Imaging lens and imaging device

Abstract

The invention provides an imaging lens which is small in F value, wide in angle, small in size and capable of maintaining good optical performance, and an imaging device provided with the imaging lens. The imaging lens sequentially comprises a front group, an aperture diaphragm and a rear group from an object side to an image side. The rear group comprises one or two focusing lens groups which move along the optical axis during focusing. During focusing, the distance on the optical axis from the lens surface closest to the object side of the front group to the image surface is not changed. The imaging lens satisfies a predetermined conditional expression.

Description

Technical Field

[0001] The technology of the present invention relates to an imaging lens and a photographing apparatus. Background Art

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

[0003] Patent Document 1: WO 2017 / 168603

[0004] There is a need for an imaging lens that has a small F-number, a wide angle, is configured to be small, and maintains good optical performance. The levels of these requirements are increasing year by year. Summary of the Invention

[0005] The present invention provides an imaging lens that has a small F-number, a wide angle, is configured to be small, and maintains good optical performance, and a photographing apparatus including the imaging lens.

[0006] A first aspect of the present invention is an imaging lens that sequentially includes a front group, an aperture stop, and a rear group from an object side to an image side. The rear group includes one or two focusing lens groups that move along the optical axis during focusing. During focusing, the distance on the optical axis from the lens surface closest to the object side of the front group to the image surface remains unchanged, where the following

[0007] 2.3 < TL / (f × tan ωm) < 7 (1)

[0008] 1.15 < Fno / tan ωm < 3.5 (2)

[0009] 0.3 < Bf / (f × tan ωm) < 1.5 (3)

[0010] The conditional expressions (1), (2), and (3) are satisfied.

[0011] Here, TL is the sum of the distance on the optical axis from the lens surface closest to the object side of the front group to the lens surface closest to the image side of the rear group and the back focal length in terms of air of the entire system in a state where an object at infinity is in focus. f is the focal length of the entire system in a state where an object at infinity is in focus. ωm is the maximum half-angle in a state where an object at infinity is in focus. Fno is the open F-number of the entire system in a state where an object at infinity is in focus. Bf is the back focal length in terms of air of the entire system in a state where an object at infinity is in focus.

[0012] In a second aspect of the present invention, in the imaging lens according to the first aspect, when the distance on the optical axis from the lens surface closest to the object side of the front group to the aperture stop in a state where an object at infinity is in focus is set to dFSt, the following is satisfied

[0013] 0.43 < dFSt / TL < 0.75 (4)

[0014] The conditional expression (4) represented by

[0015] In the imaging lens of the first aspect of the present invention, when the focal length of the front group in the state of focusing on an object at infinity is set to fF and the focal length of the rear group in the state of focusing on an object at infinity is set to fR, it satisfies

[0016] -2 < fR / fF < 4 (5)

[0017] The conditional expression (5) represented by

[0018] In the imaging lens of the fourth aspect of the present invention, when the focal length of the front group in the state of focusing on an object at infinity is set to fF, it satisfies

[0019] -1 < f / fF < 2 (6)

[0020] The conditional expression (6) represented by

[0021] In the imaging lens of the fifth aspect of the present invention, it satisfies

[0022] 6 < (TL × Fno) / (f × tanωm) < 11 (7)

[0023] The conditional expression (7) represented by

[0024] In the imaging lens of the sixth aspect of the present invention, the front group includes a focusing lens group that moves along the optical axis during focusing.

[0025] In the imaging lens of the seventh aspect of the present invention, the rear group includes two focusing lens groups that move while changing the interval between each other during focusing.

[0026] In the imaging lens of the eighth aspect of the present invention, at least one lens is disposed in the rear group, and this lens has a convex surface facing the object side in the paraxial region, and an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion on the lens surface on the object side.

[0027] In the imaging lens of the ninth aspect of the present invention, at least one lens is disposed in the rear group, and this lens has a concave surface facing the object side in the paraxial region, and an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion on the lens surface on the object side.

[0028] In the tenth aspect of the present invention, in the imaging lens of the first aspect, at least one lens is disposed in the rear group, the lens has a convex surface facing the image side in the paraxial region, and the lens surface on the image side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion.

[0029] In the eleventh aspect of the present invention, in the imaging lens of the first aspect, at least one lens is disposed in the rear group, the lens has a concave surface facing the image side in the paraxial region, and the lens surface on the image side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion.

[0030] In the twelfth aspect of the present invention, in the imaging lens of the first aspect, it includes three cemented lenses cemented in the order of a first positive lens, a second positive lens, and a negative lens.

[0031] In the thirteenth aspect of the present invention, in the imaging lens of the twelfth aspect, the surface of the second positive lens on the first positive lens side has a concave surface facing the first positive lens side.

[0032] In the fourteenth aspect of the present invention, in the imaging lens of the first aspect, it satisfies

[0033] 3.5 < TL / (f × tanωm) < 5.6 (1-1)

[0034] the conditional expression (1-1) represented.

[0035] In the fifteenth aspect of the present invention, in the imaging lens of the first aspect, it satisfies

[0036] 1.3 < Fno / tanωm < 2.7 (2-1)

[0037] the conditional expression (2-1) represented.

[0038] In the sixteenth aspect of the present invention, in the imaging lens of the fifteenth aspect, it satisfies

[0039] 3.5 < TL / (f × tanωm) < 5.6 (1-1)

[0040] the conditional expression (1-1) represented.

[0041] In the seventeenth aspect of the present invention, in the imaging lens of the sixteenth aspect, it satisfies

[0042] 6 < (TL × Fno) / (f × tanωm) < 11 (7)

[0043] the conditional expression (7) represented.

[0044] In the eighteenth aspect of the present invention, in the imaging lens of the seventeenth aspect, it includes three cemented lenses cemented in the order of a first positive lens, a second positive lens, and a negative lens.

[0045] In the 19th aspect of the present invention, in the imaging lens of the 18th aspect, the surface of the second positive lens on the first positive lens side faces the first positive lens side with a concave surface.

[0046] In the 20th aspect of the present invention, in the imaging lens of the 17th aspect, the front group includes a focusing lens group that moves along the optical axis during focusing.

[0047] In the 21st aspect of the present invention, in the imaging lens of the 20th aspect, at least one lens is arranged in the rear group, and this lens has a convex surface facing the object side in the paraxial region, and the lens surface on the object side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis to the peripheral part.

[0048] In the 22nd aspect of the present invention, in the imaging lens of the 17th aspect, the rear group includes two focusing lens groups that move while changing the distance between them during focusing.

[0049] In the 23rd aspect of the present invention, in the imaging lens of the 22nd aspect, at least one lens is arranged in the rear group, and this lens has a convex surface facing the object side in the paraxial region, and the lens surface on the object side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis to the peripheral part.

[0050] In the 24th aspect of the present invention, in the imaging lens of the 17th aspect, at least one lens is arranged in the rear group, and this lens has a concave surface facing the object side in the paraxial region, and the lens surface on the object side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis to the peripheral part.

[0051] In the 25th aspect of the present invention, in the imaging lens of the 17th aspect, it satisfies

[0052] 4.4 < TL / (f × tanωm) < 5.2 (1-2)

[0053] the conditional expression (1-2) represented.

[0054] In the 26th aspect of the present invention, in the imaging lens of the 25th aspect, it satisfies

[0055] 6.3 < (TL × Fno) / (f × tanωm) < 9.5 (7-1)

[0056] the conditional expression (7-1) represented.

[0057] In the 27th aspect of the present invention, in the imaging lens of the 26th aspect, at least one lens is arranged in the rear group, and this lens has a convex surface facing the image side in the paraxial region, and the lens surface on the image side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis to the peripheral part.

[0058] In the 28th aspect of the present invention, in the imaging lens of the 17th aspect, at least one lens is arranged in the rear group, the lens has a concave surface facing the image side in the paraxial region, and the inflection point where the concavo-convex shape changes midway exists on the lens surface on the image side as it moves from the optical axis to the peripheral part.

[0059] In the 29th aspect of the present invention, in the imaging lens of the 1st aspect, when the aspherical lens closest to the image side among the aspherical lenses included in the rear group is defined as the most image-side aspherical lens, the following is satisfied

[0060] 0.2 < |(1 / Rcf - 1 / Rcr) / (1 / Ryf - 1 / Ryr)| < 4 (8)

[0061] The conditional expression (8) represented.

[0062] Among them, the paraxial curvature radius of the object-side surface of the most image-side aspherical lens is set as Rcf. The curvature radius at the position of the maximum effective diameter of the object-side surface of the most image-side aspherical lens is set as Ryf. The paraxial curvature radius of the image-side surface of the most image-side aspherical lens is set as Rcr. The curvature radius at the position of the maximum effective diameter of the image-side surface of the most image-side aspherical lens is set as Ryr.

[0063] In the 30th aspect of the present invention, in the imaging lens of the 1st aspect, the number of focusing lens groups included in the imaging lens is two, and the following is satisfied

[0064] 0.2 < |ff1 / ff2| < 5 (9)

[0065] The conditional expression (9) represented.

[0066] Among them, the focal length of the object-side focusing lens group among the two focusing lens groups included in the imaging lens is set as ff1. The focal length of the image-side focusing lens group among the two focusing lens groups included in the imaging lens is set as ff2.

[0067] In the 31st aspect of the present invention, when the combined focal length of all the lenses closer to the image side than the focusing lens group closest to the image side among the focusing lens groups included in the imaging lens is set as ffR, the following is satisfied

[0068] -1.5 < f / ffR < 1.5 (10)

[0069] The conditional expression (10) represented.

[0070] The 32nd aspect of the present invention is an imaging device, which includes an imaging lens according to any one of the 1st to 31st aspects.

[0071] In addition, in this specification, "including ~" and "composed of ~" mean that in addition to the components listed, it may also include lenses substantially having no refractive power, and optical components other than lenses such as diaphragms, filters, and cover glasses, as well as structural parts such as lens flanges, lens barrels, imaging elements, and shake correction mechanisms.

[0072] In this specification, a "~ group having a positive refractive power" means that the group as a whole has a positive refractive power. Similarly, a "~ group having a negative refractive power" means that the group as a whole has a negative refractive power. A "lens having a positive refractive power" has the same meaning as a "positive lens". A "lens having a negative refractive power" and a "negative lens" have the same meaning. The "~ group" in this specification is not limited to a structure including multiple lenses, and may also be configured to include only one lens.

[0073] The "entire system" in this specification refers to the imaging lens. The "focal length" used in the conditional formula is the paraxial focal length. Regarding the "distance on the optical axis" used in the conditional formula, unless otherwise specified, it is the geometric distance. Unless otherwise specifically stated, the values used in the conditional formula are values based on the d-line in the state of focusing on an object at infinity.

[0074] Regarding the radius of curvature, sign of refractive power, and surface shape related to a lens including an aspherical surface, unless otherwise specified, the radius of curvature, sign of refractive power, and surface shape in the paraxial region are used. Regarding the sign of the radius of curvature, the sign of the radius of curvature of the surface with the convex shape facing the object side is set to positive, and the sign of the radius of curvature of the surface with the convex shape facing the image side is set to negative.

[0075] The "d-line", "C-line", and "F-line" described in this specification are bright lines. The wavelength of the d-line is regarded as 587.56 nm (nanometers), the wavelength of the C-line is regarded as 656.27 nm (nanometers), and the wavelength of the F-line is regarded as 486.13 nm (nanometers).

[0076] Advantages of the Invention

[0077] According to the present invention, it is possible to provide an imaging lens having a small F-number, a wide angle, being configured to be small in size, and maintaining good optical performance, and an imaging device including the imaging lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 It is a cross-sectional view showing the structure of an imaging lens according to an embodiment corresponding to the imaging lens of Embodiment 1.

[0079] Figure 2 It shows Figure 1 Cross-sectional views of the structure and light beam in each state of the imaging lens.

[0080] Figure 3It is a diagram for explaining the notations of each conditional expression.

[0081] Figure 4 It is a diagram for explaining the position of the maximum effective diameter.

[0082] Figure 5 It is a diagram of each aberration of the imaging lens of Example 1.

[0083] Figure 6 It is a cross-sectional view showing the structure of the imaging lens of Example 2.

[0084] Figure 7 It is a diagram of each aberration of the imaging lens of Example 2.

[0085] Figure 8 It is a cross-sectional view showing the structure of the imaging lens of Example 3.

[0086] Figure 9 It is a diagram of each aberration of the imaging lens of Example 3.

[0087] Figure 10 It is a cross-sectional view showing the structure of the imaging lens of Example 4.

[0088] Figure 11 It is a diagram of each aberration of the imaging lens of Example 4.

