Imaging lens and camera device

Abstract

The imaging lens successively includes, from the object side, a first lens group which is fixed at the time of focusing and a focus lens group which moves at the time of focusing. In a case where a maximum image height is set as Ymax, a focal length of the entire system is set as f, a sum of a back focal length counted from a distance on the optical axis from a lens surface on the object side to a lens surface on the image side in terms of air conversion distance is set as TL, the imaging lens satisfies conditional expressions (1) and (2). (1): 0.1 < Ymax / f < 0.26, (2): 0.4 < TL / f < 1.1.

Description

Technical Field

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

[0002] Previously, imaging lenses used in video recording devices such as digital cameras and camcorders have included lens systems described in Japanese Patent Application Publication No. 2020-160100 and Japanese Patent Application Publication No. 2018-060079. Summary of the Invention

[0003] In recent years, there has been a need for an imaging lens that is small and lightweight and has good optical performance.

[0004] The present invention was made in view of the above circumstances, and its object is to provide an imaging lens and a camera device having the imaging lens, wherein the imaging lens is configured to be small and lightweight and has good optical performance.

[0005] means for solving technical problems

[0006] One aspect of the present invention relates to an imaging lens that, from the object side to the image side, sequentially comprises a first lens group fixed relative to the image plane during focusing and a focusing lens group that moves along the optical axis during focusing.

[0007] With the maximum image height set to Ymax, the focal length of the entire system when focusing on an object at infinity set to f, and the sum of the distance on the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the entire system, and the back focal length of the air-converted distance meter set to TL, the imaging lens satisfies...

[0008] 0.1 < Ymax / f < 0.26 (1)

[0009] 0.4 < TL / f < 1.1 (2)

[0010] The conditions (1) and (2) are represented.

[0011] When the distortion aberration at 50% of the maximum image height when focusing on an object at infinity is set to Dst5, and the distortion aberration at the maximum image height when focusing on an object at infinity is set to Dst10, the imaging lens described above preferably satisfies the following conditions:

[0012] 0.2 < |Dst5 / Dst10| < 0.6 (3)

[0013] The conditional expression (3) is represented.

[0014] When focusing on an object at infinity, the distance along the optical axis from the image plane to the exit pupil position is denoted as Pe. Regarding the sign of Pe, if the exit pupil position is located closer to the object than the image plane, it is set to positive; if the exit pupil position is located closer to the image plane than the image plane, it is set to negative. In this case, the imaging lens using the above method preferably satisfies the following condition:

[0015] 1.5 < Pe / Ymax < 3 (4)

[0016] The conditional expression (4) is represented.

[0017] The imaging lens described above includes a negative lens on the image-side. When the radius of curvature of the object-side surface of the negative lens is set to Rf, and the radius of curvature of the image-side surface of the negative lens is set to Rr, the imaging lens described above preferably satisfies the following conditions:

[0018] -0.6<(Rf-Rr) / (Rf+Rr)<-0.1 (5)

[0019] The conditional expression (5) is represented.

[0020] The imaging lens described above preferably includes a positive lens continuously attached to the negative lens on the object side. When the radius of curvature of the object-side surface of the negative lens is set to Rf, and the radius of curvature of the image-side surface of the positive lens is set to Rpr, the imaging lens described above preferably satisfies the following conditions:

[0021] 0.03<(Rpr-Rf) / (Rpr+Rf)<0.4 (6)

[0022] The conditional expression (6) is represented.

[0023] When the Abbe number of the d-line reference of the aforementioned negative lens is set to νn, the imaging lens of the above method preferably satisfies the following conditions.

[0024] 12<νn<30 (7)

[0025] The conditional expression (7) is represented.

[0026] With the distance along the optical axis from the lens surface closest to the object side of the first lens group to the lens surface closest to the image side of the first lens group set to DG1, the imaging lens described above preferably satisfies the following conditions.

[0027] 0.02 < DG1 / f < 0.2 (8)

[0028] The conditional expression (8) is represented.

[0029] When the maximum half-angle of view is set to ω when focusing on an object at infinity, and the angle between the principal ray from the lens closest to the image plane to the maximum image height and the axis parallel to the optical axis when focusing on an object at infinity is set to ωi, the imaging lens described above preferably satisfies the following conditions:

[0030] 1.4<tanωi / tanω<3.6 (9)

[0031] The conditional expression (9) is represented.

[0032] When the maximum effective diameter of the lens surface closest to the object in the first lens group is set to φf, and the maximum effective diameter of the lens surface closest to the image in the entire system is set to φr, the imaging lens described above preferably satisfies the following conditions.

[0033] 0.2<φf / φr<1.5 (10)

[0034] The conditional expression (10) is represented.

[0035] When the back focal length of the air-converted distance meter is set to Bf while focusing on an object at infinity, the imaging lens described above preferably satisfies the following conditions.

[0036] 0.4 < Bf / Ymax < 1.8 (11)

[0037] The conditional expression (11) is represented.

[0038] The focusing lens group preferably has negative refractive power as a whole. The focusing lens group preferably includes two or fewer lenses.

[0039] When the focal length of the first lens group is set to f1, the imaging lens described above preferably satisfies the following conditions.

[0040] 0.25 < f1 / f < 0.5 (12)

[0041] The conditional expression (12) is represented.

[0042] The imaging lens described above, from the object side to the image side, sequentially includes a first lens group, a focusing lens group with negative refractive power, and a rear lens group that is fixed relative to the image plane during focusing. When the focal length of the rear lens group is set to fR, the imaging lens described above preferably satisfies the following conditions:

[0043] -0.9 < fR / f < -0.1 (13)

[0044] The conditional expression (13) is represented.

[0045] The imaging lens described above is mounted on a camera device, which can be configured to have an imaging element that captures an optical image formed by the imaging lens and is capable of outputting an image with a viewing angle narrower than the maximum viewing angle of the imaging element. Furthermore, the camera device can be configured to use a composite image obtained by combining multiple images captured by the imaging element, and is capable of outputting an image with a viewing angle narrower than the maximum viewing angle of the imaging element.

[0046] Another aspect of the present invention relates to a camera device having an imaging lens as described above.

[0047] 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.

[0048] In this specification, "single lens" refers to an unjoined single lens. Compound aspherical lenses (lenses in which a spherical lens and an aspherical film formed on the spherical lens are integrated and function as a single aspherical lens) are used as single lenses and not considered as joined lenses. Unless otherwise specified, the signs of refractive power, radius of curvature, and surface shape associated with lenses including aspherical surfaces use 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 side is positive, and the radius of curvature of a surface with a convex shape facing the image side is negative.

[0049] In this specification, "the entire system" refers to the imaging lens. "Back focal length of the air-converted distance meter" is the air-converted distance along the optical axis from the image-side lens surface to the image plane when focusing on an object at infinity. The "focal length" used in the conditional formulas is the paraxial focal length. The values ​​used in the conditional formulas are based on the d-line.

[0050] The “d-line,” “C-line,” and “F-line” referred to 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, an imaging lens and a camera device having the imaging lens can be provided, wherein the imaging lens is configured to be small and lightweight and has good optical performance. Attached Figure Description

[0053] Figure 1This is a cross-sectional view showing the structure and beam of an imaging lens according to an embodiment corresponding to the imaging lens of Example 1.

[0054] Figure 2 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 1.

[0055] Figure 3 This is a diagram of the aberrations of the imaging lens in Example 1.

[0056] Figure 4 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 2.

[0057] Figure 5 This is a diagram of the aberrations of the imaging lens in Example 2.

[0058] Figure 6 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 3.

[0059] Figure 7 These are aberration diagrams of the imaging lens in Example 3.

[0060] Figure 8 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 4.

[0061] Figure 9 This is a diagram of the aberrations of the imaging lens in Example 4.

[0062] Figure 10 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 5.

[0063] Figure 11 This is a diagram of the aberrations of the imaging lens in Example 5.

[0064] Figure 12 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 6.

[0065] Figure 13 This is a diagram of the aberrations of the imaging lens in Example 6.

[0066] Figure 14 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 7.

[0067] Figure 15 This is a diagram of the aberrations of the imaging lens in Example 7.

