Imaging lens and camera device

Abstract

This invention provides an imaging lens that can effectively correct aberrations even in close-up photography, and a camera device incorporating the imaging lens. The imaging lens, from the object-side to the image-side, comprises: a front lens group having positive refractive power that remains constant during focusing; an aperture, continuously arranged with the front lens group; a first focusing lens group having positive refractive power; a second focusing lens group having negative refractive power; and a final lens group, arranged on the image-side and having positive refractive power that remains constant during focusing. When focusing from an object at infinity to a closer object, the first and second focusing lens groups move by increasing their spacing from each other. The lens surface of the first focusing lens group on the object-side is concave, and the lens surface of the front lens group on the image-side is concave.

Description

Technical Field

[0001] This invention relates to an imaging lens and a camera device. Background Technology

[0002] Previously, as imaging lenses for digital cameras and the like, lens systems described in Patent Document 1 and Patent Document 2 are known.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-194630

[0004] Patent Document 2: Japanese Patent No. 6582315

[0005] In recent years, with the increasing pixel density of imaging elements, there is a need for imaging lenses that can effectively correct aberrations even in close-up photography. Summary of the Invention

[0006] The present invention was made in view of the above circumstances, and its object is to provide an imaging lens that can effectively correct aberrations even in close-up photography, and a camera device equipped with such an imaging lens.

[0007] An imaging lens according to one aspect of the present invention comprises, from the object side to the image side, the following components in sequence: a front lens group having a positive refractive power fixed relative to the image plane during focusing; an aperture continuously disposed with the front lens group; a first focusing lens group having a positive refractive power; a second focusing lens group having a negative refractive power; and a final lens group disposed on the image side and having a positive refractive power fixed relative to the image plane during focusing. When focusing from an object at infinity to a closer object, the first focusing lens group and the second focusing lens group move by widening their spacing from each other. The lens surface of the front lens group on the image side is concave, and the lens surface of the first focusing lens group on the object side is concave.

[0008] When the radius of curvature of the lens surface closest to the object in the first focusing lens group is set to RF1f and the maximum image height is set to Ymax, the imaging lens of the above method preferably satisfies the following condition (1), and more preferably satisfies the following condition (1-1).

[0009] -2<RF1f / Ymax<-0.5 (1)

[0010] -1.4<RF1f / Ymax<-0.8 (1-1)

[0011] When the radius of curvature of the lens surface closest to the image in the front lens group is set to RAr and the maximum image height is set to Ymax, the imaging lens of the above method preferably satisfies the following condition (2), and more preferably satisfies the following condition (2-1).

[0012] 0.7 < RAr / Ymax < 1.3 (2)

[0013] 0.8<RAr / Ymax<1.2 (2-1)

[0014] When the radius of curvature of the lens surface closest to the image in the front lens group is set to RAr and the radius of curvature of the lens surface closest to the object in the first focusing lens group is set to RF1f, the imaging lens of the above method preferably satisfies the following condition (3), and more preferably satisfies the following condition (3-1).

[0015] -0.2<(RAr+RF1f) / (RAr-RF1f)<0 (3)

[0016] -0.15<(RAr+RF1f) / (RAr-RF1f)<-0.01 (3-1)

[0017] When a lens component is configured as a single lens or a set of combined lenses, the lens component closest to the object in the front lens group preferably has positive refractive power.

[0018] When the maximum value of the refractive index of all lenses in the lens component closest to the object in the front lens group relative to the d line is set as NAmax, the minimum value of the Abbe number of the d line reference of all positive lenses in the lens component closest to the object in the front lens group is set as νApmin, and the maximum value of the partial dispersion ratio between the g line and the F line of all positive lenses in the lens component closest to the object in the front lens group is set as θApmax, the imaging lens of the above method preferably satisfies the following conditions (4), (5) and (6).

[0019] 1.7 < NAmax < 2.1 (4)

[0020] 10 < νApmin < 40 (5)

[0021] 0.5 < θApmax < 0.8 (6)

[0022] The front lens group includes a conjoining lens on the image-closest side, and the conjoining lens on the image-closest side of the front lens group preferably includes a negative lens and a positive lens sequentially from the image-closest side.

[0023] When the refractive index of the positive lens included in the image-side junction lens of the front lens group relative to the d-line is set to NArp, the refractive index of the negative lens included in the image-side junction lens of the front lens group relative to the d-line is set to NArn, the Abbe number of the d-line reference of the positive lens included in the image-side junction lens of the front lens group is set to νArp, the Abbe number of the d-line reference of the negative lens included in the image-side junction lens of the front lens group is set to νArn, the partial dispersion ratio between the g-line and F-line of the positive lens included in the image-side junction lens of the front lens group is set to θArp, and the partial dispersion ratio between the g-line and F-line of the negative lens included in the image-side junction lens of the front lens group is set to θArn, the imaging lens of the above-described manner preferably satisfies the following conditions (7), (8), and (9).

[0024] 0 < NArp - NArn < 0.15 (7)

[0025] 5<νArp-νArn<40 (8)

[0026] 0.01<θArn-θArp<0.06 (9)

[0027] When the focal length of the imaging lens is set to f and the focal length of the front lens group is set to fA, the imaging lens described above preferably satisfies the following condition (10).

[0028] 0.25 < f / fA < 0.8 (10)

[0029] When the focal length of the imaging lens is set to f and the focal length of the first focusing lens group is set to fF1, the imaging lens described above preferably satisfies the following condition (11).

[0030] 1.8 < f / fF1 < 4 (11)

[0031] When the focal length of the imaging lens is set to f and the focal length of the second focusing lens group is set to fF2, the imaging lens described above preferably satisfies the following condition (12).

[0032] -5<f / fF2<-1.4 (12)

[0033] When the focal length of the first focusing lens group is set to fF1 and the focal length of the second focusing lens group is set to fF2, the imaging lens of the above method preferably satisfies the following condition (13).

[0034] -1.55<fF1 / fF2<-0.4 (13)

[0035] When the lateral magnification of the first focusing lens group is set to βF1 when focusing on an object at infinity, and the combined lateral magnification of all lenses that are closer to the image side than the first focusing lens group when focusing on an object at infinity is set to βF1r, the imaging lens described above preferably satisfies the following condition (14).

[0036] 1.6 < (1-βF1) 2 )×βF1r 2 <5.8 (14)

[0037] When the lateral magnification of the second focusing lens group is set to βF2 when focusing on an object at infinity, and the combined lateral magnification of all lenses on the image side that are closer to the second focusing lens group than when focusing on an object at infinity is set to βF2r, the imaging lens described above preferably satisfies the following condition (15).

[0038] -4.2<(1-βF2 2 )×βF2r 2 <0 (15)

[0039] The first focusing lens group is preferably configured continuously with the aperture.

[0040] The imaging lens described above preferably includes an intermediate lens group that is fixed during focusing, located between the first focusing lens group and the second focusing lens group.

[0041] The camera device of the present invention includes the imaging lens of the present invention.

[0042] In addition, the terms "including" and "including" in this specification mean that, in addition to the constituent elements listed, it may also include lenses that do not substantially have refractive power, as well as optical elements other than lenses such as apertures, filters and cover glass, and mechanism parts such as lens flanges, lens barrels, imaging elements and hand shaking correction mechanisms.

[0043] Furthermore, in this specification, expressions such as "including ~ and ~ sequentially from the object side to the image side" indicate that the constituent elements are included continuously or discontinuously. For example, "including A and B sequentially from the object side to the image side" can mean that A and B are arranged continuously, or that another constituent element is arranged between A and B, and A and B are arranged discontinuously.

[0044] In this specification, "lens group with positive refractive power" means that the lens group as a whole has positive refractive power. Similarly, "lens group with negative refractive power" means that the lens group as a whole has negative refractive power. "Lens group" is not limited to a structure that includes multiple lenses; it can also be a structure that includes only one lens.

[0045] Additionally, in this specification, "lens group" refers to a structural part of an imaging lens that includes at least one lens separated by air gaps that change during focusing. During focusing, the lens group is moved or fixed as a unit, and the spacing between the lenses within a single lens group remains constant.

[0046] The terms "lens with positive refractive power," "positive lens," and "positive lens" have the same meaning. The terms "lens with negative refractive power," "negative lens," and "negative lens" have the same meaning. "Single lens" refers to a single, unjoined lens.

[0047] Unless otherwise stated, the sign of the refractive power, surface shape, and radius of curvature associated with lenses including aspherical surfaces are assumed to be considered in the paraxial region. Regarding the sign of the radius of curvature, the radius of curvature of a surface with a convex shape facing the object is signified positive, and the radius of curvature of a surface with a convex shape facing the image is signified negative. Compound aspherical lenses (lenses in which a spherical lens and an aspherical film formed on the spherical lens are integrated to function as a single aspherical lens) are used as a single lens and not considered as combined lenses.

[0048] The "focal length" used in the conditional formula is the paraxial focal length. The values ​​used in the conditional formula are based on the d-line when focusing on an object at infinity. The "d-line," "C-line," "F-line," and "g-line" described in this specification are bright lines. In this specification, the wavelength of the d-line is considered to be 587.56 nm, the wavelength of the C-line is considered to be 656.27 nm, the wavelength of the F-line is considered to be 486.13 nm, and the wavelength of the g-line is considered to be 435.84 nm. The partial dispersion ratio θgF between the g-line and F-line of a lens is defined as θgF = (Ng - NF) / (NF - NC), assuming the refractive indices of the lens relative to the g-line, F-line, and C-line are Ng, NF, and NC, respectively.

[0049] Invention Effects

[0050] According to the present invention, it is possible to provide an imaging lens that can effectively correct aberrations even in close-up photography, and a camera device equipped with the imaging lens. Attached Figure Description

[0051] Figure 1 This is a cross-sectional view showing the structure of an imaging lens according to an embodiment corresponding to the imaging lens of Example 1.

[0052] Figure 2 It means Figure 1 The structure and beam cross-section of the imaging lens in various focusing states.

[0053] Figure 3 This is a diagram of the aberrations of the imaging lens in Example 1.

[0054] Figure 4 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 2.

[0055] Figure 5 This is a diagram of the aberrations of the imaging lens in Example 2.

[0056] Figure 6 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 3.

[0057] Figure 7 These are aberration diagrams of the imaging lens in Example 3.

[0058] Figure 8 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 4.

[0059] Figure 9 This is a cross-sectional view showing the structure and beam of the imaging lens of Embodiment 4 in various focusing states.

[0060] Figure 10 This is a diagram of the aberrations of the imaging lens in Example 4.

[0061] Figure 11 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 5.

[0062] Figure 12 This is a diagram of the aberrations of the imaging lens in Example 5.

[0063] Figure 13 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 6.

[0064] Figure 14 This is a diagram of the aberrations of the imaging lens in Example 6.

[0065] Figure 15 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 7.

[0066] Figure 16 This is a diagram of the aberrations of the imaging lens in Example 7.

[0067] Figure 17 This is a perspective view of the front side of a camera device according to one embodiment.

[0068] Figure 18 This is a perspective view of the rear side of a camera device according to one embodiment.