[0089] Figure 12 It is a cross-sectional view showing the structure of the imaging lens of Example 5.

[0090] Figure 13 It is a diagram of each aberration of the imaging lens of Example 5.

[0091] Figure 14 It is a cross-sectional view showing the structure of the imaging lens of Example 6.

[0092] Figure 15 It is a diagram of each aberration of the imaging lens of Example 6.

[0093] Figure 16 It is a cross-sectional view showing the structure of the imaging lens of Example 7.

[0094] Figure 17 It is a diagram of each aberration of the imaging lens of Example 7.

[0095] Figure 18 It is a cross-sectional view showing the structure of the imaging lens of Example 8.

[0096] Figure 19 It is a diagram of each aberration of the imaging lens of Example 8.

[0097] Figure 20 It is a cross-sectional view showing the structure of the imaging lens of Example 9.

[0098] Figure 21 They are aberration diagrams of the imaging lens of Example 9.

[0099] Figure 22 It is a cross-sectional view showing the structure of the imaging lens of Example 10.

[0100] Figure 23 They are aberration diagrams of the imaging lens of Example 10.

[0101] Figure 24 It is a cross-sectional view showing the structure of the imaging lens of Example 11.

[0102] Figure 25 They are aberration diagrams of the imaging lens of Example 11.

[0103] Figure 26 It is a cross-sectional view showing the structure of the imaging lens of Example 12.

[0104] Figure 27 They are aberration diagrams of the imaging lens of Example 12.

[0105] Figure 28 It is a cross-sectional view showing the structure of the imaging lens of Example 13.

[0106] Figure 29 They are aberration diagrams of the imaging lens of Example 13.

[0107] Figure 30 It is a cross-sectional view showing the structure of the imaging lens of Example 14.

[0108] Figure 31 They are aberration diagrams of the imaging lens of Example 14.

[0109] Figure 32 It is a cross-sectional view showing the structure of the imaging lens of Example 15.

[0110] Figure 33 They are aberration diagrams of the imaging lens of Example 15.

[0111] Figure 34 It is a cross-sectional view showing the structure of the imaging lens of Example 16.

[0112] Figure 35 They are aberration diagrams of the imaging lens of Example 16.

[0113] Figure 36 It is a perspective view of the front side of the imaging device according to an embodiment.

[0114] Figure 37 It is a perspective view of the back side of the imaging device according to an embodiment.

[0115] Symbolic Explanation

[0116] 1 - Imaging lens, 20 - Interchangeable lens, 30 - Camera, 31 - Camera body, 32 - Shutter button, 33 - Power button, 34 - Operating section, 35 - Operating section, 36 - Display section, 37 - Mount, 38 - Imaging element, Bf - Back focal length, dAsI - Distance, dFSt - Distance, ED - Effective diameter, GF - Front group, GR - Rear group, L11 to L31 - Lenses, L11a - Lens, L11b - Resin, Lx - Lens, Px - Position of maximum effective diameter, Sim - Image plane, St - Aperture stop, TL - Total length, Xa - On - axis beam, Xb - Off - axis beam, Xb1 - Ray, Z - Optical axis, ωm - Maximum half - angle of view. Detailed Embodiment

[0117] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0118] Figure 1 A cross - sectional view showing the structure of the imaging lens according to an embodiment of the present invention is shown. Figure 2 Shown in Figure 1 is a cross - sectional view of the structure of the imaging lens and the light beam. In Figure 2 , in the upper part marked with "infinity", the state of focusing on an object at infinity is shown, and in the lower part marked with "close - up", the state of focusing on a close - up object is shown. Figure 2 The state of the lower part in Figure 2 is a state where the absolute value of the photographic magnification is 0.16 times. In Figure 1 and Figure 2 , the left side is the object side and the right side is the image side. Figure 1 and Figure 2 The examples shown correspond to the imaging lens of Embodiment 1 described later. Hereinafter, mainly with reference to Figure 1 will be described.

[0119] The imaging lens of the present invention sequentially includes a front group GF, an aperture stop St, and a rear group GR along the optical axis Z from the object side to the image side. The front group GF and the rear group GR each include one or more lenses.

[0120] As an example, Figure 1 the respective groups of the imaging lens in Figure 1The aperture stop St represents the position in the optical axis direction, rather than the size or shape. This illustration method of the aperture stop St is the same in other cross-sectional views.

[0121] It can also be configured such that a negative meniscus lens with its convex surface facing the object side is arranged on the object side of the front group GF closest to the object. In such a configuration, it is beneficial for wide-angle conversion.

[0122] It can also be configured such that a positive lens is arranged on the image side of the front group GF closest to the image. In such a configuration, it is beneficial for correcting spherical aberration. In this case, the positive lens on the image side of the front group GF closest to the image can also be configured in a biconvex shape. In such a configuration, it is more beneficial for correcting spherical aberration.

[0123] The imaging lens of the present invention has a focusing function. However, in the imaging lens of the present invention, during focusing, the distance on the optical axis from the lens surface on the object side of the front group GF closest to the object to the image plane Sim remains unchanged. According to this structure, the change in the center of gravity during focusing can be suppressed, and thus the convenience during shooting can be improved.

[0124] Hereinafter, the lens group that moves along the optical axis Z during focusing is referred to as the focusing lens group. The rear group GR of the present invention includes one or two focusing lens groups that move along the optical axis Z during focusing. By moving the lens group of the rear group GR during focusing, the change in the viewing angle during focusing can be suppressed.

[0125] As an example, Figure 1 In the example of, the rear group GR of the imaging lens includes one focusing lens group. Figure 1 In the example of, the focusing lens group includes lenses L21 to L26. Figure 1 The parentheses described below the imaging lens indicate the focusing lens group, and the arrow attached to the parentheses indicates the moving direction when focusing from an infinite object to a close object.

[0126] In addition, Figure 1 The example shown is just an example, and within the scope not departing from the technical gist of the present invention, the imaging lens of the present invention can be variously deformed.

[0127] For example, the front group GF can also be configured to include one focusing lens group that moves along the optical axis Z during focusing. In such a configuration, it is easy to suppress the change in image plane curvature and the change in spherical aberration during focusing.

[0128] The rear group GR can also be configured to include two focusing lens groups that move while changing the interval between each other during focusing. In this way, by moving the two focusing lens groups with different moving amounts, the change in aberration accompanying the change in the shooting distance can be well suppressed. And by arranging two focusing lens groups in the rear group GR, it is easy to suppress the change in the viewing angle during focusing.

[0129] The rear group GR can also be configured to include an aspherical lens. For example, it can also be configured such that at least one aspherical lens is disposed in the rear group GR. This aspherical lens has a concave surface facing the image side in the paraxial region, and the lens surface on the image side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion. Additionally, the phrase "having a concave surface facing the image side in the paraxial region" as used herein means that the lens surface on the image side is concave in the paraxial region. And the inflection point refers to the 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, the point where the sign of the radius of curvature changes. By providing the lens surface with an inflection point, it is possible to determine the refractive power of the peripheral portion of the lens independent of the refractive power in the paraxial region. By including an aspherical lens of the above-described shape in the rear group GR, it is possible to reduce the incident angle of the light rays emitted from the imaging lens onto the image plane Sim. In the case where an imaging element is disposed on the image plane Sim in the imaging device, it is possible to reduce the incident angle onto this imaging element. As an example, in Figure 1 the example of, the lens L27 corresponds to the above-described aspherical lens.

[0130] When the rear group GR includes an aspherical lens, its shape is not limited to the above example. For example, it can also be configured such that at least one lens is disposed in the rear group GR. This lens has a convex surface facing the image side in the paraxial region, and the lens surface on the image side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion. Additionally, the phrase "having a convex surface facing the image side in the paraxial region" as used herein means that the lens surface on the image side is convex in the paraxial region. With this structure, it is beneficial to suppress the increase in the overall optical length and to well correct the field curvature and distortion aberration.

[0131] Also, it can be configured such that at least one lens is disposed in the rear group GR. This lens has a concave surface facing the object side in the paraxial region, and the lens surface on the object side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion. Additionally, the phrase "having a concave surface facing the object side in the paraxial region" as used herein means that the lens surface on the object side is concave in the paraxial region. With this structure, it is beneficial to ensure the back focal length and to well correct the field curvature and distortion aberration.

[0132] Alternatively, it can be configured such that at least one lens is disposed in the rear group GR. This lens has a convex surface facing the object side in the paraxial region, and the lens surface on the object side has an inflection point where the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion. Additionally, the phrase "having a convex surface facing the object side in the paraxial region" as used herein means that the lens surface on the object side is convex in the paraxial region. With this structure, it is beneficial to correct astigmatism without deteriorating spherical aberration.

[0133] At least one of the aspherical lenses included in the imaging lens may be a composite aspherical lens in which a resin having an aspherical air contact surface is formed on the spherical surface of a glass lens. In such a configuration, it is possible to suppress the manufacturing cost and add an aspherical surface to the lens surface, so that it is possible to achieve both low cost and good correction of various aberrations. In addition, in this specification, the composite aspherical lens is treated as an unbonded single lens, that is, a single lens, rather than a bonded lens.

[0134] The imaging lens preferably includes a bonded lens. Figure 1 The bonded lens included in the imaging lens is two bonded lenses, but the imaging lens of the present invention may also be configured to include three bonded lenses. The three bonded lenses may be bonded lenses bonded in the order of the first positive lens, the second positive lens, and the negative lens. In this case, the first positive lens, the second positive lens, and the negative lens may be bonded in order from the object side to the image side, or the first positive lens, the second positive lens, and the negative lens may be bonded in order from the image side to the object side. With such three bonded lenses, it is beneficial to suppress longitudinal chromatic aberration.

[0135] When the imaging lens includes three bonded lenses bonded in the order of the first positive lens, the second positive lens, and the negative lens, the surface of the second positive lens on the first positive lens side may also be configured such that the concave surface faces the first positive lens side. In such a configuration, it is more beneficial to suppress longitudinal chromatic aberration.

[0136] Hereinafter, a preferred structure of the imaging lens of the present invention related to the conditional expression will be described. In the following description of the conditional expression, in order to avoid redundancy, the same notations are given to the parts having the same definition, and the repeated description of the notations is omitted. And hereinafter, in order to avoid redundancy, the "imaging lens of the present invention" is also simply referred to as "imaging lens".

[0137] The imaging lens preferably satisfies the following conditional expression (1). Among them, the sum of the distance on the optical axis from the lens surface closest to the object side of the front group GF to the lens surface closest to the image side of the rear group GR in the state of focusing on an infinitely distant object and the back focal length under the air equivalent distance of the entire system is set as TL. The focal length of the entire system in the state of focusing on an infinitely distant object is set as f. Tan is the tangent. The maximum half angle of view in the state of focusing on an infinitely distant object is set as ωm. TL is the total length in the state of focusing on an infinitely distant object. As an example, Figure 3 shows the above total length TL, Figure 2 shows the above maximum half angle of view ωm. Figure 3 is in Figure 1A diagram showing notations used conditionally in a cross-sectional view of an imaging lens. By preventing the corresponding value of conditional expression (1) from falling below the lower limit value, it is beneficial to maintain good optical performance. By preventing the corresponding value of conditional expression (1) from exceeding the upper limit value, it is beneficial to miniaturize the lens system.

[0138] 2.3 < TL / (f × tanωm) < 7 (1)

[0139] To obtain better characteristics, the lower limit value of conditional expression (1) is more preferably set to 2.7, further preferably 3.1, further preferably 3.5, further preferably 3.9, further preferably 4.4. To obtain better characteristics, the upper limit value of conditional expression (1) is more preferably set to 6.5, further preferably 6, further preferably 5.6, further preferably 5.3, further preferably 5.2. For example, the imaging lens more preferably satisfies the following conditional expression (1-1), and even more preferably satisfies the following conditional expression (1-2).

[0140] 3.5 < TL / (f × tanωm) < 5.6 (1-1)

[0141] 4.4 < TL / (f × tanωm) < 5.2 (1-2)

[0142] When the open F value in the state of focusing on an infinite object is set to Fno, the imaging lens preferably satisfies the following conditional expression (2). By preventing the corresponding value of conditional expression (2) from falling below the lower limit value, it is beneficial to obtain good optical performance and suppress the increase in the number of lens elements and the enlargement of the lens system. By preventing the corresponding value of conditional expression (2) from exceeding the upper limit value, it is easy to widen the viewing angle and reduce the open F value.