[0068] Figure 16 This is a cross-sectional view showing the structure of the imaging lens in Embodiment 8.

[0069] Figure 17 This is a diagram of the aberrations of the imaging lens in Example 8.

[0070] Figure 18This is a perspective view of the front side of a camera device according to one embodiment.

[0071] Figure 19 This is a perspective view of the rear side of a camera device according to one embodiment.

[0072] Figure 20 This is a diagram used to illustrate the technique of pixel displacement.

[0073] Figure 21 This is a diagram used to illustrate the technique of pixel displacement.

[0074] Figure 22 This is a conceptual diagram used to illustrate an example of the combination of synthetic images and digital zoom.

[0075] Figure 23 This is another conceptual diagram used to illustrate the combination of synthetic images and digital zoom. Detailed Implementation

[0076] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0077] exist Figure 1 The diagram shows a cross-sectional view of the structure and light beam of an imaging lens according to an embodiment of the present invention in a state of focusing on an object at infinity. In this specification, "object at infinity" refers to an object whose distance along the optical axis Z is infinitely far from the object to the lens surface closest to the object side of the imaging lens. Figure 1 The beams shown are the on-axis beam, the beam at the intermediate image height, and the beam at the maximum image height. Figure 1 The example shown corresponds to the imaging lens of Embodiment 1 described later. Figure 1 In the image, the left side is the object side, and the right side is the image side.

[0078] exist Figure 1 The illustration shows an example assuming an imaging lens is used in a camera device and 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 cutoff 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.

[0079] Figure 1 The imaging lens, along the optical axis Z from the object side to the image side, sequentially includes a first lens group G1 that is fixed relative to the image plane Sim during focusing, and a focusing lens group Gf that moves along the optical axis Z during focusing. The lens group closest to the object side can be made larger in diameter, so by adopting the above structure, the imaging lens is conducive to miniaturization and weight reduction of the focusing drive mechanism. Figure 1The rightward arrow below the focusing lens group Gf indicates that when focusing from an object at infinity to a closer object, the focusing lens group Gf moves towards the image side.

[0080] As an example, Figure 1 The imaging lens is configured as follows. Figure 1 The imaging lens, from the object side to the image side, includes, in sequence, a first lens group G1 that is fixed relative to the image plane Sim during focusing, a focusing lens group Gf that moves along the optical axis Z during focusing, and a rear lens group GR that is fixed relative to the image plane Sim during focusing. The first lens group G1, from the object side to the image side, includes six lenses L11 to L16 and an aperture stop St. The focusing lens group Gf, from the object side to the image side, includes two lenses L21 to L22. The rear lens group GR, from the object side to the image side, includes six lenses L31 to L36. Additionally, Figure 1 The aperture stop St indicates the position along the Z-axis of the optical axis, not its size or shape.

[0081] exist Figure 1 In the example, only the focusing lens group Gf moves during focusing. Figure 1 In the example, during focusing, lenses L21 and L22, which constitute the focusing lens group Gf, move together along the optical axis Z. In this specification, "moves together" means moving simultaneously by the same amount in the same direction.

[0082] Hereinafter, the preferred structure and achievable structure of the imaging lens of this embodiment will be described. In addition, in the following description of the preferred structure and achievable structure, to avoid being too lengthy, "the imaging lens of this embodiment" will also be simply referred to as "imaging lens".

[0083] The focusing lens group Gf preferably has negative refractive power as a whole. This configuration helps to suppress chromatic aberration during focusing.

[0084] The focusing lens group Gf preferably includes two or fewer lenses. This configuration facilitates the reduction of the size of the focusing lens group Gf.

[0085] When a single lens element is configured as either a group of combined lenses or a single lens, the focusing lens group Gf can be structured as a single lens element continuously arranged with the aperture stop St. This configuration facilitates miniaturization and weight reduction of the focusing lens group Gf. When the focusing lens group Gf includes a combined lens obtained by joining a positive and a negative lens, it helps suppress chromatic aberration during focusing. When the focusing lens group Gf includes a single lens, miniaturization and weight reduction are also advantageous.

[0086] The first lens group G1 preferably has positive refractive power as a whole. With this configuration, it is beneficial to miniaturize the imaging lens in both the Z-axis and radial directions.

[0087] With the maximum image height set to Ymax and the focal length of the entire system set to f, the imaging lens preferably satisfies the following condition (1). f is set to the value when focusing on an object at infinity. By ensuring that the corresponding value of condition (1) is not below the lower limit, a wide angle of view can be ensured, thus making it easy to keep the subject from falling out of the field of view. By ensuring that the corresponding value of condition (1) is not above the upper limit, it is easy to further magnify the subject when shooting. 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).

[0088] 0.1 < Ymax / f < 0.26 (1)

[0089] 0.12 < Ymax / f < 0.23 (1-1)

[0090] 0.15 < Ymax / f < 0.21 (1-2)

[0091] With the focal length of the entire system set to f, and the sum of the distance along the optical axis Z from the object-side lens surface of the first lens group G1 to the image-side lens surface of the entire system and the back focal length of the air-converted distance meter set to TL, the imaging lens preferably satisfies the following condition (2). f and TL are set to values ​​when focusing on an object at infinity. By ensuring that the corresponding value of condition (2) is not below the lower limit, the light beam can converge smoothly from the object-side lens surface of the first lens group G1 toward the image plane Sim, thus helping to suppress spherical aberration. By ensuring that the corresponding value of condition (2) is not above the upper limit, it is beneficial to miniaturize the optical system. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (2-1), and even more preferably satisfies the following condition (2-2).

[0092] 0.4 < TL / f < 1.1 (2)

[0093] 0.43 < TL / f < 0.92 (2-1)

[0094] 0.5 < TL / f < 0.85 (2-2)

[0095] When the distortion aberration at 50% of the maximum image height is set to Dst5 and the distortion aberration at the maximum image height is set to Dst10, the imaging lens preferably satisfies the following condition (3). Dst5 and Dst10 are set as values ​​based on the d-line when focusing on an object at infinity. By ensuring that the corresponding value of condition (3) is not below the lower limit, the height of the off-axis beam passing through the lens surface closest to the object in the first lens group G1 can be suppressed, which is beneficial for miniaturization. By ensuring that the corresponding value of condition (3) is not above the upper limit, the distortion aberration in the imaging region from near the optical axis Z to the intermediate viewing angle can be suppressed, which is beneficial for improving the resolution in this region. For example, this is effective when creating an image in which the periphery of the imaging region is excluded and only an image composed of a viewing angle narrower than the maximum viewing angle of the imaging lens is cropped, as described later. 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).

[0096] 0.2 < |Dst5 / Dst10| < 0.6 (3)

[0097] 0.22<|Dst5 / Dst10|<0.5 (3-1)

[0098] 0.25<|Dst5 / Dst10|<0.4 (3-2)

[0099] When the distance along the optical axis Z from the image plane Sim to the exit pupil position is set as Pe, and the maximum image height is set as Ymax, the imaging lens preferably satisfies the following condition (4). Pe is set to the value when focusing on an object at infinity. Furthermore, regarding the sign of Pe, if the exit pupil position is located on the object side closer than the image plane Sim, it is set to positive; if the exit pupil position is located on the image side closer than the image plane Sim, it is set to negative. By ensuring that the corresponding value of condition (4) is not below the lower limit, the incident angle of the principal ray of the off-axis beam towards the image plane Sim can be suppressed, thus reducing the influence of the incident angle characteristics of the imaging element disposed on the image plane Sim in the imaging device. By ensuring that the corresponding value of condition (4) is not above the upper limit, the maximum diameter within the imaging lens can be easily reduced, thus facilitating miniaturization. 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).

[0100] 1.5 < Pe / Ymax < 3 (4)

[0101] 1.6 < Pe / Ymax < 2.9 (4-1)

[0102] 1.8 < Pe / Ymax < 2.7 (4-2)

[0103] The imaging lens preferably includes a negative lens on the image-side of the entire system. Furthermore, when the radius of curvature of the object-side surface of the negative lens is set to Rf and the radius of curvature of the image-side surface of the negative lens is set to Rr, the imaging lens preferably satisfies the following condition (5). By ensuring that the corresponding value of condition (5) is not below the lower limit, the refraction of the on-axis beam in the negative lens on the image-side is enhanced, thus facilitating the correction of spherical aberration. By ensuring that the corresponding value of condition (5) is not above the upper limit, the refraction effect exerted by the negative lens on the off-axis beam on the image-side is enhanced, thus facilitating the correction of image plane curvature. 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).

