Imaging lens and camera device

Abstract

The present application provides an imaging lens with good optical performance and a camera device with the imaging lens. The imaging lens successively has a first lens group and a second lens group with positive refractive power from the most object side to the image side. During focusing, only the second lens group moves. The most image-side lens of the second lens group is a negative meniscus lens with the convex surface facing the object side. In the case where the paraxial radius of curvature of the object-side surface of the most image-side negative meniscus lens of the second lens group is rF and the maximum image height is Y, the imaging lens satisfies the condition formula represented by 0.5 < rF / Y < 3.

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, Patent Document 2 and Patent Document 3 are known.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-101180

[0004] Patent Document 2: Japanese Patent Application Publication No. 2016-180851

[0005] Patent Document 3: Japanese Patent Application Publication No. 2010-113248 Summary of the Invention

[0006] In recent years, there has been a need for imaging lenses with better optical performance.

[0007] The present invention was made in view of the above circumstances, and its object is to provide an imaging lens with good optical performance and a camera device having the imaging lens.

[0008] The imaging lens of the present invention comprises, sequentially from the object side to the image side, a first lens group and a second lens group having positive refractive power. During focusing, the first lens group is fixed relative to the image plane while only the second lens group moves. The image-side lens of the second lens group is a negative meniscus lens with its convex surface facing the object side. When the paraxial radius of curvature of the object-side surface of the negative meniscus lens is set to rF and the maximum image height is set to Y, the imaging lens satisfies...

[0009] 0.5 < rF / Y < 3 (1)

[0010] The conditional expression (1) is represented.

[0011] The lens closest to the object in the first lens group is preferably a negative meniscus lens with its convex surface facing the object.

[0012] When the paraxial radius of curvature of the image-side surface of the negative meniscus lens of the second lens group is set to rR, the imaging lens of the present invention preferably satisfies the following conditions:

[0013] 0.06<(rF-rR) / (rF+rR)<0.27 (2)

[0014] The conditional expression (2) is represented.

[0015] When the paraxial radius of curvature of the image-side surface of the second lens in the second lens group is set to rRR, the imaging lens of the present invention preferably satisfies the following condition.

[0016] 0.35<(rRR+rF) / (rRR-rF)<1 (3)

[0017] The conditional expression (3) is represented.

[0018] When the distance along the optical axis from the lens surface closest to the object side of the second lens group to the lens surface closest to the image side of the second lens group is set to TL2, the imaging lens of the present invention preferably satisfies the following condition.

[0019] 1.2 < TL2 / Y < 2 (4)

[0020] The conditional expression (4) is represented.

[0021] The first lens group includes at least one negative lens, and the negative lens closest to the image side among the negative lenses included in the first lens group is preferably a negative meniscus lens with its convex surface facing the image side. In this case, when the paraxial radius of curvature of the object-side surface of the negative lens closest to the image side among the negative lenses included in the first lens group is set to r1F, and the focal length of the imaging lens in the state of focusing on an object at infinity is set to f, the imaging lens of the present invention preferably satisfies the following conditions:

[0022] -2.5 < r1F / f < -0.3 (5)

[0023] The conditional expression (5) is represented.

[0024] The first lens group includes at least one negative lens, and when the Abbe number of the d-line reference of the negative lens most close to the image side among the negative lenses included in the first lens group is set to v1, the imaging lens of the present invention preferably satisfies the following conditions:

[0025] 15 < v1 < 38 (6)

[0026] The conditional expression (6) is represented.

[0027] The second lens group includes at least one positive lens, and when the Abbe number of the d-line reference of the positive lens most close to the image side among the positive lenses included in the second lens group is set to v2, the imaging lens of the present invention preferably satisfies the following conditions:

[0028] 10 < v2 < 27 (7)

[0029] The conditional expression (7) is represented.

[0030] When the focal length of the first lens group is set to f1 and the focal length of the second lens group is set to f2, the imaging lens of the present invention preferably satisfies the following conditions:

[0031] 0.05 < f2 / f1 < 0.32 (8)

[0032] The conditional expression (8) is represented.

[0033] During focusing, the spacing between the lenses in each lens group is preferably fixed.

[0034] The imaging lens of the present invention preferably includes an aperture that is fixed relative to the image plane during focusing. Furthermore, the imaging lens of the present invention preferably includes an aperture further from the image plane than the image-side lens surface of the first lens group.

[0035] The second lens group preferably includes multiple positive lenses. The second lens group preferably includes at least three positive lenses.

[0036] The imaging lens of the present invention includes at least one negative lens, and the object-side surface of the lens continuously arranged on the image side of the negative lens closest to the object side in the imaging lens can be configured as a concave surface.

[0037] The imaging lens of the present invention can be configured to include a third lens group that is fixed relative to the image plane during focusing.

[0038] The lens closest to the object in the first lens group is a negative lens, and when the focal length of the negative lens closest to the object in the first lens group is set to fL1 and the focal length of the second lens in the first lens group from the object side is set to fL2, the imaging lens of the present invention preferably satisfies the following conditions:

[0039] 0.7 < fL1 / fL2 < 2 (9)

[0040] The conditional expression (9) is represented.

[0041] The first lens group includes at least one negative lens, and the imaging lens of the present invention preferably satisfies the following conditions: The maximum value of the Abbe number based on the d-line reference for all negative lenses included in the first lens group is set to νmax, and the minimum value of the Abbe number based on the d-line reference for all negative lenses included in the first lens group is set to vmin.

[0042] 20 < vmax - vmin < 100 (10)

[0043] The conditional expression (10) is represented.

[0044] The camera device of the present invention includes the imaging lens of the present invention.

[0045] 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.

[0046] In this specification, "a group with positive refractive power" means that the group as a whole has positive refractive power. Similarly, "a group with negative refractive power" means that the group as a whole has negative refractive power. "A group of lenses" is not limited to a structure that includes multiple lenses; it can also be a structure that includes only one lens.

[0047] 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 lens group remains constant.