[0143] 1.15 < Fno / tanωm < 3.5 (2)

[0144] To obtain better characteristics, the lower limit value of conditional expression (2) is more preferably set to 1.2, further preferably 1.25, further preferably 1.3, further preferably 1.35, further preferably 1.5. To obtain better characteristics, the upper limit value of conditional expression (2) is more preferably set to 3.2, further preferably 2.9, further preferably 2.7, further preferably 2.5, further preferably 2.3. For example, the imaging lens more preferably satisfies the following conditional expression (2-1).

[0145] 1.3 < Fno / tanωm < 2.7 (2-1)

[0146] The imaging lens preferably satisfies the following conditional expression (3). Herein, the back focal length under the air equivalent distance of the entire system in the state of focusing on an object at infinity is defined as Bf. The back focal length Bf under the air equivalent distance of the entire system is the air equivalent distance on the optical axis from the lens surface closest to the image side of the imaging lens to the image plane Sim. As an example, Figure 3 the above-described back focal length Bf is shown. By preventing the corresponding value of the conditional expression (3) from becoming less than the lower limit value, an increase in the diameter of the lens closest to the image side of the imaging lens can be suppressed. By preventing the corresponding value of the conditional expression (3) from becoming greater than the upper limit value, an increase in the overall optical length can be suppressed.

[0147] 0.3 < Bf / (f × tan ωm) < 1.5 (3)

[0148] In order to obtain better characteristics, the lower limit value of the conditional expression (3) is more preferably set to 0.35, further preferably 0.4, further preferably 0.43, and further preferably 0.45. In order to obtain better characteristics, the upper limit value of the conditional expression (3) is more preferably set to 1.3, further preferably 1.2, further preferably 1.1, and further preferably 1.

[0149] The imaging lens preferably satisfies the following conditional expression (4). Herein, the distance on the optical axis from the lens surface closest to the object side of the front group GF to the aperture stop St in the state of focusing on an object at infinity is defined as dFSt. As an example, Figure 3 the above-described distance dFSt is shown. By preventing the corresponding value of the conditional expression (4) from becoming less than the lower limit value, a sufficient space on the object side of the aperture stop St can be ensured, and thus, it is possible to configure an appropriate number of lenses without forcibly reducing the absolute value of the curvature radius of the lens. As a result, it is easy to appropriately correct various aberrations. By preventing the corresponding value of the conditional expression (4) from becoming greater than the upper limit value, the position of the aperture stop St can be prevented from being too close to the image plane Sim, and thus, it is possible to prevent the incident angle of the off-axis chief ray incident on the imaging element disposed on the image plane Sim in the imaging device from becoming too large.

[0150] 0.43 < dFSt / TL < 0.75 (4)

[0151] In order to obtain better characteristics, the lower limit value of the conditional expression (4) is more preferably set to 0.45, further preferably 0.47, further preferably 0.49, further preferably 0.51, further preferably 0.53, and further preferably 0.55. In order to obtain better characteristics, the upper limit value of the conditional expression (4) is more preferably set to 0.71, further preferably 0.69, further preferably 0.67, further preferably 0.65, further preferably 0.63, and further preferably 0.61.

[0152] The imaging lens preferably satisfies the following conditional expression (5). Herein, the focal length of the front group GF in the state of focusing on an infinitely distant object is set as FF, and the focal length of the rear group GR in the state of focusing on an infinitely distant object is set as fR. The conditional expression (5) is a conditional expression for appropriately setting the ratio of the refractive power of the front group GF to the refractive power of the rear group GR. The front group GF can function as a wide converter in the entire system to increase the viewing angle and sufficiently ensure the back focal length. By preventing the corresponding value of the conditional expression (5) from falling below the lower limit value, various aberrations such as spherical aberration can be suppressed. By preventing the corresponding value of the conditional expression (5) from exceeding the upper limit value, it is beneficial to achieve a wide viewing angle.

[0153] -2 < fR / fF < 4 (5)

[0154] To obtain better characteristics, the lower limit value of the conditional expression (5) is more preferably set to -1.5, further preferably to -1, and still further preferably to -0.7. To obtain better characteristics, the upper limit value of the conditional expression (5) is more preferably set to 3.5, further preferably to 3, and still further preferably to 2.5.

[0155] The imaging lens preferably satisfies the following conditional expression (6). By preventing the corresponding value of the conditional expression (6) from falling below the lower limit value, the negative refractive power of the front group GF does not become too strong, so it is beneficial to shorten the overall optical length. By preventing the corresponding value of the conditional expression (6) from exceeding the upper limit value, the positive refractive power of the front group GF does not become too strong, so it is beneficial to correct distortion aberration and field curvature.

[0156] -1 < f / fF < 2 (6)

[0157] To obtain better characteristics, the lower limit value of the conditional expression (6) is more preferably set to -0.8, further preferably to -0.6, and still further preferably to -0.4. To obtain better characteristics, the upper limit value of the conditional expression (6) is more preferably set to 1.3, further preferably to 0.7, and still further preferably to 0.18.

[0158] The imaging lens preferably satisfies the following conditional expression (7). By preventing the corresponding value of the conditional expression (7) from falling below the lower limit value, it is beneficial to maintain good optical performance. By preventing the corresponding value of the conditional expression (7) from exceeding the upper limit value, it is beneficial to miniaturize the lens system.

[0159] 6 < (TL × Fno) / (f × tanωm) < 11 (7)

[0160] In order to obtain better characteristics, the lower limit value of conditional expression (7) is more preferably set to 6.1, further preferably to 6.2, further preferably to 6.3, and further preferably to 6.4. In order to obtain better characteristics, the upper limit value of conditional expression (7) is more preferably set to 10.5, further preferably to 10, further preferably to 9.5, and further preferably to 9. For example, the imaging lens more preferably satisfies the following conditional expression (7-1).

[0161] 6.3 < (TL × Fno) / (f × tan ωm) < 9.5 (7-1)

[0162] In a structure in which the rear group GR includes at least one aspherical lens, the imaging lens preferably satisfies the following conditional expression (8). Here, the aspherical lens closest to the image side among the aspherical lenses included in the rear group GR is defined as the most image-side aspherical lens. The paraxial curvature radius of the object-side surface of the most image-side aspherical lens is defined as Rcf. The curvature radius at the position of the maximum effective diameter of the object-side surface of the most image-side aspherical lens is defined as Ryf. The paraxial curvature radius of the image-side surface of the most image-side aspherical lens is defined as Rcr. The curvature radius at the position of the maximum effective diameter of the image-side surface of the most image-side aspherical lens is defined as Ryr. By preventing the corresponding value of conditional expression (8) from falling below the lower limit value, the refractive power on the peripheral side of the lens does not become too strong, which is thus advantageous for correcting field curvature and distortion aberration. By preventing the corresponding value of conditional expression (8) from exceeding the upper limit value, the refractive power on the peripheral side of the lens does not become too weak, which is thus advantageous for suppressing astigmatism.

[0163] 0.2 < |(1 / Rcf - 1 / Rcr) / (1 / Ryf - 1 / Ryr)| < 4 (8)

[0164] In order to obtain better characteristics, the lower limit value of conditional expression (8) is more preferably set to 0.25, further preferably to 0.3, further preferably to 0.35, and further preferably to 0.4. In order to obtain better characteristics, the upper limit value of conditional expression (8) is more preferably set to 3, further preferably to 2, further preferably to 1.4, and further preferably to 0.9.

[0165] Here, refer to Figure 4 for the description of the "position of the maximum effective diameter" in this specification. Figure 4 is an explanatory diagram. In Figure 4 the left side is the object side and the right side is the image side. Figure 4 the on-axis beam Xa and the off-axis beam Xb passing through the lens Lx are shown. In Figure 4In the example, the upper-side ray of the off-axis beam Xb, i.e., ray Xb1, is the ray passing through the outermost side. The "outer side" mentioned here refers to the radially outer side centered on the optical axis Z, i.e., the side away from the optical axis Z. In this specification, the position of the intersection of the ray passing through the outermost side and the lens surface is the position Px of the maximum effective diameter. And, twice the distance from the position Px of the maximum effective diameter to the optical axis Z becomes the effective diameter ED of the object-side surface of the lens Lx. Additionally, in Figure 4 the example, the upper-side ray of the off-axis beam Xb is the ray passing through the outermost side, but which ray becomes the ray passing through the outermost side varies depending on the lens system.

[0166] In a structure where the imaging lens includes two focusing lens groups, the imaging lens preferably satisfies the following conditional expression (9). Among them, the focal length of the object-side focusing lens group in the two focusing lens groups included in the imaging lens is set as ff1, and the focal length of the image-side focusing lens group is set as ff2. By preventing the corresponding value of conditional expression (9) from becoming below the lower limit value, the refractive power of the object-side focusing lens group will not become too strong, so it is easy to correct astigmatism. By preventing the corresponding value of conditional expression (9) from becoming above the upper limit value, the refractive power of the object-side focusing lens group will not become too weak, so it is easy to correct field curvature.

[0167] 0.2 < |ff1 / ff2| < 5 (9)

[0168] To obtain better characteristics, the lower limit value of conditional expression (9) is more preferably set to 0.25, further preferably 0.3, further preferably 0.35, and further preferably 0.4. To obtain better characteristics, the upper limit value of conditional expression (9) is more preferably set to 4, further preferably 3, further preferably 2.5, and further preferably 2.

[0169] The imaging lens preferably satisfies the following conditional expression (10). Among them, the combined focal length of all the lenses closer to the image side than the image-side focusing lens group among the focusing lens groups included in the imaging lens is set as FfR. By preventing the corresponding value of conditional expression (10) from becoming below the lower limit value, the negative combined refractive power of all the lenses closer to the image side than the above-mentioned image-side focusing lens group will not become too strong, so it is beneficial for correcting longitudinal chromatic aberration. By preventing the corresponding value of conditional expression (10) from becoming above the upper limit value, the positive combined refractive power of all the lenses closer to the image side than the above-mentioned image-side focusing lens group will not become too strong, so it is beneficial for correcting distortion aberration and field curvature.

[0170] -1.5 < f / ffR < 1.5 (10)

[0171] In order to obtain better characteristics, the lower limit value of conditional expression (10) is more preferably set to -1, further preferably to -0.7, further preferably to -0.5, further preferably to -0.3, and further preferably to -0.2. In order to obtain better characteristics, the upper limit value of conditional expression (10) is more preferably set to 1, further preferably to 0.7, further preferably to 0.5, further preferably to 0.3, and further preferably to 0.2.

[0172] The imaging lens preferably satisfies the following conditional expression (11). Herein, the paraxial curvature radius of the object side surface of the lens closest to the object side of the front group GF is designated as RL1f. The paraxial curvature radius of the image side surface of the lens closest to the object side of the front group GF is designated as RI1r. Conditional expression (11) defines the shape factor of the lens. By preventing the corresponding value of conditional expression (11) from falling below the lower limit value, it is easy to correct astigmatism well. By preventing the corresponding value of conditional expression (11) from exceeding the upper limit value, it is easy to correct spherical aberration well. Also, by preventing the corresponding value of conditional expression (11) from exceeding the upper limit value, the refractive power of the lens closest to the object side of the front group GF will not become too weak, and thus it is easy to achieve wide-angleization.

[0173] -3 < (RL1r - RL1f) / (RL1r + RL1f) < 0 (11)

[0174] In order to obtain better characteristics, the lower limit value of conditional expression (11) is more preferably set to -2, further preferably to -1, further preferably to -0.7, and further preferably to -0.5. In order to obtain better characteristics, the upper limit value of conditional expression (11) is more preferably set to -0.05, further preferably to -0.1, further preferably to -0.11, and further preferably to -0.12.

[0175] The imaging lens preferably satisfies the following conditional expression (12). By preventing the corresponding value of conditional expression (12) from falling below the lower limit value, it is easy to correct various aberrations and shorten the overall optical length. By preventing the corresponding value of conditional expression (12) from exceeding the upper limit value, the brightness of the lens system can be ensured.

[0176] 0.9 < Fno < 2.1 (12)

[0177] In order to obtain better characteristics, the lower limit value of conditional expression (12) is more preferably set to 0.95, further preferably to 1, further preferably to 1.05, and further preferably to 1.1. In order to obtain better characteristics, the upper limit value of conditional expression (12) is more preferably set to 1.9, further preferably to 1.7, further preferably to 1.5, and further preferably to 1.3.

[0178] The imaging lens preferably satisfies the following conditional expression (13). The unit of ωωm is degrees. By ensuring that the corresponding value of the conditional expression (13) does not fall below the lower limit value, a wide viewing angle can be ensured, and thus the imaging lens can have high added value. By ensuring that the corresponding value of the conditional expression (13) does not exceed the upper limit value, it is easy to achieve a balance between optical performance and miniaturization.