[0104] -0.6<(Rf-Rr) / (Rf+Rr)<-0.1 (5)

[0105] -0.58<(Rf-Rr) / (Rf+Rr)<-0.17 (5-1)

[0106] -0.55<(Rf-Rr) / (Rf+Rr)<-0.25 (5-2)

[0107] When the imaging lens includes a negative lens on the image-side of the entire system, it is preferable that the imaging lens continuously includes a positive lens on the object side of the negative lens. Furthermore, when the radius of curvature of the object-side surface of the negative lens is set to Rf and the radius of curvature of the image-side surface of the positive lens is set to Rpr, the imaging lens preferably satisfies the following condition (6). By ensuring that the corresponding value of condition (6) is not below the lower limit, the refraction of the on-axis beam between the negative and positive lenses is strengthened, thus facilitating the correction of on-axis chromatic aberration. By ensuring that the corresponding value of condition (6) is not above the upper limit, the refraction of the off-axis beam between the negative and positive lenses is strengthened, thus facilitating the correction of magnification chromatic aberration. To obtain even better characteristics, it is more preferable that the imaging lens satisfies the following condition (6-1), and even more preferably, it satisfies the following condition (6-2).

[0108] 0.03<(Rpr-Rf) / (Rpr+Rf)<0.4 (6)

[0109] 0.04<(Rpr-Rf) / (Rpr+Rf)<0.32 (6-1)

[0110] 0.07<(Rpr-Rf) / (Rpr+Rf)<0.27 (6-2)

[0111] The imaging lens includes a negative lens on the image-side of the entire system. When the Abbe number of the d-line reference of this negative lens is set to νn, the imaging lens preferably satisfies the following condition (7). By ensuring that the corresponding value of condition (7) is not below the lower limit, overcorrection of chromatic aberration can be suppressed. By ensuring that the corresponding value of condition (7) is not above the upper limit, good correction of chromatic aberration is beneficial. 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).

[0112] 12<νn<30 (7)

[0113] 14 < vn < 25 (7-1)

[0114] 17 < vn < 20 (7-2)

[0115] With the distance along the optical axis Z from the lens surface closest to the object side of the first lens group G1 to the lens surface closest to the image side of the first lens group G1 set to DG1, and the focal length of the entire system set to f, the imaging lens preferably satisfies the following condition (8). As an example, in Figure 1 DG1 is shown in the figure. f is set to the value when focusing on an object at infinity. By ensuring that the corresponding value of condition (8) is not below the lower limit, the axial chromatic aberration generated in the first lens group G1 can be easily and well corrected. By ensuring that the corresponding value of condition (8) is not above the upper limit, the first lens group G1 can be easily miniaturized, thereby facilitating weight reduction. In order to obtain better characteristics, the imaging lens more preferably satisfies the following condition (8-1), and even more preferably satisfies the following condition (8-2).

[0116] 0.02 < DG1 / f < 0.2 (8)

[0117] 0.04 < DG1 / f < 0.18 (8-1)

[0118] 0.07 < DG1 / f < 0.15 (8-2)

[0119] When the maximum half-angle of the imaging lens is set to ω, and the angle between the principal ray from the lens closest to the image side towards the maximum image height of the image plane Sim and the axis Zp parallel to the optical axis Z is set to ωi, the imaging lens preferably satisfies the following condition (9). tan is the tangent. ω and ωi are set to values ​​when focusing on an object at infinity. Furthermore, ωi is set to a value in air. As an example, in Figure 1ω, ωi, and Zp are shown. ω is the angle between the principal ray at maximum image height and the optical axis Z, and is half the maximum viewing angle 2ω. By ensuring that the corresponding value of condition (9) is not below the lower limit, it is beneficial to have a lens system structure with a viewing angle more suitable for telescope systems. By ensuring that the corresponding value of condition (9) is not above the upper limit, it is easy to reduce the maximum diameter inside the imaging lens, thus facilitating miniaturization. To obtain better characteristics, the imaging lens more preferably satisfies the following condition (9-1), and even more preferably satisfies the following condition (9-2).

[0120] 1.4<tanωi / tanω<3.6 (9)

[0121] 1.5<tanωi / tanω<3.3 (9-1)

[0122] 1.8<tanωi / tanω<2.9 (9-2)

[0123] When the maximum effective diameter of the lens surface closest to the object side of the first lens group G1 is set to φf and the maximum effective diameter of the lens surface closest to the image side of the entire system is set to φr, the imaging lens preferably satisfies the following condition (10). By ensuring that the corresponding value of condition (10) is not below the lower limit, the incident range of light rays incident on the imaging lens can be expanded, which is beneficial for reducing the F-value or increasing the amount of peripheral light. By ensuring that the corresponding value of condition (10) is not above the upper limit, the first lens group G1 can be made lighter, which allows the center of gravity of the imaging lens to be closer to the image side. 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).

[0124] 0.2<φf / φr<1.5 (10)

[0125] 0.3 < φf / φr < 1.4 (10-1)

[0126] 0.6 < φf / φr < 1.13 (10-2)

[0127] Furthermore, in the technology of this invention, the "maximum effective diameter" of the lens surface is defined as twice the distance from the point where the outermost ray of light incident from the object side onto the lens surface and emitted towards the image side intersects with the lens surface to the optical axis Z. Here, "outer side" refers to the radially outer side centered on the optical axis Z, i.e., the side furthest from the optical axis Z. Moreover, the "outermost ray" is determined considering the distances to all objects that can be focused.

[0128] With the back focal length of the air-to-ground distance meter of the entire system set to Bf and the maximum image height set to Ymax, the imaging lens preferably satisfies the following condition (11). Bf is set to the value when focusing on an object at infinity. By ensuring that the corresponding value of condition (11) is not below the lower limit, the height of off-axis rays passing through the lens closest to the image side of the entire system can be suppressed, thus reducing the diameter of the lens. This is beneficial for lightweight design. By ensuring that the corresponding value of condition (11) is not above the upper limit, it is beneficial for shortening the overall length. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (11-1), and even more preferably satisfies the following condition (11-2).

[0129] 0.4 < Bf / Ymax < 1.8 (11)

[0130] 0.5 < Bf / Ymax < 1.7 (11-1)

[0131] 0.8 < Bf / Ymax < 1.4 (11-2)

[0132] When the focal length of the first lens group G1 is set to f1 and the focal length of the entire system is set to f, the imaging lens preferably satisfies the following condition (12). f is set to the value when focusing on an object at infinity. By ensuring that the corresponding value of condition (12) is not below the lower limit, it is beneficial to correct spherical aberration generated in the first lens group G1. By ensuring that the corresponding value of condition (12) is not above the upper limit, it is beneficial to shorten the total length. 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).

[0133] 0.25 < f1 / f < 0.5 (12)

[0134] 0.27 < f1 / f < 0.48 (12-1)

[0135] 0.3 < f1 / f < 0.45 (12-2)

[0136] When the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf with negative refractive power, and a rear lens group GR that is fixed relative to the image plane Sim during focusing, the imaging lens preferably satisfies the following condition (13). Here, the focal length of the rear lens group GR is set to fR, and the focal length of the entire system when focusing on an object at infinity is set to f. By ensuring that the corresponding value of condition (13) is not below the lower limit, the negative refractive power of the rear lens group GR can be ensured, and therefore the negative refractive power of the focusing lens group Gf will not become excessive. This helps to suppress aberration variations during focusing. By ensuring that the corresponding value of condition (13) is not above the upper limit, the negative refractive power of the rear lens group GR can be suppressed, and therefore the negative refractive power of the focusing lens group Gf can be enhanced. This helps to suppress the amount of movement of the focusing lens group Gf during focusing. To obtain even better characteristics, the imaging lens more preferably satisfies the following condition (13-1), and even more preferably satisfies the following condition (13-2).