[0069] Symbol Explanation

[0070] 1-Imaging lens, 2-On-axis beam, 3-Beam with maximum image height, 20-Interchangeable lens, 30-Camera, 31-Camera body, 32-Shutter button, 33-Power button, 34, 35-Operation unit, 36-Display unit, 37-Mount, GA-Front lens group, GE-Final lens group, GF1-First focusing lens group, GF2-Second focusing lens group, GM-Intermediate lens group, L11~L51-Lens, PP-Optical components, Sim-Image plane, St-Aperture, Z-Optical axis. Detailed Implementation

[0071] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0072] exist Figure 1 The diagram shows a cross-sectional view of the structure of an imaging lens according to an embodiment of the present invention in a state of focusing on an object at infinity. Figure 2 The diagram shows a cross-sectional view of the imaging lens's structure and beam in various focusing states. Figure 2 The image shows on-axis beam 2 and beam 3 with maximum image height as beams. Figure 2 In this manual, the upper section marked "Infinity" shows the state of focusing on an object at infinity, and the lower section marked "110mm" shows the state of focusing on a closer object at a distance of 110mm. The object distance is the distance along the optical axis Z from the object to the lens surface closest to the object. In this manual, an object at an infinity distance is referred to as an infinity object. Figure 1 and Figure 2 The example shown corresponds to the imaging lens of Embodiment 1 described later. Figure 1 and Figure 2 In the image, the left side is the object side, and the right side is the image side. The following primarily refers to... Figure 1 An imaging lens according to one embodiment of the present invention will be described. In the following description, to avoid redundancy, the imaging lens of the present invention will also be referred to as an imaging lens.

[0073] exist Figure 1 The illustration shows an example where, assuming an imaging lens is used in a camera device, a parallel flat optical component PP is positioned between the imaging lens and the image plane (Sim). The optical component PP is assumed to be a component such as various filters and / or cover glass. These filters include low-pass filters, infrared cut-off filters, and / or filters that cut off specific wavelength regions. The optical component PP is a component without refractive power. The camera device can also be constructed without the optical component PP.

[0074] The imaging lens of the present invention comprises, along the optical axis Z from the object side to the image side, the following elements in sequence: a front lens group GA, having a positive refractive power fixed relative to the image plane Sim during focusing; an aperture St, continuously arranged with the front lens group GA; a first focusing lens group GF1, having a positive refractive power; a second focusing lens group GF2, having a negative refractive power; and a final lens group GE, arranged on the image side and having a positive refractive power fixed relative to the image plane Sim during focusing. When focusing from an object at infinity to a closer object, the first focusing lens group GF1 and the second focusing lens group GF2 move by increasing their spacing from each other. By employing the above structure, it is advantageous to suppress variations in various aberrations during focusing.

[0075] As an example, Figure 1 The imaging lens, from the object side to the image side, consists of the front lens group GA, the aperture St, the first focusing lens group GF1, the second focusing lens group GF2, and the final lens group GE. Figure 1 In the example, the front lens group GA consists of four lenses, L11 to L14, arranged sequentially from the object side to the image side; the first focusing lens group GF1 consists of three lenses, L21 to L23, arranged sequentially from the object side to the image side; the second focusing lens group GF2 consists of three lenses, L31 to L33, arranged sequentially from the object side to the image side; and the final lens group GE consists of one lens, L41. Additionally, Figure 1 The aperture St indicates the position along the Z-axis of the optical axis, not its size or shape.

[0076] exist Figure 1 In this example, the imaging lens includes only two lens groups that move during focusing: the first focusing lens group GF1 and the second focusing lens group GF2. This configuration makes it easy to balance suppressing aberrations during focusing with miniaturization.

[0077] When focusing from an object at infinity to a closer object, the first focusing lens group GF1 moves toward the object side, and the second focusing lens group GF2 moves toward the image side. Figure 1 The left and right arrows below the first focusing lens group GF1 and the second focusing lens group GF2 indicate the direction of movement of each focusing lens group when focusing from an object at infinity to a closer object. Furthermore, in Figure 2 In the middle, the arrows between the upper and lower sections indicate the approximate movement trajectory of each focusing lens group when focusing from an object at infinity to a closer object.

[0078] In the imaging lens of the present invention, during focusing, the second focusing lens group GF2 can move linearly or non-linearly relative to the first focusing lens group GF1. Linear movement simplifies the moving mechanism, thus providing a structural advantage. Non-linear movement facilitates obtaining a good image when focusing on a medium-distance object.

[0079] The lens surface closest to the object in the first focusing lens group GF1 is concave. This structure helps to correct image plane curvature.

[0080] When the radius of curvature of the lens surface closest to the object in the first focusing lens group GF1 is set to RF1f and the maximum image height is set to Ymax, the imaging lens preferably satisfies the following condition (1). By ensuring that the corresponding value of condition (1) is not below the lower limit, it is beneficial to correct image plane curvature. By ensuring that the corresponding value of condition (1) is not above the upper limit, it is beneficial to correct astigmatism. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (1-1), and even more preferably satisfies the following condition (1-2).

[0081] -2<RF1f / Ymax<-0.5 (1)

[0082] -1.4<RF1f / Ymax<-0.8 (1-1)

[0083] -1.2<RF1f / Ymax<-1 (1-2)

[0084] The lens surface closest to the image side of the front lens group GA is concave. This structure helps to correct image plane curvature.

[0085] When the radius of curvature of the lens surface closest to the image side of the front lens group GA is set to RAr and the maximum image height is set to Ymax, the imaging lens preferably satisfies the following condition (2). By ensuring that the corresponding value of condition (2) is not below the lower limit, it is beneficial to suppress the increase of astigmatism. By ensuring that the corresponding value of condition (2) is not above the upper limit, it is beneficial to correct the curvature of the image surface. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (2-1), and even more preferably satisfies the following condition (2-2).

[0086] 0.7 < RAr / Ymax < 1.3 (2)

[0087] 0.8<RAr / Ymax<1.2 (2-1)

[0088] 0.85<RAr / Ymax<1.1 (2-2)

[0089] When the radius of curvature of the lens surface closest to the image in the front lens group GA is set to RAr and the radius of curvature of the lens surface closest to the object in the first focusing lens group GF1 is set to RF1f, the imaging lens preferably satisfies the following condition (3). Satisfying condition (3) is beneficial for correcting astigmatism. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (3-1), and even more preferably satisfies the following condition (3-2).

[0090] -0.2<(RAr+RF1f) / (RAr-RF1f)<0 (3)

[0091] -0.15<(RAr+RF1f) / (RAr-RF1f)<-0.01 (3-1)

[0092] -0.13<(RAr+RF1f) / (RAr-RF1f)<-0.02 (3-2)

[0093] The front lens group GA preferably includes two or more positive lenses. This configuration is advantageous for correcting spherical aberration.

[0094] The lens component closest to the object in the front lens group GA preferably has positive refractive power. This configuration is advantageous for correcting spherical aberration. Furthermore, in this specification, one lens component refers to either a single lens or a group of combined lenses.

[0095] In a structure where the lens component closest to the object in the front lens group GA has positive refractive power, when the maximum value of the refractive index of all lenses included in the lens component closest to the object in the front lens group GA relative to the d-line is set to NAmax, the imaging lens preferably satisfies the following condition (4). Satisfying condition (4) is beneficial for correcting astigmatism. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (4-1), and even more preferably satisfies the following condition (4-2).

[0096] 1.7 < NAmax < 2.1 (4)

[0097] 1.8 < NAmax < 2.1 (4-1)

[0098] 1.9 < NAmax < 2.1 (4-2)

[0099] In a structure where the lens component closest to the object in the front lens group GA has positive refractive power, when the minimum Abbe number of all positive lenses included in the lens component closest to the object in the front lens group GA relative to the d-line reference is set to νApmin, the imaging lens preferably satisfies the following condition (5). Satisfying condition (5) is beneficial for correcting primary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (5-1), and even more preferably satisfies the following condition (5-2).

[0100] 10 < νApmin < 40 (5)

[0101] 15 < νApmin < 35 (5-1)

[0102] 17 < νApmin < 30 (5-2)

[0103] In a structure where the lens component closest to the object in the front lens group GA has positive refractive power, when the maximum value of the partial dispersion ratio between the g-line and F-line of all positive lenses included in the lens component closest to the object in the front lens group GA is set as θApmax, the imaging lens preferably satisfies the following condition (6). Satisfying condition (6) is beneficial for correcting secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (6-1), and even more preferably satisfies the following condition (6-2).

[0104] 0.5 < θApmax < 0.8 (6)

[0105] 0.57<θApmax<0.75 (6-1)

[0106] 0.59<θApmax<0.7 (6-2)

[0107] In a structure in which the lens component closest to the object in the front lens group GA has positive refractive power, the imaging lens preferably satisfies conditions (4), (5), and (6) simultaneously. Furthermore, in order to obtain better characteristics, the imaging lens preferably satisfies at least one of conditions (4-1), (4-2), (5-1), (5-2), (6-1), and (6-2) in addition to simultaneously satisfying conditions (4), (5), and (6).

[0108] When the partial dispersion ratio between the g-line and F-line of the positive lens included in the object-side lens component of the front lens group GA is set to θAfsp, and the Abbe number of the positive lens included in the object-side lens component of the front lens group GA relative to the d-line reference is set to νAfsp, at least one positive lens included in the object-side lens component of the front lens group GA preferably satisfies the following condition (18). Satisfying condition (18) helps to maintain a good balance between secondary and primary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (18-1), and even more preferably satisfies the following condition (18-2).

[0109] 0<θAfsp-0.64833+0.0018×νAfsp<0.06 (18)

[0110] 0<θAfsp-0.64833+0.0018×νAfsp<0.05 (18-1)

[0111] 0.003<θAfsp-0.64833+0.0018×νAfsp<0.045 (18-2)

[0112] The lens component closest to the object in the front lens group GA can be configured as a single lens with positive refractive power. This configuration helps to shorten the overall length of the lens system. When the lens component closest to the object in the front lens group GA is a single lens with positive refractive power, this single lens is preferably a meniscus lens with a convex surface on the object side. This configuration helps to correct astigmatism.

[0113] In a structure where the lens component closest to the object side of the front lens group GA is a single lens with positive refractive power, when the radius of curvature of the object-side surface of the single lens is set to Rf and the radius of curvature of the image-side surface of the single lens is set to Rr, the imaging lens preferably satisfies the following condition (45). Satisfying condition (45) is beneficial for correcting astigmatism. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (45-1), and even more preferably satisfies the following condition (45-2).

[0114] 1<(Rr+Rf) / (Rr-Rf)<3 (45)

[0115] 1.2<(Rr+Rf) / (Rr-Rf)<2.8 (45-1)

[0116] 1.55<(Rr+Rf) / (Rr-Rf)<2.1 (45-2)

[0117] The lens component closest to the object in the front lens group GA can be configured as a joint lens. This configuration is advantageous for correcting chromatic aberration. When the lens component closest to the object in the front lens group GA is a joint lens, this joint lens preferably includes a negative lens and a positive lens sequentially from the object side. This configuration is even more advantageous for correcting chromatic aberration.

[0118] In a structure where the lens component closest to the object in the front lens group GA is a joint lens and this joint lens sequentially includes a negative lens and a positive lens from the closest to the object, when the Abbe number of the positive lens relative to the d-line reference is set to νAfp and the Abbe number of the negative lens relative to the d-line reference is set to νAfn, the imaging lens preferably satisfies the following conditional expression (46). By ensuring that the corresponding value of conditional expression (46) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of conditional expression (46) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following conditional expression (46-1), and even more preferably satisfies the following conditional expression (46-2).