[0048] The terms "lens with positive refractive power," "positive lens," and "positive lens" have the same meaning. Similarly, the terms "lens with negative refractive power," "negative lens," and "negative lens" have the same meaning. "Negative meniscus lens" and "a negative lens in the shape of a crescent moon" are synonyms.

[0049] 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.

[0050] 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," and "F-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, and the wavelength of the F-line is considered to be 486.13 nm.

[0051] Invention Effects

[0052] According to the present invention, it is possible to provide an imaging lens with good optical performance and a camera device having the imaging lens. Attached Figure Description

[0053] Figure 1 This is a cross-sectional view showing the structure of the imaging lens and the light beam of Embodiment 1.

[0054] Figure 2 These are the spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and magnification chromatic aberration diagram of the imaging lens in Example 1.

[0055] Figure 3This is a lateral aberration diagram of the imaging lens of Example 1 when it is focused on an object at infinity.

[0056] Figure 4 This is a lateral aberration diagram of the imaging lens of Example 1 when it is focused on a close-range object.

[0057] Figure 5 This is a cross-sectional view showing the structure of the imaging lens and the light beam of Embodiment 2.

[0058] Figure 6 These are the spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and magnification chromatic aberration diagram of the imaging lens in Example 2.

[0059] Figure 7 This is a lateral aberration diagram of the imaging lens of Example 2 when it is focused on an object at infinity.

[0060] Figure 8 This is a lateral aberration diagram of the imaging lens of Example 2 when it is focused on a close-up object.

[0061] Figure 9 This is a cross-sectional view showing the structure of the imaging lens and the light beam of Embodiment 3.

[0062] Figure 10 These are the spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and magnification chromatic aberration diagram of the imaging lens in Example 3.

[0063] Figure 11 This is a lateral aberration diagram of the imaging lens of Example 3 when it is focused on an object at infinity.

[0064] Figure 12 This is a lateral aberration diagram of the imaging lens of Example 3 when it is focused on a close-up object.

[0065] Figure 13 This is a perspective view of the front side of a camera device according to one embodiment.

[0066] Figure 14 This is a perspective view of the rear side of a camera device according to one embodiment. Detailed Implementation

[0067] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0068] exist Figure 1 The diagram shows a cross-sectional view of the structure and beam of an imaging lens according to an embodiment of the present invention in a state of focusing on an object at infinity. Figure 1 The image shows on-axis beam 2 and beam 3 with maximum image height as beams. Figure 1 In the image, the left side is the object side, and the right side is the image side. Figure 1The example shown corresponds to the imaging lens of Embodiment 1 described later.

[0069] exist Figure 1 The illustration shows an example assuming an imaging lens is used in a camera device, with a parallel flat optical component PP 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, for example, low-pass filters, infrared cutoff filters, and filters that cut off specific wavelength regions. The optical component PP may be a component without refractive power, or it may be a structure in which the optical component PP is omitted.

[0070] The imaging lens of the present invention comprises, sequentially from the object side to the image side along the optical axis Z, a first lens group G1 and a second lens group G2 having positive refractive power.

[0071] By setting the second lens group G2 as a lens group with positive refractive power, it is beneficial to focus while suppressing aberrations in a lens system with a small F-number.

[0072] As an example, Figure 1 The imaging lens, from the object side to the image side, consists of lens group 1 G1, lens group 2 G2, and lens group 3 G3. Figure 1 In the example, the first lens group G1 includes 7 lenses L11 to L17 and the aperture St from the object side to the image side, the second lens group G2 includes 6 lenses L21 to L26 from the object side to the image side, and the third lens group G3 includes 2 lenses L31 to L32 from the object side to the image side. Figure 1 The aperture St indicates the position along the optical axis, not its size or shape.

[0073] In the imaging lens of the present invention, only the second lens group G2 moves during focusing. That is, in Figure 1 In the example, during focusing, only the second lens group G2 moves along the optical axis Z, while the first lens group G1 and the third lens group G3 remain fixed relative to the image plane Sim. Hereinafter, the lens group that moves during focusing will be referred to as the focusing group. Figure 1 The left-pointing arrow below the second lens group G2 indicates that the second lens group G2 is the focusing group, which moves towards the object side when focusing from an object at infinity to the nearest object. In the imaging lens of the present invention, the focusing group only includes the second lens group G2. Thus, by setting the first lens group G1, which is easily enlarged, to a fixed structure during focusing, it is beneficial to reduce the weight of the focusing group.

[0074] In the imaging lens of the present invention, the lens closest to the image side of the second lens group G2 is configured as a negative meniscus lens with its convex surface facing the object side. This structure facilitates the suppression of spherical aberration while correcting image plane curvature.

[0075] The preferred and possible structures of the imaging lens of the present invention will be described below. In the following description, the imaging lens of the present invention will also be referred to as an imaging lens.

[0076] When the paraxial radius of curvature of the object-side surface of the negative meniscus lens closest to the image side of the second lens group G2 is set to rF and the maximum image height is set to Y, the imaging lens preferably satisfies the following condition (1).

[0077] Furthermore, Y is set to a positive value. By ensuring that the corresponding value of condition (1) is not below the lower limit, the absolute value of the radius of curvature of the surface will not become too small, thus improving the lens's manufacturability and suppressing excessive image plane curvature correction. By ensuring that the corresponding value of condition (1) is not above the upper limit, it is beneficial to suppress insufficient image plane curvature correction. 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).

[0078] 0.5 < rF / Y < 3 (1)

[0079] 0.65 < rF / Y < 2.2 (1-1)

[0080] 0.8 < rF / Y < 1.4 (1-2)

[0081] Regarding the negative meniscus lens on the image side of the second lens group G2, when the paraxial radius of curvature of the object-side surface is set to rF and the paraxial radius of curvature of the image-side surface is set to rR, the imaging lens preferably satisfies the following condition (2). Condition (2) is related to the shape factor of the negative meniscus lens on the image side of the second lens group G2. By ensuring that the corresponding value of condition (2) is not below the lower limit, it is beneficial to suppress overcorrection of spherical aberration. By ensuring that the corresponding value of condition (2) is not above the upper limit, it is beneficial to suppress undercorrection of spherical aberration. 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).