[0137] -0.9 < fR / f < -0.1 (13)

[0138] -0.8 < fR / f < -0.15 (13-1)

[0139] -0.4 < fR / f < -0.18 (13-2)

[0140] The imaging lens preferably includes an anti-shake assembly that corrects image shake by moving in a direction intersecting the optical axis Z. With this configuration, image shake caused by hand tremors and vibrations is corrected, thereby obtaining a good image. As will be described later, in imaging devices, when producing high-resolution images, the imaging element is sometimes moved to obtain multiple images; therefore, to correct image shake, it is preferable to move the lens without moving the imaging element.

[0141] As an example, Figure 1 The vibration damping assembly includes a combined lens obtained by joining lens L31 and lens L32. Figure 1 The double arrows pointing vertically below lenses L31 and L32 indicate that these lenses are vibration damping groups.

[0142] The vibration damping unit is preferably configured to have negative refractive power. This configuration helps to suppress chromatic aberration changes when correcting image jitter.

[0143] The vibration damping assembly preferably includes two or fewer lenses. This configuration facilitates the reduction of the size of the vibration damping assembly.

[0144] The vibration damping unit is preferably positioned closer to the image side than the focusing lens group Gf. This configuration helps suppress aberrations related to on-axis rays when correcting image jitter. The vibration damping unit can also be positioned closest to the object side of the rear lens group GR. This configuration facilitates miniaturization and weight reduction of the vibration damping unit.

[0145] When a single lens component is configured as either a group of combined lenses or a single lens, the vibration damping unit can be constructed to include a single lens component. This configuration facilitates miniaturization and weight reduction of the vibration damping unit. When the vibration damping unit includes a combined lens obtained by joining a positive and a negative lens, it helps suppress chromatic aberration variations during image jitter correction. When the vibration damping unit includes a single lens, miniaturization and weight reduction are also advantageous.

[0146] When the focal length of the anti-shake assembly is set to fv and the focal length of the entire system is set to f, the imaging lens preferably satisfies the following conditional expression (14). f is set to the value when focusing on an object at infinity. By ensuring that the corresponding value of conditional expression (14) is not below the lower limit, the refractive power of the anti-shake assembly can be enhanced, thus achieving a high anti-shake effect with minimal movement. By ensuring that the corresponding value of conditional expression (14) is not above the upper limit, the refractive power of the anti-shake assembly will not become excessively strong, thus helping to suppress aberration variations when correcting image shake. To obtain even better characteristics, the imaging lens more preferably satisfies the following conditional expression (14-1), and even more preferably satisfies the following conditional expression (14-2).

[0147] -0.35 < fv / f < -0.1 (14)

[0148] -0.33 < fv / f < -0.12 (14-1)

[0149] -0.3 < fv / f < -0.15 (14-2)

[0150] Figure 1 The example shown is one example of the imaging lens of the present invention. The number of lenses in each group constituting the imaging lens of the present invention can also be set to be the same as... Figure 1 The examples shown have different numbers of lenses. "First lens group", "focusing lens group", "rear lens group" and "vibration damping group" are not limited to structures that include multiple lenses, and can also be configured to include only one lens.

[0151] Including the structures related to the conditional expressions, the above-mentioned preferred structures and achievable structures can be combined arbitrarily, and are preferably selectively adopted appropriately according to the required specifications. Furthermore, the conditional expressions preferably satisfied by the imaging lens of the present invention are not limited to those described in formula form, but also include all conditional expressions obtained by arbitrarily combining the lower and upper limits from the preferred, more preferred, and even more preferred conditional expressions.

[0152] As an example, a preferred embodiment of the imaging lens of the present invention is an imaging lens that sequentially includes, from the object side to the image side, a first lens group G1 that is fixed relative to the image plane Sim during focusing and a focusing lens group Gf that moves along the optical axis Z during focusing, wherein the imaging lens satisfies the above-mentioned conditions (1) and (2).

[0153] 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 lens in the cross-sectional views of each embodiment are used independently in each embodiment to avoid complexity in the description and drawings caused by an increase in the number of reference numerals. Therefore, even if the same reference numerals are used in the drawings of different embodiments, they do not necessarily represent the same structure.

[0154] [Example 1]

[0155] A cross-sectional view of the structure of the imaging lens of Example 1 is shown. Figure 2 In Example 1, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0156] The first lens group G1, from the object side to the image side, consists of six lenses, L11 to L16, and an aperture stop St. The focusing lens group Gf, from the object side to the image side, consists of two lenses, L21 and L22. The rear lens group GR, from the object side to the image side, consists of six lenses, L31 to L36. The image stabilization group includes lens L31 and lens L32. Additionally, Figure 2 The aperture stop St indicates the position along the Z-axis of the optical axis, not its size or shape.

[0157] Regarding the imaging lens of Embodiment 1, basic lens data is shown in Table 1, specifications are shown in Table 2, and variable surface spacing is shown in Table 3. Furthermore, in Embodiment 1, a light-shielding member (not shown) having a circular opening centered on a point on the optical axis Z is positioned at a predetermined location to limit the height of light rays that can pass through.

[0158] Table 1 is described below. The Sn column shows the surface numbers when the surface closest to the object is designated as surface 1, and the numbers are increased sequentially towards the image side. The R column shows the radius of curvature of each surface. The D column shows the surface spacing along the optical axis Z between each surface and its image-side adjacent surface. The Nd column shows the refractive index of each component relative to the d-line. The vd column shows the Abbe number of each component based on the d-line. The VigD column shows the diameter of the opening in the row where the aforementioned light-shielding member is disposed.

[0159] 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 stop St and optical components PP. The surface number and the term (St) are recorded in the column corresponding to the aperture stop St. The bottom column of D in Table 1 represents the interval between the image-side surface and the image plane Sim. In Table 1, the variable surface interval during focusing is notated using DD[], with the object-side surface number of that interval marked in [] and recorded in column D.

[0160] Table 2 shows the focal length f, F-value FNo., maximum angle of view 2ω, and maximum image height Ymax for the entire system. The (°) in the 2ω column indicates the unit as degrees. Table 2 shows the values ​​when focusing on an object at infinity.

[0161] Table 3 shows the variable surface interval values ​​when focusing on an object at infinity in the "Infinity" column, and the variable surface interval values ​​when focusing on an object at a distance of 1.5m in the "1.5m" column. Tables 1, 2, and 3 show the values ​​with the d-line as the reference.

[0162] In the data in each table, degrees are used as the unit for angles and millimeters as the unit for lengths. However, optical systems can use both magnified and reduced scales, so other appropriate units may also be used. Furthermore, the tables below contain values ​​rounded to a predetermined number of decimal places.

[0163] [Table 1]

[0164] Example 1

[0165]

[0166]

[0167] [Table 2]

[0168] Example 1

[0169] FNo. 8.26 2ω(°) 20.8 Ymax 27.35

[0170] [Table 3]

[0171] Example 1

[0172] DD

[11] 1.5000 6.2666 DD

[14] 10.1295 5.3629

[0173] exist Figure 3 The diagram shows the aberrations of the imaging lens of Example 1 when focused on an object at infinity. Figure 3 In the diagram, from left to right, spherical aberration, astigmatism, distortion aberration, and chromatic aberration are shown. 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 chromatic aberration diagram, long dashed lines and short dashed lines represent aberrations along the C-line and F-line, respectively. In the spherical aberration diagram, the F-value is shown after "FNo.=". In the other aberration diagrams, the maximum half-angle value is shown after "ω=".

[0174] Unless otherwise specified, 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.

[0175] [Example 2]

[0176] A cross-sectional view of the imaging lens structure of Example 2 is shown. Figure 4 In Example 2, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0177] The first lens group G1 consists of six lenses, L11 to L16, and an aperture stop St, arranged sequentially from the object side to the image side. The focusing lens group Gf consists of two lenses, L21 and L22, arranged sequentially from the object side to the image side. The rear lens group GR consists of six lenses, L31 to L36, arranged sequentially from the object side to the image side. The vibration damping group includes lens L31 and lens L32.

[0178] Regarding the imaging lens of Example 2, the basic lens data is shown in Table 4, the specifications are shown in Table 5, the variable surface spacing is shown in Table 6, and the aberrations when focusing on an object at infinity are illustrated in Table 6. Figure 5 middle.

