two lenses, lenses L11 to L12, in order from the object side to the image side. Lens L12 corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes four lenses, lenses L21 to L24, in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses, lenses L25 to L26, in order from the object side to the image side. When focusing from an infinite object to a close-distance object, the front group GF, the aperture stop St, and the first subsequent lens group GR1 move integrally toward the object side, and the second subsequent lens group GR2 is fixed with respect to the image plane Sim.

[0174] Regarding the imaging lens of Example 9, the basic lens data is shown in Table 25, the specifications and variable surface intervals are shown in Table 26, the aspherical coefficients are shown in Table 27, and each aberration diagram is shown in FIG. 21.

[0175]

Table 25

[0176]

Table 26

[0177]

Table 27

[0178] [Example 10] A cross-sectional view of the configuration of the imaging lens according to Embodiment 10 is shown in FIG. 22. The imaging lens according to Embodiment 10 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes three lenses L11 to L13 in order from the object side to the image side. A cemented lens formed by cementing lens L12 and lens L13 corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes four lenses L21 to L24 in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses L25 to L26 in order from the object side to the image side. When focusing from an infinite object to a close object, the front group GF, the aperture stop St, and the first subsequent lens group GR1 move integrally toward the object side, and the second subsequent lens group GR2 is fixed with respect to the image plane Sim.

[0179] Regarding the imaging lens according to Embodiment 10, the basic lens data is shown in Table 28, the specifications and variable surface intervals are shown in Table 29, the aspherical coefficients are shown in Table 30, and each aberration diagram is shown in FIG. 23.

[0180] [Table 28]

[0181] [Table 29]

[0182] [Table 30]

[0183] [Embodiment 11] A cross-sectional view of the configuration of the imaging lens of Example 11 is shown in FIG. 24. The imaging lens of Example 11 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes three lenses L11 to L13 in order from the object side to the image side. A cemented lens in which lens L12 and lens L13 are cemented corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes four lenses L21 to L24 in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses L25 to L26 in order from the object side to the image side. When focusing from an infinite object to a close object, the front group GF, the aperture stop St, and the first subsequent lens group GR1 move integrally toward the object side, and the second subsequent lens group GR2 is fixed with respect to the image plane Sim.

[0184] Regarding the imaging lens of Example 11, the basic lens data is shown in Table 31, the specifications and variable surface intervals are shown in Table 32, the aspherical coefficients are shown in Table 33, and each aberration diagram is shown in FIG. 25.

[0185]

Table 31

[0186]

Table 32

[0187]

Table 33

[0188] [Example 12] A cross-sectional view of the configuration of the imaging lens according to Example 12 is shown in FIG. 26. The imaging lens according to Example 12 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes three lenses L11 to L13 in order from the object side to the image side. A cemented lens in which lens L12 and lens L13 are cemented corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes four lenses L21 to L24 in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses L25 to L26 in order from the object side to the image side. When focusing from an infinite object to a close object, the front group GF, the aperture stop St, and the first subsequent lens group GR1 move integrally toward the object side, and the second subsequent lens group GR2 is fixed with respect to the image plane Sim.

[0189] Regarding the imaging lens according to Example 12, the basic lens data is shown in Table 34, the specifications and variable surface intervals are shown in Table 35, the aspherical coefficients are shown in Table 36, and each aberration diagram is shown in FIG. 27.

[0190] [Table 34]

[0191] [Table 35]

[0192] [Table 36]

[0193] [Example 13] A cross-sectional view of the configuration of the imaging lens according to Embodiment 13 is shown in FIG. 28. The imaging lens according to Embodiment 13 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes two lenses, L11 and L12, in order from the object side to the image side. The rear group GR includes five lenses, L21 to L25, in order from the object side to the image side. When focusing from an infinite object to a close object, the entire imaging lens moves integrally toward the object side.

[0194] Regarding the imaging lens according to Embodiment 13, the basic lens data is shown in Table 37, the specifications and variable surface intervals are shown in Table 38, the aspherical coefficients are shown in Table 39, and each aberration diagram is shown in FIG. 29.

[0195] [Table 37]

[0196] [Table 38]

[0197] [Table 39]

[0198] [Embodiment 14] A cross-sectional view of the configuration of the imaging lens according to Embodiment 14 is shown in FIG. 30. The imaging lens according to Embodiment 14 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes one lens, L11. The rear group GR includes five lenses, L21 to L25, in order from the object side to the image side. When focusing from an infinite object to a close object, the entire imaging lens moves integrally toward the object side.

[0199] Regarding the imaging lens according to Embodiment 14, the basic lens data is shown in Table 40, the specifications and variable surface intervals are shown in Table 41, the aspherical coefficients are shown in Table 42, and each aberration diagram is shown in FIG. 31.