[0082] 0.06<(rF-rR) / (rF+rR)<0.27 (2)

[0083] 0.12<(rF-rR) / (rF+rR)<0.24 (2-1)

[0084] 0.17<(rF-rR) / (rF+rR)<0.21 (2-2)

[0085] When the paraxial radius of curvature of the object-side surface of the negative meniscus lens closest to the image side of the second lens group G2 is set to rF and the paraxial radius of curvature of the image-side surface of the second lens from the image side of the second lens group G2 is set to rRR, the imaging lens preferably satisfies the following condition (3). Condition (3) is a formula related to the shape factor of the air lens formed between the second lens from the image side of the second lens group G2 and the negative meniscus lens closest to the image side of the second lens group G2. By ensuring that the corresponding value of condition (3) is not below the lower limit, excessive refraction of off-axis beams at high angles can be suppressed, thus suppressing the occurrence of coma. By ensuring that the corresponding value of condition (3) is not above the upper limit, the refraction of off-axis beams at high angles will not become too weak, thus facilitating the correction of image plane curvature. 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).

[0086] 0.35<(rRR+rF) / (rRR-rF)<1 (3)

[0087] 0.4<(rRR+rF) / (rRR-rF)<0.8 (3-1)

[0088] 0.45<(rRR+rF) / (rRR-rF)<0.6 (3-2)

[0089] With the distance along the optical axis from the lens surface closest to the object side of the second lens group G2 to the lens surface closest to the image side of the second lens group G2 set to TL2 and the maximum image height set to Y, the imaging lens preferably satisfies the following condition (4). By ensuring that the corresponding value of condition (4) is not below the lower limit, it is easy to guide light to the image side without abruptly bending the light, thus helping to suppress aberrations during focusing. By ensuring that the corresponding value of condition (4) is not above the upper limit, it is helpful to suppress the enlargement of the focusing group. 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).

[0090] 1.2 < TL2 / Y < 2 (4)

[0091] 1.3 < TL2 / Y < 1.8 (4-1)

[0092] 1.4 < TL2 / Y < 1.6 (4-2)

[0093] The lens closest to the object in the first lens group G1 is preferably a negative meniscus lens with its convex surface facing the object. This configuration is advantageous for wide-angle viewing.

[0094] The first lens group G1 includes at least one negative lens, and the negative lens closest to the image side among the negative lenses included in the first lens group G1 is preferably a negative meniscus lens with its convex surface facing the image side. With this configuration, the negative meniscus lens with its convex surface facing the image side can be positioned at a location where the separation between the on-axis beam and the off-axis beam is minimized, which is beneficial for correcting on-axis chromatic aberration.

[0095] In a structure in which the first lens group G1 includes at least one negative lens and the negative lens on the image side of the negative lens included in the first lens group G1 is a negative meniscus lens with its convex surface facing the image side, the imaging lens preferably satisfies the following condition (5). In condition (5), the paraxial radius of curvature of the object-side surface of the negative lens on the image side of the negative lens included in the first lens group G1 is set to r1F, and the focal length of the imaging lens in the state of focusing on an object at infinity is set to f. By ensuring that the corresponding value of condition (5) is not below the lower limit, the refractive power of the object-side surface will not become too weak, thus facilitating the correction of on-axis chromatic aberration. By ensuring that the corresponding value of condition (5) is not above the upper limit, the refractive power of the object-side surface will not become too strong, thus particularly facilitating the suppression of excessive chromatic aberration correction for rays passing through the periphery of the pupil in on-axis rays. 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).

[0096] -2.5 < r1F / f < -0.3 (5)

[0097] -1.8 < r1F / f < -0.5 (5-1)

[0098] -1.1 < r1F / f < -0.7 (5-2)

[0099] The first lens group G1 includes at least one negative lens, and when the Abbe number of the d-line reference of the negative lens closest to the image side among the negative lenses included in the first lens group G1 is set to v1, the imaging lens preferably satisfies the following condition (6). By ensuring that the corresponding value of condition (6) is not below the lower limit, it is beneficial to suppress overcorrection of on-axis chromatic aberration. By ensuring that the corresponding value of condition (6) is not above the upper limit, it is beneficial to suppress undercorrection of on-axis 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).

[0100] 15 < v1 < 38 (6)

[0101] 18 < v1 < 33 (6-1)

[0102] 23 < v1 < 29 (6-2)

[0103] The first lens group G1 includes at least one negative lens, and the imaging lens preferably satisfies the following condition (10) when the maximum value of the Abbe number of the d-line reference for all negative lenses included in the first lens group G1 is set to νmax and the minimum value of the Abbe number of the d-line reference for all negative lenses included in the first lens group G1 is set to vmin. By ensuring that the corresponding value of condition (10) is not below the lower limit, it is beneficial to suppress insufficient chromatic aberration correction. By ensuring that the corresponding value of condition (10) is not above the upper limit, it is beneficial to suppress excessive chromatic aberration correction. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (10-1), and even more preferably satisfies the following condition (10-2).

[0104] 20 < vmax - vmin < 100 (10)

[0105] 30 < vmax - vmin < 85 (10-1)

[0106] 40 < vmax - vmin < 75 (10-2)

[0107] The second lens group G2 includes at least one positive lens, and when the Abbe number of the d-line reference of the positive lens most close to the image side among the positive lenses included in the second lens group G2 is set to v2, the imaging lens preferably satisfies the following condition (7). By ensuring that the corresponding value of condition (7) is not below the lower limit, it is beneficial to suppress excessive magnification chromatic aberration correction. By ensuring that the corresponding value of condition (7) is not above the upper limit, it is beneficial to suppress insufficient magnification chromatic aberration correction. 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).

[0108] 10 < v2 < 27 (7)

[0109] 13 < v2 < 24 (7-1)

[0110] 16 < v2 < 21 (7-2)

[0111] The second lens group G2 preferably includes multiple positive lenses. This configuration helps suppress variations in spherical aberration during focusing. To achieve this effect more significantly, the second lens group G2 preferably includes at least three positive lenses.

