Imaging lens and camera device

Abstract

The present application provides a kind of wide-angle imaging lens of small and good optical performance and camera device with the imaging lens. Imaging lens includes 1st lens group, 2nd lens group with positive refractive power and 3rd lens group with negative refractive power from object side to image side in sequence. 1st lens group includes two pieces of negative lens and positive lens from the most object side to image side in sequence continuously. 2nd lens group includes positive lens and negative lens. In the case of focusing from infinity object to nearest object, 1st lens group is fixed relative to image plane, and 2nd lens group moves along optical axis. Predetermined condition formula is satisfied.

Description

Technical Field

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

[0002] Previously, lens systems described in Patent Documents 1 and 2 were known as imaging lenses.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-146607

[0004] Patent Document 2: Japanese Patent Application Publication No. 2017-156431

[0005] In recent years, there has been a demand for a small, wide-angle imaging lens with good optical performance. Summary of the Invention

[0006] The present invention was made in view of the above circumstances, and its object is to provide a small wide-angle imaging lens with good optical performance and a camera device having the imaging lens.

[0007] The imaging lens of the present invention comprises, from the object side to the image side, a first lens group, a second lens group with positive refractive power, and a third lens group with negative refractive power. The first lens group comprises two negative lenses and a positive lens in sequence from the object side to the image side. The second lens group comprises a positive lens and a negative lens. When focusing from an object at infinity to the nearest object, the first lens group is fixed relative to the image plane, and the second lens group moves along the optical axis. 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 the following conditional expression (1).

[0008] -0.5 < f2 / f1 < 0.5 (1)

[0009] Furthermore, in the imaging lens of the present invention, it is preferable that when the focal length of the third lens group is set to f3, the imaging lens satisfies the following condition (2).

[0010] 1 < |f3 / f2| < 3 (2)

[0011] Furthermore, in the imaging lens of the present invention, it is preferable that the distance on the optical axis from the lens surface closest to the object to the lens surface closest to the image, when the object is focused at infinity, is set to TTL, and the imaging lens satisfies the following condition (3).

[0012] -0.1 < TTL / f1 < 0.55 (3)

[0013] Furthermore, in the imaging lens of the present invention, it is preferable that when the focal length of the imaging lens is set to fA in the state of focusing on an object at infinity, the imaging lens satisfies the following conditional expression (4).

[0014] -0.1 < fA / f1 < 0.2 (4)

[0015] Furthermore, in the imaging lens of the present invention, preferably, the first lens group includes, sequentially from the object side to the image side, a negative lens with its convex surface facing the object side, a biconcave lens, and a plurality of single lenses with positive refractive power, and the lens surface of the first lens group with its image side closest to the image side is convex.

[0016] Furthermore, in the imaging lens of the present invention, the second lens group preferably includes a combined lens formed by combining a negative lens and a positive lens, and a single lens with positive refractive power disposed on the image side of the combined lens.

[0017] Furthermore, in the imaging lens of the present invention, preferably, the second lens group includes multiple groups of combined lenses formed by combining negative lenses and positive lenses, and a single lens having positive refractive power.

[0018] Furthermore, in the imaging lens of the present invention, the second lens group preferably includes an aperture.

[0019] Furthermore, in the imaging lens of the present invention, the third lens group preferably includes a positive lens and a negative lens.

[0020] Furthermore, in the imaging lens of the present invention, it is preferable that when the focal length of the third lens group is set to f3, the imaging lens satisfies the following conditional expression (5).

[0021] -1 < f3 / f1 < 0.5 (5)

[0022] Furthermore, in the imaging lens of the present invention, it is preferable that the refractive index of the lens closest to the object side is 1.7 or more relative to the d-line, and the dispersion coefficient of the second lens from the object side as a reference to the d-line is 60 or more.

[0023] Furthermore, in the imaging lens of the present invention, it is preferable that the average value of the dispersion coefficients of the d-line reference of the lens closest to the object side and the second lens from the object side is set to ν12, and the dispersion coefficient of the d-line reference of the third lens from the object side is set to ν3, and the imaging lens satisfies the following conditional expression (6).

[0024] 25<ν12-ν3<45 (6)

[0025] Furthermore, in the imaging lens of the present invention, it is preferable that when the lateral magnification of the second lens group is set to β2 when the object is focused on at infinity, and the lateral magnification of the third lens group is set to β3 when the object is focused on at infinity, the imaging lens satisfies the following conditional expression (7).

[0026] 1.5 < (1-β2) 2 )×β3 2 <2.5 (7)

[0027] Furthermore, in the imaging lens of the present invention, it is preferable that when the lateral magnification of the third lens group is set to β3 in the state of focusing on an object at infinity, the imaging lens satisfies the following conditional expression (8).

[0028] 1.4 < β3 < 1.55 (8)

[0029] Furthermore, in the imaging lens of the present invention, it is preferable that when the radius of curvature of the object-side surface of the lens closest to the object is set to R11 and the radius of curvature of the image-side surface of the lens closest to the object is set to R12, the imaging lens satisfies the following conditional expression (9).

[0030] -1<(R12-R11) / (R12+R11)<-0.5 (9)

[0031] Furthermore, in the imaging lens of the present invention, it is preferable that when the radius of curvature of the object-side surface of the second lens from the object side is set to R21 and the radius of curvature of the image-side surface of the second lens from the object side is set to R22, the imaging lens satisfies the following conditional expression (10).

[0032] -1.5<(R22+R21) / (R22-R21)<0.1 (10)

[0033] Furthermore, in the imaging lens of the present invention, it is preferable that the second lens group includes an aperture and has a lens at a position adjacent to the object side and the image side of the aperture. When the radius of curvature of the image side surface of the lens adjacent to the object side of the aperture is set to Rstf and the radius of curvature of the object side surface of the lens adjacent to the image side of the aperture is set to Rstr, the imaging lens satisfies the following conditional expression (11).

[0034] -1<(Rstr-Rstf) / (Rstr+Rstf)<-0.3 (11)

[0035] Furthermore, in the imaging lens of the present invention, it is preferable that the second lens group includes an aperture and has lenses on the object side and image side of the aperture. When the combined focal length of all lenses in the second lens group that are closer to the object side than the aperture is set to f2f and the combined focal length of all lenses in the second lens group that are closer to the image side than the aperture is set to f2r, the imaging lens satisfies the following conditional expression (12).

[0036] 0 < f2f / f2r < 2.5 (12)

[0037] Furthermore, in the imaging lens of the present invention, preferably, when a lens component is set as a single lens or a combined lens, the distance on the optical axis from the image-side surface of the second lens component of the second lens group to the object-side surface of the image-side lens component of the second lens group is set as dd, and the distance on the optical axis from the object-side lens surface of the second lens group to the image-side lens surface of the second lens group is set as TTL2, the imaging lens satisfies the following conditional expression (13).

[0038] 0.09 < dd / TTL2 < 0.17 (13)

[0039] The camera device of the present invention includes the imaging lens of the present invention.

[0040] 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.

[0041] "A group with positive refractive power" means that the group as a whole has positive refractive power, and "a group with negative refractive power" means that the group as a whole has negative refractive power. "A lens with positive refractive power", "a positive lens", and "a positive lens" have the same meaning, as do "a lens with negative refractive power", "a negative lens", and "a negative lens".