[0200] [Table 40]

[0201]

Table 41

[0202]

Table 42

[0203] [Example 15] A cross-sectional view of the configuration of the imaging lens of Example 15 is shown in FIG. 32. The imaging lens of Example 15 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes two lenses, L11 to L12, in order from the object side to the image side. The cemented lens in which L11 and L12 are cemented corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes three lenses, L21 to L23, in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses, L24 to L25, in order from the object side to the image side. The lens L22 is a composite aspherical lens in which a resin L22b having an aspherical air contact surface is formed on the spherical surface of a glass lens L22a. When focusing from an infinite object to a close object, only the first subsequent lens group GR1 moves toward the object side, and the other lenses are fixed with respect to the image plane Sim.

[0204] Regarding the imaging lens of Example 15, the basic lens data is shown in Table 43, the specifications and variable surface intervals are shown in Table 44, the aspherical coefficients are shown in Table 45, and each aberration diagram is shown in FIG. 33.

[0205]

Table 43

[0206]

Table 44

[0207]

Table 45

[0208] [Example 16] A cross-sectional view of the configuration of the imaging lens of Example 16 is shown in FIG. 34. The imaging lens of Example 16 is composed of a front group GF, an aperture stop St, and a rear group GR in order from the object side to the image side. The front group GF is composed of two lenses, lenses L11 to L12, in order from the object side to the image side. The cemented lens in which lens L11 and lens L12 are cemented corresponds to the LFp lens. The rear group GR is composed of a first subsequent lens group GR1 and a second subsequent lens group GR2 in order from the object side to the image side. The first subsequent lens group GR1 is composed of three lenses, lenses L21 to L23, in order from the object side to the image side. The second subsequent lens group GR2 is composed of two lenses, lenses L24 to L25, in order from the object side to the image side. Lens L22 is a compound aspherical lens in which a resin L22b with an aspherical air contact surface is formed on the spherical surface of a glass lens L22a. When focusing from an infinite object to a close object, only the first subsequent lens group GR1 moves toward the object side, and the other lenses are fixed with respect to the image plane Sim.

[0209] Regarding the imaging lens of Example 16, the basic lens data is shown in Table 46, the specifications and variable surface intervals are shown in Table 47, the aspherical coefficients are shown in Table 48, and each aberration diagram is shown in FIG. 35.

[0210]

Table 46

[0211]

Table 47

[0212]

Table 48

[0213] [Example 17] A cross-sectional view of the configuration of the imaging lens of Example 17 is shown in FIG. 36. The imaging lens of Example 17 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes two lenses, lenses L11 to L12, in order from the object side to the image side. Lens L12 corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes six lenses, lenses L21 to L26, in order from the object side to the image side. The second subsequent lens group GR2 includes one lens, lens L27. Lens L24 is a compound aspherical lens in which a resin L24b with an aspherical air contact surface is formed on the spherical surface of a glass lens L24a. When focusing from an infinite object to a close object, only the first subsequent lens group GR1 moves toward the object side, and the other lenses are fixed with respect to the image plane Sim.

[0214] Regarding the imaging lens of Example 17, the basic lens data is shown in Table 49, the specifications and variable surface intervals are shown in Table 50, the aspherical coefficients are shown in Table 51, and each aberration diagram is shown in FIG. 37.

[0215]

Table 49

[0216]

Table 50

[0217]

Table 51

[0218] [Example 18] A cross-sectional view of the configuration of the imaging lens according to Embodiment 18 is shown in FIG. 38. The imaging lens according to Embodiment 18 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes three lenses L11 to L13 in order from the object side to the image side. The lens L13 corresponds to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1, a second subsequent lens group GR2, and a third subsequent lens group GR3. The first subsequent lens group GR1 includes one lens L21. The second subsequent lens group GR2 includes four lenses L22 to L25 in order from the object side to the image side. The third subsequent lens group GR3 includes one lens L26. When focusing from an infinite object to a close object, only the second subsequent lens group GR2 moves toward the object side, and the other lenses are fixed with respect to the image plane Sim.

[0219] For the imaging lens according to Embodiment 18, the basic lens data is shown in Table 52, the specifications and variable surface intervals are shown in Table 53, the aspherical coefficients are shown in Table 54, and each aberration diagram is shown in FIG. 39.

[0220] [Table 52]

[0221] [Table 53]

[0222] [Table 54]

[0223] [Embodiment 19] A cross-sectional view of the configuration of the imaging lens according to Embodiment 19 is shown in FIG. 40. The imaging lens according to Embodiment 19 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes four lenses L11 to L14 in order from the object side to the image side. Lenses L12 and L14 correspond to the LFp lenses. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1, a second subsequent lens group GR2, and a third subsequent lens group GR3. The first subsequent lens group GR1 includes a single lens L21. The second subsequent lens group GR2 includes four lenses L22 to L25 in order from the object side to the image side. The third subsequent lens group GR3 includes a single lens L26. When focusing from an infinite object to a close object, only the second subsequent lens group GR2 moves toward the object side, and the other lenses are fixed with respect to the image plane Sim.