[0179] [Table 4]

[0180] Example 2

[0181]

[0182]

[0183] [Table 5]

[0184] Example 2

[0185] FNo. 6.49 2ω(°) 20.8 Ymax 27.35

[0186] [Table 6]

[0187] Example 2

[0188] DD

[11] 1.5002 6.2822 DD

[14] 10.4823 5.7003

[0189] [Example 3]

[0190] A cross-sectional view of the imaging lens structure of Example 3 is shown. Figure 6 In Example 3, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0191] The first lens group G1 consists of six lenses, L11 to L16, and an aperture stop St, arranged sequentially from the object side to the image side. The focusing lens group Gf consists of two lenses, L21 and L22, arranged sequentially from the object side to the image side. The rear lens group GR consists of six lenses, L31 to L36, arranged sequentially from the object side to the image side. The vibration damping group includes lens L31 and lens L32.

[0192] Regarding the imaging lens of Example 3, basic lens data is shown in Table 7, specifications are shown in Table 8, variable surface spacing is shown in Table 9, and aberrations when focusing on an object at infinity are illustrated in Table 1. Figure 7 middle.

[0193] [Table 7]

[0194] Example 3

[0195] 1 47.8459 1.6901 1.91082 35.25 2 118.7353 0.2410 3 20.8070 3.1975 1.49700 81.54 4 143.8807 1.1299 5 -58.5372 1.1918 1.74400 44.90 6 63.8317 2.5103 1.61772 49.81 7 -48.7631 0.9732 16.1 8 36.1443 1.5576 1.91082 35.25 9 12.5191 2.9269 1.49700 81.54 10 161.8530 1.1838 11 (St) ∞ DD

[11] 12 32.6928 3.9614 1.58267 46.61 13 -145.3491 0.7893 1.72916 54.67 14 21.1745 DD

[14] 11 15 -36.1318 1.4070 2.00330 28.32 16 -14.1613 1.1915 1.81600 46.55 17 33.4598 2.1918 18 27.9021 2.9994 1.57957 53.74 19 -18.1158 1.1837 1.71700 47.92 20 2482.9150 9.3643 21 62.7554 3.6648 1.77047 29.74 22 -47.5902 13.2688 23 -22.6381 1.1042 1.94595 17.98 24 -48.7260 22.3140 25 ∞ 3.2000 1.51680 64.20 26 ∞ 0.0000

[0196] [Table 8]

[0197] Example 3

[0198] FNo. 6.49 2ω(°) 22.2 Ymax 21.579

[0199] [Table 9]

[0200] Example 3

[0201] DD

[11] 1.1838 4.5141 DD

[14] 5.6462 2.3159

[0202] [Example 4]

[0203] A cross-sectional view of the imaging lens structure of Example 4 is shown. Figure 8 In Example 4, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0204] The first lens group G1 consists of six lenses, L11 to L16, and an aperture stop St, arranged sequentially from the object side to the image side. The focusing lens group Gf consists of two lenses, L21 and L22, arranged sequentially from the object side to the image side. The rear lens group GR consists of six lenses, L31 to L36, arranged sequentially from the object side to the image side. The vibration damping group includes lens L31 and lens L32.

[0205] Regarding the imaging lens of Example 4, the basic lens data is shown in Table 10, the specifications are shown in Table 11, the variable surface spacing is shown in Table 12, the aspherical coefficients are shown in Table 13, and the aberrations when focusing on an object at infinity are illustrated in Table 14. Figure 9 middle.

[0206] In the basic lens data, aspherical surfaces are marked with an asterisk (*), and the paraxial radius of curvature is recorded in the radius of curvature column. Table 13 shows the surface number of the aspherical surface in the Sn row, and the aspherical coefficient values ​​for each aspherical surface in the KA and Am rows. m is an integer greater than or equal to 3; for example, in surface 21 of Example 4, m = 4, 6, 8, and 10. The "E±n" (n: integer) value for the aspherical coefficients in Table 13 represents "×10". ±n KA and Am are the aspheric coefficients in the aspheric formula expressed below.

[0207] Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+∑Am×h m

[0208] in,

[0209] 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);

[0210] h: Height (distance from the optical axis Z to the lens surface);

[0211] C: The reciprocal of the paraxial radius of curvature;

[0212] KA, Am: Aspheric coefficients

[0213] In aspherical form, ∑ represents the summation related to m. Unless otherwise specified, the notation, meaning, and method of representation of aspherical coefficients are the same in the following examples.

[0214] [Table 10]

[0215] Example 4

[0216]

[0217]

[0218] [Table 11]

[0219] Example 4

[0220] FNo. 8.25 2ω(°) 19.8 Ymax 27.35

[0221] [Table 12]

[0222] Example 4

[0223] DD

[11] 1.5001 5.0833 DD

[14] 11.1792 7.5960

[0224] [Table 13]

[0225] Example 4

[0226] KA 1.0000000E+00 1.0000000E+00 A4 -4.4139451E-06 -1.1469551E-05 A6 4.5096851E-07 3.5960617E-07 A8 -5.4709270E-09 -3.6595035E-09 A10 2.6265152E-11 1.6525355E-11

[0227] [Example 5]

[0228] A cross-sectional view of the imaging lens structure of Example 5 is shown. Figure 10 In Example 5, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0229] The first lens group G1 consists of six lenses, L11 to L16, and an aperture stop St, arranged sequentially from the object side to the image side. The focusing lens group Gf consists of one lens, L21. The rear lens group GR consists of five lenses, L31 to L35, arranged sequentially from the object side to the image side. The vibration damping group includes lens L31.

[0230] Regarding the imaging lens of Example 5, basic lens data is shown in Table 14, specifications are shown in Table 15, variable surface spacing is shown in Table 16, and aberrations when focusing on an object at infinity are illustrated in Table 17. Figure 11 middle.

[0231] [Table 14]

[0232] Example 5

[0233] 1 52.8926 1.5145 1.91082 35.25 2 123.9441 0.0999 3 19.8428 3.7927 1.49700 81.54 4 142.0566 1.2131 5 -53.7057 1.5002 1.72916 54.68 6 58.1737 2.5690 1.54814 45.78 7 -41.2893 0.1346 16 8 40.5119 1.5834 1.91082 35.25 9 13.8266 3.1481 1.49700 81.54 10 116.2065 1.5005 11 (St) ∞ DD

[11] 12 33.1473 4.7492 1.70300 52.38 13 21.2486 DD

[13] 14 -124.2948 1.5001 1.77250 49.61 9.6 15 28.9818 1.6142 16 20.9913 3.7527 1.60342 38.03 17 -13.9523 1.5002 1.72916 54.68 18 44.6960 10.9657 19 62.5055 3.5148 1.84667 23.79 20 -79.2801 3.8686 21 -31.3257 1.4001 1.94595 17.98 22 -82.0545 35.6132 23 ∞ 3.2000 1.51680 64.20 24 ∞ 0.0000

[0234] [Table 15]

[0235] Example 5

[0236] FNo. 8.25 2ω(°) 20.8 Ymax 27.35

[0237] [Table 16]

[0238] Example 5

[0239] DD

[11] 1.8592 6.6239 DD

[13] 8.9229 4.1582

[0240] [Example 6]

[0241] A cross-sectional view of the imaging lens structure of Example 6 is shown. Figure 12 In Example 6, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0242] The first lens group G1 consists of six lenses, L11 to L16, and an aperture stop St, arranged sequentially from the object side to the image side. The focusing lens group Gf consists of one lens, L21. The rear lens group GR consists of six lenses, L31 to L36, arranged sequentially from the object side to the image side. The vibration damping group consists of lenses L31 and L32.

[0243] Regarding the imaging lens of Example 6, basic lens data is shown in Table 17, specifications are shown in Table 18, variable surface spacing is shown in Table 19, and aberrations when focusing on an object at infinity are illustrated in Table 10. Figure 13 middle.