[0179] 29 < ωm < 50 (13)

[0180] To obtain better characteristics, the lower limit value of the conditional expression (13) is more preferably set to 29.5, further preferably 30, further preferably 30.5, further preferably 31, further preferably 31.5. To obtain better characteristics, the upper limit value of the conditional expression (13) is more preferably set to 47, further preferably 44, further preferably 41, further preferably 38, further preferably 36.

[0181] In a structure in which a negative meniscus lens with its convex surface facing the object side is disposed on the object side of the front group GF closest to the object, the imaging lens preferably satisfies the following conditional expression (14). Here, the focal length of the negative meniscus lens with its convex surface facing the object side disposed on the object side of the front group GF closest to the object is set as fL1m. By ensuring that the corresponding value of the conditional expression (14) does not fall below the lower limit value, the negative refractive power of the above-mentioned negative meniscus lens does not become too weak relative to the refractive power of the entire system, and thus it is beneficial for correcting various aberrations such as distortion aberration and field curvature. Regarding the upper limit of the conditional expression (14), since the sign of the focal length of the negative meniscus lens is negative, it becomes fL1m / f < 0.

[0182] -7 < fL1m / f < 0 (14)

[0183] To obtain better characteristics, the lower limit value of the conditional expression (14) is more preferably set to -4, further preferably -3.5, further preferably -3, further preferably -2.5, further preferably -2. To obtain better characteristics, the upper limit value of the conditional expression (14) is preferably set to -0.4. By ensuring that the corresponding value of the conditional expression (14) does not exceed -0.4, the negative refractive power of the above-mentioned negative meniscus lens does not become too strong relative to the refractive power of the entire system, and thus it is beneficial for correcting longitudinal chromatic aberration well by the above-mentioned negative meniscus lens. To obtain better characteristics, the upper limit value of the conditional expression (14) is more preferably set to -0.6, further preferably -0.8, further preferably -0.9, further preferably -1.

[0184] In a structure in which a negative meniscus lens with its convex surface facing the object side is disposed on the object-side most of the front group GF, the imaging lens preferably satisfies the following conditional expression (15). Here, the Abbe number of the negative meniscus lens with its convex surface facing the object side disposed on the object-side most of the front group GF is defined as vdL1m with respect to the d line. By preventing the corresponding value of the conditional expression (15) from falling below the lower limit value, the Abbe number of the above negative meniscus lens will not become too small, which is thus conducive to correcting the longitudinal chromatic aberration well. By preventing the corresponding value of the conditional expression (15) from exceeding the upper limit value, the Abbe number of the above negative meniscus lens will not become too large, so the refractive index will not become too low, and the refractive power of the above negative meniscus lens will not become too weak, which is thus conducive to correcting the distortion aberration and the field curvature well.

[0185] 35 < vdL1m < 90 (15)

[0186] In order to obtain better characteristics, the lower limit value of the conditional expression (15) is more preferably set to 40, further preferably 42, further preferably 44, further preferably 46, further preferably 48, further preferably 50. In order to obtain better characteristics, the upper limit value of the conditional expression (15) is more preferably set to 85, further preferably 80, further preferably 75, further preferably 70, further preferably 65, further preferably 62.

[0187] The imaging lens preferably satisfies the following conditional expression (16). Here, the combined focal length of all the lenses on the object side of the imaging lens that are more on the object side than the frontmost focusing lens group in the focusing lens group is defined as ffF. By preventing the corresponding value of the conditional expression (16) from falling below the lower limit value, the negative combined refractive power of all the lenses on the object side of the imaging lens that are more on the object side than the frontmost focusing lens group will not become too strong, so the increase in the overall optical length can be suppressed, which is thus conducive to ensuring the peripheral light quantity. By preventing the corresponding value of the conditional expression (16) from exceeding the upper limit value, the positive combined refractive power of all the lenses on the object side of the imaging lens that are more on the object side than the frontmost focusing lens group will not become too strong, which is thus conducive to correcting the distortion aberration and the field curvature.

[0188] -2 < f / ffF < 1.5 (16)

[0189] In order to obtain better characteristics, the lower limit value of the conditional expression (16) is more preferably set to -1.5, further preferably -1.2, further preferably -0.9, further preferably -0.7, further preferably -0.5. In order to obtain better characteristics, the upper limit value of the conditional expression (16) is more preferably set to 1.2, further preferably 0.9, further preferably 0.7, further preferably 0.5, further preferably 0.3.

[0190] The imaging lens preferably satisfies the following conditional expression (17). Herein, the focal length of the positive lens having the strongest refractive power among the unjoined positive lenses included in the rear group GR is defined as fRp. By preventing the corresponding value of the conditional expression (17) from falling below the lower limit value, the refractive power of the positive lens in the rear group GR will not become too weak, which is thus beneficial for shortening the flange focal length and achieving miniaturization. By preventing the corresponding value of the conditional expression (17) from exceeding the upper limit value, the refractive power of the positive lens in the rear group GR will not become too strong, which is thus beneficial for correcting various aberrations such as spherical aberration.

[0191] 0.4 < f / fRp < 1.3 (17)

[0192] In order to obtain better characteristics, the lower limit value of the conditional expression (17) is more preferably set to 0.45, further preferably 0.5, further preferably 0.53, and further preferably 0.55. In order to obtain better characteristics, the upper limit value of the conditional expression (17) is more preferably set to 1.1, further preferably 1, further preferably 0.9, and further preferably 0.8.

[0193] The imaging lens preferably satisfies the following conditional expression (18). Herein, the Abbe number at the d line of the positive lens having the strongest refractive power among the unjoined positive lenses included in the rear group GR is defined as vdRp. By preventing the corresponding value of the conditional expression (18) from falling below the lower limit value, the Abbe number of the positive lens having the strongest refractive power among the unjoined positive lenses included in the rear group GR will not become too small, which is thus beneficial for well correcting the chromatic aberration of magnification. By preventing the corresponding value of the conditional expression (18) from exceeding the upper limit value, the Abbe number of the positive lens having the strongest refractive power among the unjoined positive lenses included in the rear group GR will not become too large, so the refractive index will not become too low, and the refractive power of this positive lens will not become too weak, which is thus beneficial for well correcting the distortion aberration and the field curvature.

[0194] 25 < vdRp < 90 (18)

[0195] In order to obtain better characteristics, the lower limit value of the conditional expression (18) is more preferably set to 40, further preferably 50, further preferably 55, and further preferably 60. In order to obtain better characteristics, the upper limit value of the conditional expression (18) is more preferably set to 85, further preferably 80, further preferably 75, and further preferably 70.

[0196] When a lens having an uneven shape with an inflection point that changes midway as it moves from the optical axis toward the peripheral part is defined as a specific aspherical lens, in a structure in which at least one specific aspherical lens is arranged in the rear group GR, the imaging lens preferably satisfies the following conditional expression (19). Here, the distance on the optical axis from the image-side surface of the specific aspherical lens closest to the image side among the specific aspherical lenses included in the rear group GR in a state of focusing on an infinitely distant object to the image-side lens surface closest to the image side of the rear group GR and the back focal length Bf in terms of air of the entire system are defined as dAsI. As an example, Figure 3 The above distance dAsI is shown in Figure 3 . By preventing the corresponding value of conditional expression (19) from falling below the lower limit value, it is easy to prevent interference between the imaging lens and various types of filters provided near the image plane. By preventing the corresponding value of conditional expression (19) from exceeding the upper limit value, it is easy to correct distortion aberration and field curvature.

[0197] 0.04 < dAsI / TL < 0.4 (19)

[0198] To obtain better characteristics, the lower limit value of conditional expression (19) is more preferably set to 0.08, further preferably to 0.1, further preferably to 0.11, and further preferably to 0.12. To obtain better characteristics, the upper limit value of conditional expression (19) is more preferably set to 0.35, further preferably to 0.3, further preferably to 0.25, and further preferably to 0.2.

[0199] In a structure in which the imaging lens includes three cemented lenses cemented in the order of a first positive lens, a second positive lens, and a negative lens, the imaging lens preferably satisfies the following conditional expression (20). Here, the refractive index of the second positive lens with respect to the d line is defined as Ndp2. The Abbe number of the second positive lens based on the d line is defined as vdp2. By preventing the corresponding value of conditional expression (20) from falling below the lower limit value, it is possible to select materials other than those with a low refractive index and a low Abbe number, and thus it is easy to correct lateral chromatic aberration. By preventing the corresponding value of conditional expression (20) from exceeding the upper limit value, it is possible to select materials other than those with a high refractive index and a high Abbe number, and thus it is possible to select materials with a low specific gravity and it is easy to reduce the weight.

[0200] 1.7 < Ndp2 + 0.01×vdp2 < 2.05 (20)

[0201] To obtain better characteristics, the lower limit value of conditional expression (20) is more preferably set to 1.74, further preferably to 1.76, further preferably to 1.77, and further preferably to 1.78. To obtain better characteristics, the upper limit value of conditional expression (20) is more preferably set to 2.02, further preferably to 2, further preferably to 1.99, and further preferably to 1.98.

[0202] The above-described preferred structures and possible structures can be arbitrarily combined within a non-contradictory range, and are preferably selectively adopted according to the required specifications.

[0203] As an example, a preferred embodiment of the imaging lens of the present invention 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 rear group GR includes one or two focusing lens groups that move along the optical axis Z during focusing. During focusing, the distance on the optical axis from the lens surface closest to the object side of the front group GF to the image plane Sim remains unchanged, and the above-mentioned conditional expressions (1), (2), and (3) are satisfied.

[0204] Next, embodiments of the imaging lens of the present invention will be described with reference to the accompanying drawings. In addition, in order to avoid complication of the description and the drawings caused by an increase in the number of digits of the reference symbols, the reference symbols on the groups and lenses in the cross-sectional views of the respective embodiments are used independently in each embodiment. Therefore, even if the same reference symbol is marked in the drawings of different embodiments, it does not necessarily mean the same structure.

[0205] [Embodiment 1]

[0206] A cross-sectional view of the structure of the imaging lens of Embodiment 1 is shown in Figure 1 As described above for the illustration method and structure, a part of the repeated description is omitted here. The imaging lens of Embodiment 1 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The imaging lens includes only one focusing lens group. When focusing from an infinitely distant object to a near object, the focusing lens group moves toward the object side.

[0207] Regarding 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.

[0208] The table of the basic lens data is described as follows. In the column "Sn", the surface number is shown when the surface closest to the object side is set as the first surface and the numbers are sequentially increased toward the image side. In the column "R", the curvature radius of each surface is shown. In the column "D", the surface interval on the optical axis between each surface and the surface adjacent to its image side is shown. In the column "Nd", the refractive index of each lens with respect to the d line is shown. In the column "v d", the Abbe number of each lens based on the d line is shown.

[0209] In the table of basic lens data, including the tables of the following-described embodiments, the "Material" column is described as follows. In the "Material" column, for lenses with a resin material, it is described as "Plastic", and for lenses with a material other than resin, a period is added between the material name and its manufacturing company name to indicate it. In the table, the manufacturing company names are shown schematically as follows. "OHARA" represents OHARA INC. "CDGM" represents Chengdu Guangming Optoelectronic Co., Ltd. "HOYA" represents HOYA Corporation. "NHG" represents Hubei Xinhua Optoelectronic Information Materials Co., Ltd. The "ED" column shows the effective diameter of each surface. In addition, in the "ED" column, for surfaces not related to the conditional formula, part of the description is omitted.

[0210] In the table of basic lens data, the sign of the radius of curvature of the surface with the convex shape facing the object side is set to positive, and the sign of the radius of curvature of the surface with the convex shape facing the image side is set to negative. In the surface number column of the surface corresponding to the aperture stop St, the surface number and the statement (St) are entered. The value in the bottom row of column D in the table is the interval between the surface closest to the image side in the table and the image plane Sim. For the variable surface interval during focusing, the notation DD[] is used, and the surface number on the object side of the interval is marked in [] and entered in the surface interval column.

[0211] In Table 2, the focal length, back focal length, open F value, maximum full viewing angle, and variable surface interval of the entire system are represented based on the d line. The [°] in the maximum full viewing angle column indicates that the unit is degrees. In Table 2, in the "Infinity" column, the values in the state of focusing on an object at infinity are shown, and in the "Close" column, the values in the state of focusing on the nearest object are shown. Among them, only the value in the state of focusing on an object at infinity is shown for the focal length. In the "Close" column, "times" is added to the absolute value of the photographic magnification in the state of focusing on the nearest object to represent it.