[0112] When the focal length of the first lens group G1 is set to f1 and the focal length of the second lens group G2 is set to f2, the imaging lens preferably satisfies the following condition (8). When the imaging lens satisfies the following condition (8), the first lens group G1 becomes a lens group with positive refractive power. Compared with the case where the first lens group G1 is a lens group with negative refractive power, it is beneficial to the miniaturization of the focusing group. By ensuring that the corresponding value of condition (8) is not below the lower limit, the positive refractive power of the first lens group G1 will not become too weak, so it is easy to reduce the diameter of the beam incident on the second lens group G2, thereby benefiting the miniaturization of the focusing group. By ensuring that the corresponding value of condition (8) is not above the upper limit, the refractive power of the second lens group G2 will not become too weak, so it is easy to suppress the amount of movement of the focusing group during focusing, thereby benefiting the miniaturization of the overall optical system. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (8-1), and more preferably satisfies the following condition (8-2).

[0113] 0.05 < f2 / f1 < 0.32 (8)

[0114] 0.1 < f2 / f1 < 0.27 (8-1)

[0115] 0.15 < f2 / f1 < 0.22 (8-2)

[0116] The object-side lens of the first lens group G1 is a negative lens. When the focal length of the object-side negative lens of the first lens group G1 is set to fL1 and the focal length of the second lens of the first lens group G1 from the object side is set to fL2, the imaging lens preferably satisfies the following condition (9). By ensuring that the corresponding value of condition (9) is not below the lower limit, the refractive power of the second lens of the first lens group G1 from the object side will not become too weak, thus facilitating the correction of coma aberration at high angles. By ensuring that the corresponding value of condition (9) is not above the upper limit, the refractive power of the object-side negative lens of the first lens group G1 will not become too weak, thus suppressing the large diameter of the negative lens when widening its angle, thereby facilitating miniaturization. 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).

[0117] 0.7 < fL1 / fL2 < 2 (9)

[0118] 0.9 < fL1 / fL2 < 1.8 (9-1)

[0119] 1.1 < fL1 / fL2 < 1.6 (9-2)

[0120] When the imaging lens includes at least one negative lens, the object-side surface of the lens continuously arranged on the image side of the negative lens closest to the object in the imaging lens can be configured as a concave surface. This configuration facilitates miniaturization of the negative lens closest to the object in the imaging lens. Figure 1 The imaging lens has this structure. Figure 1 In the example, the object-side surface of the lens L12, which is continuously arranged on the image side of the negative lens L11 closest to the object side, becomes a concave surface.

[0121] When the imaging lens includes an aperture St, it is preferable that the aperture St is fixed relative to the image plane Sim during focusing. This configuration facilitates a lighter focusing assembly. Furthermore, the aperture St is preferably positioned further from the image side than the image-side lens surface of the first lens group G1. This configuration reduces the height of high-angle off-axis beams incident on the second lens group G2 from the optical axis Z, thus contributing to a lighter focusing assembly.

[0122] like Figure 1 As shown, the imaging lens can have a third lens group G3, which is fixed relative to the image plane (Sim) during focusing, located further on the image side than the second lens group G2. This configuration facilitates correction of chromatic aberration. Furthermore, the imaging lens can be configured to include a first lens group G1, a second lens group G2, and the aforementioned third lens group G3. This configuration facilitates both good aberration correction and miniaturization.

[0123] When the imaging lens includes the aforementioned third lens group G3, the third lens group G3 is preferably a lens group with negative refractive power. With this configuration, the positive refractive power of the second lens group G2 can be enhanced, which is beneficial for suppressing the amount of movement of the focus group during focusing.

[0124] During focusing, the spacing between the lenses within each lens group is preferably fixed. This configuration simplifies the drive mechanism of the focusing group.

[0125] Specifically, each lens group can adopt the following structure, for example.

[0126] The first lens group G1 can be configured to include 4 negative lenses and 3 positive lenses. Alternatively, the first lens group G1 can be configured to include 5 negative lenses and 3 positive lenses. The first lens group G1 can be configured to include two sets of combined lenses, which is beneficial for correcting chromatic aberration. The lens closest to the image side of the first lens group G1 can be configured as a positive lens, which is beneficial for miniaturizing the focusing group.

[0127] The second lens group G2 can be configured to include three positive lenses and three negative lenses. The second lens group G2 can also be configured to include at least one set of joint lenses; this configuration is advantageous for correcting chromatic aberration. When the second lens group G2 includes joint lenses, the joint surface can be shaped with the convex surface facing the image side; this configuration is advantageous for suppressing aberrations.

[0128] The third lens group G3 can be configured to include one positive lens and one negative lens. This configuration offers the advantage of balancing good performance and miniaturization. Furthermore, in this configuration, the positive and negative lenses of the third lens group G3 can be joined together. This joining arrangement is more conducive to miniaturization compared to the unjoined arrangement.

[0129] 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 from the preferred, more preferred and further preferred conditional expressions.

[0130] As an example, a preferred embodiment of the imaging lens of the present invention is an imaging lens comprising, sequentially from the object side to the image side, a first lens group G1 and a second lens group G2 having positive refractive power. During focusing, the first lens group G1 is fixed relative to the image plane Sim while only the second lens group G2 moves. The lens of the second lens group G2 closest to the image side is a negative meniscus lens with its convex surface facing the object side. The imaging lens satisfies the above-described conditional expression (1). According to this preferred embodiment, the imaging lens is advantageous in maintaining good performance and achieving a lightweight focusing assembly, while suppressing aberration variations in a lens system with a small F-number during focusing.

[0131] Next, embodiments of the imaging lens of the present invention will be described with reference to the accompanying drawings.

[0132] [Example 1]

[0133] A cross-sectional view showing the structure and beam of the imaging lens of Embodiment 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 a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. When focusing from an object at infinity to the nearest object, only the second lens group G2 moves along the optical axis Z towards the object side, while the first lens group G1 and the third lens group G3 remain fixed relative to the image plane Sim.