[0244] [Table 17]

[0245] Example 6

[0246] 1 53.6674 1.5120 1.91082 35.25 2 125.3378 0.1004 3 19.9202 3.7965 1.49700 81.54 4 149.6770 1.1980 5 -53.9042 1.5005 1.71300 53.83 6 69.3397 2.5628 1.53172 48.85 7 -41.9773 0.1005 16 8 40.1036 1.5005 1.91082 35.25 9 13.5963 3.2522 1.49700 81.54 10 139.0641 1.5000 11 (St) ∞ DD

[11] 12 32.4925 4.7497 1.61309 60.61 13 20.5761 DD

[13] 14 -87.9760 2.2027 1.80610 33.27 9.6 15 -10.0417 1.5003 1.81600 46.55 16 29.5183 1.8977 17 25.3837 3.8321 1.59551 39.23 18 -16.6772 1.5001 1.69680 56.20 19 44.0247 7.5650 20 48.0163 5.0804 1.64769 33.84 21 -43.8702 3.9767 22 -29.9832 1.4005 1.94595 17.98 23 -73.7262 34.1033 24 ∞ 3.2000 1.51680 64.20 25 ∞ 0.0000

[0247] [Table 18]

[0248] Example 6

[0249] FNo. 8.25 2ω(°) 20.8 Ymax 27.35

[0250] [Table 19]

[0251] Example 6

[0252] DD

[11] 2.1894 7.3364 PP

[13] 9.2795 4.1326

[0253] [Example 7]

[0254] A cross-sectional view of the imaging lens structure of Example 7 is shown. Figure 14 In Example 7, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0255] The first lens group G1 consists of six lenses, L11 to L16, and an aperture stop St, arranged sequentially from the object side to the image side. The focusing lens group Gf consists of two lenses, L21 and L22, arranged sequentially from the object side to the image side. The rear lens group GR consists of six lenses, L31 to L36, arranged sequentially from the object side to the image side. The vibration damping group includes lens L31 and lens L32.

[0256] Regarding the imaging lens of Example 7, basic lens data is shown in Table 20, specifications are shown in Table 21, variable surface spacing is shown in Table 22, aspherical coefficients are shown in Table 23, and aberrations when focusing on an object at infinity are illustrated in Table 24. Figure 15 middle.

[0257] [Table 20]

[0258] Example 7

[0259] 1 54.7942 1.5004 1.91082 35.25 2 108.7645 0.0997 3 24.2556 2.9593 1.49700 81.54 4 783.5374 1.3941 5 -79.0677 1.5001 1.64000 60.21 6 383.3119 0.6500 1.59833 20.31 *7 490.4342 1.8522 8 42.0909 1.6651 1.90366 31.32 15 9 17.1830 3.1591 1.49700 81.54 10 -101.4058 2.8157 11 (St) ∞ DD

[11] 12 31.0121 2.7441 1.74693 51.01 13 15.0369 2.5103 1.56732 42.81 14 24.1060 DD

[14] 11 15 -78.5559 1.8375 1.85025 30.05 9 16 -10.7712 1.5099 1.81600 46.55 17 22.9573 1.9919 18 24.2583 4.1493 1.60342 38.01 19 -13.2263 1.5005 1.78800 47.52 20 47.0185 5.9424 21 47.2146 6.3316 1.62004 36.26 22 -29.7474 3.6742 23 -25.8573 1.3996 1.94595 17.98 24 -54.7644 32.0661 25 ∞ 3.2000 1.51680 64.20 26 ∞ 0.0000

[0260] [Table 21]

[0261] Example 7

[0262] FNo. 8.25 2ω(°) 20.6 Ymax 27.35

[0263] [Table 22]

[0264] Example 7

[0265] DD

[11] 2.0738 6.9041 DD

[14] 8.7158 3.8855

[0266] [Table 23]

[0267] Example 7

[0268] KA 1.0000000E+00 A3 0.0000000E+00 A4 -2.1272702E-06 A5 0.0000000E+00 A6 -3.1648017E-08 A7 0.0000000E+00 A8 1.0381418E-09 A9 0.0000000E+00 A10 -8.9155235E-12 A11 0.0000000E+00 A12 -3.4017350E-13 A13 0.0000000E+00 A14 8.9702198E-15 A15 0.0000000E+00 A16 -7.6335774E-17 A17 0.0000000E+00 A18 2.6597878E-19 A19 0.0000000E+00 A20 -8.1110642E-22

[0269] [Example 8]

[0270] A cross-sectional view of the structure of the imaging lens of Example 8 is shown. Figure 16 In Example 8, the imaging lens comprises, from the object side to the image side, a first lens group G1, a focusing lens group Gf, and a rear lens group GR. When focusing from an object at infinity to a closer object, the focusing lens group Gf moves as a whole towards the image side, while the first lens group G1 and the rear lens group GR remain fixed relative to the image plane Sim.

[0271] The first lens group G1 consists of five lenses, L11 to L15, and an aperture stop St, arranged sequentially from the object side to the image side. The focusing lens group Gf consists of one lens, L21. The rear lens group GR consists of six lenses, L31 to L36, arranged sequentially from the object side to the image side. The vibration damping group consists of lenses L31 and L32.

[0272] Regarding the imaging lens of Example 8, basic lens data is shown in Table 24, specifications are shown in Table 25, variable surface spacing is shown in Table 26, aspherical coefficients are shown in Table 27, and aberrations when focusing on an object at infinity are illustrated in Table 28. Figure 17 middle.

[0273] [Table 24]

[0274] Example 8

[0275] 1 34.8890 1.5003 1.64769 33.84 18 2 110.1558 0.0996 3 16.3772 3.4174 1.49700 81.54 4 -131.3364 0.0998 5 -165.4946 0.7496 1.80400 46.56 6 73.4562 1.7591 7 22.8923 0.7496 1.95375 32.32 8 10.7113 2.4289 1.49700 81.54 9 34.9713 1.6409 10 (St) ∞ DD

[10] 11 48.1940 0.7496 1.49700 81.54 12 25.4164 DD

[12] 13 -153.2728 1.4995 1.71736 29.51 8.4 14 -9.7557 0.7596 1.69680 56.20 15 21.4924 1.6790 16 18.0406 4.0098 1.60342 38.03 17 -11.9910 0.7500 1.75500 52.34 18 51.5332 1.4996 *19 -158.6476 2.0394 1.73077 40.51 *20 -22.6813 6.2159 21 -13.0096 0.9996 1.94595 17.98 22 -24.4761 34.8473 23 ∞ 3.2000 1.51680 64.20 24 ∞ 0.0000

[0276] [Table 25]

[0277] Example 8

[0278] FNo. 8.27 2ω(°) 20.0 Ymax 27.35

[0279] [Table 26]

[0280] Example 8

[0281] DD

[10] 2.8502 4.8599 DD

[12] 11.0620 9.0523

[0282] [Table 27]

[0283] Example 8

[0284] KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 -2.1205300E-05 -3.8823667E-05 A5 1.8044024E-06 5.9301000E-06 A6 9.0456964E-07 -9.1042134E-07 A7 2.2148081E-08 1.7532241E-07 A8 -4.7325902E-08 1.9758712E-09 A9 6.0374595E-09 -5.0642656E-09 A10 1.0529713E-10 5.4447896E-10 A11 -1.0817473E-11 1.0840451E-11 A12 -2.3351531E-13 2.3179875E-13 A13 5.9108346E-15 -8.0529223E-15 A14 5.8926615E-16 -8.8052875E-17 A15 2.0548262E-18 -8.4284292E-18 A16 1.1384101E-21 -2.4878280E-21 A17 -5.0892911E-24 2.0106766E-23 A18 0.0000000E+00 3.6697955E-25 A19 0.0000000E+00 -1.6079158E-27 A20 0.0000000E+00 -3.1199616E-29

[0285] Table 28 shows the corresponding values ​​of conditional expressions (1) to (14) for the imaging lens of the above embodiment. Table 28 shows the values ​​with the d-line as the reference.