[0224] Regarding the imaging lens according to Embodiment 19, the basic lens data is shown in Table 55, the specifications and variable surface intervals are shown in Table 56, the aspherical coefficients are shown in Table 57, and each aberration diagram is shown in FIG. 41.

[0225] [Table 55]

[0226] [Table 56]

[0227] [Table 57]

[0228] [Embodiment 20] A cross-sectional view of the configuration of the imaging lens according to Example 20 is shown in FIG. 42. The imaging lens according to Example 20 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF consists of a single lens, lens L11. Lens L11 corresponds to the LFp lens. The rear group GR consists of a first subsequent lens group GR1 and a second subsequent lens group GR2, in order from the object side to the image side. The first subsequent lens group GR1 consists of four lenses, lenses L21 to L24, in order from the object side to the image side. The second subsequent lens group GR2 consists of two lenses, lenses L25 to L26, in order from the object side to the image side. When focusing from an infinite object to a close object, the front group GF, the aperture stop St, and the first subsequent lens group GR1 move integrally toward the object side, and the second subsequent lens group GR2 is fixed with respect to the image plane Sim.

[0229] Regarding the imaging lens according to Example 20, the basic lens data is shown in Table 58, the specifications and variable surface intervals are shown in Table 59, the aspherical coefficients are shown in Table 60, and each aberration diagram is shown in FIG. 43.

[0230]

Table 58

[0231]

Table 59

[0232]

Table 60

[0233] [Example 21] A cross-sectional view of the configuration of the imaging lens according to Example 21 is shown in FIG. 44. The imaging lens according to Example 21 includes, in order from the object side to the image side, a front group GF, an aperture stop St, and a rear group GR. The front group GF includes, in order from the object side to the image side, a first front lens group GF1, a second front lens group GF2, and a third front lens group GF3. The first front lens group GF1 includes five lenses L11 to L15 in order from the object side to the image side. The second front lens group GF2 includes one lens L16. The third front lens group GF3 includes two lenses L17 to L18 in order from the object side to the image side. Lenses L12, L15, and L16 correspond to the LFp lens. The rear group GR includes, in order from the object side to the image side, a first subsequent lens group GR1 and a second subsequent lens group GR2. The first subsequent lens group GR1 includes four lenses L21 to L24 in order from the object side to the image side. The second subsequent lens group GR2 includes two lenses L25 to L26 in order from the object side to the image side. When focusing from an infinite object to a close object, the second front lens group GF2 and the first subsequent lens group GR1 move toward the object side while changing the mutual distance, and the other lenses are fixed with respect to the image plane Sim.

[0234] Regarding the imaging lens of Example 21, the basic lens data is shown in Tables 61A and 61B, the specifications and variable surface intervals are shown in Table 62, the aspherical coefficients are shown in Table 63, and each aberration diagram is shown in FIG. 45. Here, in order to avoid making one table too long, the basic lens data is shown in two tables.

[0235]

Table 61A

[0236]

Table 61B

[0237]

Table 62

[0238]

Table 63

[0239] Tables 64 to 67 show the corresponding values of conditional expressions (1), (3) to (10), (12) to (19), (21), and (22) of the imaging lenses of Examples 1 to 21. In the columns of the corresponding values of conditional expressions (15) and (17), for those with multiple corresponding values, the reference signs of the corresponding lenses are entered in parentheses below each corresponding value. Note that the corresponding values of conditional expressions (2), (11), and (20) are shown in the table of the basic lens data of each example, so they are not described in Tables 64 to 67. The corresponding values of the examples shown in Tables 64 to 67 may be used as the upper limit or the lower limit of the conditional expression to set the preferable range of the conditional expression.

[0240]

Table 64

[0241]

Table 65

[0242]

Table 66

[0243]

Table 67

[0244] The imaging lenses of Examples 1 to 21 are configured to be small, while various aberrations are well corrected and high optical performance is maintained.

[0245] Next, an imaging device according to an embodiment of the present disclosure will be described. FIGS. 46 and 47 show external views of a camera 30 which is an imaging device according to an embodiment of the present disclosure. FIG. 46 shows a perspective view of the camera 30 as seen from the front side, and FIG. 47 shows a perspective view of the camera 30 as seen from the back side. The camera 30 is a so-called mirrorless type digital camera, and an interchangeable lens 20 can be detachably attached thereto. The interchangeable lens 20 includes an imaging lens 1 according to an embodiment of the present disclosure housed in a lens barrel.

[0246] The camera 30 includes a camera body 31. A shutter button 32 and a power button 33 are provided on the upper surface of the camera body 31. Further, 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 an image that has been captured and an image within the angle of view before being captured.

