JP2022012964A - Large diameter imaging lens - Google Patents

Abstract

To provide a large diameter imaging lens which has the sufficient optical performance from the infinity to the short range as a single focus lens to be used in imaging from semi-wide angle to middle telephoto being the short-range imaging side while being miniaturized.SOLUTION: A large diameter imaging lens comprises: a plurality of front positive lenses LF continuous from an object OBJ side; and a front negative lens L4 on the most aperture stop STO side. The entire lenses LF are constituted by meniscus lenses whose object OBJ side is the convex shape. The large diameter imaging lens comprises: a front lens group 101 in which a curvature radius of each lens surface on the aperture stop STO side gradually becomes smaller from the object OBJ side to the aperture stop STO side and the lens surfaces of the entire lenses are in contact with the air; a plurality of rear positive lenses L6 which are held between a biconcave lens L5 arranged on the most aperture stop STO side and a final lens LE which is arranged on the most image IMG side, in which both surfaces are curved in the same direction on an optical axis Dc and has the negative power; and a rear lens group 102 which includes at least a biconvex lens in the rear positive lens L6.SELECTED DRAWING: Figure 1

Description

The present invention relates to a large-diameter image pickup lens suitable for use as an interchangeable lens used in a digital camera or the like.

In general, interchangeable lenses used in digital cameras, etc. have less restrictions on back focus and rear lens diameter due to mirrorless cameras and larger mount diameters, and the variety of lens types is expanding. The size of the lens is increasing and the performance is higher than that of the photo film (higher definition). As a result, in a bright single focus lens (interchangeable lens) in the quasi-wide-angle to medium telephoto range (shooting diagonal angle of view 57-28 °), an F number of 1.8 or less is common, and a brighter lens is required. .. Further, by downsizing the digital camera body, it is required to make the interchangeable lens compact, and further to stabilize the aberration in the entire focusing shooting region according to consumer needs.

In response to such a request, by arranging the front lens group on the object side in the optical axis direction with respect to the aperture aperture and the rear lens group on the image side, each lens surface of the on-axis ray and the off-axis main ray is arranged. An optical system having a symmetrical arrangement type lens configuration is also known in which the angle of incidence on the lens is reduced so that the occurrence of spherical aberration, astigmatism, and coma on each lens surface can be suppressed. In particular, in this type of optical system, the closer the power arrangement of the lens is to symmetry with respect to the aperture aperture, the more various aberrations such as spherical aberration, coma aberration, distortion, and chromatic aberration of magnification are caused between the front lens group and the rear lens group. Since they can cancel each other out with each other, good aberration correction can be realized for the entire optical system. However, this type of symmetrical arrangement type is generally not compatible with long-distance photography and has significantly different specifications such as imaging size. Therefore, it is mainly used for copying lenses and plate-making camera lenses. Limited to a specific field of. On the other hand, as a so-called modified double gauss type, which is a modification of this type of general symmetrical arrangement type lens configuration, it has evolved from a lens for range finder cameras (film cameras) with a short back focus, and is a compact digital camera and mirrorless. Large-diameter imaging lenses that can be used in digital cameras and the like have also been proposed.

Conventionally, such a large-diameter image pickup lens, particularly a symmetrical arrangement type photographing optical system in which an F number is 1.7 or less and 3 to 5 lenses are arranged before and after an aperture diaphragm, is disclosed in Patent Document 1. A large-diameter medium-telephoto lens for a single-lens reflex camera and a lens system for a range finder camera disclosed in Patent Document 2 are known. The large-diameter medium-telephoto lens disclosed in Document 1 is an example of a modified double-Gauss type lens in which four positive lenses and one negative lens are arranged in the front group. In particular, we provide a high-performance large-diameter medium-telephoto lens with a shooting angle of view of about 29 ° and an F number of about 1.4, with good blur in the defocus area before and after the in-focus position. Specifically, the front group including at least three positive lenses with a strong convex surface facing the object side and one negative lens with a strong concave surface facing the image side, and a junction lens. It is composed of a rear group including a negative lens with a strong concave surface facing the object side and at least two positive lenses, and is configured by using a refractive index distribution type lens in the rear group. On the other hand, the lens system disclosed in Document 2 is an example of a Sonnar type lens in which a negative lens is arranged in the rear lens group. Specifically, the front lens group is composed of one positive lens from the object side, and the three-element junction lens of the positive lens, the positive lens, and the negative lens, and the rear lens group is composed of the negative lens, the positive lens, and the negative lens. It is composed of the three-lens junction lens of. As described above, in the case of the Sonnar type standard lens having the original configuration in the F1.5 class, a junction lens is often used. In addition, the rear lens group of the modified double gauss type lens often has one negative lens, while the Sonnar type has two negative lenses, and it is used as a junction lens in which a positive lens is sandwiched between these negative lenses. There is.