[0119] -45<νAfp-νAfn<-20 (46)

[0120] -40<νAfp-νAfn<-25 (46-1)

[0121] -36<νAfp-νAfn<-30 (46-2)

[0122] In a structure where the lens component closest to the object in the front lens group GA is a joint lens and this joint lens sequentially includes a negative lens and a positive lens from the closest to the object, when the partial dispersion ratio between the g-line and the F-line of the positive lens is set to θAfp and the partial dispersion ratio between the g-line and the F-line of the negative lens is set to θAfn, the imaging lens preferably satisfies the following condition (47). By ensuring that the corresponding value of condition (47) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (47) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (47-1), and even more preferably satisfies the following condition (47-2).

[0123] 0.03<θAfn-θAfp<0.1 (47)

[0124] 0.05<θAfn-θAfp<0.08 (47-1)

[0125] 0.06<θAfn-θAfp<0.07 (47-2)

[0126] In a structure in which the lens component closest to the object in the front lens group GA is a conjoined lens and the conjoined lens sequentially includes a negative lens and a positive lens from the closest to the object, the imaging lens preferably satisfies conditions (46) and (47) simultaneously. Furthermore, in order to obtain better characteristics, the imaging lens preferably satisfies at least one of conditions (46-1), (46-2), (47-1), and (47-2) in addition to simultaneously satisfying conditions (46) and (47).

[0127] In a structure where the lens component closest to the object in the front lens group GA is a joint lens, and this joint lens sequentially includes a negative lens and a positive lens from the closest to the object, the imaging lens preferably satisfies the following condition (48) when the Abbe number of the positive lens relative to the d-line reference is set to νAfp, the Abbe number of the negative lens relative to the d-line reference is set to νAfn, the partial dispersion ratio between the g-line and the F-line of the positive lens is set to θAfp, and the partial dispersion ratio between the g-line and the F-line of the negative lens is set to θAfn. By satisfying condition (48), it is beneficial to maintain a good balance between secondary and primary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (48-1), and even more preferably satisfies the following condition (48-2).

[0128] -0.2<θAfp-θAfn+0.00163×(νAfp-νAfn)<-0.05 (48)

[0129] -0.18<θAfp-θAfn+0.00163×(νAfp-νAfn)<-0.08 (48-1)

[0130] -0.15<θAfp-θAfn+0.00163×(νAfp-νAfn)<-0.1 (48-2)

[0131] The front lens group GA includes a joining lens on the image-closest side, and the joining lens on the image-closest side of the front lens group GA preferably includes a negative lens and a positive lens sequentially from the image-closest side. With this configuration, it is advantageous to correct axial chromatic aberration.

[0132] In a configuration where the front lens group GA includes a joint lens on the image-closest side, and this joint lens sequentially includes a negative lens and a positive lens from the image-closest side, the imaging lens preferably satisfies the following condition (7) when the refractive index of the positive lens relative to the d-line is set to NArp and the refractive index of the negative lens relative to the d-line is set to NArn. Satisfying condition (7) facilitates the correction of higher-order spherical aberrations. In addition, in this specification, higher-order aberrations are represented as 5th order or higher. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (7-1), and even more preferably satisfies the following condition (7-2).

[0133] 0 < NArp - NArn < 0.15 (7)

[0134] 0.01<NArp-NArn<0.12 (7-1)

[0135] 0.02<NArp-NArn<0.11 (7-2)

[0136] In a structure where the front lens group GA includes a joint lens on the image-closest side, and this joint lens sequentially includes a negative lens and a positive lens from the image-closest side, when the Abbe number of the positive lens relative to the d-line reference is set to νArp and the Abbe number of the negative lens relative to the d-line reference is set to νArn, the imaging lens preferably satisfies the following condition (8). By ensuring that the corresponding value of condition (8) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (8) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (8-1), and even more preferably satisfies the following condition (8-2).

[0137] 5<νArp-νArn<40 (8)

[0138] 8<νArp-νArn<30 (8-1)

[0139] 10<νArp-νArn<25 (8-2)

[0140] In a structure where the front lens group GA includes a joint lens on the image-closest side, and this joint lens sequentially includes a negative lens and a positive lens from the image-closest side, when the partial dispersion ratio between the g-line and F-line of the positive lens is set to θArp and the partial dispersion ratio between the g-line and F-line of the negative lens is set to θArn, the imaging lens preferably satisfies the following condition (9). By ensuring that the corresponding value of condition (9) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (9) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (9-1), and even more preferably satisfies the following condition (9-2).

[0141] 0.01<θArn-θArp<0.06 (9)

[0142] 0.016<θArn-θArp<0.05 (9-1)

[0143] 0.02<θArn-θArp<0.042 (9-2)

[0144] In a structure in which the front lens group GA includes a conjoining lens on the image-closest side, and the conjoining lens includes a negative lens and a positive lens sequentially from the image-closest side, the imaging lens preferably satisfies conditions (7), (8), and (9) simultaneously. Furthermore, in order to obtain better characteristics, the imaging lens preferably satisfies at least one of conditions (7-1), (7-2), (8-1), (8-2), (9-1), and (9-2) in addition to simultaneously satisfying conditions (7), (8), and (9).

[0145] When the partial dispersion ratio between the g-line and F-line of the positive lens included in the image-side lens component of the front lens group GA is set to θArsp, the partial dispersion ratio between the g-line and F-line of the negative lens included in the image-side lens component of the front lens group GA is set to θArsn, the Abbe number of the positive lens included in the image-side lens component of the front lens group GA relative to the d-line reference is set to νArsp, and the Abbe number of the negative lens included in the image-side lens component of the front lens group GA relative to the d-line reference is set to νArsn, the at least one positive lens and at least one negative lens included in the object-side lens component of the front lens group GA preferably satisfy the following condition (19). By satisfying condition (19), it is beneficial to maintain a good balance between secondary and primary chromatic aberration. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (19-1), and even more preferably satisfies the following condition (19-2).

[0146] -0.01<θArsp-θArsn+0.00163×(νArsp-νArsn)<0 (19)

[0147] -0.009<θArsp-θArsn+0.00163×(νArsp-νArsn)<0 (19-1)

[0148] -0.008<θArsp-θArsn+0.00163×(νArsp-νArsn)<0 (19-2)

[0149] When the maximum Abbe number of all lenses included in the front lens group GA relative to the d-line reference is set to νGAmax, the imaging lens preferably satisfies the following condition (24). By ensuring that the corresponding value of condition (24) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (24) is not above the upper limit, it is possible to suppress the refractive index from becoming too low, thus benefiting the correction of spherical aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (24-1), and even more preferably satisfies the following condition (24-2).

[0150] 70 < νGAmax < 120 (24)

[0151] 70 < νGAmax < 90 (24-1)

[0152] 70 < νGAmax < 80 (24-2)

[0153] When the focal length of the imaging lens is set to f when focusing on an object at infinity, and the focal length of the front lens group GA is set to fA, the imaging lens preferably satisfies the following condition (10). By ensuring that the corresponding value of condition (10) is not below the lower limit, it is beneficial to suppress the large-diameter increase of the aperture St. By ensuring that the corresponding value of condition (10) is not above the upper limit, it is beneficial to maintain an appropriate back focal length. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (10-1), and even more preferably satisfies the following condition (10-2).

[0154] 0.25 < f / fA < 0.8 (10)

[0155] 0.3 < f / fA < 0.7 (10-1)

[0156] 0.35 < f / fA < 0.62 (10-2)

[0157] When the focal length of the imaging lens is set to f when focusing on an object at infinity, and the focal length of the first focusing lens group GF1 is set to fF1, the imaging lens preferably satisfies the following condition (11). By ensuring that the corresponding value of condition (11) is not below the lower limit, it is beneficial to suppress the amount of movement of the first focusing lens group GF1 during focusing. By ensuring that the corresponding value of condition (11) is not above the upper limit, it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (11-1), and even more preferably satisfies the following condition (11-2).

[0158] 1.8 < f / fF1 < 4 (11)

[0159] 2 < f / fF1 < 3.5 (11-1)

[0160] 2.2 < f / fF1 < 3 (11-2)

[0161] When the focal length of the imaging lens is set to f when focusing on an object at infinity, and the focal length of the second focusing lens group GF2 is set to fF2, the imaging lens preferably satisfies the following condition (12). By ensuring that the corresponding value of condition (12) is not below the lower limit, it is beneficial to shorten the total length of the lens system. By ensuring that the corresponding value of condition (12) is not above the upper limit, it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (12-1), and even more preferably satisfies the following condition (12-2).

[0162] -5<f / fF2<-1.4 (12)

[0163] -3.5<f / fF2<-1.5 (12-1)

[0164] -3.2<f / fF2<-1.6 (12-2)

[0165] When the focal length of the first focusing lens group GF1 is set to fF1 and the focal length of the second focusing lens group GF2 is set to fF2, the imaging lens preferably satisfies the following condition (13). By ensuring that the corresponding value of condition (13) is not below the lower limit, it is beneficial to suppress the variation of astigmatism when the object distance changes. By ensuring that the corresponding value of condition (13) is not above the upper limit, it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (13-1), and even more preferably satisfies the following condition (13-2).

[0166] -1.55<fF1 / fF2<-0.4 (13)

[0167] -1.5<fF1 / fF2<-0.48 (13-1)

[0168] -1.45<fF1 / fF2<-0.6 (13-2)

[0169] When the focal length of the front lens group GA is set to fA and the focal length of the first focusing lens group GF1 is set to fF1, the imaging lens preferably satisfies the following condition (25). By ensuring that the corresponding value of condition (25) is not below the lower limit, it is beneficial to suppress the amount of movement of the first focusing lens group GF1 during focusing. By ensuring that the corresponding value of condition (25) is not above the upper limit, it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (25-1), and even more preferably satisfies the following condition (25-2).

[0170] 2.5 < fA / fF1 < 8.5 (25)

[0171] 3 < fA / fF1 < 8 (25-1)

[0172] 3.6 < fA / fF1 < 7.3 (25-2)

[0173] When the focal length of the front lens group GA is set to fA and the focal length of the second focusing lens group GF2 is set to fF2, the imaging lens preferably satisfies the following condition (30). By ensuring that the corresponding value of condition (30) is not below the lower limit, it is beneficial to shorten the total length of the lens system. By ensuring that the corresponding value of condition (30) is not above the upper limit, it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (30-1), and even more preferably satisfies the following condition (30-2).

[0174] -7.5<fA / fF2<-2 (30)

[0175] -7 < fA / fF2 < -2.5 (30-1)

[0176] -6.5 < fA / fF2 < -3 (30-2)

[0177] When the lateral magnification of the first focusing lens group GF1 is set to βF1 when focusing on an object at infinity, and the combined lateral magnification of all lenses closer to the image side than the first focusing lens group GF1 when focusing on an object at infinity is set to βF1r, the imaging lens preferably satisfies the following condition (14). By ensuring that the corresponding value of condition (14) is not below the lower limit, it is beneficial to suppress the amount of movement of the first focusing lens group GF1 during focusing. By ensuring that the corresponding value of condition (14) is not above the upper limit, it is beneficial to tighten the stopping accuracy of the first focusing lens group GF1 during focusing. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (14-1), and even more preferably satisfies the following condition (14-2).