[0212] In the basic lens data, an asterisk mark is attached to the surface number of the aspherical surface, and the value of the paraxial radius of curvature is described in the radius of curvature column of the aspherical surface. In Table 3, the surface numbers of the aspherical surfaces are shown in the Sn row, and the values of the aspherical coefficients for each aspherical surface are shown in the KA and Am rows. In addition, m in Am is an integer of 3 or more and varies depending on the surface. For example, in the first surface of Embodiment 1, m = 4, 6, 8, 10, 12. The "E±n" (n: integer) of the value of the aspherical coefficient in Table 3 represents "×10 ±n ". KA and Am are the aspherical coefficients in the aspherical formula represented by the following formula.

[0213] Zd = C×h 2 / {1+(1 - KA×C 2 ×h 2 )1 / 2}+∑Am×h m

[0214] Wherein,

[0215] Zd: Aspherical depth (the length of the perpendicular line from a point on the aspherical surface at height h to the plane that is tangent to the aspherical vertex and perpendicular to the optical axis Z)

[0216] h: Height (the distance from the optical axis Z to the lens surface)

[0217] C: Reciprocal of the paraxial radius of curvature

[0218] KA, Am: Aspherical coefficients

[0219] The ∑ in the aspherical formula represents the sum with respect to m.

[0220] In the data of each table, degrees are used as the angle unit and mm (millimeter) is used as the length unit. However, the optical system can also be used with magnification or reduction ratios, so other appropriate units can also be used. And, the values rounded to a preset number of digits are recorded in each of the following tables.

[0221] [Table 1]

[0222] Example 1

[0223] Sn R D Nd v d Material ED *1 36.9114 2.0002 1.51633 64.06 L-BSL7.OHARA *2 16.0546 6.5972 3 28.4756 0.7514 1.49700 81.54 S-FPL51.OHARA 4 15.7915 13.7278 5 -22.8236 0.5634 1.89286 20.36 S-NPH4.OHARA 6 27.0898 6.2064 1.88300 39.22 H-ZLAF68N.CDGM 7 -35.6195 4.4441 8 66.6436 3.6612 1.95906 17.47 S-NPH3.OHARA 9 -76.3070 4.8313 10(St) ∞ DD

[10] 11 31.6590 3.9924 1.49700 81.54 S-FPL51.OHARA 12 -653.8511 1.5295 13 54.7953 7.1980 1.49700 81.54 S-FPL51.OHARA 14 -19.0274 0.6239 1.69895 30.13 S-TIM35.OHARA 15 -98.4522 0.0500 16 34.8118 5.7847 1.49700 81.54 S-FPL51.OHARA 17 -33.9389 0.0500 18 -362.8038 0.5887 2.00100 29.14 S-LAH99.OHARA 19 32.4455 2.3525 *20 -19082.0007 0.5832 1.88202 37.22 MC-TAFD307.HOYA 22.11 *21 239.1593 DD

[21] 22.60 *22 -284.7229 0.7499 1.76450 49.10 L-LAH91.OHARA 27.90 *23 83.3333 0.3628 30.00 24 51.0834 4.0723 1.64000 60.08 S-BSM81.OHARA 25 806.1847 11.2200

[0224] [Table 2]

[0225] Example 1

[0226]

[0227] [Table 3]

[0228] Example 1

[0229] Sn 1 2 KA 1.0000000E+00 1.0000000E+00 A4 2.7581553E-05 2.3977919E-05 A6 -1.3476994E-07 -1.0873318E-07 A8 4.5680464E-10 -2.3607650E-10 A10 -8.0666844E-13 2.6111995E-12 A12 6.6120989E-16 -6.8994378E-15

[0230] Sn 20 21 22 23 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -2.0721333E-05 1.9583400E-05 -4.5890634E-05 -4.6451990E-05 A6 8.2411291E-08 1.3488726E-07 1.5193795E-07 1.8099821E-07 A8 -1.4162671E-09 -1.1232077E-09 -2.9358963E-10 -5.0500218E-10 A10 3.4540512E-12 3.1943252E-12 -4.7523559E-13 3.2040402E-13

[0231] Figure 5 Shows the aberration diagrams of the imaging lens of Example 1. In Figure 5 From left to right, spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification are shown. In Figure 5Among them, above the section marked with "infinity", aberration diagrams showing the state of focusing on an object at infinity are shown, and below the section marked with "close range", aberration diagrams showing the state of focusing on the nearest object are shown. In the spherical aberration diagram, the aberrations on the d-line, C-line, and F-line are shown by solid lines, long dashed lines, and short dashed lines, respectively. In the astigmatism diagram, the aberration on the d-line in the sagittal direction is shown by a solid line, and the aberration on the d-line in the meridional direction is shown by a short dashed line. In the distortion aberration diagram, the aberration on the d-line is shown by a solid line. In the longitudinal chromatic aberration diagram, the aberrations on the C-line and F-line are shown by long dashed lines and short dashed lines, 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 half field angle is shown after "ω =".

[0232] Regarding the notations, meanings, description methods, and illustration methods of the respective data related to the above-described Embodiment 1, unless otherwise specified, they are basically the same in the following embodiments, and thus repeated descriptions are omitted below.

[0233] [Embodiment 2]

[0234] Figure 6 A cross-sectional view showing the structure of the imaging lens of Embodiment 2 is shown. The imaging lens of Embodiment 2 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, five lenses L11 to L15. The rear group GR includes, in order from the object side to the image side, eight lenses L21 to L28. The imaging lens includes only one focusing lens group. The focusing lens group includes the aperture stop St and lenses L21 to L27. When focusing from an object at infinity to a close object, the focusing lens group moves toward the object side.

[0235] Regarding the imaging lens of Embodiment 2, the basic lens data are shown in Table 4, the specifications and variable surface intervals are shown in Table 5, the aspherical coefficients are shown in Table 6, and the respective aberration diagrams are shown in Figure 7 .

[0236] [Table 4] Embodiment 2

[0237]

[0238] [Table 5] Embodiment 2

[0239]

[0240] [Table 6]

[0241] Embodiment 2

[0242] Sn 1 2 21 22 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 3.9651598E-06 1.5421722E-06 -8.7627274E-05 -7.0131011E-05 A6 -3.4032600E-08 -7.2935457E-08 -3.5752457E-07 -3.5428099E-07 A8 1.6140338E-10 3.3564210E-10 1.3987961E-09 2.6244808E-09 A10 -3.6712115E-13 -1.0852169E-12 1.2636917E-12 -4.9700906E-12 A12 3.7583680E-16 9.8754650E-16 -6.8824360E-15 2.3455090E-15

[0243] Sn 23 24 KA 1.0000000E+00 1.0000000E+00 A4 -1.7440095E-05 -1.6297372E-05 A6 -1.6142211E-07 -9.3751148E-08 A8 8.7291140E-11 -2.0945795E-10 A10 3.8579220E-13 8.1033927E-13

[0244] [Example 3]

[0245] Figure 8 A cross-sectional view showing the structure of the imaging lens of Example 3 is shown. The imaging lens of Example 3 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, eight lenses L11 to L18. The rear group GR includes, in order from the object side to the image side, six lenses L21 to L26. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L16, and the focusing lens group on the image side includes the lenses L21 to L24. When focusing from an infinitely distant object to a nearby object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between them and move toward the object side.

[0246] Regarding 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 the aberration diagrams are shown in Figure 9 .

[0247] [Table 7] Example 3

[0248]

[0249] [Table 8] Example 3

[0250]

[0251] [Table 9]

[0252] Example 3

[0253] Sn 3 4 21 22 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 6.1752805E-05 6.0751817E-05 -2.2248673E-05 -1.2315307E-05 A6 -1.0744654E-07 -1.2773482E-07 -5.1778727E-08 -6.5095362E-08 A8 3.4964370E-10 3.9442521E-10 -4.1881846E-10 -2.1532037E-10 A10 -5.1763098E-13 -9.6101897E-13 7.7327800E-13 5.3483700E-13

[0254] Sn 23 24 25 26 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 1.0318407E-04 -6.6892480E-05 -1.2136085E-05 9.5189950E-05 A6 -1.0432371E-07 6.0800247E-08 -1.4147008E-07 -8.7588854E-08 A8 -3.2588517E-10 -4.3111851E-11 1.9651026E-10 -4.9430378E-10 A10 1.0236074E-12 6.7398241E-14 6.7215050E-14 1.0178137E-12

[0255] [Example 4]

[0256] Figure 10A cross-sectional view showing the structure of the imaging lens of Example 4 is shown. The imaging lens of Example 4 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, nine lenses L11 to L19. The rear group GR includes, in order from the object side to the image side, six lenses L21 to L26. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L16, and the focusing lens group on the image side includes the lenses L21 to L24. When focusing from an infinite object to a close object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between them and move toward the object side.

[0257] Regarding 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 the various aberration diagrams are shown in Figure 11 .

[0258] [Table 10]

[0259] Example 4

[0260]

[0261] [Table 11]

[0262] Example 4

[0263]

[0264] [Table 12]

[0265] Example 4

[0266] Sn 22 23 24 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -8.1438024E-06 1.3270138E-05 7.8523701E-05 A6 7.3102741E-09 -5.3230147E-08 -4.2453112E-09 A8 -3.2572464E-10 -8.1963245E-11 -4.2342072E-10 A10 7.7327800E-13 5.3483700E-13 1.0718953E-12

[0267] Sn 25 26 27 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -6.6885439E-05 -1.7810027E-06 7.6183267E-05 A6 5.4226654E-08 -1.7532824E-07 -1.4050322E-08 A8 -8.2283279E-11 2.9819180E-10 -4.3115424E-10 A10 3.1347448E-13 8.4424958E-14 7.0981077E-13

[0268] [Example 5]

[0269] Figure 12A cross-sectional view showing the structure of the imaging lens of Example 5 is shown. The imaging lens of Example 5 sequentially includes a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power from the object side to the image side. The front group GF sequentially includes eight lenses L11 to L18 from the object side to the image side. The rear group GR sequentially includes seven lenses L21 to L27 from the object side to the image side. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L16, and the focusing lens group on the image side includes the lenses L21 to L25. When focusing from an infinitely distant object to a nearby object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between them and move toward the object side.

[0270] 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 the aberration diagrams are shown in Figure 13 .

[0271] [Table 13]

[0272] Example 5

[0273]

[0274] [Table 14]

[0275] Example 5

[0276]

[0277] [Table 15]

[0278] Example 5

[0279] Sn 22 23 24 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -8.9520200E-06 9.9315096E-06 5.7714345E-05 A6 3.6566802E-08 -1.9210191E-08 3.8219751E-09 A8 -3.4456559E-10 -1.3482245E-10 -2.8979993E-10 A10 7.7327800E-13 5.3483700E-13 4.6815282E-13

[0280] Sn 25 26 27 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -4.4991230E-05 2.0851230E-05 7.0378888E-05 A6 -1.3341281E-08 -2.2010739E-07 -9.1329591E-09 A8 -1.2268936E-10 3.1614401E-10 -3.0068501E-10 A10 5.1543693E-13 7.3312094E-14 3.8726005E-13

[0281] [Example 6]

[0282] Figure 14 A cross-sectional view showing the structure of the imaging lens of Example 6 is shown. The imaging lens of Example 6 sequentially includes a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power from the object side to the image side. The front group GF sequentially includes five lenses L11 to L15 from the object side to the image side. The rear group GR sequentially includes eight lenses L21 to L28 from the object side to the image side. The imaging lens includes only one focusing lens group. The focusing lens group includes the lenses L21 to L26. When focusing from an infinitely distant object to a nearby object, the focusing lens group moves toward the object side.

[0283] Regarding 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 the aberration diagrams are shown in Figure 15 .

[0284] [Table 16]

[0285] Example 6

[0286]

[0287] [Table 17]

[0288] Example 6

[0289]

[0290] [Table 18]

[0291] Example 6

[0292] Sn 1 2 KA 1.0000000E+00 1.0000000E+00 A4 1.5777886E-05 5.7798046E-06 A6 -8.3327236E-08 -6.2735003E-08 A8 4.1877997E-10 -5.1624651E-10 A10 -1.0699444E-12 4.1638675E-12 A12 1.4379269E-15 -1.8844459E-14

[0293] Sn 20 21 22 23 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 1.3227111E-05 5.0550915E-05 1.4330973E-05 1.6522092E-05 A6 1.0592029E-07 7.0415213E-08 -1.3545777E-08 6.6094779E-08 A8 -1.4586433E-09 -1.0083235E-09 -6.7183726E-10 -8.3657843E-10 A10 2.1639264E-12 1.8218409E-12 1.6641741E-14 1.5851383E-12

[0294] [Example 7]

[0295] Figure 16 A cross-sectional view showing the structure of the imaging lens of Example 7 is shown. The imaging lens of Example 7 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, five lenses L11 to L15. The rear group GR includes, in order from the object side to the image side, eight lenses L21 to L28. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes lenses L14 to L15, and the focusing lens group on the image side includes lenses L21 to L27. When focusing from an infinite object to a near object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between each other and move toward the object side.