Japanese Unexamined Patent Publication No. 5-142469 U.S. Patent Publication No. 2186621

However, the conventional lens of the symmetrical arrangement type as disclosed in the above-mentioned Patent Documents 1 and 2 also has the following problems.

That is, in the case of a lens in the medium telephoto shooting region, such as the modified double gauss type of Patent Document 1, the total length of the lens tends to be long because the positive power is divided by a known aberration correction technique to increase the number of lenses. On the other hand, in the case of the Sonnar type lens of Patent Document 2, since there is a tendency to use a lot of bonded lenses, the difference in refraction coefficient is smaller than that of the case of using a single lens. As a result, the lens becomes thicker and tends to increase in weight. After all, it is not easy to make a large-diameter image pickup lens compact while ensuring high performance. Moreover, in the case of this type of conventional lens, since the emphasis is mainly on the correction of various aberrations for distant objects, there remains a problem that sufficient optical performance cannot be ensured at close range.

As described above, at present, as a single focus lens used for shooting in the quasi-wide-angle to medium-television range, an interchangeable lens used for digital cameras, etc., which covers from infinity to short distances with sufficient optical performance and is compact and compact. It is not easy to realize a bright interchangeable lens from the viewpoint of obtaining a single focus lens, and even now, the reality is that such an interchangeable lens does not fully meet the needs of consumers.
An object of the present invention is to provide a large-diameter image pickup lens that solves the problems existing in such a background technique.

In order to solve the above-mentioned problems, the present invention has a front lens group 101 having a positive power arranged on the object OBJ side and a positive lens arranged on the image IMG side with respect to the aperture aperture STO in the entire lens system 100. When constructing the large-diameter image pickup lens 1 including the rear lens group 102 having power, a plurality of front positive lenses LF, L2, L3 continuous from the object OBJ side and a front negative lens L4 on the most open pattern STO side are included. All lenses LF, L2, L3, L4 are composed of a meniscus lens having a convex shape on the object OBJ side, and the radius of curvature of each lens surface (i = 2, 4, 6, 8) on the aperture aperture STO side is the object OBJ side. Front lens group that gradually decreases from the aperture to the STO side and the lens surfaces (i = 1,2,3,4,5,6,7,8) of all lenses LF, L2, L3, L4 come into contact with air. A plurality of lenses sandwiched between 101, a biconcave lens L5 arranged on the most open aperture STO side, and a final lens LE having a negative power arranged on the image IMG side and having both sides curved in the same direction on the optical axis Dc. The entire lens system 100 including the posterior positive lenses L6 and L7 and having the posterior lens group 102 including at least one biconvex lens (L6, L7) in the posterior positive lenses L6 and L7 is provided with an object distance. At infinity, the focal distance of the entire system is AFL, the optical axis length of the entire lens system 100 is TLL, the optical axis length from the lens surface (i = 1) on the most object OBJ side to the image IMG is TLi, and the image of the final lens LE. When the optical axis length from the lens surface on the IMG side to the image IMG is IMD, "0.68 <[TLL / AFL] <1.00" (conditional formula [1]), "0.8 <[TLi / AFL] <1.4 "(conditional expression [2]) and" 0.2 <[IMD / AFL] "(conditional expression [3]) are configured to satisfy each condition.