[0247] A photographing aperture through which light from a subject enters is provided at the center of the front surface of the camera body 31. A mount 37 is provided at a position corresponding to the photographing aperture, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0248] An image sensor 38 is provided inside the camera body 31. The image sensor 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. As the image sensor 38, for example, a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), or the like is used. A signal processing circuit (not shown), a recording medium (not shown), and the like are provided inside the camera body 31. The signal processing circuit processes the imaging signal output from the image sensor 38 to generate an image. The recording medium is for recording the generated image. In the camera 30, it is possible to take a still image or a moving image by pressing the shutter button 32, and the image data obtained by this photographing is recorded on the above recording medium.

[0249] The above has described the technology of the present disclosure by way of embodiments and examples. However, the technology of the present disclosure is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, surface interval, refractive index, Abbe number, aspherical coefficient, etc. of each lens are not limited to the values shown in the above examples, and other values can be taken.

[0250] Also, the imaging device according to the embodiment of the present disclosure is not limited to the above example. For example, it can be in various forms such as cameras other than the mirrorless type, film cameras, video cameras, and security cameras.

[0251] Regarding the above embodiments and examples, the following additional remarks are further disclosed. [Appendix 1] Comprising, in order from the object side to the image side, a front group including one or more lenses, a diaphragm, and a rear group including a plurality of lenses, The rear group includes at least one first aspherical lens having a concave surface facing the image side in the paraxial region and having an inflection point on the lens surface on the image side where the concavo-convex shape changes midway from the optical axis to the peripheral part, Let the back focus at the air-equivalent distance of the entire system in the state of focusing on an infinite object be Bf, Let the focal length of the entire system in the state of focusing on an infinite object be f, When the maximum semi-field angle in the state of focusing on an infinite object is ωm, 0.3 < Bf / (f × tan ωm) < 1.5 (1) Satisfying the conditional expression (1) represented by, Let the temperature coefficient of the refractive index with respect to the d-line at 25°C of the lenses included in the entire system be (dN / dT)×10 -6 And, Let the unit of dN / dT be °C -1 When, 0 < |dN / dT| < 15 (2) An imaging lens including at least one lens that satisfies the conditional expression (2) represented by. [Appendix 2] 0.36 < Bf / (f × tan ωm) < 1.2 (1-1) The imaging lens according to Appendix 1 that satisfies the conditional expression (1-1) represented by [Appendix 3] When the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group in the state of being focused on an infinite object and the sum of Bf are defined as TL, 1.1 < TL / f < 3.5 (3) The imaging lens according to Appendix 1 or Appendix 2 that satisfies the conditional expression (3) represented by [Appendix 4] 1.2 < TL / f < 3 (3-1) The imaging lens according to Appendix 3 that satisfies the conditional expression (3-1) represented by [Appendix 5] When the open F-number in the state of being focused on an infinite object is defined as Fno, 1.6 < Fno / tanωm < 5 (4) The imaging lens according to any one of Appendices 1 to 4 that satisfies the conditional expression (4) represented by [Appendix 6] 2 < Fno / tanωm < 3.2 (4-1) The imaging lens according to Appendix 5 that satisfies the conditional expression (4-1) represented by [Appendix 7] The minimum value of the distance on the optical axis from the most image-side lens surface of the front group to the aperture is defined as dFSt, The sign of dFSt is positive if the aperture is on the image side of the most image-side lens surface of the front group, and negative if the aperture is on the object side of the most image-side lens surface of the front group, The minimum value of the distance on the optical axis from the aperture to the most object-side lens surface of the rear group is defined as dStR, The sign of dStR is positive if the most object-side lens surface of the rear group is on the image side of the aperture, and negative if the most object-side lens surface of the rear group is on the object side of the aperture, When the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group in the state of being focused on an infinite object and the sum of Bf are defined as TL, 0 < dFSt / TL < 0.8 (5) 0 < dStR / TL < 0.8 (6) The imaging lens according to any one of Appendices 1 to 6 that satisfies the conditional expressions (5) and (6) represented by [Appendix 8] In a state of being focused on an infinite object, the sum of the distance on the optical axis from the aperture stop to the most image-side lens surface of the rear group and Bf is defined as dSt, When the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf in a state of being focused on an infinite object is defined as TL, 0.67 < dSt / TL < 0.93 (7) The imaging lens according to any one of Appendices 1 to 7 that satisfies the conditional expression (7) represented by [Appendix 9] Let the paraxial curvature radius of the object-side surface of the most object-side lens of the front group be RL1f, When the paraxial curvature radius of the image-side surface of the most object-side lens of the front group is RL1r, -3 < (RL1r - RL1f) / (RL1r + RL1f) < 0 (8) The imaging lens according to any one of Appendices 1 to 7 that satisfies the conditional expression (8) represented by [Appendix 10] -1 < (RL1r - RL1f) / (RL1r + RL1f) < -0.07 (8-1) The imaging lens according to Appendix 9 that satisfies the conditional expression (8-1) represented by [Appendix 11] In a state of being focused on an infinite object, among the first aspherical lenses included in the rear group, the sum of the distance on the optical axis from the image-side surface of the most image-side first aspherical lens to the most image-side lens surface of the rear group and Bf is defined as dA1, When the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf in a state of being focused on an infinite object is defined as TL, 0.02 < dA1 / TL < 0.6 (9) The imaging lens according to any one of Appendices 1 to 10 that satisfies the conditional expression (9) represented by [Appendix 12] 0.08 < dA1 / TL < 0.35 (9-1) The imaging lens according to Appendix 11 that satisfies the conditional expression (9-1) represented by [Appendix 13] The imaging lens according to any one of Appendices 1 to 12, wherein the front group includes at least one lens that satisfies the conditional expression (2). [Appendix 14] The