[0178] 1.6 < (1-βF1) 2 )×βF1r 2 <5.8 (14)

[0179] 2 < (1-βF1) 2 )×βF1r 2 <4.8 (14-1)

[0180] 2.4 < (1-βF1) 2 )×βF1r 2 <4 (14-2)

[0181] When the lateral magnification of the second focusing lens group GF2 is set to βF2 when focusing on an object at infinity, and the combined lateral magnification of all lenses closer to the image side than the second focusing lens group GF2 when focusing on an object at infinity is set to βF2r, the imaging lens preferably satisfies the following conditional expression (15). By ensuring that the corresponding value of conditional expression (15) is not below the lower limit, it is beneficial to tighten the stopping accuracy of the second focusing lens group GF2 during focusing. By ensuring that the corresponding value of conditional expression (15) is not above the upper limit, it is beneficial to suppress the amount of movement of the second focusing lens group GF2 during focusing. In order to obtain better characteristics, the imaging lens more preferably satisfies the following conditional expression (15-1), and even more preferably satisfies the following conditional expression (15-2).

[0182] -4.2<(1-βF2 2 )×βF2r 2 <0 (15)

[0183] -3.7 < (1-βF2) 2 )×βF2r 2 <-0.4 (15-1)

[0184] -3.1<(1-βF2 2 )×βF2r2 <-0.8 (15-2)

[0185] When the lateral magnification of the first focusing lens group GF1 is set to βF1 when focusing on an object at infinity, the combined lateral magnification of all lenses closer to the image side than the first focusing lens group GF1 when focusing on an object at infinity is set to βF1r, the lateral magnification of the second focusing lens group GF2 when focusing on an object at infinity is set to βF2, and the combined lateral magnification of all lenses closer to the image side than the second focusing lens group GF2 when focusing on an object at infinity is set to βF2r, the imaging lens preferably satisfies the following conditional expression (16). By ensuring that the corresponding value of conditional expression (16) is not below the lower limit, it is beneficial to suppress the variation of astigmatism when the object distance changes. By ensuring that the corresponding value of conditional expression (16) is not above the upper limit, it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following conditional expression (16-1), and even more preferably satisfies the following conditional expression (16-2).

[0186] -5.5 < {(1-βF1)} 2 )×βF1r 2} / {(1-βF2) 2 )×βF2r 2} < -0.2 (16)

[0187] -5 < {(1-βF1)} 2 )×βF1r 2} / {(1-βF2) 2 )×βF2r 2} < -0.5 (16-1)

[0188] -4.8 < {(1-βF1)} 2 )×βF1r 2} / {(1-βF2) 2 )×βF2r 2} < -0.8 (16-2)

[0189] The first focusing lens group GF1 includes a joining lens on the object-side closest to the object. Preferably, the joining lens on the object-side closest to the object includes a negative lens and a positive lens sequentially from the object-side closest to the object. This configuration is advantageous for correcting axial chromatic aberration.

[0190] In a structure where the first focusing lens group GF1 includes a joint lens on the object-side side, and this joint lens sequentially includes a negative lens and a positive lens from the object-side side, the imaging lens preferably satisfies the following condition (26) when the refractive index of the positive lens relative to the d-line is set to NF1p and the refractive index of the negative lens relative to the d-line is set to NF1n. Satisfying condition (26) is beneficial for correcting higher-order spherical aberrations. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (26-1), and even more preferably satisfies the following condition (26-2).

[0191] 0.1<NF1p-NF1n<0.3 (26)

[0192] 0.12<NF1p-NF1n<0.24 (26-1)

[0193] 0.135<NF1p-NF1n<0.2 (26-2)

[0194] In a structure where the first focusing lens group GF1 includes a joint lens on the object-side and the joint lens sequentially includes a negative lens and a positive lens from the object-side, the imaging lens preferably satisfies the following condition (27) when the Abbe number of the positive lens relative to the d-line reference is set to νF1p and the Abbe number of the negative lens relative to the d-line reference is set to νF1n. By ensuring that the corresponding value of condition (27) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (27) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (27-1), and even more preferably satisfies the following condition (27-2).

[0195] 5<νF1p-νF1n<18 (27)

[0196] 6.5<νF1p-νF1n<16 (27-1)

[0197] 8<νF1p-νF1n<14 (27-2)

[0198] In a structure where the first focusing lens group GF1 includes a joint lens on the object-side side, and this joint lens sequentially includes a negative lens and a positive lens from the object-side side, when the partial dispersion ratio between the g-line and F-line of the positive lens is set to θF1p and the partial dispersion ratio between the g-line and F-line of the negative lens is set to θF1n, the imaging lens preferably satisfies the following condition (28). By ensuring that the corresponding value of condition (28) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (28) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (28-1), and even more preferably satisfies the following condition (28-2).

[0199] 0.015<θF1n-θF1p<0.06 (28)

[0200] 0.02<θF1n-θF1p<0.05 (28-1)

[0201] 0.025<θF1n-θF1p<0.04 (28-2)

[0202] In a structure in which the first focusing lens group GF1 includes a conjoining lens on the object-side side and the conjoining lens sequentially includes a negative lens and a positive lens from the object-side side, the imaging lens preferably satisfies conditions (26), (27), and (28) simultaneously. Furthermore, in order to obtain better characteristics, the imaging lens preferably satisfies at least one of conditions (26-1), (26-2), (27-1), (27-2), (28-1), and (28-2) in addition to simultaneously satisfying conditions (26), (27), and (28).

[0203] In a structure where the first focusing lens group GF1 includes a joint lens on the object-side side, and this joint lens sequentially includes a negative lens and a positive lens from the object-side side, the imaging lens preferably satisfies the following condition (29) when the partial dispersion ratio between the g-line and F-line of the positive lens is set to θF1p, the partial dispersion ratio between the g-line and F-line of the negative lens is set to θF1n, the Abbe number of the positive lens relative to the d-line reference is set to νF1p, and the Abbe number of the negative lens relative to the d-line reference is set to νF1n. By satisfying condition (29), it is beneficial to maintain a good balance between secondary and primary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (29-1), and even more preferably satisfies the following condition (29-2).

[0204] -0.024<θF1p-θF1n+0.00163×(νF1p-νF1n)<-0.008 (29)

[0205] -0.02<θF1p-θF1n+0.00163×(νF1p-νF1n)<-0.01 (29-1)

[0206] -0.017<θF1p-θF1n+0.00163×(νF1p-νF1n)<-0.012 (29-2)

[0207] The first focusing lens group GF1 preferably includes at least one aspherical lens. This configuration is advantageous for correcting spherical aberration. For example, the lens closest to the image side of the first focusing lens group GF1 can be configured as an aspherical lens. This configuration is advantageous for suppressing variations in spherical aberration as the object distance changes.

[0208] The first focusing lens group GF1 can be configured to include a conjoined lens and a single lens with positive refractive power. This configuration helps to suppress variations in axial chromatic aberration and spherical aberration when the object's distance changes.

[0209] The first focusing lens group GF1 is preferably configured continuously with the aperture St. This configuration helps to suppress astigmatism variations during focusing.

[0210] The second focusing lens group GF2 preferably includes a combined lens in which a negative lens and a positive lens are sequentially joined from the object side. This configuration is advantageous for correcting chromatic aberration due to magnification.

[0211] The second focusing lens group GF2 includes a conjoining lens on the image-closest side. Preferably, the conjoining lens on the image-closest side of the second focusing lens group GF2 includes a positive lens and a negative lens sequentially from the image-closest side. This configuration is advantageous for correcting chromatic aberration due to magnification.

[0212] In a structure where the second focusing lens group GF2 includes a joint lens on the image-closest side, and this joint lens sequentially includes a positive lens and a negative lens from the image-closest side, the imaging lens preferably satisfies the following condition (31) when the refractive index of the positive lens relative to the d-line is set to NF2p and the refractive index of the negative lens relative to the d-line is set to NF2n. By satisfying condition (31), it is beneficial to suppress astigmatism variations when the object distance changes. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (31-1), and even more preferably satisfies the following condition (31-2).

[0213] -0.5<NF2p-NF2n<-0.1 (31)

[0214] -0.42<NF2p-NF2n<-0.15 (31-1)

[0215] -0.38<NF2p-NF2n<-0.2 (31-2)

[0216] In a structure where the second focusing lens group GF2 includes a joint lens on the image-closest side, and this joint lens sequentially includes a positive lens and a negative lens from the image-closest side, when the Abbe number of the positive lens relative to the d-line reference is set to νF2p and the Abbe number of the negative lens relative to the d-line reference is set to νF2n, the imaging lens preferably satisfies the following conditional expression (32). By ensuring that the corresponding value of conditional expression (32) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of conditional expression (32) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following conditional expression (32-1), and even more preferably satisfies the following conditional expression (32-2).

[0217] 10<νF2p-νF2n<70 (32)

[0218] 24<νF2p-νF2n<62 (32-1)

[0219] 28<νF2p-νF2n<55 (32-2)

[0220] In a structure where the second focusing lens group GF2 includes a joint lens on the image-closest side, and this joint lens sequentially includes a positive lens and a negative lens from the image-closest side, when the partial dispersion ratio between the g-line and F-line of the positive lens is set to θF2p and the partial dispersion ratio between the g-line and F-line of the negative lens is set to θF2n, the imaging lens preferably satisfies the following condition (33). By ensuring that the corresponding value of condition (33) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (33) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (33-1), and even more preferably satisfies the following condition (33-2).

[0221] 0.01<θF2n-θF2p<0.15 (33)

[0222] 0.014<θF2n-θF2p<0.12 (33-1)

[0223] 0.017<θF2n-θF2p<0.1 (33-2)

[0224] In a structure in which the second focusing lens group GF2 includes a conjoint lens on the image-closest side, and the conjoint lens sequentially includes a positive lens and a negative lens from the image-closest side, the imaging lens preferably satisfies conditions (31), (32), and (33) simultaneously. Furthermore, in order to obtain better characteristics, the imaging lens preferably satisfies at least one of conditions (31-1), (31-2), (32-1), (32-2), (33-1), and (33-2) in addition to simultaneously satisfying conditions (31), (32), and (33).

[0225] In a structure where the second focusing lens group GF2 includes a joint lens on the image-closest side, and this joint lens sequentially includes a positive lens and a negative lens from the image-closest side, the imaging lens preferably satisfies the following condition (34) when the partial dispersion ratio between the g-line and F-line of the positive lens is set to θF2p, the partial dispersion ratio between the g-line and F-line of the negative lens is set to θF2n, the Abbe number of the positive lens relative to the d-line reference is set to νF2p, and the Abbe number of the negative lens relative to the d-line reference is set to νF2n. By satisfying condition (34), it is beneficial to maintain a good balance between secondary and primary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (34-1), and even more preferably satisfies the following condition (34-2).

[0226] -0.015<θF2p-θF2n+0.00163×(νF2p-νF2n)<0.042 (34)

[0227] -0.012<θF2p-θF2n+0.00163×(νF2p-νF2n)<0.037 (34-1)

[0228] -0.01<θF2p-θF2n+0.00163×(νF2p-νF2n)<0.031 (34-1)

[0229] In a structure where the second focusing lens group GF2 includes a joint lens on the image-closest side, and this joint lens sequentially includes a positive lens and a negative lens from the image-closest side, when the Abbe number of the positive lens relative to the d-line reference is set to νF2p, the imaging lens preferably satisfies the following conditional expression (35). Satisfying conditional expression (35) is beneficial for correcting chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following conditional expression (35-1), and even more preferably satisfies the following conditional expression (35-2).