[0134] The first lens group G1, from the object side to the image side, includes, in sequence, a meniscus-shaped negative lens L11 with its convex surface facing the object side, a biconcave negative lens L12, a biconvex positive lens L13, a biconcave negative lens L14, a meniscus-shaped positive lens L15 with its convex surface facing the image side, a meniscus-shaped negative lens L16 with its convex surface facing the image side, a biconvex positive lens L17, and an aperture diaphragm St. Lenses L12, L13, and L14 are joined together. Lenses L15 and L16 are joined together.

[0135] The second lens group G2, from the object side to the image side, includes, in sequence, a biconvex positive lens L21, a negative lens L22 with its concave surface facing the object side, a positive lens L23 with its convex surface facing the image side, a negative lens L24 with its concave surface facing the object side, a biconvex positive lens L25, and a meniscus negative lens L26 with its convex surface facing the object side. Lenses L21 and L22 are joined together. Lenses L23 and L24 are joined together.

[0136] The third lens group G3, from the object side to the image side, includes a positive lens L31 with a biconvex shape and a negative lens L32 with its concave surface facing the object side. Lens L31 and lens L32 are joined together.

[0137] 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, column S 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; column r shows the radius of curvature of each surface; column d shows the surface spacing on the optical axis between each surface and its image-side adjacent surface; column nd shows the refractive index of each component relative to the d-line; and column vd shows the Abbe number of each component based on the d-line.

[0138] 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 (S t) 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 zooming, with the object-side surface number of that interval marked in [] and recorded in the d column.

[0139] Table 2 shows the focal length f, open F-number FNo., maximum total angle of view 2ωmax, and variable surface spacing during focusing. The (°) in the 2ωmax column indicates the unit as degrees. Table 2 also shows the cases for object distances of infinity and 110 mm. That is, 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 "110 mm." Object distance is the distance along the optical axis from the object to the lens surface of the first lens group G1 closest to the object. The values ​​shown in Table 2 are based on the d-line.

[0140] In Table 1, the surface numbers of aspherical surfaces are marked with an asterisk (*). The column for radius of curvature of aspherical surfaces records the values ​​of paraxial radii of curvature. In Table 3, the surface number of the aspherical surface is shown in the S column, and the values ​​of the aspherical coefficients for each aspherical surface are shown in the KA and Am (m = 3, 4, 5, ... 16) columns. The values ​​of the aspherical coefficients in Table 3, "E±n" (n: an integer), represent "×10". ±n KA and Am are the aspheric coefficients in the aspheric formula expressed below.

[0141] Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+∑Am×h m

[0142] in,

[0143] 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);

[0144] h: Height (distance from the optical axis to the lens surface);

[0145] C: The reciprocal of the paraxial radius of curvature;

[0146] KA, Am: Aspheric coefficients

[0147] In aspherical form, ∑ represents the summation related to m.

[0148] 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.

[0149] [Table 1]

[0150] Implementation Column 1

[0151]

[0152]

[0153] [Table 2]

[0154] Implementation Column 1

[0155] object distance Infinity 110mm f 17.90 17.65 FNo. 1.44 1.54 2ωmax(°) 78.6 76.0 Y 14.2 14.2 DD

[12] 6.58 4.08 DD

[22] 6.72 9.22

[0156] [Table 3]

[0157] Implementation Column 1

[0158] S 1 2 7 KA 3.8510739E+00 -4.3296751E+00 -3.0025899E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 8.2101298E-05 3.1069943E-04 -5.9789840E-05 A5 -9.5739997E-06 -1.0193003E-05 4.0272162E-07 A6 5.9588626E-07 -9.9029127E-07 -1.2393722E-06 A7 -3.0455959E-08 7.4165898E-09 3.9428093E-07 A8 -1.9480492E-09 5.8171636E-09 -3.5102283E-08 A9 4.0864450E-10 1.7037688E-10 -2.4364513E-09 A10 -1.4919699E-11 -1.6321215E-11 3.7344047E-10 A11 -1.8257720E-13 -1.4903567E-12 3.9820245E-11 A12 -2.7147724E-14 -2.8746210E-13 -6.3260902E-12 A13 3.4618551E-15 5.1753338E-14 -2.0073400E-13 A14 -2.7227826E-18 -2.5285882E-15 7.3073525E-14 A15 -6.6705344E-18 4.0808858E-17 -4.4848603E-15 A16 1.4994304E-19 -8.7993111E-21 9.4036412E-17

[0159] S 21 22 KA -5.0000027E+00 -1.4211109E+00 A3 0.0000000E+00 0.0000000E+00 A4 -1.5689881E-05 3.0065970E-05 A5 -6.5802732E-06 -1.9431301E-05 A6 -6.9255100E-07 3.3138973E-06 A7 1.4479909E-08 -4.3716353E-07 A8 1.4122715E-08 2.8105186E-08 A9 -3.4964926E-10 1.7441042E-09 A10 -7.5590845E-11 -1.5417488E-10 A11 6.1173246E-12 -2.3068826E-11 A12 -9.6603698E-13 1.2815061E-12 A13 7.7251258E-14 2.3110962E-13 A14 1.1107596E-15 -2.7371328E-14 A15 -3.0214962E-16 1.2010839E-15 A16 7.8465436E-18 -2.1499728E-17

[0160] exist Figure 2 , Figure 3 and Figure 4 The diagram shows the aberrations of the imaging lens in Example 1. Figure 2 In the middle, from left to right, are shown spherical aberration, astigmatism, distortion aberration, and magnification chromatic aberration. Figure 2 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, and short dashed lines represent aberrations along the d-line, C-line, and F-line, respectively. In the astigmatism diagram, solid lines represent aberrations along the d-line in the sagittal direction, and short dashed lines represent aberrations along the d-line in the meridional direction. In the distortion aberration diagram, solid lines represent aberrations along the d-line. In the magnification chromatic aberration diagram, long dashed lines and short dashed lines represent aberrations along the C-line and F-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 2 The values ​​of FNo. and ω are shown in the figure, corresponding to the upper end of the vertical axis.