imaging lens according to Appendix 13, wherein the lens on the most object side of the front group satisfies the conditional expression (2). [Appendix 15] The imaging lens according to any one of Appendices 1 to 14, wherein the rear group includes at least one lens that satisfies the conditional expression (2). [Appendix 16] When the distance on the optical axis from the lens surface on the most object side of the front group to the lens surface on the most image side of the rear group in the state of focusing on an infinite object is TL when added to Bf, 1.2 < TL / (f × tan ωm) < 3 (10) The imaging lens according to any one of Appendices 1 to 15 that satisfies the conditional expression (10) represented by [Appendix 17] 1.7 < TL / (f × tan ωm) < 2.5 (10-1) The imaging lens according to Appendix 16 that satisfies the conditional expression (10-1) represented by [Appendix 18] When the refractive index with respect to the d-line and the Abbe number based on the d-line of the lenses included in the entire system are Nd and νd, respectively, 1.6 < Nd + 0.01 × νd < 2.6 (11) The imaging lens according to any one of Appendices 1 to 17, wherein the front group includes at least one lens that satisfies the conditional expression (11) represented by [Appendix 19] The imaging lens according to Appendix 18, wherein the lens on the most object side of the front group satisfies the conditional expression (11). [Appendix 20] When the focal length of the lens on the most object side of the front group is fL1, -1.5 < f / fL1 < 0 (12) The imaging lens according to any one of Appendices 1 to 19 that satisfies the conditional expression (12) represented by [Appendix 21] Among the first aspherical lenses included in the rear group, when the paraxial curvature radius of the image-side surface of the first aspherical lens closest to the image side is RA1c, Among the first aspherical lenses included in the rear group, when the curvature radius at the position of the maximum effective diameter of the image-side surface of the first aspherical lens closest to the image side is RA1y, -100 < RA1y / RA1c < 0 (13) The imaging lens according to any one of Appendices 1 to 20 that satisfies the conditional expression (13) represented by [Appendix 22] Among the first aspherical lenses included in the rear group, when the refractive index for the d-line and the Abbe number based on the d-line of the first aspherical lens closest to the image side are NdA1 and νdA1, respectively, 1.8 < NdA1 + 0.01×νdA1 < 2.14 (14) The imaging lens according to any one of Appendices 1 to 21 that satisfies the conditional expression (14) represented by [Appendix 23] The rear group includes at least one second aspherical lens having an image-side lens surface that is convex toward the image side in the paraxial region and whose refractive power at the position of the maximum effective diameter is shifted in the negative direction compared to the refractive power in the paraxial region. The imaging lens according to any one of Appendices 1 to 22 [Appendix 24] When the paraxial curvature radius of the image-side surface of the second aspherical lens is RA2c, When the curvature radius at the position of the maximum effective diameter of the image-side surface of the second aspherical lens is RA2y, -1 < RA2c / RA2y < 1 (15) The imaging lens according to Appendix 23, in which all the second aspherical lenses included in the rear group satisfy the conditional expression (15) represented by [Appendix 25] In a state of focusing on an infinitely distant object, among the second aspherical lenses included in the rear group, the sum of the distance on the optical axis from the image-side surface of the second aspherical lens closest to the image side to the image-side lens surface of the rear group and Bf is defined as dA2. When the sum of the distance on the optical axis from the object-side lens surface of the front group closest to the object side to the image-side lens surface of the rear group and Bf in a state of focusing on an infinitely distant object is defined as TL, 0.2 < dA2 / TL < 0.6 (16) The imaging lens according to Supplementary Note 23 or Supplementary Note 24 that satisfies the conditional expression (16) represented by the above. [Supplementary Note 26] The second lens from the image side of the rear group is the imaging lens according to any one of Supplementary Notes 23 to 25, which is the second aspherical lens closest to the image side among the second aspherical lenses included in the rear group. [Supplementary Note 27] The second lens from the image side of the rear group is the imaging lens according to any one of Supplementary Notes 1 to 26, which has an inflection point on the image-side lens surface where the concavo-convex shape changes halfway from the optical axis to the peripheral part. [Supplementary Note 28] The image-side lens of the rear group is the imaging lens according to any one of Supplementary Notes 1 to 27, which is the first aspherical lens. [Supplementary Note 29] The image-side lens of the rear group is the imaging lens according to any one of Supplementary Notes 1 to 28, which has a convex surface facing the object side in the paraxial region and has an inflection point on the object-side lens surface where the concavo-convex shape changes halfway from the optical axis to the peripheral part. [Supplementary Note 30] The rear group includes two of the first aspherical lenses, and the imaging lens according to any one of Supplementary Notes 1 to 29. [Supplementary Note 31] The rear group includes two of the second aspherical lenses, and the imaging lens according to any one of Supplementary Notes 23 to 26. [Supplementary Note 32] The imaging lens according to any one of Supplementary Notes 1 to 31, which includes at least one cemented lens. [Supplementary Note 33] The lens on the object side of the front group satisfies the conditional expression (2), With the object focused at infinity, the sum of the distance on the optical axis from the lens surface on the object side of the front group to the lens surface on the image side of the rear group and Bf is defined as TL, With the object focused at infinity, the open F-number is defined as Fno, With the object focused at infinity, the sum of the distance on the optical axis from the aperture stop to the lens surface on the image side of the rear group and Bf is defined as dSt, When the object is focused at infinity, for the first aspherical lens included in the rear group, the sum of the distance on the optical axis from the image-side surface of the first aspherical lens closest to the image side to the lens surface on the image side of the rear group and Bf is defined as dA1, 1.2 < TL / f < 1.6 (3-2) 2.5 < Fno / tanωm < 4 (4-2) 0.67 < dSt / TL < 0.93 (7) 0.08 < dA1 / TL < 0.35 (9-1) The imaging lens according to any one of Appendices 1 to 32 that satisfies the conditional expressions (3-2), (4-2), (7), and (9-1) represented by the above. [Appendix 34] An imaging device including the imaging lens according to any one of Appendices 1 to 33.