[0042] "Single lens" refers to an unjoined lens. However, a compound aspherical lens (a lens in which a spherical lens and an aspherical film formed on the spherical lens are integrated to function as a single aspherical lens) is used as a single lens and not considered a joined lens. Regarding lenses including aspherical surfaces, unless otherwise specified, the sign of the refractive power, the radius of curvature of the lens surface, and the surface shape of the lens surface are assumed to be considered in the paraxial region. Regarding the sign of the radius of curvature, the radius of curvature of the surface with a convex shape facing the object is set to positive, and the radius of curvature of the surface with a convex shape facing the image is set to negative.

[0043] 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, with the wavelength of the d-line being 587.56 nm, the wavelength of the C-line being 656.27 nm, and the wavelength of the F-line being 486.13 nm.

[0044] Invention Effects

[0045] According to the present invention, a small wide-angle imaging lens with good optical performance and a camera device having the imaging lens can be provided. Attached Figure Description

[0046] Figure 1 This is a cross-sectional view showing the structure and optical path of an imaging lens (the imaging lens of Embodiment 1) according to one embodiment.

[0047] 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.

[0048] Figure 3 This is a lateral aberration diagram of the imaging lens in Example 1.

[0049] Figure 4 This is a cross-sectional view showing the structure and optical path of the imaging lens in Embodiment 2.

[0050] Figure 5 These are the spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and magnification chromatic aberration diagram of the imaging lens in Example 2.

[0051] Figure 6 This is a lateral aberration diagram of the imaging lens in Example 2.

[0052] Figure 7 This is a cross-sectional view showing the structure and optical path of the imaging lens in Embodiment 3.

[0053] Figure 8 These are the spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and magnification chromatic aberration diagram of the imaging lens in Example 3.

[0054] Figure 9 This is a lateral aberration diagram of the imaging lens in Example 3.

[0055] Figure 10 This is a cross-sectional view showing the structure and optical path of the imaging lens in Embodiment 4.

[0056] Figure 11 These are the spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and magnification chromatic aberration diagram of the imaging lens in Example 4.

[0057] Figure 12 This is a lateral aberration diagram of the imaging lens in Example 4.

[0058] Figure 13 This is a cross-sectional view showing the structure and optical path of the imaging lens in Embodiment 5.

[0059] Figure 14 These are the spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and magnification chromatic aberration diagram of the imaging lens in Example 5.

[0060] Figure 15 This is a lateral aberration diagram of the imaging lens in Example 5.

[0061] Figure 16 This is a perspective view of the front side of a camera device according to one embodiment.

[0062] Figure 17 This is a perspective view of the rear side of a camera device according to one embodiment. Detailed Implementation

[0063] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a diagram showing the structure and optical path of an imaging lens according to an embodiment of the present invention, including a cross-section along the optical axis Z, corresponding to the lens structure 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, showing the state of focusing on an object at infinity. Furthermore, as a light beam, Figure 1 The image also shows the on-axis beam 2 and the beam 3 with the maximum viewing angle.

[0064] In addition, Figure 1 The image illustrates an example where, assuming the imaging lens is suitable for a camera device, a parallel flat optical component PP is positioned between the imaging lens and the image plane (Sim). The optical component PP is assumed to be a component such as various filters and / or cover glass. These filters include, 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.

[0065] The imaging lens of the present invention comprises, along the optical axis Z from the object side to the image side, a first lens group G1, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. As an example, in... Figure 1 In the imaging lens shown, the first lens group G1 consists of four lenses, L11 to L14, arranged sequentially from the object side to the image side. The second lens group G2 consists of five lenses, L21 to L25, arranged sequentially from the object side to the image side. The third lens group G3 consists of four lenses, L31 to L34, arranged sequentially from the object side to the image side.

[0066] In the imaging lens of the present invention, when focusing from an object at infinity to the nearest object, the first lens group G1 is fixed relative to the image plane Sim, and the second lens group G2 moves along the optical axis Z. Figure 1 The image shows an example where the second lens group G2 moves toward the object side when focusing from an object at infinity to the nearest object. Figure 1 The arrow pointing to the left on the lower side of the second lens group G2 shown indicates that when focusing from an object at infinity to the nearest object, the second lens group G2 is a focusing group that moves towards the object. Hereinafter, the lens group that moves during focusing will be referred to as the "focusing group".

[0067] Alternatively, it can be configured such that, during focusing, in addition to the second lens group G2, the third lens group G3 also moves. By setting the focusing group to the second lens group G2 or both the second and third lens groups G3, compared to a lens system that moves the entire imaging lens for focusing, it is possible to achieve miniaturization and weight reduction of the focusing group. Therefore, the focusing unit, including the focusing group and its associated mechanical parts, can be miniaturized and weighted, which is beneficial for reducing the load on the drive system that drives the focusing group and for achieving higher focusing speeds.

[0068] In the imaging lens of the present invention, the first lens group G1 comprises two negative lenses and a positive lens sequentially from the object side to the image side. As an example, Figure 1 The first lens group G1 shown includes, from the object side to the image side, a negative lens L11, a negative lens L12, a positive lens L13, and a positive lens L14. By configuring the first lens group G1 to include two negative lenses, radial miniaturization of the lens system can be achieved. By including both negative and positive lenses in the first lens group G1, chromatic aberration and distortion aberrations can be easily corrected, and variations in chromatic aberration caused by the movement of the focusing group during focusing can be suppressed. Placing the negative lens on the object side of the first lens group G1 is beneficial for wide-angle viewing. Arranging the lenses of the first lens group G1 in negative-to-positive order from the object side is beneficial for improving sagittal coma.

[0069] Furthermore, preferably, the first lens group G1 sequentially includes a negative lens with its convex surface facing the object side, a biconcave lens, and multiple single lenses with positive refractive power, from the object side to the image side. By making the lens closest to the object side a negative lens with its convex surface facing the object side, it is beneficial to suppress distortion aberrations. The biconcave lens reduces the angle of off-axis rays relative to the optical axis Z, thus helping to suppress angle changes (breathing) during focusing. Furthermore, the biconcave lens widens the beam width, thus helping to suppress sagittal coma. By including multiple single lenses with positive refractive power in the first lens group G1, the positive refractive power of the first lens group G1 is strengthened, which is beneficial for miniaturization in the optical axis direction of the imaging lens.

[0070] Furthermore, preferably, the lens surface of the first lens group closest to the image is convex. By making the lens surface of the first lens group G1 closest to the image convex, it is beneficial to correct distortion aberrations and astigmatism.

[0071] Furthermore, preferably, the lens closest to the object in the first lens group G1 is an aspherical lens. By setting the lens closest to the object in the first lens group G1 to be an aspherical lens, it is beneficial to correct distortion aberrations, astigmatism, and coma aberrations.

[0072] Furthermore, preferably, the first lens group G1 as a whole has positive refractive power. By making the first lens group G1 have positive refractive power, it is beneficial to shorten the overall length of the lens system.

[0073] In the imaging lens of the present invention, the second lens group G2 includes a positive lens and a negative lens. As an example, Figure 1 The second lens group G2 shown includes, from the object side to the image side, a negative lens L11, a positive lens L22, an aperture St, a negative lens L23, a positive lens L24, and a positive lens L25. By including both positive and negative lenses in the second lens group G2, chromatic aberration can be appropriately suppressed with a single second lens group G2, and distortion aberrations can be easily corrected.