[0161] exist Figure 3 The image shows the lateral aberrations of a state focused on an object at infinity. Figure 3 In the diagram, the left column shows the lateral aberrations along the meridional direction, and the right column shows the lateral aberrations along the sagittal direction. Figure 3 In the diagram, solid lines, long dashed lines, and short dashed lines represent the aberrations under the d-line, C-line, and F-line, respectively. Figure 3 ω represents the half-angle of view. (And...) Figure 3 Similarly, in Figure 4 The image shows the lateral aberrations of an object focused at a distance of 110 mm.

[0162] 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.

[0163] [Example 2]

[0164] A cross-sectional view showing the structure and beam of the imaging lens of Embodiment 2 is shown. Figure 5 In Example 2, the imaging lens comprises, from the object side to the image side, a first lens group G1 with positive refractive power and a second lens group G2 with positive refractive power. When focusing from an object at infinity to the nearest object, only the second lens group G2 moves along the optical axis Z towards the object side, while the first lens group G1 remains fixed relative to the image plane Sim.

[0165] The first lens group G1, from the object side to the image side, includes, in sequence, a meniscus-shaped negative lens L11 with its convex surface facing the object side, a biconcave negative lens L12, a meniscus-shaped positive lens L13 with its convex surface facing the object side, a biconcave negative lens L14, a biconvex positive lens L15, a meniscus-shaped negative lens L16 with its convex surface facing the image side, a biconvex positive lens L17, and an aperture diaphragm St. Lenses L12 and L13 are joined together. Lenses L14 and L15 are joined together.

[0166] The second lens group G2, from the object side to the image side, includes, in sequence, a biconvex positive lens L21, a biconcave negative lens L22, a biconvex positive lens L23, a biconcave negative lens L24, a biconvex positive lens L25, and a meniscus negative lens L26 with its convex surface facing the object side. Lenses L21 and L22 are joined together. Lenses L23 and L24 are joined together.

[0167] 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. Figures 6-8 In. Figure 6 The upper section shows spherical aberration, astigmatism, distortion aberration, and chromatic aberration when focused on an object at infinity, while the lower section shows the same conditions when focused on an object at a distance of 110 mm. Figure 7 The image shows the lateral aberrations of a state focused on an object at infinity. Figure 8 The image shows the lateral aberrations of an object focused at a distance of 110 mm.

[0168] [Table 4]

[0169] Implement column 2

[0170] S r d nd vd *1 50.9202 1.8721 1.58313 59.38 *2 15.5929 11.1254 3 -41.2861 1.1918 1.48749 70.44 4 28.6638 4.2247 2.00069 25.46 5 547.2491 5.8234 6 -45.3239 2.1805 1.68893 31.07 7 68.3842 4.6317 1.69680 55.53 8 -26.2063 1.1493 9 -18.8555 0.9231 1.74077 27.79 10 -317.6806 0.1000 11 83.7496 4.1391 1.95375 32.32 12 -37.6767 3.5285 13 (St) ∞ DD

[13] 14 26.4192 8.7875 1.55032 75.50 15 -20.4793 0.8968 1.78880 28.43 16 94.9622 0.1000 17 43.8350 5.9348 1.75500 52.32 18 -19.0896 0.9112 1.85478 24.80 19 873.6132 0.1000 20 34.7161 4.2520 1.92286 18.90 21 -55.7621 0.1000 *22 12.8449 1.1053 1.80625 40.91 *23 8.6197 DD

[23] 24 ∞ 2.8500 1.51680 64.20 25 ∞ 1.1000

[0171] [Table 5]

[0172] Implement column 2

[0173] object distance Infinity 110mm f 18.20 18.07 FNo. 1.44 1.56 2ωmax(°) 78.2 74.4 Y 14.2 14.2 DD

[13] 6.84 4.11 DD

[23] 16.51 19.25

[0174] [Table 6]

[0175] Implement column 2

[0176] S 1 2 22 23 KA -3.5524107E+00 -4.3839153E-01 -8.7749470E-01 -1.7564944E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 1.4562563E-04 1.9987653E-04 -2.9457203E-04 4.5987345E-05 A5 -1.5586134E-05 -1.4237156E-05 -3.0213717E-05 -4.2734089E-05 A6 5.2002049E-07 3.8653493E-08 8.8294930E-06 8.3923312E-06 A7 4.4576460E-08 9.7639392E-08 -6.3236083E-07 -6.7249893E-07 A8 -7.2822532E-09 1.3127811E-10 6.6065017E-08 3.8700650E-08 A9 2.3897513E-10 -1.7402613E-09 -1.8681912E-08 -1.0369127E-09 A10 2.0729060E-11 1.0104915E-10 2.8496418E-09 -7.1101541E-10 A11 -4.2346876E-13 1.0980116E-11 -2.1192026E-10 1.4318222E-10 A12 -2.6304469E-13 -1.4408297E-12 5.7452181E-12 -4.3454846E-12 A13 2.7068251E-14 5.0098114E-14 1.3592773E-13 -1.7638060E-12 A14 -1.2272789E-15 2.0411475E-16 -3.2656663E-15 2.5353158E-13 A15 2.8191990E-17 -5.1685374E-17 -6.9338244E-16 -1.4072532E-14 A16 -2.6907030E-19 9.6690889E-19 2.5709964E-17 2.9452493E-16

[0177] [Example 3]

[0178] A cross-sectional view showing the structure and beam of the imaging lens of Embodiment 3 is shown. Figure 9 In Example 3, the imaging lens comprises, from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. When focusing from an object at infinity to the nearest object, only the second lens group G2 moves along the optical axis Z towards the object side, while the first lens group G1 and the third lens group G3 remain fixed relative to the image plane Sim.

[0179] The first lens group G1, from the object side to the image side, includes, in sequence, a meniscus-shaped negative lens L11 with its convex surface facing the object side, a meniscus-shaped negative lens L12 with its convex surface facing the object side, a biconcave negative lens L13, a biconvex positive lens L14, a biconcave negative lens L15, a meniscus-shaped positive lens L16 with its convex surface facing the image side, a meniscus-shaped negative lens L17 with its convex surface facing the image side, a biconvex positive lens L18, and an aperture diaphragm St. Lenses L14 and L15 are joined together. Lenses L16 and L17 are joined together.