Explanation of symbols

[0252] 1 Imaging lens 20 Interchangeable lens 30 Camera 31 Camera body 32 Shutter button 33 Power button 34 Operation unit 35 Operation unit 36 Display unit 37 Mount 38 Image sensor Bf Back focus dA1 Distance dA2 Distance dSt Distance Minimum dStR interval Minimum dFSt interval Effective diameter of ED Front group GF First front lens group GF1 Second front lens group GF2 Third front lens group GF3 Rear group GR First subsequent lens group GR1 Second subsequent lens group GR2 Third subsequent lens group GR3 Lenses L11~L27 Lens L22a Resin L22b Lens L24a Resin L24b First aspherical lens LA1 Second aspherical lens LA2 Lens Lx Position of the maximum effective diameter Px Image plane Sim Aperture stop St Overall length TL Axial beam on the X-axis Off-axis beam on the X-axis Ray Xb1 Optical axis Z Maximum semi-field angle ωm

Claims

1. It consists of a front group including one or more lenses, a diaphragm, and a rear group including a plurality of lenses, in order from the object side to the image side, The rear group includes at least one first aspherical lens having a concave surface facing the image side in the paraxial region and having an inflection point on the lens surface on the image side where the concavo-convex shape changes midway from the optical axis to the peripheral part, Let the back focus at the air equivalent distance of the entire system in the state of focusing on an infinite object be Bf, Let the focal length of the entire system in the state of focusing on an infinite object be f, When the maximum half angle of view in the state of focusing on an infinite object is ωm, 0.3 < Bf / (f × tan ωm) < 1.5 (1) Satisfies the conditional expression (1) represented by, The temperature coefficient of the refractive index for the d-line at 25°C of the lenses included in the entire system is (dN / dT) × 10 －６ is defined as The unit of dN / dT is °C －１ when 0 < |dN / dT| < 15 (2) An imaging lens including at least one lens that satisfies the conditional expression (2) represented by.

2. When the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group in the state of focusing on an infinite object and the sum with Bf is TL, 1.1 < TL / f < 3.5 (3) The imaging lens according to claim 1 that satisfies the conditional expression (3) represented by.

3. 1.2 < TL / f < 3 (3-1) The imaging lens according to claim 2 that satisfies the conditional expression (3-1) represented by.

4. 0.36 < Bf / (f × tan ωm) < 1.2 (1-1) The imaging lens according to claim 1 that satisfies the conditional expression (1-1) represented by.

5. When the open F number in the state of focusing on an infinite object is Fno, 1.6 < Fno / tan ωm < 5 (4) The imaging lens according to claim 1 that satisfies the conditional expression (4) represented by.