Further, in the present invention, according to a preferred embodiment, the rear lens group 102 has a lens surface (i = 9) on the aperture stop STO side of the biconcave lens L5 up to a third lens surface (i = 9) in which the lens surface (i = 9) sequentially comes into contact with air toward the image IMG side. The bending direction (+, +,-) of i = 9,11,13) and the lens surface (i = 15) on the image IMG side of the final lens LE to the third lens surface (i = 15) that sequentially contacts the air toward the aperture stop STO side. The bending direction (-,-, +) of the lens surface (i = 15, 14, 13) can be set in the opposite direction. Further, since the rear lens group 102 has two rear regular lenses L6 and L7, the rear lens group A 102A on the aperture aperture STO side, the rear lens group A 102A on the aperture aperture STO side, and the image IMG side from the rear lens group L6 on the aperture aperture STO side. The rear lens B group 102B on the image IMG side from the rear positive lens L7 is provided, the rear lens A group 102A is an infinite object, and the object OBJ of the frontmost lens LF arranged on the most object OBJ side of the entire lens system 100. When the absolute value of the length from the lens surface (i = 1) on the side to the near-axis image position after the emission of the rear lens group A 102A becomes the largest, the object distance is set to infinity and the entire system is F. The number is FNO, the optical axis length of the front lens group 101 is LF1, the optical axis length of the rear lens group 102 is LF2, the optical axis length of the rear lens group A 102A is TL2A, and the optical axis length of the rear lens group B 102B is TL2B. Then, "0.8 <[TLl / TL2] <1.6" (conditional expression [4]), "0.6 << [TL2A / TL2B] <1.6" (conditional expression [5]), " 1.0 <[TLL / (AFL / FNO)] <1.5 "(conditional expression [6])," 0.3 <[TL2 / (FL2 / FNO)] <0.6 "(conditional expression [7]" ]) Can be set to satisfy each condition.

In addition, the entire lens system 100 includes three or more front positive lenses LF, L2, L3 ... And two or more rear positive lenses L6, L7 ..., and all positive lenses LF, L2 ..., L6, L7. In ..., all positive lenses LF, L2 in the entire lens system 100 are included, including two or more positive lenses using a glass material having a d-line refractive index of 1.75 or more, and an average Abbe number of 38.0 or more. It is desirable to set the absolute value of the focal distances of ..., L6, L7 ... In all the positive lenses LF, L2 ..., L6, L7 ..., it is more desirable to include at least one positive lens using a glass material having a d-line refractive index of 1.85 or more. At this time, the front lens group 101 can be configured to include at least one lens using a low refractive index low dispersion glass material having an absolute partial dispersion value dPgf of 0.02 or more. Further, the rear lens group 102 includes a biconcave lens L5 arranged on the most aperture stop STO side and a junction lens Ja by a rear positive lens L6 arranged on the image IMG side of the biconcave lens L5, and the biconcave lens L5 is an abnormal portion. It is possible to form the rear positive lens L6 by using a glass material having an absolute value of the dispersion value dPgf of 0.02 or more, and to form the rear positive lens L6 by using a high refraction glass having a refractive index of 1.75 or more of the d line. can.

On the other hand, in the entire lens system 100, the absolute value of the radius of curvature of the lens surface (i = 8, 9) facing the aperture stop STO is set small on the front lens group 101 side, and the lens surface on the front lens group 101 side. When the radius of curvature of (i = 8) is SR1 and the spatial spacing of the aperture stop STO is TLS, the condition of "1.0 <[SR1 / TLS] <1.5" (conditional expression [8]) is satisfied. Is desirable. Further, when the final lens LE includes a meniscus-shaped aspherical surface and the focal length of the final lens LE is FLE, "-4.0 <[FLE / AFL] <-0.8" (conditional expression []. It is desirable to form it so as to satisfy the conditions of 9]). Further, in the entire lens system 100, four lenses LF, L2, L3, L4 are arranged in the front lens group 101, and four lenses L5, L6, L7, LE are arranged in the rear lens group 102B. A total of eight lenses LF, L2 ... L7, LE can be used, and the F number can be set to 1.7 or less and the half angle of view can be set to 12-25 [°].

On the other hand, regarding the focus adjustment, in the rear lens group 102, the object OBJ side between the adjacent front and rear rear lenses L6 and L7 in the plurality of rear lenses L6 and L7 is set as the rear lens A group 102A, and the image IMG side. Can be set as the rear lens group B 102B, and at least one of the air spaces Sf and Fr before and after the rear lens group A 102A can be set as an adjustment interval to be changed at the time of focus adjustment. At this time, the adjustment interval is the air space Sf on the object OBJ side with respect to the rear lens group A 102A, the air space Sr on the image IMG side with respect to the rear lens group A 102A, and the air before and after with respect to the rear lens group A 102A. A maximum of three lens groups 101, 102A, 102B can be configured to be movable, including any one of the spaces Sf and Sr.