[0180] The second lens group G2, from the object side to the image side, includes, in sequence, a biconvex positive lens L21, a biconcave negative lens L22, a biconvex positive lens L23, a meniscus negative lens L24 with its concave surface facing the object side, a biconvex positive lens L25, and a meniscus negative lens L26 with its convex surface facing the object side. Lenses L21, L22, L23, and L24 are joined together.

[0181] The third lens group G3, from the object side to the image side, consists of a biconvex positive lens L31 and a biconcave negative lens L32. Lens L31 and lens L32 are joined together.

[0182] 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. Figures 10-12 In. Figure 10 The upper section shows spherical aberration, astigmatism, distortion aberration, and chromatic aberration when focused on an object at infinity, while the lower section shows the same conditions when focused on an object at a distance of 110 mm. Figure 11 The image shows the lateral aberrations of a state focused on an object at infinity. Figure 12 The image shows the lateral aberrations of an object focused at a distance of 110 mm.

[0183] [Table 7]

[0184] Implement column 3

[0185] S r d nd vd 1 32.5237 1.7367 1.60342 38.03 2 18.1246 3.2146 *3 118.2213 1.9376 1.58313 59.46 *4 31.7640 8.7773 5 -44.0686 1.3096 1.41390 100.82 6 32.2786 0.1000 7 28.4634 4.9124 2.00100 29.13 8 -89.6905 1.0185 1.66382 27.35 9 71.1945 5.5368 *10 -30.3755 4.2401 1.58313 59.46 11 -14.2487 1.0100 1.85000 27.03 12 -86.3968 0.5147 13 85.0938 3.8968 2.00069 25.46 14 -38.0093 2.7758 15 (St) ∞ DD

[15] 16 28.1690 7.5244 1.59282 68.62 17 -19.3899 0.9038 1.85478 24.80 18 92.6846 6.5358 1.78800 47.37 19 -15.7861 0.9098 1.85478 24.80 20 -137.8402 0.1000 21 41.5128 4.1040 2.00272 19.32 22 -50.9457 0.4000 *23 15.2198 1.3471 1.83441 37.28 *24 10.3108 DD

[24] 25 675.7519 1.8011 1.81600 46.62 26 -87.9022 0.9767 1.84666 23.78 27 445.1891 8.6971 28 ∞ 2.8500 1.51680 64.20 29 ∞ 1.1000

[0186] [Table 8]

[0187] Implement column 3

[0188] object distance Infinity 110mm f 17.65 17.47 FNo. 1.44 1.54 2ωmax(°) 79.6 76.6 Y 14.2 14.2 DD

[15] 7.46 5.00 DD

[24] 6.69 9.16

[0189] [Table 9]

[0190] Implement column 3

[0191] S 3 4 10 KA -1.2442500E+00 -2.4913659E+00 1.6776334E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 2.3771598E-04 2.5856714E-04 -1.0765813E-06 A5 -1.2607488E-05 -9.0050605E-06 -5.6964828E-07 A6 1.4241661E-08 -1.7847991E-07 -9.1209489E-07 A7 5.0997323E-09 -5.3953930E-08 4.1223932E-07 A8 -1.6937865E-09 1.9709031E-08 -7.8584313E-08 A9 4.9416757E-10 -3.1829110E-09 7.1809552E-09 A10 -4.3828231E-11 2.7740065E-10 -1.3611121E-10 A11 2.1620693E-12 -7.5091993E-12 -4.2233166E-11 A12 -4.7088064E-14 -5.6930575E-13 4.4620280E-12 A13 -6.5700378E-15 4.4609993E-14 9.1541757E-15 A14 7.6202549E-16 -7.1708391E-16 -3.6295381E-14 A15 -3.0917130E-17 -2.4032121E-17 2.7958673E-15 A16 4.5073788E-19 7.7317408E-19 -6.9292382E-17

[0192] S 23 24 KA -6.5436100E-01 -4.3424382E-01 A3 0.0000000E+00 0.0000000E+00 A4 -1.9290291E-04 -1.1433926E-04 A5 -1.9044850E-06 -1.4513853E-05 A6 5.8920955E-07 3.8719978E-06 A7 -1.0931297E-08 -3.4663182E-07 A8 2.8026172E-10 -5.7906950E-09 A9 7.6219137E-10 5.0763868E-09 A10 -6.9429731E-11 -6.7452922E-11 A11 1.7070329E-12 -7.0887086E-11 A12 -5.9103796E-13 4.0732254E-12 A13 9.3853193E-15 4.7558996E-13 A14 9.5615292E-15 -7.0220622E-14 A15 -7.8178735E-16 3.5201965E-15 A16 1.8080420E-17 -6.7534974E-17

[0193] Table 10 shows the corresponding values ​​of conditional expressions (1) to (10) for the imaging lenses of Examples 1 to 3.

[0194] [Table 10]

[0195] Formula number Implementation Column 1 Implement column 2 Implement column 3 (1) rF / Y 1.14 0.90 1.07 (2) (rF-rR) / (rF+rR) 0.19 0.20 0.19 (3) (rRR+rF) / (rRR-rF) 0.47 0.63 0.54 (4) TL2 / Y 1.59 1.56 1.54 (5) r1F / f -0.78 -1.04 -0.81 (6) v1 25.43 27.79 27.03 (7) v2 19.32 18.90 19.32 (8) f2 / f1 0.20 0.16 0.17 (9) fL1 / fL2 1.43 1.14 0.95 (10) vmax-vmin 44.98 42.65 73.80

[0196] The imaging lenses of Examples 1 to 3 have an F-number of less than 1.5 when focusing on an object at infinity, and a maximum angle of view of 75 degrees or more. Thus, although the imaging lenses of Examples 1 to 3 have small F-numbers and large angles of view, they achieve lightweight and miniaturized focusing groups, less aberration variation during focusing, and good correction of various aberrations to achieve high optical performance.