6. 2 < Fno / tan ωm < 3.2 (4-1) The imaging lens according to claim 5 that satisfies the conditional expression (4-1) represented by.

7. Let the minimum value of the distance on the optical axis from the most image-side lens surface of the front group to the diaphragm be dFSt, The sign of dFSt is positive if the diaphragm is on the image side of the most image-side lens surface of the front group, and negative if the diaphragm is on the object side of the most image-side lens surface of the front group, Let the minimum value of the distance on the optical axis from the diaphragm to the most object-side lens surface of the rear group be dStR, The sign of dStR is positive if the most object-side lens surface of the rear group is on the image side of the diaphragm, and negative if the most object-side lens surface of the rear group is on the object side of the diaphragm, When the sum of the distance on the optical axis from the lens surface closest to the object of the front group to the lens surface closest to the image of the rear group in the state of being focused on an infinite object and Bf is defined as TL, 0 < dFSt / TL < 0.8 (5) 0 < dStR / TL < 0.8 (6) The imaging lens according to claim 1, which satisfies the conditional expressions (5) and (6) represented by the above.

8. In the state of being focused on an infinite object, the sum of the distance on the optical axis from the aperture stop to the lens surface closest to the image of the rear group and Bf is defined as dSt, When the sum of the distance on the optical axis from the lens surface closest to the object of the front group to the lens surface closest to the image of the rear group in the state of being focused on an infinite object and Bf is defined as TL, 0.67 < dSt / TL < 0.93 (7) The imaging lens according to claim 1, which satisfies the conditional expression (7) represented by the above.

9. Let the paraxial curvature radius of the object side surface of the lens closest to the object of the front group be RL1f, When the paraxial curvature radius of the image side surface of the lens closest to the object of the front group is RL1r, −3 < (RL1r − RL1f) / (RL1r + RL1f) < 0 (8) The imaging lens according to claim 1, which satisfies the conditional expression (8) represented by the above.

10. In the state of being focused on an infinite object, among the first aspherical lenses included in the rear group, the sum of the distance on the optical axis from the image side surface of the first aspherical lens closest to the image to the lens surface closest to the image of the rear group and Bf is defined as dA1, When the sum of the distance on the optical axis from the lens surface closest to the object of the front group to the lens surface closest to the image of the rear group in the state of being focused on an infinite object and Bf is defined as TL, 0.02 < dA1 / TL < 0.6 (9) The imaging lens according to claim 1, which satisfies the conditional expression (9) represented by the above.

11. 0.08 < dA1 / TL < 0.35 (9 - 1) The imaging lens according to claim 10, which satisfies the conditional expression (9 - 1) represented by the above.

12. The imaging lens according to claim 1, wherein the front group includes at least one lens that satisfies the conditional expression (2).

13. The imaging lens according to claim 12, wherein the lens closest to the object of the front group satisfies the conditional expression (2).

14. The imaging lens according to claim 13, wherein the rear group includes at least one lens that satisfies the conditional expression (2).

15. When the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf in the state of being focused on an infinite object is defined as TL, 1.2 < TL / (f × tanωm) < 3 (10) The imaging lens according to claim 1, which satisfies the conditional expression (10) represented by

16. 1.7 < TL / (f × tanωm) < 2.5 (10-1) The imaging lens according to claim 15, which satisfies the conditional expression (10-1) represented by

17. 1.2 < TL / f < 3 (3-1) The imaging lens according to claim 16, which satisfies the conditional expression (3-1) represented by

18. When the open F-number in the state of being focused on an infinite object is defined as Fno, 2 < Fno / tanωm < 3.2 (4-1) The imaging lens according to claim 17, which satisfies the conditional expression (4-1) represented by

19. 0.36 < Bf / (f × tanωm) < 1.2 (1-1) The imaging lens according to claim 18, which satisfies the conditional expression (1-1) represented by

20. When the paraxial curvature radius of the object-side surface of the most object-side lens of the front group is RL1f, and the paraxial curvature radius of the image-side surface of the most object-side lens of the front group is RL1r, -1 < (RL1r - RL1f) / (RL1r + RL1f) < -0.07 (8-1) The imaging lens according to claim 19, which satisfies the conditional expression (8-1) represented by

21. When the sum of the distance on the optical axis from the aperture stop to the most image-side lens surface of the rear group and Bf in the state of being focused on an infinite object is defined as dSt, 0.67 < dSt / TL < 0.93 (7) The imaging lens according to claim 18, which satisfies the conditional expression (7) represented by

22. In the state of being focused on an infinite object, among the first aspherical lenses included in the rear group, when the sum of the distance on the optical axis from the image-side surface of the most image-side first aspherical lens to the most image-side lens surface of the rear group and Bf is defined as dA1, 0.08 < dA1 / TL < 0.35 (9-1) The imaging lens according to claim 21, which satisfies the conditional expression (9-1) represented by

23. The imaging lens according to claim 22, wherein the front group includes at least one lens that satisfies the conditional expression (2).