[0230] 70<νF2p<120 (35)

[0231] 72<νF2p<80 (35-1)

[0232] 75<νF2p<76 (35-2)

[0233] When the maximum Abbe number of all lenses included in the second focusing lens group GF2 relative to the d-line reference is set to νGF2max, the imaging lens preferably satisfies the following condition (36). Satisfying condition (36) is beneficial for correcting magnification chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (36-1), and even more preferably satisfies the following condition (36-2).

[0234] 70<νGF2max<120 (36)

[0235] 72 < νGF2max < 80 (36-1)

[0236] 75 < νGF2max < 76 (36-2)

[0237] The second focusing lens group GF2 can be configured to include a negative lens and a converging lens. This configuration is advantageous for correcting chromatic aberration and astigmatism. Preferably, the second focusing lens group GF2 includes a negative lens and a converging lens sequentially from the object side to the image side. This configuration further facilitates the correction of chromatic aberration.

[0238] In the structure of the first focusing lens group GF1, which includes a joint lens on the object-side and which sequentially includes a negative lens and a positive lens from the object-side, the imaging lens preferably satisfies the following condition (37) when the refractive index of the positive lens relative to the d-line is set to NF1p and the refractive index of the negative lens relative to the d-line is set to NF1n. Similarly, in the structure of the second focusing lens group GF2, which includes a joint lens on the image-side and which sequentially includes a positive lens and a negative lens from the image-side, the imaging lens preferably satisfies the following condition (37) when the refractive index of the positive lens relative to the d-line is set to NF2p and the refractive index of the negative lens relative to the d-line is set to NF2n. Satisfying condition (37) facilitates better correction of various aberrations. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (37-1), and even more preferably satisfies the following condition (37-2).

[0239] -1.5<(NF1p-NF1n) / (NF2p-NF2n)<-0.25 (37)

[0240] -0.1<(NF1p-NF1n) / (NF2p-NF2n)<-0.3 (37-1)

[0241] -0.85<(NF1p-NF1n) / (NF2p-NF2n)<-0.35 (37-2)

[0242] When the movement of the first focusing lens group GF1 is set to DF1 and the movement of the second focusing lens group GF2 is set to DF2 when the magnification is changed from focusing on an object at infinity to a state where the magnification is -0.5, the imaging lens preferably satisfies the following conditional expression (38). By ensuring that the corresponding value of conditional expression (38) is not below the lower limit, it is beneficial to suppress the variation of astigmatism when the object distance changes. By ensuring that the corresponding value of conditional expression (38) is not above the upper limit, it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following conditional expression (38-1), and even more preferably satisfies the following conditional expression (38-2).

[0243] -5.5 < DF1 / DF2 < -1 (38)

[0244] -5<DF1 / DF2<-1.6 (38-1)

[0245] -4.2<DF1 / DF2<-2 (38-2)

[0246] Furthermore, in this specification, the sign of the movement of the first focusing lens group GF1 is negative when moving towards the object side and positive when moving towards the image side. The sign of the movement of the second focusing lens group GF2 is the same.

[0247] When the movement of the first focusing lens group GF1 when changing from a state of focusing on an object at infinity to a state of magnification of -0.5x is set to DF1 and the focal length of the first focusing lens group GF1 is set to fF1, the imaging lens preferably satisfies the following conditional expression (39). By ensuring that the corresponding value of conditional expression (39) is not below the lower limit, it is beneficial to shorten the total length of the lens system. By ensuring that the corresponding value of conditional expression (39) is not above the upper limit, it is beneficial to suppress the variation of astigmatism when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following conditional expression (39-1), and even more preferably satisfies the following conditional expression (39-2).

[0248] -0.45<DF1 / fF1<-0.15 (39)

[0249] -0.4<DF1 / fF1<-0.2 (39-1)

[0250] -0.34<DF1 / fF1<-0.25 (39-2)

[0251] When the movement of the second focusing lens group GF2 when changing from a state focused on an object at infinity to a state with a magnification of -0.5 is set to DF2 and the focal length of the second focusing lens group GF2 is set to fF2, the imaging lens preferably satisfies the following conditional expression (40). By ensuring that the corresponding value of conditional expression (40) is not below the lower limit, it is beneficial to shorten the total length of the lens system. By ensuring that the corresponding value of conditional expression (40) is not above the upper limit, it is beneficial to suppress the variation of astigmatism when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following conditional expression (40-1), and even more preferably satisfies the following conditional expression (40-2).

[0252] -0.18<DF2 / fF2<-0.03 (40)

[0253] -0.17<DF2 / fF2<-0.04 (40-1)

[0254] -0.162<DF2 / fF2<-0.05 (40-2)

[0255] When the movement of the first focusing lens group GF1 when changing from a state of focusing on an object at infinity to a state of magnification of -0.5x is set to DF1, and the focal length of the imaging lens when focusing on an object at infinity is set to f, the imaging lens preferably satisfies the following condition (41). By ensuring that the corresponding value of condition (41) is not below the lower limit, it is beneficial to shorten the total length of the lens system. By ensuring that the corresponding value of condition (41) is not above the upper limit, it is beneficial to suppress the variation of astigmatism when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (41-1), and even more preferably satisfies the following condition (41-2).

[0256] -0.25<DF1 / f<-0.05 (41)

[0257] -0.18<DF1 / f<-0.09 (41-1)

[0258] -0.15<DF1 / f<-0.1 (41-2)

[0259] When the movement of the second focusing lens group GF2 when changing from a state focused on an object at infinity to a state with a magnification of -0.5x is set to DF2, and the focal length of the imaging lens when focusing on an object at infinity is set to f, the imaging lens preferably satisfies the following conditional expression (42). By ensuring that the corresponding value of conditional expression (42) is not below the lower limit, it is beneficial to suppress the variation of astigmatism when the object distance changes. By ensuring that the corresponding value of conditional expression (42) is not above the upper limit, it is beneficial to shorten the overall length of the lens system. In order to obtain better characteristics, the imaging lens more preferably satisfies the following conditional expression (42-1), and even more preferably satisfies the following conditional expression (42-2).

[0260] 0.02 < DF2 / f < 0.075 (42)

[0261] 0.027<DF2 / f<0.065 (42-1)

[0262] 0.033<DF2 / f<0.057 (42-2)

[0263] When the focal length of the imaging lens is set to f when focusing on an object at infinity, and the focal length of the final lens group GE is set to fE, the imaging lens preferably satisfies the following condition (17). By ensuring that the corresponding value of condition (17) is not below the lower limit, it is possible to suppress the positive refractive power of the final lens group GE from becoming too weak. As a result, it is possible to suppress the weakening of the negative refractive power of the second focusing lens group GF2, which is located close to the final lens group GE, thus easily ensuring the effect of floating focus. By ensuring that the corresponding value of condition (17) is not above the upper limit, it is beneficial to correct chromatic aberration and distortion aberration. In order to obtain better characteristics, it is more preferable for the imaging lens to satisfy the following condition (17-1), and even more preferable to satisfy the following condition (17-2).

[0264] 1 < f / fE < 2.5 (17)

[0265] 1.3 < f / fE < 2.1 (17-1)

[0266] 1.6 < f / fE < 1.92 (17-2)

[0267] When the refractive index of the positive lens included in the final lens group GE relative to the d-line is set to NEp, the Abbe number of the positive lens included in the final lens group GE relative to the d-line reference is set to νEp, and the partial dispersion ratio between the g-line and F-line of the positive lens included in the final lens group GE is set to θEp, the at least one positive lens included in the final lens group GE preferably simultaneously satisfies the following conditions (20), (21), and (22). Satisfying condition (20) is beneficial for correcting astigmatism. Satisfying condition (21) is beneficial for correcting primary chromatic aberration. Satisfying condition (22) is beneficial for correcting secondary chromatic aberration. Furthermore, in order to obtain better characteristics, the at least one positive lens included in the final lens group GE preferably satisfies at least one of the following conditions (20-1), (20-2), (21-1), (21-2), (22-1), and (22-2) in addition to simultaneously satisfying conditions (20), (21), and (22).

[0268] 1.8 < NEP < 2.1 (20)

[0269] 1.85 < NEP < 2.1 (20-1)

[0270] 1.9 < NEP < 2.1 (20-2)

[0271] 10 < νEp < 30 (21)

[0272] 15 < νEp < 25 (21-1)

[0273] 16 < νEp < 21 (21-2)

[0274] 0.4 < θEp < 0.9 (22)

[0275] 0.5 < θEp < 0.8 (22-1)

[0276] 0.6 < θEp < 0.7 (22-2)

[0277] When the partial dispersion ratio between the g-line and F-line of the positive lens included in the final lens group GE is set to θEp and the Abbe number of the positive lens included in the final lens group GE relative to the d-line reference is set to νEp, at least one positive lens included in the final lens group GE preferably satisfies the following condition (23). By satisfying condition (23), it is beneficial to maintain a good balance between secondary and primary chromatic aberrations. To obtain even better characteristics, at least one positive lens included in the final lens group GE more preferably satisfies the following condition (23-1), and even more preferably satisfies the following condition (23-2).

[0278] 0.02<θEp-0.64833+0.0018×νEp<0.07 (23)

[0279] 0.025<θEp-0.64833+0.0018×νEp<0.06 (23-1)

[0280] 0.028<θEp-0.64833+0.0018×νEp<0.05 (23-2)

[0281] With the focal length of the front lens group GA set to fA and the focal length of the final lens group GE set to fE, the imaging lens preferably satisfies the following condition (43). Satisfying condition (43) helps to maintain a good balance between magnification chromatic aberration and distortion aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (43-1), and even more preferably satisfies the following condition (43-2).

[0282] 2 < fA / fE < 7 (43)

[0283] 2.5 < fA / fE < 6 (43-1)

[0284] 2.95 < fA / fE < 5 (43-2)

[0285] When the focal length of the imaging lens in the state of focusing on an object at infinity is set to f, and the combined focal length from the front lens group GA in the state of focusing on an object at infinity to the lens group arranged adjacent to the final lens group GE on the object side is set to fexE, the imaging lens preferably satisfies the following condition (44). That is, fexE is the focal length of the optical system excluding the final lens group GE in the state of focusing on an object at infinity. Figure 1 In the example imaging lens, when focusing on an object at infinity, the combined focal length of the front lens group GA, the first focusing lens group GF1, and the second focusing lens group GF2 is fexE. By satisfying condition (44), it is beneficial to suppress the variation of spherical aberration when the object distance changes. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (44-1), and even more preferably satisfies the following condition (44-2).

[0286] -0.2 < f / fexE < 0.25 (44)

[0287] -0.05<f / fexE<0.2 (44-1)

[0288] -0.01<f / fexE<0.17 (44-2)

[0289] The lens component closest to the image side of the final lens group GE preferably has positive refractive power. This configuration is advantageous for correcting astigmatism.

[0290] The final lens group GE's image-side lens component can be configured as a single lens with positive refractive power. This configuration helps to shorten the overall length of the lens system.

[0291] The image-side lens component of the final lens group GE can be configured as a combined lens. This configuration is advantageous for correcting chromatic aberration. When the image-side lens component of the final lens group GE is a combined lens, this combined lens preferably includes a positive lens and a negative lens sequentially from the image-side. This configuration is even more advantageous for correcting chromatic aberration.

[0292] In a final lens group GE, where the lens component closest to the image is a joint lens and the joint lens sequentially includes a positive lens and a negative lens from the closest image side, the imaging lens preferably satisfies the following condition (49) when the Abbe number of the positive lens relative to the d-line reference is set to νErp and the Abbe number of the negative lens relative to the d-line reference is set to νErn. By ensuring that the corresponding value of condition (49) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (49) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (49-1), and even more preferably satisfies the following condition (49-2).