[0074] Furthermore, preferably, the second lens group G2 includes a combined lens formed by joining a negative lens and a positive lens, and a single lens with positive refractive power disposed on the image side of the combined lens. Figure 1 In the second lens group G2, a combination of negative lens L21 and positive lens L22 is shown, as is a combination of negative lens L23 and positive lens L24. Positive lens L25 is an example of a single lens. The combined lens, constructed by combining negative and positive lenses, is advantageous for appropriately suppressing chromatic aberration within the second lens group G2 while correcting image plane curvature and astigmatism. It also facilitates miniaturization along the optical axis of the second lens group G2. A single lens with positive refractive power is beneficial for correcting spherical aberration.

[0075] Furthermore, preferably, the second lens group G2 includes multiple sets of combined lenses formed by combining negative and positive lenses, and a single lens with positive refractive power. By including multiple sets of combined lenses, the design freedom is increased, chromatic aberration can be more appropriately suppressed within the second lens group G2, and miniaturization along the optical axis of the second lens group G2 is more advantageous. The single lens with positive refractive power is beneficial for correcting spherical aberration.

[0076] Furthermore, preferably, the second lens group G2 includes an aperture diaphragm St. Figure 1 The image shows an example where the second lens group G2 includes an aperture stop St. By arranging the aperture stop St within the second lens group G2, which serves as the focusing group, changes in optical performance during focusing group movement are easily suppressed. Furthermore, Figure 1The aperture St shown indicates the position on the optical axis, not the size or shape.

[0077] Furthermore, preferably, the second lens group G2 has lenses on both the object side and the image side of the aperture St. Figure 1 The diagram shows an example where the second lens group G2 has a negative lens L21 and a positive lens L22 on the object side of the aperture St, and a negative lens L23, a positive lens L24, and a positive lens L25 on the image side of the aperture St. By having the second lens group G2, which serves as the focusing group, sandwich lenses on both the object and image sides of the aperture St, it is easier to suppress changes in optical performance when the focusing group moves.

[0078] In the imaging lens of the present invention, preferably, the third lens group G3 includes a positive lens and a negative lens. As an example, Figure 1 The third lens group G3 shown includes a positive lens L31, a negative lens L32, a negative lens L33, and a positive lens L34. By dividing the third lens group G3 into positive and negative lenses, chromatic aberration can be appropriately suppressed with a single third lens group G3.

[0079] In the imaging lens of the present invention, preferably, when focusing from an object at infinity to the nearest object, the first lens group G1 and the third lens group G3 are fixed relative to the image plane Sim, and only the second lens group G2 is used as the focusing group. By fixing the first lens group G1 and the third lens group G3 relative to the image plane Sim, dustproof and waterproof effects can be obtained.

[0080] Next, the structure related to the conditional expression will be explained. 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 of the present invention satisfies the following conditional expression (1). By setting it to not be below the lower limit of conditional expression (1), the refractive power of the second lens group G2 will not become too weak, thus it is beneficial to shorten the amount of movement of the focusing group during focusing, and thus it is beneficial to shorten the overall length of the lens system. By setting it to not be above the upper limit of conditional expression (1), the positive refractive power of the first lens group G1 will not become too strong, thus it is possible to reduce the angle of the off-axis principal ray incident from the first lens group G1 to the second lens group G2 relative to the optical axis Z, which is beneficial to suppress breathing. In addition, if the structure satisfies the following conditional expression (1-1), it can become a better characteristic, and if the structure satisfies the following conditional expression (1-2), it can become a further better characteristic.

[0081] -0.5 < f2 / f1 < 0.5 (1)

[0082] -0.1 < f2 / f1 < 0.5 (1-1)

[0083] -0.05 < f2 / f1 < 0.4 (1-2)

[0084] Preferably, when the focal length of the second lens group G2 is set to f2 and the focal length of the third lens group G3 is set to f3, the imaging lens of the present invention satisfies the following conditional expression (2). By setting it to not be below the lower limit of conditional expression (2), the refractive power of the third lens group G3 will not become too strong, so the angle between the light incident on the third lens group G3 and the light emitted from the third lens group G3 will not change drastically, which is beneficial for suppressing breathing. By setting it to not be above the upper limit of conditional expression (2), the refractive power of the second lens group G2 will not become too strong, which is beneficial for appropriately suppressing chromatic aberration with a single second lens group G2. In addition, if the structure satisfies the following conditional expression (2-1), even better characteristics can be achieved.

[0085] 1 < |f3 / f2| < 3 (2)

[0086] 2 < |f3 / f2| < 2.7 (2-1)

[0087] Preferably, when the focal length of the first lens group G1 is set to f1, and the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image when focusing on an object at infinity is set to TTL, the imaging lens of the present invention satisfies the following conditional expression (3). By setting it to not be below the lower limit of conditional expression (3), the negative refractive power of the first lens group G1 will not become too strong, thus facilitating a reduction in the overall length of the lens system. By setting it to not be above the upper limit of conditional expression (3), the positive refractive power of the first lens group G1 will not become too strong, thus reducing the angle of the off-axis principal ray incident from the first lens group G1 to the second lens group G2 relative to the optical axis Z, which is beneficial for suppressing breathing. Furthermore, if the structure satisfies the following conditional expression (3-1), even better characteristics can be achieved.

[0088] -0.1 < TTL / f1 < 0.55 (3)

[0089] -0.08 < TTL / f1 < 0.5 (3-1)

[0090] Preferably, when the focal length of the first lens group G1 is set to f1 and the focal length of the imaging lens in the state of focusing on an object at infinity is set to fA, the imaging lens of the present invention satisfies the following conditional expression (4). By setting it to not be below the lower limit of conditional expression (4), the negative refractive power of the first lens group G1 will not become too strong, thus which is beneficial to shorten the overall length of the lens system. By setting it to not be above the upper limit of conditional expression (4), the positive refractive power of the first lens group G1 will not become too strong, thus it is possible to reduce the angle of the off-axis principal ray incident from the first lens group G1 to the second lens group G2 relative to the optical axis Z, which is beneficial to suppress breathing. In addition, if the structure satisfies the following conditional expression (4-1), it can have even better characteristics.

[0091] -0.1 < fA / f1 < 0.2 (4)

[0092] -0.05 < fA / f1 < 0.16 (4-1)

[0093] Preferably, when the focal length of the first lens group G1 is set to f1 and the focal length of the third lens group G3 is set to f3, the imaging lens of the present invention satisfies the following conditional expression (5). By setting it to not be below the lower limit of conditional expression (5), the positive refractive power of the first lens group G1 will not become too strong, and the positive refractive power of the second lens group G2 can be prevented from becoming relatively weak. Therefore, it is beneficial to shorten the amount of movement of the focusing group during focusing, and thus beneficial to shorten the overall length of the lens system. By setting it to not be above the upper limit of conditional expression (5), the negative refractive power of the first lens group G1 will not become too strong, and thus it is beneficial to shorten the overall length of the lens system. Furthermore, the refractive power of the second lens group G2 will not become relatively strong, so the angle between the light incident on the second lens group G2 and the light emitted from the second lens group G2 will not change drastically, which is beneficial to suppress breathing. In addition, if the structure satisfies the following conditional expression (5-1), it can have even better characteristics.