24. The imaging lens according to claim 23, wherein the most object-side lens of the front group satisfies the conditional expression (2).

25. When the refractive index with respect to the d-line of the lenses included in the entire system and the Abbe number based on the d-line are Nd and νd, respectively, 1.6 < Nd + 0.01 × νd < 2.6 (11) The imaging lens according to claim 1, wherein the front group includes at least one lens that satisfies the conditional expression (11) represented by the above.

26. The imaging lens according to claim 25, wherein the lens on the most object side of the front group satisfies the conditional expression (11).

27. When the focal length of the lens on the most object side of the front group is fL1, −1.5 < f / fL1 < 0 (12) The imaging lens according to claim 1, which satisfies the conditional expression (12) represented by the above.

28. Among the first aspherical lenses included in the rear group, the paraxial curvature radius of the image-side surface of the first aspherical lens on the most image side is RA1c, When the curvature radius at the position of the maximum effective diameter of the image-side surface of the first aspherical lens on the most image side among the first aspherical lenses included in the rear group is RA1y, −100 < RA1y / RA1c < 0 (13) The imaging lens according to claim 1, which satisfies the conditional expression (13) represented by the above.

29. Among the first aspherical lenses included in the rear group, when the refractive index with respect to the d-line of the first aspherical lens on the most image side and the Abbe number based on the d-line are NdA1 and νdA1, respectively, 1.8 < NdA1 + 0.01 × νdA1 < 2.14 (14) The imaging lens according to claim 1, which satisfies the conditional expression (14) represented by the above.

30. The imaging lens according to claim 1, wherein the rear group includes at least one second aspherical lens having an image-side lens surface that is convex toward the image side in the paraxial region and whose refractive power at the position of the maximum effective diameter is shifted in the negative direction compared to the refractive power in the paraxial region.

31. The paraxial curvature radius of the image-side surface of the second aspherical lens is RA2c, When the curvature radius at the position of the maximum effective diameter of the image-side surface of the second aspherical lens is RA2y, −1 < RA2c / RA2y < 1 (15) The imaging lens according to claim 30, wherein all the second aspherical lenses included in the rear group satisfy the conditional expression (15) represented by the above.

32. In a state of focusing on an infinite object, among the second aspherical lenses included in the rear group, the distance on the optical axis from the image-side surface of the second aspherical lens on the most image side to the most image-side lens surface of the rear group and the sum with Bf is dA2, When the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf in the state of being focused on an infinite object is defined as TL, 0.2 < dA2 / TL < 0.6 (16) The imaging lens according to claim 30, which satisfies the conditional expression (16) represented by

33. The imaging lens according to claim 32, wherein the second lens from the image side of the rear group is the most image-side second aspherical lens among the second aspherical lenses included in the rear group.

34. The imaging lens according to claim 33, wherein the second lens from the image side of the rear group has an inflection point on the image-side lens surface where the concavo-convex shape changes midway from the optical axis to the peripheral part.

35. The imaging lens according to claim 1, wherein the most image-side lens of the rear group is the first aspherical lens.

36. The imaging lens according to claim 35, wherein the most image-side lens of the rear group has a convex surface facing the object side in the paraxial region and has an inflection point on the object-side lens surface where the concavo-convex shape changes midway from the optical axis to the peripheral part.

37. The imaging lens according to claim 1, wherein the rear group includes two of the first aspherical lenses.

38. The imaging lens according to claim 30, wherein the rear group includes two of the second aspherical lenses.

39. The imaging lens according to claim 1, including at least one cemented lens.

40. The most object-side lens of the front group satisfies the conditional expression (2), In the state of being focused on an infinite object, the sum of the distance on the optical axis from the most object-side lens surface of the front group to the most image-side lens surface of the rear group and Bf is defined as TL, The open F-number in the state of being focused on an infinite object is defined as Fno, In the state of being focused on an infinite object, the sum of the distance on the optical axis from the aperture stop to the most image-side lens surface of the rear group and Bf is defined as dSt, In the state of being focused on an infinite object, when the sum of the distance on the optical axis from the image-side surface of the most image-side first aspherical lens among the first aspherical lenses included in the rear group to the most image-side lens surface of the rear group and Bf is defined as dA1, 1.2 < TL / f < 1.6 (3-2) 2.5 < Fno / tanωm < 4 (4-2) 0.67 < dSt / TL < 0.93 (7) 0.08 < dA1 / TL < 0.35 (9-1) The imaging lens according to claim 1, which satisfies the conditional expressions (3-2), (4-2), (7), and (9-1) represented by

41. An imaging device including the imaging lens according to any one of claims 1 to 40.

Images