[0293] -45<νErp-νErn<-20 (49)

[0294] -40<νErp-νErn<-25 (49-1)

[0295] -35<νErp-νErn<-30 (49-2)

[0296] In a final lens group GE, where the lens component closest to the image is a combined lens and the combined lens sequentially includes a positive lens and a negative lens from the closest image side, the imaging lens preferably satisfies the following condition (50) when the partial dispersion ratio between the g-line and F-line of the positive lens is set to θErp and the partial dispersion ratio between the g-line and F-line of the negative lens is set to θErn. By ensuring that the corresponding value of condition (50) is not below the lower limit, it is beneficial to correct primary chromatic aberration. By ensuring that the corresponding value of condition (50) is not above the upper limit, it is beneficial to correct secondary chromatic aberration. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (50-1), and even more preferably satisfies the following condition (50-2).

[0297] -0.2<θErn-θErp<0 (50)

[0298] -0.15<θErn-θErp<-0.05 (50-1)

[0299] -0.1<θErn-θErp<-0.09 (50-2)

[0300] In a final lens group GE, the lens component closest to the image is a combined lens, and the combined lens sequentially includes a positive lens and a negative lens from the closest image side. Preferably, the imaging lens satisfies both conditions (49) and (50). Furthermore, to obtain better characteristics, the imaging lens preferably satisfies at least one of conditions (49-1), (49-2), (50-1), and (50-2) in addition to simultaneously satisfying conditions (49) and (50).

[0301] The final lens group GE can be configured to include a single lens component. This configuration helps to shorten the overall length of the lens system.

[0302] The final lens group GE can be configured as a single lens with positive refractive power. This configuration helps to shorten the overall length of the lens system.

[0303] In addition, Figure 1 The illustration shows an example where the first focusing lens group GF1 and the second focusing lens group GF2 are arranged adjacent to each other. However, as shown in the embodiments described later, the imaging lens of the present invention can be configured to include an intermediate lens group GM fixed during focusing between the first focusing lens group GF1 and the second focusing lens group GF2. In this configuration, it is advantageous to suppress astigmatism variations during focusing.

[0304] The imaging lens preferably includes a stabilized lens group that corrects image shake by moving in a direction intersecting the optical axis Z. The stabilized lens group is preferably configured as part of or the entirety of any lens group that is fixed during focusing.

[0305] For example, the anti-vibration lens group can be configured to include any of the lens components included in the front lens group GA. In such a configuration, compared to using lenses from the intermediate lens group GM to construct the anti-vibration lens group, it is not necessary to increase the overall length of the lens system or reduce the amount of movement of the focusing lens group, thus it is advantageous to shorten the overall length of the lens system or ensure the amount of movement of the focusing lens group.

[0306] More specifically, the anti-vibration lens group can be configured as a second lens component from the object side of the front lens group GA, or it can be configured as a lens component from the image side of the front lens group GA. In these cases, miniaturization of the anti-vibration lens group is advantageous.

[0307] When the imaging lens includes the aforementioned intermediate lens group GM, the anti-vibration lens group can be configured as a whole including the intermediate lens group GM. In this configuration, compared to using a lens with the front lens group GA to construct the anti-vibration lens group, it is advantageous for aberration correction and for reducing the weight of the anti-vibration lens group.

[0308] As an example, in Figure 1 The image shows the anti-vibration lens assembly including lens L12. Figure 1 The brackets and vertical double arrows below lens L12 indicate that lens L12 constitutes a vibration-damping lens group.

[0309] When the lateral magnification of the anti-vibration lens group is set to βIS when focusing on an object at infinity, and the combined lateral magnification of all lenses on the image side further from the anti-vibration lens group than when focusing on an object at infinity is set to βISr, the imaging lens preferably satisfies the following condition (51). By ensuring that the corresponding value of condition (51) is not below the lower limit, it is beneficial to suppress the amount of movement of the anti-vibration lens group during image shake correction. By ensuring that the corresponding value of condition (51) is not above the upper limit, it is possible to suppress the sensitivity of the anti-vibration lens group from becoming too high during image shake correction. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (51-1), and even more preferably satisfies the following condition (51-2).

[0310] 0.5<|(1-βIS)×βISr|<2 (51)

[0311] 0.65<|(1-βIS)×βISr|<1.6 (51-1)

[0312] 0.75<|(1-βIS)×βISr|<1 (51-2)

[0313] in addition, Figure 1 The example shown is one example of the imaging lens of the present invention. In the imaging lens of the present invention, the number of lenses constituting each lens group can also be set to be the same as that of the present invention. Figure 1 The example shown has the same number of lenses. Specifically, each lens group can, for example, adopt the following structure.

[0314] The front lens group GA can be configured to include 4 or 5 lenses. More specifically, the front lens group GA can be configured to include 3 positive lenses and 1 negative lens. In this case, the front lens group GA can be configured to include, from the object side to the image side, 2 positive lenses as single lenses and a combined lens that combines a positive lens and a negative lens in sequence from the object side. Alternatively, the front lens group GA can be configured to include 3 positive lenses and 2 negative lenses. In this case, the front lens group GA can be configured to include, from the object side to the image side, a combined lens that combines a negative lens and a positive lens in sequence from the object side, a positive lens as a single lens, and a combined lens that combines a positive lens and a negative lens in sequence from the object side.

[0315] The first focusing lens group GF1 can be configured to include three lenses. The first focusing lens group GF1 can also be configured to include two positive lenses and one negative lens. More specifically, the first focusing lens group GF1 can be configured to include, from the object side to the image side, a combined lens and a positive lens, with the negative lens and positive lens sequentially joined together from the object side.

[0316] The intermediate lens group GM can be configured to include two lenses. Alternatively, the intermediate lens group GM can be configured to include one positive lens and one negative lens. Or, the intermediate lens group GM can be configured such that, from the object side to the image side, it sequentially includes a negative lens as a single lens and a positive lens as a single lens.

[0317] The second focusing lens group GF2 can be configured to include three lenses. The second focusing lens group GF2 can also be configured to include one positive lens and two negative lenses. More specifically, the second focusing lens group GF2 can be configured to include, from the object side to the image side, a negative lens as a single lens and a combined lens from the object side, in which the negative lens and the positive lens are sequentially joined.

[0318] The final lens group GE can be configured to include one or two lenses. The final lens group GE can be configured to include one positive lens. Alternatively, the final lens group GE can be configured to include a combined lens in which a negative lens and a positive lens are sequentially joined from the object side.

[0319] Including the structures related to the conditional expressions, the above-mentioned preferred structures and possible structures can be combined arbitrarily, and are preferably adopted selectively and appropriately according to the required specifications. In addition, the preferred structures related to the conditional expressions are not limited to the conditional expressions described in the form of formulas, but also include all conditional expressions obtained by arbitrarily combining the lower and upper limits of the preferred, more preferred and further preferred conditional expressions.

[0320] As an example, a preferred embodiment of the present invention is an imaging lens comprising: a front lens group GA having a positive refractive power fixed relative to the image plane Sim during focusing; an aperture St continuously disposed with the front lens group GA; a first focusing lens group GF1 having a positive refractive power; a second focusing lens group GF2 having a negative refractive power; and a final lens group GE disposed on the image side and having a positive refractive power fixed relative to the image plane Sim during focusing. When focusing from an object at infinity to a closer object, the first focusing lens group GF1 and the second focusing lens group GF2 move by increasing their spacing from each other. The lens surface of the front lens group GA on the image side is concave, and the lens surface of the first focusing lens group GF1 on the object side is concave.

[0321] Next, embodiments of the imaging lens of the present invention will be described with reference to the accompanying drawings. Furthermore, the reference numerals on the lenses in the cross-sectional views of each embodiment are used independently for each embodiment to avoid complexity in the description due to an increase in the number of reference numerals. Therefore, even if common reference numerals are used in the drawings of different embodiments, they do not necessarily represent a common structure.

[0322] [Example 1]

[0323] A cross-sectional view of the structure of the imaging lens of Example 1 is shown. Figure 1 The illustrated method and structure are as described above, therefore some repetitive descriptions are omitted here. The imaging lens of Embodiment 1, from the object side to the image side, includes, in sequence, a front lens group GA with positive refractive power, an aperture St, a first focusing lens group GF1 with positive refractive power, a second focusing lens group GF2 with negative refractive power, and a final lens group GE with positive refractive power. When focusing from an object at infinity to the nearest object, the first focusing lens group GF1 moves along the optical axis Z towards the object side, the second focusing lens group GF2 moves along the optical axis Z towards the image side, and the other lens groups and the aperture St are fixed relative to the image plane Sim.

[0324] The front lens group GA, from the object side to the image side, includes positive lenses L11, L12, and L13, and a negative lens L14. Lenses L13 and L14 are coupled together. The first focusing lens group GF1, from the object side to the image side, includes negative lenses L21, L22, and L23, and a positive lens L21 and L22, respectively. Lenses L21 and L22 are coupled together. The second focusing lens group GF2, from the object side to the image side, includes negative lenses L31 and L32, and a positive lens L33, respectively. Lenses L32 and L33 are coupled together. The final lens group GE includes a positive lens L41. Figure 1 The image shows an example of a vibration damping lens assembly including lens L12.

[0325] in addition, Figure 1The anti-vibration lens group shown is one example. As described above, the anti-vibration lens group can be configured to include part of any lens group fixed during focusing, or the entire lens group thereof. Therefore, in the imaging lens of Embodiment 1, the anti-vibration lens group can also be configured to include one or more lenses different from lens L12. This is also the case in all embodiments described below. In all embodiments, the anti-vibration lens group shown in each cross-sectional view is an example, and the anti-vibration lens group can be composed of one or more lenses different from the lens shown in the figures.

[0326] Regarding the imaging lens of Example 1, basic lens data is shown in Table 1, specifications and variable surface spacing are shown in Table 2, and aspherical coefficients are shown in Table 3. In Table 1, the Sn column shows the surface number when the surface closest to the object side is designated as surface 1 and the numbering increases sequentially towards the image side; the R column shows the radius of curvature of each surface; and the D column shows the surface spacing of each surface and its image-side adjacent surface along the optical axis Z. The Nd column shows the refractive index of each component relative to the d-line; the νd column shows the Abbe number of each component relative to the d-line reference; and the θgF column shows the partial dispersion ratio between the g-line and F-line of each component. Regarding the lens, the Material column shows the material name and manufacturer name of each lens with a period between them. As described below, the names of the manufacturers are shown in the table in a general sense. "HOYA" refers to HOYA Corporation. "CDGM" refers to Chengdu Guangming Optoelectronic Co., Ltd. “OHARA” refers to OHARA INC. “HIKARI” refers to HIKARI GLASS Co., Ltd. “SUMITA” refers to SUMITAOPTICAL GLASS, Inc.

[0327] In Table 1, the radius of curvature of the convex surface facing the object side is marked positive, and the radius of curvature of the convex surface facing the image side is marked negative. Table 1 also shows the aperture St and optical components PP. The surface number and the term (St) are recorded in the column corresponding to the aperture St. The bottom column of d in Table 1 shows the interval between the image-side surface and the image plane Sim. In Table 1, the notation DD[ ] is used for the variable surface interval during focusing; the object-side surface number of this interval is marked in [ ] and recorded in column D.