[0094] -1 < f3 / f1 < 0.5 (5)

[0095] -0.5 < f3 / f1 < 0.1 (5-1)

[0096] Preferably, the object-side lens of the imaging lens of the present invention has a refractive index of 1.7 or higher relative to the d-line, and the d-line reference dispersion coefficient of the second lens from the object side is 60 or higher. By using a material with a refractive index of 1.7 or higher (i.e., high refractive index) for the object-side lens, the negative refractive power of the object-side lens can be strengthened, which is beneficial for radial miniaturization. By using a material with a dispersion coefficient of 60 or higher (i.e., low dispersion) for the second lens from the object side, chromatic aberration correction is beneficial.

[0097] Preferably, when the average value of the chromatic dispersion coefficients of the lens closest to the object and the second lens from the object side is set to ν12, and the chromatic dispersion coefficient of the third lens from the object side is set to ν3, the imaging lens of the present invention satisfies the following conditional expression (6). By setting it to not be below the lower limit of conditional expression (6), the chromatic dispersion of the lens closest to the object will not become too strong, thus facilitating chromatic aberration correction. By setting it to not be above the upper limit of conditional expression (6), since the lens not closest to the object and the second lens from the object side are both combinations of low-dispersion materials, the negative refractive power of each lens will not become too weak, thus facilitating radial miniaturization. Furthermore, materials with appropriate chromatic dispersion coefficients can be selected, thus facilitating chromatic aberration correction. In addition, if the structure satisfies the following conditional expression (6-1), even better characteristics can be achieved.

[0098] 25<ν12-ν3<45 (6)

[0099] 30<ν12-ν3<42 (6-1)

[0100] Preferably, when the lateral magnification of the second lens group G2 is set to β2 when focusing on an object at infinity, and the lateral magnification of the third lens group G3 is set to β3 when focusing on an object at infinity, the imaging lens of the present invention satisfies the following conditional expression (7). By setting it to not be below the lower limit of conditional expression (7), the refractive power of the second lens group G2 will not become too weak, thus facilitating a reduction in the amount of movement of the focusing group during focusing, and consequently, a reduction in the overall length of the lens system. By setting it to not be above the upper limit of conditional expression (7), the refractive power of the second lens group G2 will not become too strong, thus preventing a sharp change in the angle between the light incident on the second lens group G2 and the light emitted from the second lens group G2, which helps to suppress breathing. Furthermore, if the structure satisfies the following conditional expression (7-1), even better characteristics can be achieved.

[0101] 1.5 < (1-β2) 2 )×β3 2 <2.5 (7)

[0102] 1.8 < (1-β2) 2 )×β3 2 <2.2 (7-1)

[0103] Preferably, when the lateral magnification of the third lens group G3 is set to β3 when focusing on an object at infinity, the imaging lens of the present invention satisfies the following conditional expression (8). By setting it to not be below the lower limit of conditional expression (8), the refractive power of the second lens group G2 will not become too weak, thus facilitating a reduction in the amount of movement of the focusing group during focusing, and consequently, a reduction in the overall length of the lens system. By setting it to not be above the upper limit of conditional expression (8), the negative refractive power of the third lens group G3 will not become too strong, thus facilitating a reduction in the overall length of the lens system. Furthermore, if the structure satisfies the following conditional expression (8-1), even better characteristics can be achieved.

[0104] 1.4 < β3 < 1.55 (8)

[0105] 1.4 < β3 < 1.5 (8-1)

[0106] Preferably, when the radius of curvature of the object-side surface of the lens closest to the object is set to R11 and the radius of curvature of the image-side surface of the lens closest to the object is set to R12, the imaging lens of the present invention satisfies the following conditional expression (9). As an example, (R12-R11) / (R12+R11) in conditional expression (9) is... Figure 1 The term related to the lens shape of the negative lens L11. By setting it to not be below the lower limit of condition (9), the refractive power of the object-side surface of the lens closest to the object will not become too weak, and the refraction of off-axis rays can be appropriately controlled, thus making it easy to correct distortion aberrations. By setting it to not be above the upper limit of condition (9), the refractive power of the image-side surface of the lens closest to the object will not become too weak, thus facilitating radial miniaturization. In addition, if the structure satisfies the following condition (9-1), even better characteristics can be achieved.

[0107] -1<(R12-R11) / (R12+R11)<-0.5 (9)

[0108] -0.8<(R12-R11) / (R12+R11)<-0.6 (9-1)

[0109] Preferably, when the radius of curvature of the object-side surface of the second lens from the object side is set to R21 and the radius of curvature of the image-side surface of the second lens from the object side is set to R22, the imaging lens of the present invention satisfies the following conditional expression (10). As an example, (R22+R21) / (R22-R21) of conditional expression (10) is equal to... Figure 1The term related to the lens shape of the negative lens L12. By setting it to not be below the lower limit of condition (10), the refractive power of the object-side surface of the second lens from the object side will not become too weak, thus facilitating radial miniaturization. By setting it to not be above the upper limit of condition (10), the refractive power of the image-side surface of the second lens from the object side will not become too weak, making it easier to suppress sagittal coma. In addition, if the structure satisfies the following condition (10-1), even better characteristics can be achieved.

[0110] -1.5<(R22+R21) / (R22-R21)<0.1 (10)

[0111] -1<(R22+R21) / (R22-R21)<0.05 (10-1)

[0112] Preferably, when the second lens group G2 includes an aperture St, and a lens is located adjacent to both the object side and the image side of the aperture St, and the radius of curvature of the image-side surface of the lens adjacent to the object side of the aperture St is set to Rstf, and the radius of curvature of the object-side surface of the lens adjacent to the image side of the aperture St is set to Rstr, the imaging lens of the present invention satisfies the following conditional expression (11). As an example, (Rstr-Rstf) / (Rstr+Rstf) in conditional expression (11) is... Figure 1 The terms related to the lens shape of the image-side surface of the positive lens L22 and the object-side surface of the negative lens L23. By setting it to not be below the lower limit of condition (11), the total length of the second lens group G2 will not become too large, thus facilitating a reduction in the total length of the lens system. By setting it to not be above the upper limit of condition (11), the refractive power of the image-side surface of the lens adjacent to the object side of the aperture St will not become too strong, thus reducing the angular change of light rays before and after the aperture St, which is beneficial for correcting various aberrations. Furthermore, if the structure satisfies the following condition (11-1), even better characteristics can be achieved.

[0113] -1<(Rstr-Rstf) / (Rstr+Rstf)<-0.3 (11)

[0114] -0.82<(Rstr-Rstf) / (Rstr+Rstf)<-0.35 (11-1)

[0115] Preferably, when the second lens group G2 includes an aperture St, and lenses are provided on the object side and image side of the aperture St, the imaging lens of the present invention satisfies the following conditional expression (12) when the combined focal length of all lenses in the second lens group G2 that are closer to the object side than the aperture St is set to f2f, and the combined focal length of all lenses in the second lens group G2 that are closer to the image side than the aperture St is set to f2r. By setting it to not be below the lower limit of conditional expression (12), the refractive power of the second lens group G2 that is closer to the image side than the aperture St will not become too weak, and the angle of the off-axis principal ray emitted from the second lens group G2 relative to the optical axis Z can be reduced, thus helping to suppress breathing. By setting it to not be above the upper limit of conditional expression (12), the refractive power of the second lens group G2 that is closer to the object side than the aperture St will not become too weak, and the spacing between the lenses before and after the aperture St can be reduced. Therefore, the total length of the second lens group G2 will not become too large, which is beneficial for shortening the total length of the lens system. In addition, if the structure satisfies the following condition (12-1), it can achieve even better characteristics.