[0286] [Table 28]

[0287] (1) Ymax / f 0.1880 0.1880 0.2030 0.1880 (2) TL / f 0.6765 0.6764 0.8355 0.6244 (3) |Dst5 / Dst10| 0.3684 0.4207 0.2735 0.2635 (4) Pe / Ymax 2.5005 2.4448 2.5867 2.0389 (5) (Rf-Rr) / (Rf+Rr) -0.3551 -0.2952 -0.3656 -0.5263 (6) (Rpr-Rf) / (Rpr+Rf) 0.2220 0.1766 0.3553 0.2508 (7) vn 17.98 17.98 17.98 17.98 (8) DG1 / f 0.1061 0.1214 0.1448 0.1061 (9) tanωi / tanω 1.9947 1.9391 1.8629 2.8059 (10) φf / φr 0.9967 0.8641 0.8259 1.0882 (11) Bf / Ymax 1.3198 1.1754 1.1320 1.3197 (12) f1 / f 0.3468 0.3555 0.4192 0.3533 (13) fR / f -0.3293 -0.3545 -0.7822 -0.3110 (14) fv / f -0.1851 -0.1676 -0.2385 -0.2715

[0288] (1) Ymax / f 0.1880 0.1880 0.1880 0.1883 (2) TL / f 0.6764 0.6764 0.6609 0.5751 (3) |Dst5 / Dst10| 0.3054 0.3851 0.4036 0.2597 (4) Pe / Ymax 2.5229 2.4882 2.4008 2.0087 (5) (Rf-Rr) / (Rf+Rr) -0.4474 -0.4218 -0.3586 -0.3059 (6) (Rpr-Rf) / (Rpr+Rf) 0.4336 0.1880 0.0700 0.2710 (7) vn 17.98 17.98 17.98 17.98 (8) DG1 / f 0.1069 0.1067 0.1016 0.0744 (9) tanωi / tanω 2.0327 2.0065 2.0506 2.8120 (10) φf / φr 0.7686 0.7430 0.6640 1.0309 (11) Bf / Ymax 1.3793 1.3241 1.2496 1.3513 (12) f1 / f 0.3472 0.3371 0.3086 0.3109 (13) fR / f -0.3203 -0.2917 -0.2352 -0.2048 (14) fv / f -0.2082 -0.1793 -0.1571 -0.1959

[0289] Next, the imaging device according to the embodiments of the present invention will be described. Figure 18 and Figure 19 The diagram shows the external appearance of the camera 30 of the imaging device according to one embodiment of the present invention. Figure 18 This is a stereoscopic view of camera 30 viewed from the front side. Figure 19 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, 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. The imaging lens 1 forms an optical image of the subject.

[0290] 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, according to the user's operation, a live view image of the subject within the field of view before shooting, an image captured by pressing the shutter button 32, recorded images, and various other information.

[0291] A photographic opening for light from the subject is provided in the center of the front surface of the camera body 31. A bayonet 37 is provided at the position corresponding to the photographic opening, and the interchangeable lens 20 is mounted on the camera body 31 via the bayonet 37.

[0292] The camera 30 includes an imaging element 38 within the camera body 31. The imaging element 38 captures an optical image formed by the imaging lens 1 and outputs a signal representing the captured image. The imaging element 38 can be, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging element 38 has a two-dimensional imaging area 38A (see reference) composed of multiple pixels that convert the received light into an electrical signal through photoelectric conversion. Figure 20 and Figure 22The imaging area 38A has a size capable of capturing an optical image corresponding to the maximum angle of view of the imaging lens 1. The imaging element 38 is configured such that its imaging surface is aligned with the image surface Sim of the imaging lens 1. Furthermore, the term "aligned" here also includes allowable errors in practical use. In this configuration, the maximum value of the angle of view that can be captured across the entire area of ​​the imaging area 38A is called the maximum imaging angle of the imaging element 38.

[0293] The camera 30 has a processor (not shown) within the camera body 31 that performs various processes such as image processing and output processing. The processor processes the signal of the captured image output from the imaging element 38. For example, as an image processor, in addition to performing image correction processing, the processor also performs compositing processing to create a composite image by combining multiple captured images. Furthermore, the processor creates a storage image based on the captured image and the composite image, and performs output processing to record the created storage image onto a recording medium such as a memory card. Moreover, the processor creates a display image based on the captured image and the composite image, and performs output processing to display the created display image on the display unit 36.

[0294] Furthermore, the processor can create an image with a viewing angle narrower than the maximum viewing angle of the imaging element 38, and output this image as a display image and a storage image. This is the so-called digital zoom function, and it is possible to output an image corresponding to a magnified image of a portion of the optical image through digital zoom. When creating a narrow-viewing-angle image, it is preferable to exclude high-viewing-angle regions with relatively large aberrations in the optical image and use low-viewing-angle regions including the optical axis Z with relatively small aberrations. However, even with such region selection, the magnified image obtained by digital zoom using only one captured image will have a lower resolution compared to the captured image. Therefore, in order to obtain a high-resolution image, it is preferable, for example, to use a combination of composite image and digital zoom as described below.

[0295] First, as an example of compositing processing for creating composite images, a compositing process using a technique called pixel displacement will be explained. Pixel displacement is generally a technique aimed at increasing the resolution of an image. The pixel displacement technique involves acquiring multiple images by moving the imaging element 38 in a direction orthogonal to the optical axis Z of the imaging lens 1, i.e., parallel to the imaging plane, while taking pictures at multiple positions during the displacement. The compositing process using the pixel displacement technique involves combining the multiple images acquired through pixel displacement to obtain a composite image with a resolution higher than that of the original images. Regarding the compositing process using the pixel displacement technique, as an example, when using a color sensor having an imaging area 38A with pixels arranged to correspond to red (R), green (G), and blue (B) as the imaging element 38, such as... Figure 20 and Figure 21 As shown.

[0296] like Figure 20 As shown, multiple RGB pixels are arranged in two dimensions in the imaging area 38A of the imaging element 38. Figure 20 An example is the Bayer pixel arrangement, where in a region of four adjacent cubic pixels, two G pixels are arranged diagonally, and one B and one R pixel are arranged diagonally on the other side. Figure 20 A portion of the camera area 38A is shown in the image.

[0297] Thus, since the RGB pixels are arranged in a two-dimensional pattern in the imaging area 38A, it is not possible to obtain the signal of any one of the three colors (RGB) at the position of each pixel. Figure 20 The processing shown is for obtaining the RGB color signals at the position of each pixel using pixel shifting technology. More precisely, as... Figure 20 As shown, the imaging element 38 is shifted by one pixel each, corresponding to the cubic arrangement of four pixels: R pixel × 1, G pixel × 2, and B pixel × 1, thereby acquiring image data at four different shifted positions. Figure 20 In the text, the displacement of the imaging element 38 is represented as "1 pixel", and the direction of displacement is indicated by an arrow.

[0298] exist Figure 20 In the diagram, if the leftmost position is set as the reference position for camera area 38A, then the second displacement position from the left is one pixel away from the reference position in the left direction of the image. The third displacement position is one pixel away from the second displacement position in the downward direction of the image. The fourth displacement position is one pixel away from the third displacement position in the right direction of the image. Figure 20The camera images 40-1 to 40-4 are images captured at four positions, including a reference position and various displacement positions. If we focus on four pixels at the same position in the four camera images 40-1 to 40-4, they become combinations of 1 R pixel, 2 G pixels, and 1 B pixel, respectively. Therefore, it is possible to obtain accurate color signals including all three colors (RGB) at a single pixel position, rather than a monochrome signal. Figure 20 The four images shown, 40-1 to 40-4, are called the four-image set ST40.

[0299] Figure 21 This is an illustration of pixel displacement for the purpose of achieving higher resolution. The resolution of the captured image is determined by the number of pixels within the capture area 38A. Figure 21 The processing shown is as follows: by displacing the imaging element 38 in a direction orthogonal to the optical axis Z by half the distance between adjacent pixels, i.e., 0.5 pixels, image sets ST40 are acquired at four displaced positions. Figure 21 In the text, the displacement of the imaging element 38 is expressed as "0.5 pixels," and the direction of displacement is indicated by an arrow. Additionally, in... Figure 21 In order to avoid complicating the accompanying drawings, the illustration of the camera area 38A is omitted, and the location of the camera area 38A is shown at the location of image set ST40.