According to the large-diameter image pickup lens 1 according to the present invention having such a configuration, the following remarkable effects are obtained.

(1) A plurality of front positive lenses LF, L2 ... Continuous from the object OBJ side and a front negative lens L4 on the most open pattern STO side are included, and all lenses LF, L2 ... In addition, the radius of curvature of each lens surface (i = 2 ...) on the aperture aperture STO side gradually decreases from the object OBJ side to the aperture aperture STO, and the lens surfaces (i = 1, 2 ...) of all lenses LF, L2 ... ...) has a front lens group 101 that comes into contact with air, a biconcave lens L5 that is arranged on the most aperture aperture STO side, and a negative power that is arranged on the image IMG side and both sides are curved in the same direction on the optical axis Dc. It includes a plurality of posterior regular lenses L6, L7 sandwiched by the final lens LE, and has a posterior lens group 102 in which the posterior regular lenses L6, L7 include at least one biconvex lens (L6, L7). Since the entire lens system 100 is provided, the object distance is set to infinity, and the above-mentioned conditional equations [1]-[3] are satisfied, the length in the optical axis Dc direction can be shortened by the constructed front lens group 101. By loosening the entrance / exit angle of each lens surface, the occurrence of aberration can be suppressed, and in addition, by making the rear lens group 102 function as a partially symmetric lens group, the residual aberration generated in the previous stage can be corrected in a well-balanced manner. This is a bright replacement that is ideal for digital cameras that can fully meet consumer needs, such as being able to cover from infinity to short distances with sufficient optical performance as a single focus lens used for shooting in the quasi-wide-angle to medium-television range. It is possible to obtain a large-diameter image pickup lens 1 that can realize a lens and can also be used for a large-sized high-definition image pickup element while reducing the size and compactness of the entire optical system.

(2) According to a preferred embodiment, when the rear lens group 102 is formed, the lens surface (i = 9) on the aperture aperture STO side of the biconcave lens L5 to the third lens surface (i = 9) that sequentially comes into contact with air toward the image IMG side (2). The bending direction of i = 9 ...) and the bending of the third lens surface (i = 15 ...) that sequentially comes into contact with air from the lens surface (i = 15) on the image IMG side of the final lens LE to the aperture aperture STO side. If the direction is set to the opposite direction, a desirable partially symmetric lens group in the entire lens system 100 can be constructed, so that it is possible to realize a more well-balanced correction for residual aberration and reduce aberration fluctuation. ..

(3) According to a preferred embodiment, when the rear lens group 102 is configured, by having two rear positive lenses L6 and L7, the rear lens A from the rear positive lens L6 on the aperture aperture STO side to the rear lens A on the aperture aperture STO side. The rear lens group 102A and the rear positive lens L7 on the image IMG side to the rear lens B group 102B on the image IMG side are provided, and the rear lens group A 102A is at the time of an infinite object and is on the most object OBJ side of the entire lens system 100. When the absolute value of the length from the lens surface (i = 1) on the object OBJ side of the frontmost lens LF to the near-axis image position after the emission of the rear lens group A 102A is the largest, the object distance is set. If the distance is set to infinity and the above-mentioned conditional equations [4]-[7] are set, the light beam after passing through the rear lens group A 102A can be brought into a state close to that of the afocal lens to reduce the change in the light beam angle. Therefore, even when the front and rear lens groups including the rear lens A group 102A are moved at the time of focus adjustment, the fluctuation of the aberration can be further reduced and the lens group can be used as an adjustment point in the assembly process.