[0116] 0 < f2f / f2r < 2.5 (12)

[0117] 0.8 < f²f / f²r < 2 (12-1)

[0118] Preferably, when a lens component is set as a single lens or a combined lens, if the distance on the optical axis from the image-side surface of the second lens component to the object-side surface of the image-side lens component of the second lens group G2 is set to dd, and the distance on the optical axis from the object-side lens surface of the second lens group G2 to the image-side lens surface of the second lens group G2 is set to TTL2, the imaging lens of the present invention satisfies the following conditional expression (13). By setting it to not be below the lower limit of conditional expression (13), dd will not become too small, thus the angle of the off-axis principal ray of the second lens group G2 relative to the optical axis Z can be sufficiently reduced, which is beneficial for suppressing coma. By setting it to not be above the upper limit of conditional expression (13), dd will not become too large, thus the total length of the second lens group G2 will not become too large, which is beneficial for shortening the total length of the lens system. In addition, if the structure satisfies the following conditional expression (13-1), even better characteristics can be achieved.

[0119] 0.09 < dd / TTL2 < 0.17 (13)

[0120] 0.11 < dd / TTL2 < 0.15 (13-1)

[0121] Including structures related to conditional expressions, the above-mentioned preferred structures and / or implementable structures can be combined in any way, preferably selectively and appropriately according to the required specifications.

[0122] Next, a numerical embodiment of the imaging lens of the present invention will be described.

[0123] [Example 1]

[0124] A cross-sectional view showing the structure of the imaging lens of Embodiment 1 is shown in 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, comprises 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 infinity object to the nearest object, the first lens group G1 and the third lens group G3 are fixed relative to the image plane Sim, while only the second lens group G2 moves along the optical axis Z towards the object side. The first lens group G1, from the object side to the image side, comprises four lenses L11 to L14. The second lens group G2, from the object side to the image side, comprises five lenses L21 to L25. The third lens group G3, from the object side to the image side, comprises four lenses L31 to L34. The above is a summary of the imaging lens of Embodiment 1.

[0125] Regarding the imaging lens of Embodiment 1, basic lens data is shown in Table 1, specifications and variable surface spacing are shown in Table 2, and aspherical coefficients are shown in Table 3. In Table 1, the Sn column shows the surface number when the surface closest to the object side is designated as surface 1 and the numbering increases sequentially towards the image side; the R column shows the radius of curvature of each surface; and the D column shows the surface spacing on the optical axis between each surface and its image-side adjacent surface. Furthermore, the Nd column shows the refractive index of each component relative to the d-line, and the νd column shows the dispersion coefficient of each component based on the d-line reference.

[0126] In Table 1, the radius of curvature of the convex surface facing the object is marked positive, and the radius of curvature of the convex surface facing the image is marked negative. Table 1 also shows the aperture St and optical components PP, with the surface number and the term (St) listed in the surface number column corresponding to the aperture St. In Table 1, the variable surface interval that changes with the focusing time interval is notated using the notation DD[], with the object-side surface number of that interval marked in [] and recorded in column D.

[0127] Table 2 shows the focal length f and F-number FNo. of the imaging lens when focusing on an object at infinity. Furthermore, Table 2 shows the maximum full angle of view 2ω and the variable plane spacing for both the object at infinity and the object at a distance of 1.2 m. The (°) in the 2ω column indicates the unit as degrees. The object distance is the distance along the optical axis from the object to the image plane Sim. The values ​​shown in Table 2 are based on the d-line.

[0128] In Table 1, the surface numbers of aspherical surfaces are marked with an asterisk (*), and the paraxial radius of curvature is recorded in the radius of curvature column. In Table 3, the surface number of the aspherical surface is shown in the Sn column, and the aspherical coefficients for each aspherical surface are shown in the KA and Am (m = 3, 4, 5, ..., 20) columns. The aspherical coefficient values ​​in Table 3, where "E±n" (n is an integer), represent "×10⁻¹⁰". ±n KA and Am are the aspheric coefficients in the aspheric formula expressed by the following equation.

[0129] Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+∑Am×h m

[0130] in,

[0131] 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);

[0132] h: Height (distance from the optical axis to the lens surface);

[0133] C: The reciprocal of the paraxial radius of curvature;

[0134] KA, Am: Aspheric coefficients

[0135] In aspherical form, ∑ represents the summation related to m.

[0136] 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 at both magnified and reduced scales, so other appropriate units can also be used. Furthermore, the values ​​are rounded to a specified number of decimal places in the tables shown below.

[0137] [Table 1]

[0138] Example 1

[0139]

[0140]

[0141] [Table 2]

[0142] Example 1

[0143] Infinity 1.2m f 30.890 - FNo. 3.51 - 2ω(°) 84.2 84.0 DD[8] 6.190 5.791 DD

[17] 5.220 5.619

[0144] [Table 3]

[0145] Example 1

[0146] Sn 1 2 16 17 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 -2.8886874E-06 -1.9266855E-05 1.1426426E-10 2.1286361E-05 A5 -6.5306725E-07 -6.8136315E-07 -5.7428082E-06 -1.1336064E-05 A6 2.0127359E-08 -5.1386769E-08 -5.1973760E-08 3.2648953E-06 A7 1.3907664E-09 1.5435168E-09 2.9635184E-07 -7.1293049E-07 A8 1.3104211E-11 -1.8823117E-10 -1.8237844E-08 1.0856552E-07 A9 -2.3166044E-12 1.2882017E-11 -9.4716911E-09 -4.7133356E-09 A10 -1.5905045E-13 -5.8433378E-14 8.3598439E-10 -1.9454358E-09 A11 -3.5069163E-15 -9.2461790E-14 2.1406144E-10 3.3012812E-10 A12 -4.0112500E-17 1.1586160E-14 -2.2603381E-11 1.3422800E-12 A13 -1.3482658E-18 -1.3601845E-15 2.7933578E-12 -3.7812852E-12 A14 2.3430938E-18 2.3396195E-17 3.2181986E-13 9.4470544E-14 A15 7.8738693E-20 4.6200395E-18 2.2872157E-14 3.1663551E-14 A16 6.0688836E-21 -9.1617300E-19 -2.6332566E-15 -1.7021310E-15 A17 -5.8425280E-22 7.7555717E-20 -1.0554255E-16 -9.4195383E-17 A18 -6.8412335E-23 -3.5245709E-22 9.1228254E-18 6.0289050E-18 A19 4.7409996E-24 -1.7353689E-22 6.2511786E-19 2.0266550E-19 A20 -7.1601272E-26 3.7488999E-24 -3.9051285E-20 -1.2179780E-20

[0147] exist Figure 2 The diagram shows the spherical aberration map, astigmatism map, distortion aberration map, and magnification chromatic aberration map of the imaging lens of Example 1. Figure 2 In the diagram, the upper section marked "Infinity" shows aberration diagrams for focusing on an object at infinity, and the lower section marked "1.2m" shows aberration diagrams for focusing on an object at a distance of 1.2m. In the spherical aberration diagram, aberrations along the d-line, C-line, and F-line are shown with solid lines, long dashed lines, and short dashed lines, respectively. In the astigmatism diagram, aberrations along the d-line in the sagittal direction are shown with solid lines, and aberrations along the d-line in the meridional direction are shown with short dashed lines. In the distortion aberration diagram, aberrations along the d-line are shown with solid lines. In the magnification chromatic aberration diagram, aberrations along the C-line and F-line are shown with long and short dashed lines, 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 corresponding to the upper end of the vertical axis of each graph are shown in the figure.