[0328] Table 2 shows the values ​​for focal length f, opening F-number FNo., maximum total angle of view 2ω, maximum image height Ymax, and variable plane spacing. The units (°) in the 2ω column are degrees. In Table 2, the values ​​for focusing on an object at infinity are shown in the column labeled "Infinity," and the values ​​for focusing on an object at a distance of 110 mm are shown in the column labeled "Close." The values ​​shown in Table 2 are based on the d-line.

[0329] In Table 1, the surface numbers of aspherical surfaces are marked with an asterisk (*). The column for the radius of curvature of the aspherical surface records the values ​​of the paraxial radius of curvature. In Table 3, the surface number of the aspherical surface is shown in the Sn column, and the values ​​of the aspherical coefficients for each aspherical surface are shown in the KA and Am (m=3, 4, 5, ... 20) columns. The "E±n" (n: integer) values ​​for the aspherical coefficients in Table 3 represent "×10". ±n KA and Am are the aspheric coefficients in the aspheric formula expressed below.

[0330] Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m

[0331] in,

[0332] Zd: Aspherical depth (the length of the perpendicular line from a point on the aspherical surface at height h to a plane tangent to the vertex of the aspherical surface and perpendicular to the optical axis Z).

[0333] h: Height (distance from the optical axis Z to the lens surface);

[0334] C: The reciprocal of the paraxial radius of curvature;

[0335] KA, Am: Aspheric coefficients

[0336] In aspherical form, Σ represents the sum related to m.

[0337] In the data in each table, degrees are used as the unit for angles and millimeters as the unit for lengths. Optical systems can be used in both magnified and reduced scales, so other appropriate units may also be used. Furthermore, the tables below contain values ​​rounded to a specified number of decimal places.

[0338] [Table 1]

[0339]

[0340] [Table 2]

[0341]

[0342] [Table 3]

[0343]

[0344] exist Figure 3 The diagram shows the aberrations of the imaging lens in Example 1. Figure 3 In the middle, from left to right, are shown spherical aberration, astigmatism, distortion aberration, and magnification chromatic aberration. Figure 3 In the diagram, the upper section marked "Infinity" shows the aberration diagrams for focusing on an object at infinity, and the lower section marked "110mm" shows the aberration diagrams for focusing on an object at a distance of 110mm. In the spherical aberration diagram, solid lines, long dashed lines, short dashed lines, and two-dotted lines represent aberrations below the d-line, C-line, F-line, and g-line, respectively. In the astigmatism diagram, solid lines represent aberrations below the d-line in the sagittal direction, and short dashed lines represent aberrations below the d-line in the meridional direction. In the distortion aberration diagram, solid lines represent aberrations below the d-line. In the magnification chromatic aberration diagram, long dashed lines, short dashed lines, and two-dotted lines represent aberrations below the C-line, F-line, and g-line, respectively. FNo. in the spherical aberration diagram represents the F-value, and ω in other aberration diagrams represents the half-angle of view. Figure 3 The values ​​of FNo. and ω corresponding to the upper end of the vertical axis of each figure are also shown.

[0345] Unless otherwise stated, the notation, meaning, recording method and illustration method of the data related to Embodiment 1 above are the same in the following embodiments, so repeated descriptions are omitted below.

[0346] [Example 2]

[0347] A cross-sectional view of the imaging lens structure of Example 2 is shown. Figure 4 In Example 2, the imaging lens, from the object side to the image side, comprises, in sequence, a front lens group GA with positive refractive power, an aperture St, a first focusing lens group GF1 with positive refractive power, a second focusing lens group GF2 with negative refractive power, and a final lens group GE with positive refractive power. When focusing from an object at infinity to the nearest object, the first focusing lens group GF1 moves along the optical axis Z towards the object side, the second focusing lens group GF2 moves along the optical axis Z towards the image side, and the other lens groups and the aperture St remain fixed relative to the image plane Sim.

[0348] The front lens group GA, from the object side to the image side, includes positive lenses L11, L12, and L13, and a negative lens L14. Lenses L13 and L14 are coupled together. The first focusing lens group GF1, from the object side to the image side, includes negative lenses L21, L22, and L23, and a positive lens L21 and L22, respectively. Lenses L21 and L22 are coupled together. The second focusing lens group GF2, from the object side to the image side, includes negative lenses L31 and L32, and a positive lens L33, respectively. Lenses L32 and L33 are coupled together. The final lens group GE includes a positive lens L41. Figure 4 In the example shown, the vibration damping lens group includes lens L12.

[0349] Regarding the imaging lens of Example 2, the basic lens data is shown in Table 4, the specifications and variable surface spacing are shown in Table 5, the aspherical coefficients are shown in Table 6, and the various aberrations are illustrated in Table 7. Figure 5 In. Figure 5 In the middle section, the upper section shows the aberration diagrams for the state of focusing on an object at infinity, and the lower section shows the aberration diagrams for the state of focusing on an object at a distance of 110 mm.

[0350] [Table 4]

[0351]

[0352] [Table 5]

[0353]

[0354] [Table 6]

[0355]

[0356] [Example 3]

[0357] A cross-sectional view of the imaging lens structure of Example 3 is shown. Figure 6 In Example 3, the imaging lens, from the object side to the image side, comprises, in sequence, a front lens group GA with positive refractive power, an aperture St, a first focusing lens group GF1 with positive refractive power, a second focusing lens group GF2 with negative refractive power, and a final lens group GE with positive refractive power. When focusing from an object at infinity to the nearest object, the first focusing lens group GF1 moves along the optical axis Z towards the object side, the second focusing lens group GF2 moves along the optical axis Z towards the image side, and the other lens groups and the aperture St remain fixed relative to the image plane Sim.

[0358] The front lens group GA, from the object side to the image side, includes positive lenses L11, L12, and L13, and a negative lens L14. Lenses L13 and L14 are coupled together. The first focusing lens group GF1, from the object side to the image side, includes negative lenses L21, L22, and L23, and a positive lens L21 and L22, respectively. Lenses L21 and L22 are coupled together. The second focusing lens group GF2, from the object side to the image side, includes negative lenses L31 and L32, and a positive lens L33, respectively. Lenses L32 and L33 are coupled together. The final lens group GE includes a positive lens L41. Figure 6 In the example shown, the vibration damping lens group includes lens L12.

[0359] Regarding the imaging lens of Example 3, the basic lens data is shown in Table 7, the specifications and variable surface spacing are shown in Table 8, the aspherical coefficients are shown in Table 9, and the various aberrations are illustrated in Table 1. Figure 7 In. Figure 7 In the middle section, the upper section shows the aberration diagrams for the state of focusing on an object at infinity, and the lower section shows the aberration diagrams for the state of focusing on an object at a distance of 110 mm.

[0360] [Table 7]

[0361]

[0362] [Table 8]

[0363]

[0364] [Table 9]

[0365]

[0366] [Example 4]

[0367] Regarding the imaging lens of Embodiment 4, a cross-sectional view of the structure is shown below. Figure 8 The cross-sectional views of the structure and beam under various focusing states will be shown in the diagram. Figure 9 In Example 4, the imaging lens, from the object side to the image side, comprises, in sequence, a front lens group GA with positive refractive power, an aperture St, a first focusing lens group GF1 with positive refractive power, an intermediate lens group GM, a second focusing lens group GF2 with negative refractive power, and a final lens group GE with positive refractive power. When focusing from an object at infinity to the nearest object, the first focusing lens group GF1 moves along the optical axis Z towards the object side, the second focusing lens group GF2 moves along the optical axis Z towards the image side, and the other lens groups and the aperture St remain fixed relative to the image plane Sim.

[0368] The front lens group GA, from the object side to the image side, includes positive lenses L11, L12, and L13, and a negative lens L14. Lenses L13 and L14 are coupled together. The first focusing lens group GF1, from the object side to the image side, includes negative lenses L21, positive lenses L22 and L23, and a positive lens L23. Lenses L21 and L22 are coupled together. The intermediate lens group GM, from the object side to the image side, includes negative lenses L31 and positive lenses L32. The second focusing lens group GF2, from the object side to the image side, includes negative lenses L41 and L42, and a positive lens L43, and a positive lens L43. Lenses L42 and L43 are coupled together. The final lens group GE includes a positive lens L51. Figure 8 In the example shown, the vibration damping lens group includes the intermediate lens group GM as a whole.

[0369] Regarding the imaging lens of Example 4, the basic lens data is shown in Table 10, the specifications and variable surface spacing are shown in Table 11, the aspherical coefficients are shown in Table 12, and the various aberrations are illustrated in Table 13. Figure 10 In. Figure 10 In the middle section, the upper section shows the aberration diagrams for the state of focusing on an object at infinity, and the lower section shows the aberration diagrams for the state of focusing on an object at a distance of 110 mm.

[0370] [Table 10]

[0371]

[0372] [Table 11]

[0373]

[0374] [Table 12]

[0375]

[0376] [Example 5]

[0377] A cross-sectional view of the imaging lens structure of Example 5 is shown. Figure 11 In Example 5, the imaging lens, from the object side to the image side, comprises, in sequence, a front lens group GA with positive refractive power, an aperture St, a first focusing lens group GF1 with positive refractive power, an intermediate lens group GM, a second focusing lens group GF2 with negative refractive power, and a final lens group GE with positive refractive power. When focusing from an object at infinity to the nearest object, the first focusing lens group GF1 moves along the optical axis Z towards the object side, the second focusing lens group GF2 moves along the optical axis Z towards the image side, and the other lens groups and the aperture St remain fixed relative to the image plane Sim.

[0378] The front lens group GA, from the object side to the image side, includes positive lenses L11, L12, and L13, and a negative lens L14. Lenses L13 and L14 are coupled together. The first focusing lens group GF1, from the object side to the image side, includes negative lenses L21, positive lenses L22 and L23, and a positive lens L23. Lenses L21 and L22 are coupled together. The intermediate lens group GM, from the object side to the image side, includes negative lenses L31 and positive lenses L32. The second focusing lens group GF2, from the object side to the image side, includes negative lenses L41 and L42, and a positive lens L43, and a positive lens L43. Lenses L42 and L43 are coupled together. The final lens group GE includes a positive lens L51. Figure 11 In the example shown, the vibration damping lens group includes the intermediate lens group GM as a whole.

[0379] Regarding the imaging lens of Example 5, the basic lens data is shown in Table 13, the specifications and variable surface spacing are shown in Table 14, the aspherical coefficients are shown in Table 15, and the various aberrations are illustrated in Table 16. Figure 12 In. Figure 12 In the middle section, the upper section shows the aberration diagrams for the state of focusing on an object at infinity, and the lower section shows the aberration diagrams for the state of focusing on an object at a distance of 110 mm.

[0380] [Table 13]

[0381]

[0382] [Table 14]

[0383]

[0384] [Table 15]

[0385]

[0386] [Example 6]

[0387] A cross-sectional view of the imaging lens structure of Example 6 is shown. Figure 13 In Example 6, the imaging lens, from the object side to the image side, comprises, in sequence, a front lens group GA with positive refractive power, an aperture St, a first focusing lens group GF1 with positive refractive power, a second focusing lens group GF2 with negative refractive power, and a final lens group GE with positive refractive power. When focusing from an object at infinity to the nearest object, the first focusing lens group GF1 moves along the optical axis Z towards the object side, the second focusing lens group GF2 moves along the optical axis Z towards the image side, and the other lens groups and the aperture St remain fixed relative to the image plane Sim.