[0296] Regarding 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 the aberration diagrams are shown in Figure 17 .

[0297] [Table 19]

[0298] Example 7

[0299]

[0300] [Table 20]

[0301] Example 7

[0302]

[0303] [Table 21]

[0304] Example 7

[0305] Sn 1 2 KA 1.0000000E+00 1.0000000E+00 A4 -4.2168810E-06 -5.3446475E-06 A6 2.6904566E-09 -6.2277244E-09 A8 1.7060065E-12 3.3893822E-13 A10 -1.0190040E-14 -2.0359707E-14 A12 9.9405200E-18 0.0000000E+00

[0306] Sn 21 22 23 24 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -2.9644179E-05 7.7719185E-06 3.4385589E-06 1.0481518E-06 A6 1.2507619E-07 1.7009736E-07 4.1275567E-08 3.3063347E-08 A8 -3.9306515E-10 -3.1792882E-10 -3.2394873E-11 -2.4676171E-11 A10 3.2230400E-13 0.0000000E+00 0.0000000E+00 0.0000000E+00

[0307] [Example 8]

[0308] Figure 18 A cross-sectional view showing the structure of the imaging lens of Example 8 is shown. The imaging lens of Example 8 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, four lenses L11 to L14. The rear group GR includes, in order from the object side to the image side, eight lenses L21 to L28. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes lenses L13 to L14, and the focusing lens group on the image side includes lenses L21 to L27. When focusing from an infinite object to a close object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between each other and move toward the object side.

[0309] 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 the aberration diagrams are shown in Figure 19 .

[0310] [Table 22]

[0311] Example 8

[0312]

[0313] [Table 23]

[0314] Example 8

[0315]

[0316] [Table 24]

[0317] Example 8

[0318] Sn 1 2 KA 1.0000000E+00 1.0000000E+00 A4 -5.0727765E-07 -2.2266630E-06 A6 -2.0389507E-09 -5.5366476E-09 A8 7.3171674E-12 5.5967335E-12 A10 -1.3591213E-14 -6.6003787E-15 A12 9.9405200E-18 0.0000000E+00

[0319] Sn 19 20 21 22 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -1.4026830E-04 -1.2790154E-04 -2.7930862E-05 -2.9942083E-05 A6 3.3986280E-07 3.8206818E-07 1.1404824E-07 8.8063721E-08 A8 -5.8686250E-10 -6.0511434E-10 -8.9600446E-11 -4.9322212E-11 A10 3.2230400E-13 0.0000000E+00 0.0000000E+00 0.0000000E+00

[0320] [Example 9]

[0321] Figure 20 A cross-sectional view showing the structure of the imaging lens of Example 9 is shown. The imaging lens of Example 9 includes, in order from the object side to the image side, a front group GF having a negative refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, five lenses L11 to L15. The lens L11 is a compound aspherical lens in which a resin L11b having an aspherical shape of an air contact surface is formed on the spherical surface of a glass lens L11a. The rear group GR includes, in order from the object side to the image side, nine lenses L21 to L29. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L15, and the focusing lens group on the image side includes the lens L28. When focusing from an infinite object to a near object, the focusing lens group on the object side moves toward the image side, and the focusing lens group on the image side moves toward the object side.

[0322] 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 Tables 27A and 27B, and the respective aberration diagrams are shown in Figure 21 .

[0323] [Table 25]

[0324] Example 9

[0325]

[0326] [Table 26]

[0327] Example 9

[0328]

[0329] [Table 27A]

[0330] Example 9

[0331] Sn 3 23 24 KA -1.0000000E+00 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 7.3312727E-05 2.9446252E-05 5.1026223E-05 A5 4.6207035E-07 1.6600992E-07 1.5045373E-06 A6 -8.6372566E-08 -8.5661731E-08 -3.4402415E-07 A7 1.2934027E-09 -1.2119114E-09 -1.4311993E-09 A8 1.1761842E-10 1.6601734E-09 3.1619262E-09 A9 7.2353185E-12 4.3177961E-12 -2.4989833E-13 A10 3.5433586E-13 -8.8883406E-12 -1.6078442E-11 A11 8.4182226E-15 2.4681852E-14 4.0646297E-14 A12 1.4644189E-16 1.3646500E-15 5.3561641E-15 A13 -1.0395564E-17 1.3639435E-16 7.7428370E-16 A14 -1.0593020E-18 1.1013994E-17 7.4115468E-17 A15 -7.6793480E-20 1.8344398E-18 4.4715818E-18 A16 -4.9469129E-21 2.3964514E-19 2.1795990E-19 A17 -2.6545553E-22 1.1797722E-20 -2.3676864E-20 A18 -2.0841156E-24 -5.8730683E-22 -1.9856838E-22 A19 1.7792975E-24 -8.3518930E-23 -3.6727551E-22 A20 3.2399484E-25 6.0968698E-26 2.0934204E-23

[0332] [Table 27B]

[0333] Example 9

[0334] Sn 25 26 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 -7.3263743E-05 -2.7800878E-05 A5 7.9265345E-07 -3.6035532E-06 A6 -8.2046620E-07 -3.4128977E-07 A7 -8.2031628E-10 1.0633774E-08 A8 3.8629679E-09 2.9397392E-09 A9 1.4998760E-11 7.3874950E-12 A10 -9.5828930E-12 -6.6163481E-12 A11 1.0573106E-13 -3.2974352E-14 A12 6.5599552E-15 -5.3842408E-16 A13 3.3227060E-16 1.8084089E-16 A14 -2.5206052E-18 2.3061609E-17 A15 -3.4526280E-18 6.2862022E-19 A16 -4.5746628E-19 2.5580398E-19 A17 -1.6626000E-20 -1.8051245E-21 A18 1.5446186E-20 -5.4414372E-21 A19 -8.6894860E-22 2.3207668E-22 A20 5.2390937E-24 2.6457697E-24

[0335] [Example 10]

[0336] Figure 22A cross-sectional view showing the structure of the imaging lens of Embodiment 10 is shown. The imaging lens of Embodiment 10 includes, in order from the object side to the image side, a front group GF having a negative refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes four lenses L11 to L14 in order from the object side to the image side. The rear group GR includes eleven lenses L21 to L31 in order from the object side to the image side. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L14, and the focusing lens group on the image side includes the lens L29. When focusing from an infinite object to a close object, the focusing lens group on the object side moves toward the image side, and the focusing lens group on the image side moves toward the object side.

[0337] Regarding the imaging lens of 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 Tables 30A and 30B, and the aberration diagrams are shown in Figure 23 .

[0338] [Table 28]

[0339] Embodiment 10

[0340]

[0341] [Table 29]

[0342] Embodiment 10

[0343]

[0344] [Table 30A]

[0345] Embodiment 10

[0346]

[0347]

[0348] Sn 2 23 24 KA -1.0000000E+00 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 6.0710948E-05 1.0538366E-05 2.6152233E-05 A5 -2.1865468E-07 -6.8517198E-07 6.1710934E-07 A6 -5.7707817E-08 -1.2074727E-07 -2.8141456E-07 A7 3.3193302E-10 1.0876923E-09 4.8425499E-10 A8 3.0820569E-11 1.8239582E-09 3.1862990E-09 A9 2.3211016E-12 1.2857339E-11 -2.3501830E-12 A10 1.4539812E-13 -8.4086713E-12 -1.6138262E-11 A11 2.8261000E-15 4.5831405E-14 7.1673305E-14 A12 1.3617395E-16 1.6329110E-15 1.1078300E-14 A13 -1.0350937E-17 6.9037779E-17 1.3660950E-15 A14 -1.9244641E-18 6.7409202E-19 1.1431772E-16 A15 -1.0751223E-19 8.6094181E-19 5.5288955E-18 A16 -9.6258759E-24 1.6041994E-19 2.0210367E-20 A17 3.2234659E-22 5.2019219E-21 -6.6413800E-20 A18 1.7769211E-23 -1.1249032E-21 -4.6918925E-21 A19 8.3975387E-26 7.2891520E-24 -5.1840799E-22 A20 -4.1811153E-26 2.1544895E-24 6.8007581E-23

[0349] [Table 30B]

[0350] Embodiment 10

[0351] Sn 25 26 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 3.8562362E-05 7.6038643E-05 A5 2.1904653E-06 -3.7092395E-07 A6 -7.2434140E-07 -4.5102151E-07 A7 1.4982789E-10 5.2039214E-09 A8 3.7498834E-09 2.7826738E-09 A9 6.0291605E-12 -4.4002924E-13 A10 -1.0260445E-11 -7.3576115E-12 A11 3.6651658E-14 -9.6485861E-14 A12 -7.0019885E-16 -3.7596068E-15 A13 -2.8559269E-16 3.7285836E-17 A14 -2.9718033E-17 1.3906202E-17 A15 -1.2040584E-18 -3.5828383E-19 A16 4.9099743E-20 1.3436978E-19 A17 -2.2457930E-20 9.0532000E-21 A18 9.4493643E-21 -2.3742058E-22 A19 -1.6819586E-22 1.6732116E-22 A20 -1.8641945E-23 -1.3818491E-23

[0352] [Embodiment 11]

[0353] Figure 24A cross-sectional view showing the structure of the imaging lens of Embodiment 11 is shown. The imaging lens of Embodiment 11 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes six lenses L11 to L16 in order from the object side to the image side. The rear group GR includes six lenses L21 to L26 in order from the object side to the image side. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L16, and the focusing lens group on the image side includes the lenses L23 to L24. When focusing from an infinite object to a close object, the focusing lens group on the object side and the focusing lens group on the image side change the interval therebetween and move toward the image side.

[0354] Regarding the imaging lens of Embodiment 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 the respective aberration diagrams are shown in Figure 25 .

[0355] [Table 31]

[0356] Embodiment 11

[0357]

[0358] [Table 32]

[0359] Embodiment 11

[0360]

[0361] [Table 33]

[0362] Embodiment 11

[0363] Sn 3 4 10 11 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 5.6909317E-05 4.7264012E-05 -9.3286606E-07 2.2602025E-05 A6 -3.0754992E-07 -1.7823746E-07 4.0069148E-08 4.3682444E-08 A8 1.1773011E-09 -9.6480784E-10 3.0684128E-10 3.2532462E-10 A10 -2.2353698E-13 1.4418647E-11 -1.3908300E-12 -1.9127404E-12 A12 -9.7976431E-15 -3.9084767E-14 5.0407317E-15 1.3034678E-14 A14 1.6274400E-17 -4.5572300E-18 0.0000000E+00 0.0000000E+00

[0364] Sn 16 17 22 23 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 5.5664368E-06 6.6373084E-07 2.2576476E-05 5.9576899E-05 A6 -4.1051770E-08 -8.6997376E-08 7.5274177E-08 1.2991654E-07 A8 -3.5852275E-10 -5.6470715E-11 -7.5423623E-10 -3.6525689E-10 A10 1.2399108E-12 2.9074549E-13 2.1861255E-12 -2.2089161E-14

[0365] Sn 20 21 KA 1.0000000E+00 1.0000000E+00 A4 3.3652232E-05 2.4657630E-06 A6 -2.4049388E-08 -7.8886673E-08 A8 -3.4914607E-10 4.9645680E-10 A10 7.2138749E-13 -1.0184865E-12 A12 -1.0236769E-15 -2.8940752E-16

[0366] [Embodiment 12]

[0367] Figure 26A cross-sectional view showing the structure of the imaging lens of Embodiment 12 is shown. The imaging lens of Embodiment 12 includes, in order from the object side to the image side, a front group GF having a negative refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, five lenses L11 to L15. The rear group GR includes, in order from the object side to the image side, six lenses L21 to L26. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L15, and the focusing lens group on the image side includes the lenses L23 to L24. When focusing from an infinite object to a close object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between them and move toward the image side.

[0368] Regarding the imaging lens of Embodiment 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 the various aberration diagrams are shown in Figure 27 .