[0148] exist Figure 3 The image shows a lateral aberration map along the d-line of the imaging lens of Embodiment 1. Figure 3 In the diagram, for each half-viewpoint, the aberrations in the meridional direction are shown in the left column, and the aberrations in the sagittal direction are shown in the right column. Figure 3 ω represents half the angle of view.

[0149] 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.

[0150] [Example 2]

[0151] A cross-sectional view showing the structure of the imaging lens of Embodiment 2 is shown in Figure 4The third lens group G3 comprises three lenses, L31 to L33, arranged sequentially from the object side to the image side. Apart from this, the imaging lens of Embodiment 2 has the same general structure as the imaging lens of Embodiment 1. Regarding the imaging lens of Embodiment 2, basic lens data are shown in Table 4, specifications and variable surface spacing are shown in Table 5, aspherical coefficients are shown in Table 6, and various aberrations are illustrated in Table 7. Figure 5 The lateral aberration is plotted on Figure 6 .

[0152] [Table 4]

[0153] Example 2

[0154] Sn R D Nd νd *1 104.47029 1.291 1.75370 52.63 *2 15.89522 7.970 3 -291.95379 1.500 1.51600 77.54 4 31.93399 2.445 5 42.75743 6.506 1.82507 23.76 6 100.97491 7.680 7 38.55662 5.135 1.58000 63.82 8 -65.12036 DD[8] 9 24.69836 1.410 1.76081 41.68 10 12.91696 6.711 1.62049 60.37 11 71.38147 6.510 12 (St) ∞ 4.056 13 32.08293 1.500 1.88927 39.07 14 10.85144 4.843 1.58961 66.21 15 107.18997 4.900 *16 -89.90856 5.000 1.54955 63.09 *17 -20.85723 DD

[17] 18 -64.08739 5.516 2.00000 19.84 19 -18.12725 1.010 1.80000 25.00 20 69.23273 7.830 21 89.85994 3.122 1.66118 58.44 22 901.54915 24.875 23 ∞ 3.200 1.51680 64.20 24 ∞ 0.003

[0155] [Table 5]

[0156] Example 2

[0157] Infinity 1.2m f 30.906 - FNo. 3.60 - 2ω(°) 84.8 84.4 DD[8] 6.102 5.663 DD

[17] 1.237 1.676

[0158] [Table 6]

[0159] Example 2

[0160] Sn 1 2 16 17 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 1.0288468E-05 -2.5251951E-06 -2.7724468E-05 4.7085228E-08 A5 -9.4999688E-07 -1.7502288E-06 9.4568703E-07 -2.7316900E-06 A6 1.0087618E-08 3.8008839E-08 -1.1586850E-07 4.8467173E-07 A7 4.0896001E-11 7.6773366E-10 -7.8626675E-08 -7.6590038E-08 A8 3.7316777E-11 -3.7247454E-10 6.2147787E-09 3.2996243E-09 A9 2.3147219E-13 -1.3229091E-11 1.9094713E-09 1.4969822E-10 A10 -3.1159720E-14 -4.4887710E-13 -7.3415852E-11 1.1199435E-11 A11 -4.1643952E-15 -5.1085339E-14 -1.6691031E-11 -2.5607321E-13 A12 -1.6848162E-16 1.2046523E-14 -1.2011700E-12 -8.8958188E-14 A13 -2.3056204E-17 -7.0899201E-16 1.9822903E-13 -4.2686601E-14 A14 2.4631948E-18 4.0890638E-17 -2.3701735E-16 9.8090849E-16 A15 7.1204198E-20 2.6780382E-18 1.3981547E-16 3.0250212E-16 A16 8.7300955E-21 -9.5043250E-19 -8.1283916E-17 1.0082628E-17 A17 -5.4394755E-22 7.2501252E-20 3.4758445E-17 -1.7896603E-19 A18 -4.8998053E-23 -5.5528618E-22 -1.0699300E-18 -9.8619023E-21 A19 1.6612900E-24 -1.7085435E-22 -4.5723232E-19 -3.2839404E-20 A20 2.3913314E-26 4.4479295E-24 2.8967385E-20 2.1095476E-21

[0161] [Example 3]

[0162] A cross-sectional view showing the structure of the imaging lens of Embodiment 3 is shown in Figure 7 The first lens group, G1, has negative refractive power. Apart from this, the imaging lens of Embodiment 3 has the same general structure as the imaging lens of Embodiment 1. Regarding the imaging lens of Embodiment 3, basic lens data is shown in Table 7, specifications and variable surface spacing are shown in Table 8, aspherical coefficients are shown in Table 9, and various aberrations are illustrated in... Figure 8 The lateral aberration is plotted on Figure 9 .

[0163] [Table 7]

[0164] Example 3

[0165] Sn R D Nd νd *1 147.31292 2.000 1.81000 41.00 *2 17.38594 7.970 3 -61.02975 1.050 1.49700 81.59 4 55.99901 2.444 5 -175.23762 2.994 1.71736 29.51 6 -64.67485 7.677 7 47.96286 5.233 1.72000 43.69 8 -71.42953 DD[8] 9 24.00874 1.000 1.80166 44.28 10 14.00153 6.713 1.60042 61.94 11 156.45803 6.513 12 (St) ∞ 4.988 13 48.14207 1.500 1.91082 35.25 14 10.59120 5.790 1.56907 71.31 15 346.00707 4.853 *16 -84.02309 5.000 1.58913 61.15 *17 -18.00757 DD

[17] 18 -356.46683 5.407 2.00272 19.32 19 -30.01424 1.026 1.73800 32.33 20 48.39223 3.672 21 -48.10262 0.900 1.98613 16.48 22 -122.10592 3.020 23 137.79530 3.842 1.63545 59.73 24 -115.98254 24.391 25 ∞ 3.200 1.51680 64.20 26 ∞ 0.023

[0166] [Table 8]

[0167] Example 3

[0168] Infinity 1.2m f 30.913 - FNo. 3.57 - 2ω(°) 86.0 85.6 DD[8] 6.126 5.702 DD

[17] 1.232 1.656

[0169] [Table 9]

[0170] Example 3

[0171] Sn 1 2 16 17 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 1.7190323E-06 -1.0324755E-05 -3.6874743E-05 -1.7507432E-05 A5 -7.4474335E-07 -9.9518618E-07 1.5262016E-06 1.8963888E-06 A6 3.0051321E-08 -6.4950083E-09 2.2784479E-07 -1.6630172E-07 A7 8.1417469E-12 1.0528595E-09 -9.8209300E-08 -4.0718008E-08 A8 2.6419440E-11 -1.9802457E-10 4.2866430E-10 3.0729611E-09 A9 -8.4613032E-13 9.3801528E-12 1.4337539E-09 2.2019263E-10 A10 -6.7674963E-14 -2.6840622E-14 4.1053517E-11 -1.0135846E-11 A11 -5.2825214E-15 -9.6141003E-14 -1.4808362E-11 -1.3635971E-12 A12 1.3685955E-17 9.2320265E-15 -7.4799199E-13 3.6925212E-14 A13 -2.1817230E-17 -9.7218804E-16 9.9226988E-14 -2.6847120E-14 A14 1.9880799E-18 3.3672325E-17 2.1856025E-15 1.3212027E-15 A15 7.8661839E-20 4.2370872E-18 2.2178857E-16 1.8274698E-16 A16 9.0261546E-21 -9.1536371E-19 -2.2420853E-16 3.5944816E-17 A17 -5.4358767E-22 7.0329374E-20 3.2929455E-17 -3.1433068E-18 A18 -4.4806487E-23 -3.5736344E-22 2.2161945E-19 -6.0753510E-19 A19 2.0403062E-24 -1.5453784E-22 -2.7567893E-19 6.0854810E-20 A20 -5.5439226E-27 3.7714093E-24 1.1764954E-20 -9.4474266E-22