[0388] The front lens group GA, from the object side to the image side, includes, in sequence, a negative lens L11, a positive lens L12, a positive lens L13, a positive lens L14, and a negative lens L15. Lenses L11 and L12 are coupled together. Lenses L14 and L15 are coupled together. The first focusing lens group GF1, from the object side to the image side, includes, in sequence, a negative lens L21, a positive lens L22, and a positive lens L23. Lenses L21 and L22 are coupled together. The second focusing lens group GF2, from the object side to the image side, includes, in sequence, a negative lens L31, a negative lens L32, and a positive lens L33. Lenses L32 and L33 are coupled together. The final lens group GE includes a positive lens L41. Figure 13 In the example shown, the vibration damping lens group includes lens L13.

[0389] Regarding the imaging lens of Example 6, the basic lens data is shown in Table 16, the specifications and variable surface spacing are shown in Table 17, the aspherical coefficients are shown in Table 18, and the various aberrations are illustrated in Table 19. Figure 14 In. Figure 14 In the middle section, the upper section shows the aberration diagrams for the state of focusing on an object at infinity, and the lower section shows the aberration diagrams for the state of focusing on an object at a distance of 110 mm.

[0390] [Table 16]

[0391]

[0392] [Table 17]

[0393]

[0394] [Table 18]

[0395]

[0396] [Example 7]

[0397] A cross-sectional view of the imaging lens structure of Example 7 is shown. Figure 15 In Example 7, the imaging lens, from the object side to the image side, comprises, in sequence, a front lens group GA with positive refractive power, an aperture St, a first focusing lens group GF1 with positive refractive power, a second focusing lens group GF2 with negative refractive power, and a final lens group GE with positive refractive power. When focusing from an object at infinity to the nearest object, the first focusing lens group GF1 moves along the optical axis Z towards the object side, the second focusing lens group GF2 moves along the optical axis Z towards the image side, and the other lens groups and the aperture St remain fixed relative to the image plane Sim.

[0398] The front lens group GA, from the object side to the image side, includes positive lenses L11, L12, and L13, and a negative lens L14. Lenses L13 and L14 are coupled together. The first focusing lens group GF1, from the object side to the image side, includes negative lenses L21, L22, and L23, and a positive lens L21 and L22, respectively. Lenses L21 and L22 are coupled together. The second focusing lens group GF2, from the object side to the image side, includes negative lenses L31 and L32, and a positive lens L33, respectively. Lenses L32 and L33 are coupled together. The final lens group GE, from the object side to the image side, includes negative lens L41 and a positive lens L42, respectively. Lenses L41 and L42 are coupled together. Figure 15 In the example shown, the vibration damping lens group includes lens L13 and lens L14.

[0399] Regarding the imaging lens of Example 7, the basic lens data is shown in Table 19, the specifications and variable surface spacing are shown in Table 20, the aspherical coefficients are shown in Table 21, and the various aberrations are illustrated in Table 21. Figure 16 In. Figure 16 In the middle section, the upper section shows the aberration diagrams for the state of focusing on an object at infinity, and the lower section shows the aberration diagrams for the state of focusing on an object at a distance of 110 mm.

[0400] [Table 19]

[0401]

[0402] [Table 20]

[0403]

[0404] [Table 21]

[0405]

[0406] Table 22 shows the corresponding values ​​of conditional expressions (1) to (25) for the imaging lenses of Embodiments 1 to 7, and Table 23 shows the corresponding values ​​of conditional expressions (26) to (51) for the imaging lenses of Embodiments 1 to 7. The corresponding value of conditional expression (51) is the value when the anti-vibration lens group is composed of the lenses shown in the accompanying drawings of each embodiment.

[0407] [Table 22]

[0408]

[0409] [Table 23]

[0410]

[0411] The imaging lenses of Examples 1 to 7 can effectively correct various aberrations and achieve high optical performance not only when focusing on an object at infinity, but also when focusing on a close-range object.

[0412] Next, the imaging device according to the embodiments of the present invention will be described. Figure 17 and Figure 18 The diagram shows the external appearance of the camera 30 of the imaging device according to one embodiment of the present invention. Figure 17 This is a stereoscopic view of camera 30 viewed from the front side. Figure 18 This is a perspective view of the camera 30 as seen from the rear side. The camera 30 is a so-called mirrorless digital camera, with an interchangeable lens 20 that can be easily detached and mounted. The interchangeable lens 20 is configured to include an imaging lens 1 according to an embodiment of the present invention, housed within a lens barrel.

[0413] The camera 30 includes a camera body 31, and a shutter button 32 and a power button 33 are provided on the upper surface of the camera body 31. Furthermore, an operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back of the camera body 31. The display unit 36 ​​can display the captured image and the image existing in the field of view before shooting.

[0414] A camera body 31 has a camera aperture for light from the subject to enter at the center of the front. A bayonet 37 is provided at the position corresponding to the camera aperture, and the interchangeable lens 20 is mounted on the camera body 31 via the bayonet 37.

[0415] The camera body 31 includes an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an image signal corresponding to the image of the subject formed by the interchangeable lens 20, a signal processing circuit that processes the image signal output from the imaging element to generate an image, and a recording medium for recording the generated image. In the camera 30, still images or moving images can be captured by pressing the shutter button 32, and the image data obtained through this capture is recorded in the aforementioned recording medium.

[0416] The present invention has been described above with examples of embodiments and examples. However, the present invention is not limited to the above embodiments and examples and can be modified in various ways. For example, the radius of curvature, interplanar spacing, refractive index, Abbe number, and aspherical coefficient of each lens are not limited to the values ​​shown in the above embodiments and other values ​​can be used.

[0417] Furthermore, the imaging device involved in the embodiments of the present invention is not limited to the above examples. For example, it can be configured as a camera other than a mirrorless camera, a film camera, a video camera, or other similar devices.

Claims

1. An imaging lens, comprising, from the object side to the image side, the following components in sequence: The front lens group has a positive refractive power that is fixed relative to the image plane during focusing; The aperture is continuously arranged with the front lens group; The first focusing lens group has positive refractive power; the second focusing lens group has negative refractive power. And the final lens group, positioned closest to the image side and possessing positive refractive power that remains fixed relative to the image plane during focusing. When focusing from an object at infinity to a closer object, the first focusing lens group and the second focusing lens group move while widening their distance from each other. The lens surface closest to the object in the first focusing lens group is concave. The front lens group is configured to include, from the object side to the image side, two positive lenses as single lenses, and a combined lens consisting of a positive lens and a negative lens joined together from the object side; or, the front lens group is configured to include, from the object side to the image side, a combined lens consisting of a negative lens and a positive lens joined together from the object side, a positive lens as a single lens, and a combined lens consisting of a positive lens and a negative lens joined together from the object side. The first focusing lens group is configured to include, from the object side to the image side, a combined lens in which a negative lens and a positive lens are joined sequentially from the object side, and a positive lens. The second focusing lens group is configured to include, from the object side to the image side, a negative lens as a single lens, and a combined lens consisting of a negative lens and a positive lens joined together from the object side. The final lens group is configured to include a single positive lens, or the final lens group is configured to include a combined lens with a negative lens and a positive lens sequentially joined from the object side.

2. The imaging lens according to claim 1, wherein, The lens surface closest to the image side of the front lens group is concave.

3. The imaging lens according to claim 1 or 2, wherein, When the radius of curvature of the lens surface closest to the object in the first focusing lens group is set to RF1f and the maximum image height is set to Ymax, the imaging lens satisfies the following condition (1): 。 4. The imaging lens according to claim 2, wherein, When the radius of curvature of the lens surface closest to the image side of the front lens group is set to RAr and the maximum image height is set to Ymax, the imaging lens satisfies the following condition (2): 。 5. The imaging lens according to claim 2 or 4, wherein, When the radius of curvature of the lens surface closest to the image in the front lens group is set to RAr and the radius of curvature of the lens surface closest to the object in the first focusing lens group is set to RF1f, the imaging lens satisfies the following condition (3): 。 6. The imaging lens according to claim 1 or 2, wherein, When a lens component is configured as a single lens or a group of combined lenses... The lens component closest to the object in the front lens group has positive refractive power.

7. The imaging lens according to claim 6, wherein, When the maximum refractive index of all lenses in the object-side lens group of the front lens group relative to the d-line is set to NAmax, the minimum Abbe number of the d-line reference of all positive lenses in the object-side lens group of the front lens group is set to νApmin, and the maximum partial dispersion ratio between the g-line and F-line of all positive lenses in the object-side lens group of the front lens group is set to θApmax, the imaging lens satisfies the following conditions (4), (5), and (6): 。 8. The imaging lens according to claim 1, wherein, When the refractive index of the positive lens included in the image-side of the front lens group relative to the d-line is set to NArp, the refractive index of the negative lens included in the image-side of the front lens group relative to the d-line is set to NArn, the Abbe number of the d-line reference of the positive lens included in the image-side of the front lens group is set to νArp, the Abbe number of the d-line reference of the negative lens included in the image-side of the front lens group is set to νArn, the partial dispersion ratio between the g-line and F-line of the positive lens included in the image-side of the front lens group is set to θArp, and the partial dispersion ratio between the g-line and F-line of the negative lens included in the image-side of the front lens group is set to θArn, the imaging lens satisfies the following conditions (7), (8), and (9): 。 9. The imaging lens according to claim 1 or 2, wherein, When the focal length of the imaging lens is set to f and the focal length of the front lens group is set to fA, the imaging lens satisfies the following condition (10): 。 10. The imaging lens according to claim 1 or 2, wherein, When the focal length of the imaging lens is set to f and the focal length of the first focusing lens group is set to fF1, the imaging lens satisfies the following condition (11): 。 11. The imaging lens according to claim 1 or 2, wherein, When the focal length of the imaging lens is set to f and the focal length of the second focusing lens group is set to fF2, the imaging lens satisfies the following condition (12): 。 12. The imaging lens according to claim 1 or 2, wherein, When the focal length of the first focusing lens group is set to fF1 and the focal length of the second focusing lens group is set to fF2, the imaging lens satisfies the following condition (13): 。 13. The imaging lens according to claim 1 or 2, wherein, When the lateral magnification of the first focusing lens group is set to βF1 when focusing on an object at infinity, and the combined lateral magnification of all lenses on the image side of the first focusing lens group that are closer to the image side than when focusing on an object at infinity is set to βF1r, the imaging lens satisfies the following condition (14). 。 14. The imaging lens according to claim 1 or 2, wherein, When the lateral magnification of the second focusing lens group is set to βF2 when the object is focused at infinity, and the combined lateral magnification of all lenses on the image side of the second focusing lens group that are closer to the object than when the object is focused at infinity is set to βF2r, the imaging lens satisfies the following condition (15): 。 15. The imaging lens according to claim 1 or 2, wherein, The first focusing lens group is arranged continuously with the aperture.

16. The imaging lens according to claim 1 or 2, wherein, An intermediate lens group, which is fixed during focusing, is included between the first focusing lens group and the second focusing lens group.

17. The imaging lens according to claim 3, wherein, The imaging lens satisfies the following conditional expression (1-1): 。 18. The imaging lens according to claim 4, wherein, The imaging lens satisfies the following conditional expression (2-1): 。 19. The imaging lens according to claim 5, wherein, The imaging lens satisfies the following conditional expression (3-1): 。 20. A camera device comprising an imaging lens according to any one of claims 1 to 19.

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