(4) According to a preferred embodiment, when the entire lens system 100 is configured, three or more front positive lenses LF, L2, L3 ... And two or more rear positive lenses L6, L7 ... Are included, and all positive lenses are included. In LF, L2 ..., L6, L7 ..., two or more positive lenses using a glass material having a d-line refractive index of 1.75 or more are included, and the average Abbe number is 38.0 or more, and the entire lens system is 100. The absolute value of the focal distances of all the positive lenses LF, L2 ..., L6, L7 ... If set, the glass characteristics and lens shape can be combined in a well-balanced manner by considering the glass material characteristics and power distribution of all positive lenses LF, L2 ..., L6, L7 ..., so fine adjustment can be made in the entire lens system. It is possible to easily and satisfactorily adjust the lens including the lens. In particular, since the power balance of each front lens LF, L2, L3 ... In the front lens group 101 can be selected to the curvature combined with the high refractive index glass material, the front lens group 101 can be made compact and the aberration correction effect can be enhanced. At the same time, it is possible to advantageously correct the axial aberration (chromatic aberration) by the rear lens group 102. In all the positive lenses LF, L2 ..., L6, L7 ..., a more desirable effect can be obtained by including at least one positive lens using a glass material having a refractive index of 1.85 or more of the d-line. Can be done.

(5) According to a preferred embodiment, when the front lens group 101 is configured, at least one lens using a low refractive index low dispersion glass material having an absolute partial dispersion value dPgf of 0.02 or more is included. If configured, in particular, by including a positive lens using a low-refractive index, low-dispersion glass material, it is possible to further enhance the effect of capturing chromatic aberration in the medium telephoto imaging region where chromatic aberration tends to be conspicuous.

(6) According to a preferred embodiment, when the rear lens group 102 is configured, the biconcave lens L5 arranged on the most aperture aperture STO side and the junction lens Ja by the rear positive lens L6 arranged on the image IMG side of the biconcave lens L5 are provided. The biconcave lens L5 is formed by using a glass material having an abnormal partial dispersion value dPgf of 0.02 or more, and the rear positive lens L6 has a high refraction index of 1.75 or more. If it is formed by using a refracting glass, it is possible to further enhance the correction effect on spherical aberration and axial chromatic aberration, in particular by utilizing a glass having a large Abbe number and a refraction coefficient difference.

(7) According to a preferred embodiment, when the entire lens system 100 is configured, the absolute value of the radius of curvature of the lens surface (i = 8, 9) facing the aperture aperture STO is set small on the front lens group 101 side. And when the radius of curvature of the lens surface (i = 8) on the front lens group 101 side is SR1 and the spatial spacing of the aperture aperture STO is TLS, "1.0 <[SR1 / TLS] <1.5" (conditional expression). If it is configured to satisfy [8]), the absolute value of the radius of curvature of the lens surface (i = 8,9) facing the aperture aperture STO can be set small on the front lens group 101 side, so that it is a modified Gaussian type. It is possible to effectively suppress the occurrence of sagittal coma, which is a drawback. Further, since the conditional expression [8] is set, the processability of the lens can be improved by suppressing the hemispherical degree, and the effectiveness of the aberration correction can be further enhanced by improving the aperture symmetry.

(8) According to a preferred embodiment, when the final lens LE includes a meniscus-shaped aspherical surface and the focal length of the final lens LE is FLE, "-4.0 <[FLE / AFL] <-0. If it is formed so as to satisfy 8 ”(conditional expression [9]), the ingress / egress characteristics of the light rays passing through the final lens LE can be set by an aspherical surface, so that off-axis aberrations in the final stage can be effectively suppressed and at the same time. Aberration correction from on-axis aberration to off-axis can also be effectively performed.

(9) According to a preferred embodiment, when the entire lens system 100 is configured, four lenses LF, L2, L3, L4 are arranged in the front lens group 101, and four lenses L5, L6 are arranged in the rear lens group 102B. By arranging, L7, LE, a total of eight lenses LF, L2 ... L7, LE are arranged, the F number is 1.7 or less, and the half angle of view is 12-25 [°], respectively. If set, from the viewpoint of setting the number of lenses, it is possible to secure the optical performance of a single focus lens having an F number of 1.7 or less and a half angle of view of 12-25 [°] while achieving compactness. .. That is, it can be implemented as an optimum embodiment in which the total length of the lens can be shortened while ensuring the necessary and sufficient optical performance (various aberrations) in the large-diameter image pickup lens 1 according to the present embodiment.