[0172] [Example 4]

[0173] A cross-sectional view showing the structure of the imaging lens of Embodiment 4 is shown in Figure 10 The imaging lens of Example 4 has the same general structure as the imaging lens of Example 1. Regarding the imaging lens of Example 4, basic lens data are shown in Table 10, specifications and variable surface spacing are shown in Table 11, aspherical coefficients are shown in Table 12, and various aberrations are illustrated in Table 13. Figure 11 The lateral aberration is plotted on Figure 12 .

[0174] [Table 10]

[0175] Example 4

[0176] Sn R D Nd νd *1 89.72389 2.000 1.81000 41.00 *2 16.34104 8.020 3 -71.73549 1.050 1.49700 81.59 4 50.83843 5.450 5 -330.93917 2.717 1.72397 28.80 6 -80.02855 4.690 7 44.14348 5.273 1.78590 44.21 8 -113.03519 DD[8] 9 28.92056 1.500 1.79450 45.39 10 13.93312 6.726 1.60311 60.64 11 368.25947 6.547 12 (St) ∞ 5.000 13 40.93425 1.500 1.90070 37.05 14 11.21704 6.010 1.49600 81.76 15 -83.89388 4.666 *16 -46.50945 5.000 1.59554 61.33 *17 -17.52221 DD

[17] 18 157.26048 5.351 2.00272 19.32 19 -51.23987 1.010 1.73800 32.33 20 32.64581 3.888 21 -65.49325 0.900 1.94595 17.98 22 -467.51328 3.032 23 ∞ 3.832 1.63000 60.00 24 -50.44990 27.349 25 ∞ 3.200 1.51680 64.20 26 ∞ 0.017

[0177] [Table 11]

[0178] Example 4

[0179] Infinity 1.2m f 30.911 - FNo. 3.61 - 2ω(°) 82.2 81.8 DD[8] 6.204 5.765 DD

[17] 1.500 1.939

[0180] [Table 12]

[0181] Example 4

[0182] Sn 1 2 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 -3.4155625E-06 -1.9107463E-05 A5 -6.5512662E-07 -1.1416274E-06 A6 2.6880842E-08 -1.1657866E-09 A7 3.4247514E-10 -4.9500638E-10 A8 2.3685629E-11 -2.4119314E-10 A9 -5.8156453E-13 8.3170627E-12 A10 -6.5088755E-14 -7.1324595E-14 A11 -7.8198378E-15 -7.0073316E-14 A12 7.8587704E-17 8.2513891E-15 A13 -2.3430565E-17 -8.6549574E-16 A14 2.3366340E-18 2.8635869E-17 A15 7.6226720E-20 3.9009264E-18 A16 9.4130546E-21 -9.5613959E-19 A17 -6.2440394E-22 7.1920293E-20 A18 -4.8935171E-23 -3.9924657E-22 A19 2.2440208E-24 -1.4860612E-22 A20 3.5231466E-28 3.4475197E-24

[0183] [Example 5]

[0184] A cross-sectional view showing the structure of the imaging lens of Embodiment 5 is shown in Figure 13 The first lens group G1 has negative refractive power as a whole. Apart from this, the imaging lens of Embodiment 5 has the same general structure as the imaging lens of Embodiment 1. Regarding the imaging lens of Embodiment 5, basic lens data are shown in Table 13, specifications and variable surface spacing are shown in Table 14, aspherical coefficients are shown in Table 15, and various aberrations are illustrated in... Figure 14 The lateral aberration is plotted on Figure 15 .

[0185] [Table 13]

[0186] Example 5

[0187] Sn R D Nd νd *1 81.41749 1.050 1.81000 41.00 *2 16.87348 7.970 3 -83.49248 1.500 1.49700 81.59 4 33.70011 2.445 5 66.56054 3.000 1.80811 22.69 6 315.43341 7.680 7 45.10867 5.225 1.69680 55.53 8 -71.42950 DD[8] 9 28.19202 1.000 1.80166 44.28 10 13.80947 6.711 1.66330 59.52 11 303.42858 6.511 12 (St) ∞ 5.000 13 46.29398 1.500 1.90070 37.05 14 10.99195 5.010 1.56907 71.31 15 199.24240 4.851 *16 -100.50580 5.000 1.58913 61.15 *17 -19.42692 DD

[17] 18 -198.74315 5.417 2.00272 19.32 19 -29.74449 1.010 1.73800 32.33 20 55.43413 3.631 21 -89.84468 0.800 1.95906 17.47 22 491.19263 3.002 23 70.08481 3.709 1.73909 54.09 24 -471043.65325 22.826 25 ∞ 3.200 1.51680 64.20 26 ∞ 0.009

[0188] [Table 14] Example 5

[0189] Infinity 1.2m f 30.923 - FNo. 3.51 - 2ω(°) 86.0 85.6 DD[8] 6.110 5.674 DD

[17] 1.241 1.677

[0190] [Table 15]

[0191] Example 5

[0192] Sn 1 2 16 17 KA 1.0000000E+00 1.0000000E+00 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 A4 1.2281122E-07 -1.0786505E-05 -3.7208403E-05 -1.9193642E-05 A5 -8.0918552E-07 -1.0264242E-06 2.4918853E-06 2.9830437E-06 A6 3.0894208E-08 -1.2603954E-08 8.2587863E-08 -2.4788105E-07 A7 -1.4949584E-10 7.2850530E-10 -9.7105562E-08 -5.0818631E-08 A8 3.0853454E-11 -1.9552704E-10 1.8355715E-09 4.9197427E-09 A9 -8.0744135E-13 1.5982032E-12 1.5177218E-09 1.3996079E-10 A10 -3.6267415E-14 1.6462503E-13 2.6265178E-11 -6.6449624E-12 A11 -5.3282930E-15 -9.2532245E-14 -1.5302546E-11 -6.7712184E-13 A12 -2.4053076E-16 1.0128245E-14 -8.1345029E-13 -6.1036418E-14 A13 -2.0985747E-17 -9.8589728E-16 9.2009885E-14 -2.8389102E-14 A14 2.6891746E-18 3.6516714E-17 2.7738118E-15 1.2053373E-15 A15 8.5950377E-20 2.7693033E-18 2.8556468E-16 1.9296208E-16 A16 8.9705856E-21 -9.0005895E-19 -1.8855929E-16 3.4420524E-17 A17 -5.1171638E-22 7.4637371E-20 3.0916630E-17 -3.0564156E-18 A18 -4.8917720E-23 -2.4287075E-22 4.4502685E-20 -5.2642755E-19 A19 1.6388550E-24 -1.6686214E-22 -2.8980417E-19 5.9877719E-20 A20 1.4937497E-26 3.6961748E-24 1.3587040E-20 -1.4280268E-21

[0193] Table 16 shows the corresponding values ​​of conditional equations (1) to (13) for the imaging lenses of Examples 1 to 5. Table 16 shows the values ​​for Examples 1 to 5 based on the d-line wavelength.