[0197] Next, the imaging device according to the embodiments of the present invention will be described. Figure 13 and Figure 14 The diagram shows the external appearance of the camera 30 of the imaging device according to one embodiment of the present invention. Figure 13 This is a stereoscopic view of camera 30 viewed from the front side. Figure 14This is a perspective view of the camera 30 as seen from the rear side. The camera 30 is a so-called mirrorless digital camera, which allows for the detachable mounting of an interchangeable lens 20. 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] Symbol Explanation

[0204] 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, G1-First lens group, G2-Second lens group, G3-Third lens group, L11~L32-Lens, PP-Optical components, Sim-Image plane, St-Aperture, Y-Maximum image height, Z-Optical axis.

Claims

1. An imaging lens, comprising, sequentially from the object side to the image side, a first lens group and a second lens group having positive refractive power. During focusing, the first lens group is fixed relative to the image plane while only the second lens group moves. The lens closest to the image side in the second lens group is a negative meniscus lens with its convex surface facing the object side. When the paraxial radius of curvature of the object-side surface of the negative meniscus lens in the second lens group is set to rF and the maximum image height is set to Y, the imaging lens satisfies... 0.5 < rF / Y < 3 (1) The conditional expression (1) is represented. The second lens group includes at least one positive lens. When the Abbe number of the d-line reference of the positive lens closest to the image side among the positive lenses included in the second lens group is set to ν2, the imaging lens satisfies 10 < ν2 < 27 (7) The conditional expression (7) is represented.

2. An imaging lens, comprising, sequentially from the object side to the image side, a first lens group and a second lens group having positive refractive power. During focusing, the first lens group is fixed relative to the image plane while only the second lens group moves. The lens closest to the image side in the second lens group is a negative meniscus lens with its convex surface facing the object side. The lens closest to the object in the first lens group is a negative meniscus lens with its convex surface facing the object. When the focal length of the first lens group is set to f1 and the focal length of the second lens group is set to f2, the imaging lens satisfies 0.05 < f2 / f1 < 0.32 (8) The conditional expression (8) is represented.

3. An imaging lens, comprising, sequentially from the object side to the image side, a first lens group and a second lens group having positive refractive power. During focusing, the first lens group is fixed relative to the image plane while only the second lens group moves. The lens closest to the image side in the second lens group is a negative meniscus lens with its convex surface facing the object side. When the paraxial radius of curvature of the object-side surface of the negative meniscus lens of the second lens group is set to rF and the paraxial radius of curvature of the image-side surface of the second lens of the second lens group (from the image side) is set to rRR, the imaging lens satisfies... 0.35<(rRR+rF) / (rRR-rF)<1 (3) The conditional expression (3) is represented. The first lens group includes at least one negative lens. When the Abbe number of the d-line reference of the negative lens closest to the image side among the negative lenses included in the first lens group is set to ν1, the imaging lens satisfies 15 < ν1 < 38 (6) The conditional expression (6) is represented.

4. The imaging lens according to any one of claims 1 to 3, wherein, The second lens group includes multiple positive lenses.

5. An imaging lens, comprising, sequentially from the object side to the image side, a first lens group and a second lens group having positive refractive power. The second lens group includes multiple positive lenses. During focusing, the first lens group is fixed relative to the image plane while only the second lens group moves. The lens closest to the image side in the second lens group is a negative meniscus lens with its convex surface facing the object side. The first lens group includes at least one negative lens. The negative lens closest to the image side among the negative lenses included in the first lens group is a negative meniscus lens with its convex surface facing the image side. When the paraxial radius of curvature of the object-side surface of the negative lens closest to the image side in the first lens group is set to r1F, and the focal length of the imaging lens in the state of focusing on an object at infinity is set to f, the imaging lens satisfies... -2.5 < r1F / f < -0.3 (5) The conditional expression (5) is represented.

6. An imaging lens, comprising, sequentially from the object side to the image side, a first lens group and a second lens group having positive refractive power. During focusing, the first lens group is fixed relative to the image plane while only the second lens group moves. The lens closest to the image side in the second lens group is a negative meniscus lens with its convex surface facing the object side. The imaging lens includes an aperture that is fixed relative to the image plane during focusing. The first lens group includes at least one negative lens. When the maximum Abbe number of the d-line reference for all negative lenses included in the first lens group is set to νmax and the minimum Abbe number of the d-line reference for all negative lenses included in the first lens group is set to νmin, the imaging lens satisfies 20<νmax-νmin<100 (10) The conditional expression (10) is represented.

7. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, When the paraxial radius of curvature of the object-side surface of the negative meniscus lens of the second lens group is set to rF and the paraxial radius of curvature of the image-side surface of the negative meniscus lens of the second lens group is set to rR, the imaging lens satisfies 0.06<(rF-rR) / (rF+rR)<0.27 (2) The conditional expression (2) is represented.

8. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, When the distance along the optical axis from the lens surface closest to the object side of the second lens group to the lens surface closest to the image side of the second lens group is set to TL2, the imaging lens satisfies... 1.2 < TL2 / Y < 2 (4) The conditional expression (4) is represented.

9. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, During focusing, the spacing between all lenses in each lens group is fixed.

10. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, The imaging lens includes an aperture that is further from the image side than the lens surface of the first lens group that is closest to the image.

11. The imaging lens according to claim 6, wherein, The second lens group includes multiple positive lenses.

12. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, The second lens group includes at least three positive lenses.

13. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, The imaging lens includes at least one negative lens. The object-side surface of the lens continuously arranged on the image side of the negative lens closest to the object side in the imaging lens is concave.

14. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, The imaging lens has a third lens group that is fixed relative to the image plane during focusing.

15. The imaging lens according to any one of claims 1 to 3, 5, and 6, wherein, The lens closest to the object in the first lens group is a negative lens. When the focal length of the negative lens closest to the object in the first lens group is set to fL1 and the focal length of the second lens in the first lens group from the object side is set to fL2, the imaging lens satisfies... 0.7 < fL1 / fL2 < 2 (9) The conditional expression (9) is represented.

16. A camera device comprising an imaging lens according to any one of claims 1 to 15.

Images