(10) According to a preferred embodiment, regarding the focus adjustment, the rear lens group 102 is used, and the rear lens group A 102A on the object OBJ side between the adjacent front and rear rear lenses L6 and L7 in the plurality of rear lenses L6 and L7. If the image IMG side is the rear lens B group 102B and at least one of the air spaces Sf and Fr before and after the rear lens A group 102A is set as the adjustment interval to be changed at the time of focus adjustment, the rear lens Since the light beam after passing through the group A 102A can be made close to the afocal lens to reduce the change in the light beam angle, it is possible to enhance the correction effect of various aberrations and suppress unnecessary aberration fluctuations at the time of focus adjustment. be able to.

(11) According to a preferred embodiment, the adjustment interval to be changed at the time of focus adjustment is set to the air space Sf on the object OBJ side with respect to the rear lens group A 102A, the air space Sr on the image IMG side with respect to the rear lens group A 102A, and the rear. If one of the front and rear air spaces Sf and Sr is included with respect to the lens group A 102A and a maximum of three lens groups 101, 102A and 102B are configured to be movable, soft focus photography due to changes in spherical aberration can be performed. Increasing or decreasing the amount of blurring of the peripheral image due to the change in curvature of field It is possible to enhance the variety and functionality of photography such as correction of curvature of field. In addition, by controlling the actuator (not shown) that moves each lens group 101, 102A, 102B and using the image sensor as a sensor, in addition to the original focus adjustment, spherical aberration and curvature of field can be controlled. Furthermore, it can be used for adjustment processes during manufacturing, and can further enhance diversity and expandability.

The block diagram of the large-diameter image pickup lens of Example 1 which concerns on a preferred embodiment of this invention, Conditional item explanatory diagram of the large-diameter image pickup lens according to the first embodiment, Longitudinal aberration diagram of the large-diameter image pickup lens according to the first embodiment at infinity, The longitudinal aberration diagram of the focus method F11-F13 shown in FIG. 1 of the large-diameter image pickup lens according to the first embodiment. The longitudinal aberration diagram of the focus method F14 shown in FIG. 1 and the focus methods F12A and F13A shown in Table 1 of the large-diameter image pickup lens according to the first embodiment. A list of optical conditions of the large-diameter image pickup lens in each embodiment according to the preferred embodiment of the present invention. Configuration diagram of the large-diameter image pickup lens of Example 2 according to the preferred embodiment of the present invention, The longitudinal aberration diagram of the large-diameter image pickup lens according to the second embodiment at infinity and the focus method F14 shown in FIG. 7. Configuration diagram of the large-diameter image pickup lens of Example 3 according to the preferred embodiment of the present invention, The longitudinal aberration diagram of the large-diameter image pickup lens according to the third embodiment at infinity and the focus method F12 shown in FIG. Configuration diagram of the large-diameter image pickup lens of Example 4 according to the preferred embodiment of the present invention, The longitudinal aberration diagram of the large-diameter image pickup lens according to the fourth embodiment at infinity and the focus method F12 shown in FIG.

Next, Examples 1-4, which are preferred embodiments according to the present invention, will be given and will be described in detail with reference to the drawings.

First, the large-diameter image pickup lens 1 of the first embodiment according to the present embodiment will be specifically described with reference to FIGS. 1 to 6.

First, the large-diameter image pickup lens 1 according to the present embodiment (Example 1) will be described with reference to FIG. It should be noted that this large-diameter image pickup lens 1 can be assumed to be applied to an interchangeable lens for a digital camera. In FIG. 1, OBJ indicates an object (subject), and IMG indicates an image (image sensor). Therefore, the object OBJ side is in front of the optical axis Dc direction, and the image IMG side is behind in the optical axis Dc direction.

The large-diameter image pickup lens 1 according to the present embodiment has a front lens group 101 having a positive power arranged on the object OBJ side and a rear lens group having a positive power arranged on the image IMG side with respect to the aperture stop STO. The 102 is provided, and the front lens group 101 and the rear lens group 102 constitute the entire basic lens system 100.