[0369] [Table 34]

[0370] Embodiment 12

[0371]

[0372] [Table 35]

[0373] Embodiment 12

[0374]

[0375] [Table 36]

[0376] Embodiment 12

[0377] Sn 1 2 8 9 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 5.6375374E-05 4.3674990E-05 3.3919008E-06 2.2850559E-05 A6 -3.1042048E-07 3.4829007E-08 8.8794531E-08 9.4301199E-08 A8 9.2150056E-10 -4.0463092E-09 3.0389341E-10 2.2355726E-10 A10 9.2863501E-13 3.1907432E-11 -1.4866663E-12 -3.3204657E-13 A12 -1.0523397E-14 -7.6904208E-14 5.3224960E-15 6.1629912E-15 A14 1.6274400E-17 -4.5572300E-18 0.0000000E+00 0.0000000E+00

[0378] Sn 14 15 20 21 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -1.2143153E-05 -1.9584757E-05 2.1281487E-05 7.1942123E-05 A6 3.6167083E-08 -4.5693477E-08 1.4224257E-07 1.7163705E-07 A8 4.8802846E-11 3.1954329E-10 -4.4022959E-10 1.9716929E-10 A10 -1.9990106E-12 -2.9622557E-12 -8.9746378E-14 -3.4004113E-12

[0379] Sn 18 19 KA 1.0000000E+00 1.0000000E+00 A4 2.7388688E-05 -7.9574204E-06 A6 -7.2104849E-08 -6.8176946E-08 A8 -3.4164999E-10 4.7245419E-10 A10 1.9028101E-12 -8.5937913E-13 A12 -2.9167461E-15 2.0760774E-17

[0380] [Embodiment 13]

[0381] Figure 28A cross-sectional view showing the structure of the imaging lens of Embodiment 13 is shown. The imaging lens of Embodiment 13 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, six lenses L11 to L16. The rear group GR includes, in order from the object side to the image side, nine lenses L21 to L29. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L21, and the focusing lens group on the image side includes the lens L26. When focusing from an infinitely distant object to a close object, the focusing lens group on the object side moves toward the object side, and the focusing lens group on the image side moves toward the image side.

[0382] Regarding the imaging lens of 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 the aberration diagrams are shown in Figure 29 .

[0383] [Table 37]

[0384] Embodiment 13

[0385]

[0386] [Table 38]

[0387] Embodiment 13

[0388]

[0389] [Table 39]

[0390] Embodiment 13

[0391] Sn 18 19 22 23 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -1.3257656E-05 4.1233831E-05 -2.2577852E-05 -9.9988266E-05 A6 -8.7971135E-09 -6.5090536E-08 1.0080730E-07 -2.6343211E-07 A8 3.7148305E-12 1.7495933E-10 2.9218675E-10 1.1521839E-09 A10 -6.1665272E-14 -2.3458527E-13 -7.0516617E-13 5.1531731E-13 A12 0.0000000E+00 0.0000000E+00 0.0000000E+00 -4.4448000E-16

[0392] Sn 24 25 26 27 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -1.9752354E-04 -2.5990785E-04 -2.2083547E-05 4.8854843E-05 A6 9.3686177E-08 5.6460969E-07 -2.8860872E-07 -1.1209309E-07 A8 7.4712093E-10 -1.2996974E-09 -1.1860070E-09 -1.2336979E-10 A10 -8.6147411E-13 4.3522714E-12 1.1822128E-11 -1.2826789E-12 A12 6.0254836E-15 -1.3725302E-14 -3.3820867E-14 3.9951483E-15

[0393] [Embodiment 14]

[0394] Figure 30 A cross-sectional view showing the structure of the imaging lens of Embodiment 14 is shown. The imaging lens of Embodiment 14 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a negative refractive power. The front group GF includes, in order from the object side to the image side, seven lenses L11 to L17. The rear group GR includes, in order from the object side to the image side, four lenses L21 to L24. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L21, and the focusing lens group on the image side includes the lens L22. When focusing from an infinitely distant object to a close object, the focusing lens group on the object side moves toward the image side, and the focusing lens group on the image side moves toward the object side.

[0395] Regarding the imaging lens of Example 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 Figure 31 .

[0396] [Table 40]

[0397] Example 14

[0398]

[0399] [Table 41]

[0400] Example 14

[0401]

[0402] [Table 42]

[0403] Example 14

[0404] Sn 4 5 14 15 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 1.8665670E-05 2.2083355E-05 -1.8378516E-06 -3.9393464E-06 A6 2.5962433E-08 1.4361024E-08 -2.4823174E-09 -9.8629460E-09 A8 -1.2016831E-10 -7.1202209E-11 -4.6972448E-11 -2.8272389E-11 A10 2.7049116E-13 8.8375128E-14 1.4100195E-13 1.7399418E-14

[0405] Sn 16 17 20 21 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 1.9839370E-07 6.3214807E-06 2.0428095E-05 5.3122070E-06 A6 -1.7001147E-09 -7.3275129E-09 -2.8433115E-08 -2.8133870E-11 A8 9.7839077E-12 1.8537271E-11 4.0041901E-11 -1.1602464E-11 A10 -2.4506600E-14 -2.8358946E-14 6.0212242E-14 7.8393349E-14

[0406] [Example 15]

[0407] Figure 32 A cross-sectional view showing the structure of the imaging lens of Example 15 is shown. The imaging lens of Example 15 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, ten lenses L11 to L20. The rear group GR includes, in order from the object side to the image side, six lenses L21 to L26. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes lenses L16 to L17, and the focusing lens group on the image side includes lenses L21 to L24. When focusing from an infinite object to a close object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between each other and move toward the object side.

[0408] 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 Figure 33 .

[0409] [Table 43]

[0410] Example 15

[0411]

[0412] [Table 44]

[0413] Example 15

[0414]

[0415] [Table 45]

[0416] Example 15

[0417]

[0418]

[0419] Sn 27 28 29 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -6.4981120E-05 -1.2576024E-05 7.6104440E-05 A6 1.0898205E-07 -4.3006728E-08 -5.8679620E-08 A8 -2.6776855E-10 -2.7204086E-10 -4.7939333E-10 A10 3.5889645E-13 2.7976805E-13 7.6980060E-13

[0420] [Example 16]

[0421] Figure 34 A cross-sectional view showing the structure of the imaging lens of Example 16 is shown. The imaging lens of Example 16 includes, in order from the object side to the image side, a front group GF having a positive refractive power, an aperture stop St, and a rear group GR having a positive refractive power. The front group GF includes, in order from the object side to the image side, nine lenses L11 to L19. The rear group GR includes, in order from the object side to the image side, seven lenses L21 to L27. The imaging lens includes only two focusing lens groups. Among the two focusing lens groups, the focusing lens group on the object side includes the lens L17, and the focusing lens group on the image side includes the lenses L21 to L25. When focusing from an infinite object to a close object, the focusing lens group on the object side and the focusing lens group on the image side change the interval between them and move toward the object side.

[0422] 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 the various aberration diagrams are shown in Figure 35 .

[0423] [Table 46]

[0424] Example 16

[0425]

[0426] [Table 47]

[0427] Example 16

[0428]

[0429] [Table 48]

[0430] Example 16

[0431]

[0432]

[0433] Sn 27 28 29 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 A4 -7.9673132E-05 -2.6283266E-05 6.5545511E-05 A6 6.8983789E-08 -1.1150141E-07 -1.2712307E-07 A8 -3.1094137E-11 4.3139857E-10 1.8589123E-10 A10 -2.6375949E-14 -4.4049510E-13 -1.8534438E-13

[0434] Tables 49 to 52 show the corresponding values ​​of conditional expressions (1) to (20) and the values ​​of Ryf and Ryr of the imaging lenses of Examples 1 to 16. The corresponding values ​​of the examples shown in Tables 49 to 52 may be used as the upper limit or lower limit of the conditional expression to set the preferred range of the conditional expression.

[0435] [Table 49]

[0436]

[0437] [Table 50]

[0438]

[0439] [Table 51]

[0440]

[0441] [Table 52]

[0442]

[0443] The F value of the imaging lenses of Examples 1 to 16 is less than 1.9. In particular, the F value of the imaging lenses of some embodiments is less than 1.5. Furthermore, the imaging lenses of Examples 1 to 16 have a maximum half viewing angle of more than 30 degrees when focused on an object at infinity and are configured as wide angles. In particular, the above-mentioned maximum half viewing angle of the imaging lenses of some embodiments is more than 40 degrees. Furthermore, the imaging lenses of Examples 1 to 16 are all configured to be compact, and various aberrations are well corrected to maintain high optical performance.

[0444] Next, an imaging device according to an embodiment of the present invention will be described. Figure 36 and Figure 37 2 shows an external view of a camera 30 which is an imaging device according to an embodiment of the present invention. Figure 36 1 is a perspective view showing the camera 30 as viewed from the front side. Figure 37 The camera 30 is a perspective view viewed from the back. The camera 30 is a so-called mirrorless digital camera, and can detachably attach an interchangeable lens 20. The interchangeable lens 20 includes an imaging lens 1 according to an embodiment of the present invention housed in a lens barrel.

[0445] 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. In addition, 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 the captured image and the image existing within the perspective before shooting.

[0446] A photographing opening through which light from a subject enters is provided at the center of the front surface of the camera body 31. A bayonet mount 37 is provided at a position corresponding to the photographing opening, and the interchangeable lens 20 is attached to the camera body 31 via the bayonet mount 37.

[0447] An imaging element 38 is provided within the camera body 31. The imaging element 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. As the imaging element 38, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) etc. can be used. A signal processing circuit (not shown), a recording medium (not shown), etc. are provided within the camera body 31. The signal processing circuit processes the imaging signal output from the imaging element 38 to generate an image. The recording medium is used to record the generated image. In the camera 30, a still image or a moving image can be captured by pressing the shutter button 32, and the image data obtained through this capture is recorded in the above-mentioned recording medium.

[0448] As described above, the technology of the present invention has been described by way of embodiments and examples, but the technology of the present invention is not limited to the above-mentioned embodiments and examples, and various modifications can be made. For example, the curvature radius, surface interval, refractive index, Abbe number, aspherical coefficient, etc. of each lens are not limited to the values shown in the above-mentioned respective examples, and other values can be adopted.

[0449] Moreover, regarding the imaging device according to the embodiment of the present invention, it is not limited to the above example either. For example, it can be configured in various forms such as cameras other than mirrorless types, film cameras, video cameras, and security cameras.

[0450] Regarding the above-mentioned embodiments and examples, the following additional notes are further disclosed.

[0451] [Additional Note 1]

[0452] An imaging lens that sequentially includes a front group, an aperture stop, and a rear group from the object side to the image side,

[0453] The rear group includes one or two focusing lens groups that move along the optical axis during focusing,

[0454] When focusing, the distance on the optical axis from the lens surface closest to the object side of the front group to the image plane remains unchanged.

[0455] Let the sum of the distance on the optical axis from the lens surface closest to the object side of the front group to the lens surface closest to the image side of the rear group in the state of focusing on an infinitely distant object and the back focal length in the air equivalent distance of the entire system be TL.

[0456] Let the focal length of the entire system in the state of focusing on an infinitely distant object be f.

[0457] Let the maximum half field angle in the state of focusing on an infinitely distant object be ωm.

[0458] Let the open F-number in the state of focusing on an infinitely distant object be Fno.

[0459] When the back focal length in the air equivalent distance of the entire system in the state of focusing on an infinitely distant object is Bf, the conditional expressions (1), (2), and (3) represented by

[0460] 2.3 < TL / (f × tanωm) < 7 (1)

[0461] 1.15 < Fno / tanωm < 3.5 (2)

[0462] 0.3 < Bf / (f × tanωm) < 1.5 (3)

[0463] are satisfied.

[0464] [Supplementary Note 2]

[0465] For the imaging lens according to Supplementary Note 1, wherein the conditional expression (1-1) represented by

[0466] 3.5 < TL / (f × tanωm) < 5.6 (1-1)

[0467] is satisfied.

[0468] [Supplementary Note 3]

[0469] For the imaging lens according to Supplementary Note 1, wherein the conditional expression (1-2) represented by

[0470] 4.4 < TL / (f × tanωm) < 5.2 (1-2)

[0471] is satisfied.