[0194] [Table 16]

[0195]

[0196] As can be seen from the above data, the imaging lenses of Examples 1 to 5 respectively satisfy the conditions (1) to (13), are small and have good optical performance, and are configured as wide-angle lenses of 70 degrees or more.

[0197] Next, the imaging device according to the embodiments of the present invention will be described. Figure 16 and Figure 17 The diagram shows the external appearance of a camera 30, an imaging device according to an embodiment of the present invention. Figure 16 This indicates a stereoscopic view of camera 30 viewed from the front side. Figure 17 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 can be detachably fitted with 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 ​​displays the captured image and the image existing within the field of view before shooting.

[0199] A shooting opening for light from the subject is provided in the center of the front of the camera body 31. A bayonet 37 is provided at the position corresponding to the shooting opening, 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 imaging signal corresponding to the image of the subject formed by the interchangeable lens 20; a signal processing circuit that processes the imaging signal output from the imaging element to generate an image; and a recording medium for recording the generated image. In this camera 30, still images or moving images can be captured by pressing the shutter button 32, and the image data obtained is recorded in the aforementioned recording medium.

[0201] The present invention has been described above with examples of embodiments and examples, but the technology of the present invention is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, surface spacing, refractive index, dispersion coefficient, and aspherical coefficient of each lens are not limited to the values ​​shown in the above numerical 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 examples described above. For example, it can also be configured as a camera other than a mirrorless camera, a film camera, or a video camera, etc.

[0203] Symbol Explanation

[0204] 1-Imaging lens, 2-On-axis beam, 3-Brightness beam with maximum angle of view, 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~L14, L21~L25, L31~L34-Lens, PP-Optical components, Sim-Image plane, St-Aperture, Z-Optical axis.

Claims

1. An imaging lens, comprising, from the object side to the image side, a first lens group, a second lens group with positive refractive power, and a third lens group with negative refractive power. The first lens group, from the object side to the image side, consists of a negative lens with its convex surface facing the object side, a biconcave lens, a single lens with positive refractive power, and another single lens with positive refractive power. The lens surface of the first lens group closest to the image side is convex. The second lens group consists of a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens sequentially from the object side to the image side. The third lens group consists of a positive lens, a negative lens, another negative lens, and a positive lens in sequence from the object side to the image side; or the third lens group consists of a positive lens, a negative lens, and a positive lens in sequence from the object side to the image side. When focusing from an object at infinity to the nearest object, the first lens group is fixed relative to the image plane, and the second lens group moves along the optical axis. When the focal length of the first lens group is set to f1, Set the focal length of the second lens group to f2. When the focal length of the third lens group is set to f3... The imaging lens satisfies the following conditions (1) and (2). -0.5 < f2 / f1 < 0.5 (1), 1 < |f3 / f2| < 3 (2).

2. The imaging lens according to claim 1, wherein, The distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image, when the image is focused on an object at infinity, is defined as TTL. When the focal length of the first lens group is set to f1... The imaging lens satisfies the following condition (3). -0.1<TTL / f1<0.55 (3).

3. The imaging lens according to claim 1, wherein, The focal length of the imaging lens when focusing on an object at infinity is set to fA. When the focal length of the first lens group is set to f1... The imaging lens satisfies the following condition (4). -0.1 < fA / f1 < 0.2 (4).

4. The imaging lens according to claim 1, wherein, The second lens group includes a combined lens consisting of a negative lens and a positive lens, and a single lens with positive refractive power disposed on the image side of the combined lens.

5. The imaging lens according to claim 1, wherein, The second lens group includes multiple sets of combined lenses consisting of negative and positive lenses and single lenses with positive refractive power.

6. The imaging lens according to claim 1, wherein, The second lens group includes an aperture.

7. The imaging lens according to claim 1, wherein, When the focal length of the third lens group is set to f3, When the focal length of the first lens group is set to f1... The imaging lens satisfies the following condition (5). -1 < f3 / f1 < 0.5 (5).

8. The imaging lens according to claim 1, wherein, The refractive index of the lens closest to the object is greater than 1.7 relative to the d-line. The dispersion coefficient of the d-line reference of the second lens from the object side is 60 or higher.

9. The imaging lens according to claim 1, wherein, Let the average value of the dispersion coefficients of the lens closest to the object and the second lens from the object side be ν12. When the dispersion coefficient of the d-line reference of the third lens from the object side is set to ν3, The imaging lens satisfies the following condition (6). 25<ν12-ν3<45 (6)。 10. The imaging lens according to claim 1, wherein, When the second lens group is focused on an object at infinity, the lateral magnification is set to β2. When the lateral magnification of the third lens group is set to β3 while focusing on an object at infinity, The imaging lens satisfies the following condition (7). 1.5＜（1-β2 2 ）×β3 2 ＜2.5 （7）。 11. The imaging lens according to claim 1, wherein, When the lateral magnification of the third lens group is set to β3 while focusing on an object at infinity, The imaging lens satisfies the following condition (8). 1.4＜β3＜1.55 （8）。 12. The imaging lens according to claim 1, wherein, The radius of curvature of the object-side surface of the lens closest to the object is set to R11. When the radius of curvature of the image-side surface of the lens closest to the object is set to R12, The imaging lens satisfies the following condition (9). -1<(R12-R11) / (R12+R11)<-0.5 (9).

13. The imaging lens according to claim 1, wherein, Let the radius of curvature of the surface of the second lens on the object side be R21. If the radius of curvature of the image-side surface of the second lens from the object side is set to R22, The imaging lens satisfies the following condition (10). -1.5<(R22+R21) / (R22-R21)<0.1 (10).

14. The imaging lens according to claim 1, wherein, The second lens group includes an aperture, and has lenses positioned adjacent to the object side and image side of the aperture. Let the radius of curvature of the image-side surface of the lens adjacent to the object side of the aperture be Rstf. When the radius of curvature of the object-side surface of the lens adjacent to the image side of the aperture is set to Rstr. The imaging lens satisfies the following condition (11). -1<(Rstr-Rstf) / (Rstr+Rstf)<-0.3 (11).

15. The imaging lens according to claim 1, wherein, The second lens group includes an aperture, and has lenses on both the object side and the image side of the aperture. The combined focal length of all lenses in the second lens group that are closer to the object than the aperture is set to f2f. When the combined focal length of all lenses in the second lens group that are closer to the image side than the aperture is set to f2r... The imaging lens satisfies the following condition (12). 0 < f2f / f2r < 2.5 (12).

16. The imaging lens according to claim 1, wherein, When a lens component is configured as a single lens or a combined lens, the distance on the optical axis from the image-side surface of the second lens component of the second lens group to the object-side surface of the image-side lens component of the second lens group is defined as dd. If 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 TTL2, The imaging lens satisfies the following condition (13). 0.09<dd / TTL2<0.17 (13).

17. The imaging lens according to claim 1, wherein, The imaging lens satisfies the following condition (1-1). -0.1<f2 / f1<0.5 (1-1).

18. The imaging lens according to claim 1, wherein, The imaging lens satisfies the following condition (1-2). -0.05<f2 / f1<0.4 (1-2).

19. A camera device comprising an imaging lens according to any one of claims 1 to 18.

Images