[0300] exist Figure 21 In the image, if the leftmost position is set as the reference position of camera area 38A (represented by image set ST40), then the second displacement position from the left is a position shifted 0.5 pixels to the right from the reference position in the image. The third displacement position is a position shifted 0.5 pixels upwards from the second displacement position in the image. The fourth displacement position is a position shifted 0.5 pixels to the left from the third displacement position in the image. Figure 21 Also performed at each displacement position shown Figure 20 The pixel displacement shown is thus achieved by performing... Figure 21 The pixel shift shown is used to acquire an image set ST40 consisting of four camera images 40-1 to 40-4. Figure 21 The four image sets ST40 shown are acquired at each displacement position, specifically at a position with a displacement of 0.5 pixels. In camera 30, the processor generates a composite image 42 by combining a total of 16 captured images included in the four image sets ST40. The composite image 42 is a high-definition image with a resolution four times that of the captured images included in each image set ST40.

[0301] As an example, in Figure 22 The diagram shows a concept illustration of the combination of the aforementioned composite image 42 and digital zoom. Figure 22 The main focus is on showing the approximate size of each image. Figure 22 The leftmost column shows the imaging region 38A corresponding to the maximum imaging angle of the imaging element 38. From... Figure 22 The second column from the left shows multiple photographic images 40 captured by the imaging element 38. These multiple photographic images 40 are 16 images obtained using the pixel shift technique described above. The camera 30 synthesizes these 16 images 40 to create a composite image 42. The camera 30 then crops a portion from the composite image 42, outputting a composite image 42A with a narrower field of view than the maximum viewing angle, as a saved image 44.

[0302] Obtained through the aforementioned pixel displacement technique Figure 22 The composite image 42 is an image with a higher resolution than the photographed image 40. An enlarged image obtained without this composite processing, using only digital zoom of a single photographed image, would have a lower resolution compared to the photographed image 40. However, by combining the composite image 42 and digital zoom, the user can be shown an enlarged image whose resolution is not lower than that of the photographed image 40.

[0303] exist Figure 23 The text shows the connection between... Figure 22 Different methods are used to output images 44 with a narrower field of view than the maximum camera angle. Figure 22 Compared to the example, in Figure 23 In the example, the camera acquires multiple video images in 30 seconds to replace... Figure 22 The example uses multiple captured images 40. Captured images 40S are 16 captured images obtained using the pixel shift technique described above, and are captured in region 38B, a portion of the imaging region 38A of the imaging element 38. Therefore, captured images 40S are captured images with a viewing angle narrower than the maximum viewing angle of the imaging element 38. The camera 30 combines the multiple captured images 40S to create a composite image 42A with a viewing angle narrower than the maximum viewing angle, and outputs the composite image 42A as a saved image 44. Figure 23 In this method, by combining the above-mentioned composite image 42A and digital zoom, the user can be prompted with a magnified image whose resolution has not been reduced compared to the captured image 40S.

[0304] Furthermore, the above example is just one instance; the displacement of the imaging element in the technique for generating composite images, including the number of camera images and pixel displacement, can also be set to a different value than in the above example.

[0305] 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.

[0306] Furthermore, the imaging device involved in the embodiments of the present invention is not limited to the above examples, and can be configured in various ways, such as a camera other than a mirrorless camera, a film camera, and a video camera.

[0307] All documents, patent applications and technical standards described in this specification, and the specific and separately described documents, patent applications and technical standards incorporated herein by reference, are incorporated herein by reference to the same extent.

Claims

1. An imaging lens, comprising, from the object side to the image side, a first lens group having positive refractive power and fixed relative to the image plane during focusing, a focusing lens group having negative refractive power and moving along the optical axis during focusing, and a rear lens group having negative refractive power and fixed relative to the image plane during focusing. Set the maximum image height to Ymax. Let f be the focal length of the entire system when focusing on an object at infinity. Let TL be the sum of the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the entire system, when the lens is focused on an object at infinity, and the back focal length of the air-converted distance meter. When the focal length of the rear lens group is set to fR... The imaging lens satisfies 0.1 < Ymax / f < 0.26 (1) 0.4 < TL / f < 1.1 (2) -0.9 < fR / f < -0.1 (13) The conditions (1), (2) and (13) are represented.

2. The imaging lens according to claim 1, wherein, When focusing on an object at infinity, the distortion aberration at 50% of the maximum image height is set to Dst5. Furthermore, when the distortion aberration at the maximum image height is set to Dst10 when focusing on an object at infinity, The imaging lens satisfies 0.2<|Dst5 / Dst10|<0.6 (3) The conditional expression (3) is represented.

3. The imaging lens according to claim 1 or 2, wherein, Let Pe be the distance along the optical axis from the image plane to the exit pupil when the image is focused on an object at infinity. Regarding the sign of Pe, if the position of the exiting pupil is located closer to the object side than the image plane, it is set to positive; if the position of the exiting pupil is located closer to the image side than the image plane, it is set to negative. The imaging lens satisfies 1.5 < Pe / Ymax < 3 (4) The conditional expression (4) is represented.

4. The imaging lens according to claim 1 or 2, wherein, The negative lens is located on the image-side. Let the radius of curvature of the object-side surface of the negative lens be Rf. Furthermore, if the radius of curvature of the image-side surface of the negative lens is set to Rr, The imaging lens satisfies -0.6<(Rf-Rr) / (Rf+Rr)<-0.1 (5) The conditional expression (5) is represented.

5. The imaging lens according to claim 4, wherein, A positive lens is continuously included on the object side of the negative lens. When the radius of curvature of the image-side surface of the positive lens is set to Rpr, The imaging lens satisfies 0.03<(Rpr-Rf) / (Rpr+Rf)<0.4 (6) The conditional expression (6) is represented.

6. The imaging lens according to claim 4, wherein, When the Abbe number of the d-line reference of the negative lens is set to νn, The imaging lens satisfies 12<νn<30 (7) The conditional expression (7) is represented.

7. The imaging lens according to claim 1 or 2, wherein, If the distance along the optical axis from the lens surface closest to the object side of the first lens group to the lens surface closest to the image side of the first lens group is set to DG1, The imaging lens satisfies 0.02 < DG1 / f < 0.2 (8) The conditional expression (8) is represented.

8. The imaging lens according to claim 1 or 2, wherein, When focusing on an object at infinity, the maximum half-angle of view is set to ω. Furthermore, when focusing on an object at infinity, the angle between the principal ray from the lens closest to the image plane to the maximum image height and the axis parallel to the optical axis is set as ωi. The imaging lens satisfies 1.4<tanωi / tanω<3.6 (9) The conditional expression (9) is represented.

9. The imaging lens according to claim 1 or 2, wherein, The maximum effective diameter of the lens surface closest to the object in the first lens group is set as φf. And if the maximum effective diameter of the lens surface closest to the image side of the entire system is set to φr, The imaging lens satisfies 0.2<φf / φr<1.5 (10) The conditional expression (10) is represented.

10. The imaging lens according to claim 1 or 2, wherein, When the back focal length of the air-converted distance meter is set to Bf while focusing on an object at infinity, The imaging lens satisfies 0.4 < Bf / Ymax < 1.8 (11) The conditional expression (11) is represented.

11. The imaging lens according to claim 1, wherein, The focusing lens group includes two or fewer lenses.

12. The imaging lens according to claim 1 or 2, wherein, When the focal length of the first lens group is set to f1... The imaging lens satisfies 0.25 < f1 / f < 0.5 (12) The conditional expression (12) is represented.

13. The imaging lens according to claim 1, wherein, The imaging lens is mounted on the camera device. The camera device has an imaging element that captures an optical image formed by the imaging lens, and is capable of outputting an image with a viewing angle narrower than the maximum viewing angle of the imaging element.

14. The imaging lens according to claim 2, wherein, The imaging lens is mounted on the camera device. The camera device has an imaging element that captures an optical image formed by the imaging lens, and is capable of outputting an image with a viewing angle narrower than the maximum viewing angle of the imaging element.

15. The imaging lens according to claim 14, wherein, The camera device uses a composite image obtained by combining multiple images captured by the imaging element to output an image with a narrower field of view than the maximum field of view of the imaging element.

16. The imaging lens according to claim 1, wherein, The imaging lens is mounted on the camera device. The camera device includes an imaging element that captures an optical image formed by the imaging lens, and uses a composite image obtained by combining multiple images captured by the imaging element to output an image with a narrower field of view than the maximum field of view of the imaging element.

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

Images