[0472] [Supplementary Note 4]

[0473] For the imaging lens according to any one of Supplementary Notes 1 to 3, wherein the conditional expression represented by

[0474] 1.3 < Fno / tanωm < 2.7 (2-1)

[0475] The conditional expression (2-1) represented by

[0476] [Supplementary Note 5]

[0477] The imaging lens according to any one of Supplementary Notes 1 to 4, wherein

[0478] When the distance on the optical axis from the lens surface closest to the object side of the front group to the aperture stop in the state of focusing on an infinitely distant object is defined as dFSt, it satisfies

[0479] 0.43 < dFSt / TL < 0.75 (4)

[0480] The conditional expression (4) represented by

[0481] [Supplementary Note 6]

[0482] The imaging lens according to any one of Supplementary Notes 1 to 5, wherein

[0483] When the focal length of the front group in the state of focusing on an infinitely distant object is defined as fF,

[0484] When the focal length of the rear group in the state of focusing on an infinitely distant object is defined as fR, it satisfies

[0485] -2 < fR / fF < 4 (5)

[0486] The conditional expression (5) represented by

[0487] [Supplementary Note 7]

[0488] The imaging lens according to any one of Supplementary Notes 1 to 6, wherein

[0489] When the focal length of the front group in the state of focusing on an infinitely distant object is defined as fF, it satisfies -1 < f / fF < 2 (6)

[0490] The conditional expression (6) represented by

[0491] [Supplementary Note 8]

[0492] The imaging lens according to any one of Supplementary Notes 1 to 7, wherein it satisfies

[0493] 6 < (TL × Fno) / (f × tanωm) < 11 (7)

[0494] The conditional expression (7) represented by

[0495] [Supplementary Note 9]

[0496] The imaging lens according to any one of Appendices 1 to 7, wherein

[0497] 6.3 < (TL × Fno) / (f × tan ωm) < 9.5 (7-1)

[0498] The conditional expression (7-1) represented by

[0499] [Appendix 10]

[0500] The imaging lens according to any one of Appendices 1 to 9, wherein the front group includes a focusing lens group that moves along the optical axis during focusing.

[0501] [Appendix 11]

[0502] The imaging lens according to any one of Appendices 1 to 10, wherein the rear group includes two focusing lens groups that move while changing the interval between them during focusing.

[0503] [Appendix 12]

[0504] The imaging lens according to any one of Appendices 1 to 11, wherein at least one lens is disposed in the rear group, the convex surface of which faces the object side in the paraxial region, and the lens surface on the object side has an inflection point at which the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion.

[0505] [Appendix 13]

[0506] The imaging lens according to any one of Appendices 1 to 12, wherein at least one lens is disposed in the rear group, the concave surface of which faces the object side in the paraxial region, and the lens surface on the object side has an inflection point at which the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion.

[0507] [Appendix 14]

[0508] The imaging lens according to any one of Appendices 1 to 13, wherein at least one lens is disposed in the rear group, the convex surface of which faces the image side in the paraxial region, and the lens surface on the image side has an inflection point at which the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion.

[0509] [Appendix 15]

[0510] The imaging lens according to any one of Appendices 1 to 14, wherein at least one lens is disposed in the rear group, the concave surface of which faces the image side in the paraxial region, and the lens surface on the image side has an inflection point at which the concavo-convex shape changes midway as it moves from the optical axis toward the peripheral portion.

[0511] [Appendix 16]

[0512] The imaging lens according to any one of Addenda 1 to 15, wherein the imaging lens includes three cemented lenses cemented in the order of a first positive lens, a second positive lens, and a negative lens.

[0513] [Addendum 17]

[0514] The imaging lens according to Addendum 16, wherein the surface of the second positive lens on the first positive lens side faces the first positive lens side with a concave surface.

[0515] [Addendum 18]

[0516] The imaging lens according to any one of Addenda 1 to 17, wherein

[0517] the rear group includes at least one aspherical lens,

[0518] the aspherical lens closest to the image side among the aspherical lenses included in the rear group is defined as the most image-side aspherical lens,

[0519] the paraxial curvature radius of the object-side surface of the most image-side aspherical lens is defined as Rcf,

[0520] the curvature radius at the position of the maximum effective diameter of the object-side surface of the most image-side aspherical lens is defined as Ryf,

[0521] the paraxial curvature radius of the image-side surface of the most image-side aspherical lens is defined as Rcr,

[0522] when the curvature radius at the position of the maximum effective diameter of the image-side surface of the most image-side aspherical lens is defined as Ryr, the following conditional expression (8) is satisfied

[0523] 0.2 < |(1 / Rcf - 1 / Rcr) / (1 / Ryf - 1 / Ryr)| < 4 (8)

[0524] represented conditional expression (8).

[0525] [Addendum 19]

[0526] The imaging lens according to any one of Addenda 1 to 18, wherein

[0527] the number of focusing lens groups included in the imaging lens is two,

[0528] the focal length of the focusing lens group on the object side among the two focusing lens groups included in the imaging lens is defined as ff1,

[0529] when the focal length of the focusing lens group on the image side among the two focusing lens groups included in the imaging lens is defined as ff2, the following is satisfied

[0530] 0.2 < |ff1 / ff2| < 5 (9)

[0531] The conditional expression (9) represented

[0532] [Supplementary Note 20]

[0533] The imaging lens according to any one of Supplementary Notes 1 to 19, wherein

[0534] When the combined focal length of all the lenses closer to the image side than the most image-side focusing lens group in the imaging lens is set to ffR, the following is satisfied

[0535] -1.5 < f / ffR < 1.5 (10)

[0536] The conditional expression (10) represented

[0537] [Supplementary Note 21]

[0538] An imaging device including the imaging lens according to any one of Supplementary Notes 1 to 20

Claims

1. An imaging lens, which comprises, from the object side to the image side, a front group, an aperture stop and a rear group, The rear group includes one or two focusing lens groups that move along the optical axis during focusing. When focusing, the distance on the optical axis from the lens surface closest to the object side of the front group to the image plane remains unchanged. The sum of the distance on the optical axis from the lens surface closest to the object side of the front group to the lens surface closest to the image side of the rear group in a state of focusing on an infinitely distant object and the back focal length of the entire system at the air conversion distance is set to TL. Let the focal length of the entire system when focusing on an object at infinity be f, The maximum half angle of view when focusing on an object at infinity is set to ωm. Set the open F value when focusing on an object at infinity to Fno. When the back focal length of the entire system at the air conversion distance in the state of focusing on an infinitely distant object is set to Bf, 2.3<TL / (f×tanωm)<7 (1) 1.15<Fno / tanωm<3.5 (2) 0.3<Bf / (f×tanωm)<1.5 (3) The conditional expressions (1), (2) and (3) are represented.

2. The imaging lens according to claim 1, wherein: When the distance on the optical axis from the lens surface of the front group closest to the object to the aperture stop in a state of focusing on an infinitely distant object is dFSt, 0.43<dFSt / TL<0.75 (4) The conditional expression (4) is represented.

3. The imaging lens according to claim 1 or 2, wherein: The focal length of the front group in the state of focusing on an object at infinity is set to fF, When the focal length of the rear group in a state of focusing on an object at infinity is set to fR, -2<fR / fF<4 (5) The conditional expression (5) is represented.

4. The imaging lens according to claim 1 or 2, wherein: When the focal length of the front group in the state of focusing on an object at infinity is set to fF, -1<f / fF<2 (6) The conditional expression (6) is represented.

5. The imaging lens according to claim 1 or 2, wherein: satisfy 6<(TL×Fno) / (f×tanωm)<11 (7) The conditional expression (7) is represented.

6. The imaging lens according to claim 1 or 2, wherein: The front group includes a focusing lens group that moves along the optical axis during focusing.

7. The imaging lens according to claim 1 or 2, wherein: The rear group includes two focus lens groups that move by changing the interval between them during focusing.

8. The imaging lens according to claim 1 or 2, wherein: The rear group includes at least one lens having a convex surface facing the object side in a paraxial region and having an inflection point on the lens surface on the object side where the concavoconvex shape changes as it moves from the optical axis toward the periphery.

9. The imaging lens according to claim 1 or 2, wherein: The rear group includes at least one lens having a concave surface facing the object side in a paraxial region and having an inflection point on the lens surface on the object side where the concave and convex shape changes as it moves from the optical axis toward the periphery.

10. The imaging lens according to claim 1 or 2, wherein: The rear group includes at least one lens having a convex surface facing the image side in a paraxial region and having an inflection point on the image side lens surface where the concavoconvex shape changes as it moves from the optical axis toward the periphery.

11. The imaging lens according to claim 1 or 2, wherein: The rear group includes at least one lens having a concave surface facing the image side in a paraxial region and having an inflection point on the image side lens surface where the concavo-convex shape changes as it moves from the optical axis toward the periphery.

12. The imaging lens according to claim 1 or 2, wherein: The lens includes three cemented lenses, namely, a first positive lens, a second positive lens, and a negative lens cemented in this order.

13. The imaging lens according to claim 12, wherein: The surface of the second positive lens on the first positive lens side has a concave surface facing the first positive lens side.

14. The imaging lens according to claim 1 or 2, wherein: satisfy 3.5<TL / (f×tanωm)<5.6 (1-1) The conditional expression (1-1) is represented.

15. The imaging lens according to claim 1 or 2, wherein: satisfy 1.3<Fno / tanωm<2.7 (2-1) The conditional expression (2-1) is represented.

16. The imaging lens according to claim 15, wherein: satisfy 3.5<TL / (f×tanωm)<5.6 (1-1) The conditional expression (1-1) is represented.

17. The imaging lens according to claim 16, wherein: satisfy 6<(TL×Fno) / (f×tanωm)<11 (7) The conditional expression (7) is represented.

18. The imaging lens according to claim 17, wherein: The lens includes three cemented lenses, namely, a first positive lens, a second positive lens, and a negative lens cemented in this order.

19. The imaging lens according to claim 18, wherein: The surface of the second positive lens on the first positive lens side has a concave surface facing the first positive lens side.

20. The imaging lens according to claim 17, wherein: The front group includes a focusing lens group that moves along the optical axis during focusing.

21. The imaging lens according to claim 20, wherein: The rear group includes at least one lens having a convex surface facing the object side in a paraxial region and having an inflection point on the lens surface on the object side where the concavoconvex shape changes as it moves from the optical axis toward the periphery.

22. The imaging lens according to claim 17, wherein: The rear group includes two focus lens groups that move by changing the interval between them during focusing.

23. The imaging lens according to claim 22, wherein: The rear group includes at least one lens having a convex surface facing the object side in a paraxial region and having an inflection point on the lens surface on the object side where the concavoconvex shape changes as it moves from the optical axis toward the periphery.

24. The imaging lens according to claim 17, wherein: The rear group includes at least one lens having a concave surface facing the object side in a paraxial region and having an inflection point on the lens surface on the object side where the concave and convex shape changes as it moves from the optical axis toward the periphery.

25. The imaging lens according to claim 17, wherein: satisfy 4.4<TL / (f×tanωm)<5.2 (1-2) The conditional expression (1-2) is represented.

26. The imaging lens according to claim 25, wherein: satisfy 6.3<(TL×Fno) / (f×tanωm)<9.5 (7-1) The conditional expression (7-1) is represented.

27. The imaging lens according to claim 26, wherein: The rear group includes at least one lens having a convex surface facing the image side in a paraxial region and having an inflection point on the image side lens surface where the concavoconvex shape changes as it moves from the optical axis toward the periphery.

28. The imaging lens according to claim 17, wherein: The rear group includes at least one lens having a concave surface facing the image side in a paraxial region and having an inflection point on the image side lens surface where the concavo-convex shape changes as it moves from the optical axis toward the periphery.

29. The imaging lens according to claim 1 or 2, wherein: The rear group includes at least one aspherical lens, The aspheric lens closest to the image side among the aspheric lenses included in the rear group is set as the most image side aspheric lens, The paraxial curvature radius of the object-side surface of the most image-side aspheric lens is set to Rcf, The curvature radius at the position of the maximum effective diameter of the object-side surface of the most image-side aspherical lens is defined as Ryf. The paraxial curvature radius of the image side surface of the most image side aspheric lens is set to Rcr, When the curvature radius at the position of the maximum effective diameter of the image side surface of the most image side aspherical lens is denoted as Ryr, 0.2<|(1 / Rcf-1 / Rcr) / (1 / Ryf-1 / Ryr)|<4 (8) The conditional expression (8) is represented.

30. The imaging lens according to claim 1 or 2, wherein: The number of the focusing lens groups included in the imaging lens is two, The focal length of the object-side focusing lens group of the two focusing lens groups included in the imaging lens is set to ff1, When the focal length of the image-side focus lens group of the two focus lens groups included in the imaging lens is set to ff2, 0.2<|ff1 / ff2|<5 (9) The conditional expression (9) is represented.

31. The imaging lens according to claim 1 or 2, wherein: When the composite focal length of all lenses included in the imaging lens that are closer to the image side than the focus lens group closest to the image side of the focus lens group is set to ffR, -1.5<f / ffR<1.5 (10) The conditional expression (10) is represented.

32. An imaging device comprising the imaging lens according to any one of claims 1 to 31.

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