As shown in FIG. 1, the front lens group 101 includes four front positive lenses LF, L2, L3 continuous from the object OBJ side and a front negative lens L4 on the most aperture pattern STO side, and all lenses LF, L2. , L3 and L4 are composed of a meniscus lens having a convex object OBJ side. More specifically, from the object OBJ side, the first front positive lens (frontmost lens) LF using a convex meniscus lens, the second front positive lens L2 using a convex meniscus lens, and a convex meniscus lens were used. A third front positive lens L3 and a fourth front negative lens L4 using a concave meniscus lens are provided. The radius of curvature of each lens surface (i = 2, 4, 6, 8) on the aperture stop STO side is set so as to gradually decrease from the object OBJ side to the aperture stop STO side, and all lenses LF, L2, The lens surfaces of L3 and L4 (i = 1,2,3,4,5,6,7,8) come into contact with air. Therefore, all lenses LF, L2, L3, and L4 are each composed of a single lens.

In this way, the front lens group 101 is made compact by reducing the length in the optical axis Dc direction by forming a meniscus shape in which all lenses LF, L2, L3, and L4 are convex toward the object OBJ side. At the same time, the occurrence of aberration is suppressed by loosening the entrance / exit angles of each lens surface (i = 2, 4, 6, 8). In particular, the front positive lenses LF, L2, and L3 disperse the power by dividing the positive power, and as shown in FIG. 1, the front negative lens L4 is on the object OBJ side (i = 6 and 7). By providing a meniscus-shaped narrow space (negative air lens) La in the space), the effect of correcting spherical aberration is enhanced.

On the other hand, the rear lens group 102 includes a biconcave lens L5 arranged on the most aperture stop STO side and a final lens LE arranged on the image IMG side and having negative power on both sides curved in the same direction on the optical axis Dc. At the same time, two posterior positive lenses L6 and L7 sandwiched between the biconcave lens L5 and the final lens LE, that is, a biconvex lens (L6) and a biconvex lens (L7) are provided from the aperture stop STO side to the image IMG side. As described above, the posterior positive lenses L6 and L7 include at least one biconvex lens (L6, L7), and the biconcave lens L5 and the posterior positive lens (biconvex lens) L6 are composed of the junction lens Ja.

Due to this configuration, the rear lens group 102 is a partially symmetrical lens group including two positive lenses (L6, L7) sandwiched between the front and rear negative lenses (L5, LE), and is generated by the front lens group 101. It is possible to correct the residual aberration in a well-balanced manner. Further, as will be described later, fluctuations in various aberrations are suppressed by using a junction lens Ja (rear lens A group 102A) as the lens group that moves during focus adjustment.

By configuring the entire lens system 100 with such a front lens group 101 and a rear lens group 102, light rays parallel to the optical axis Dc incident from an infinite object pass through the front lens group 101 and converge. The oblique light rays incident on the rear lens group 102 and incident on the rear lens group 102 from off-axis are at an angle close to the normal line of the surface with respect to the lens surface (i = 9) of the biconcave lens L5 located first. Incident at.

On the other hand, in the above basic lens configuration, the object distance is set to infinity, the focal length of the entire system is AFL, the optical axis length of the entire lens system 100 is TLL, and the image is taken from the lens surface (i = 1) on the most object OBJ side. When the optical axis length to IMG is TLi and the optical axis length from the lens surface on the image IMG side of the final lens LE to the image IMG is IMD, the following conditions, that is, the conditional equations [1]-[3] are satisfied. To set. Note that FIG. 2 illustrates some of these condition items.
0.68 <[TLL / AFL] <1.00 ... [1]
0.8 <[TLi / AFL] <1.4 ... [2]
0.2 <[IMD / AFL] ... [3]

In this case, the conditional equations [1] and [2] set the range for making the large-diameter image pickup lens 1 according to the present embodiment compact, and when the upper limit is exceeded, the curvature of the lens and the refractive index of the glass material are changed. Since it can be lowered, the occurrence of aberration can be suppressed, but compactness cannot be ensured. On the other hand, when it is below the lower limit, although compactness can be ensured, the power of each lens becomes stronger, so that aberrations occur more frequently. By satisfying the conditional expression [3], the required back focus can be secured. In the case of the large-diameter image pickup lens 1, it is necessary to secure an optical axis distance that does not interfere with a parallel flat plate such as a wavelength cut filter or dustproof glass installed in front of the image pickup element (IMG: image), and in particular, as an interchangeable lens. When using it, it is necessary to make it compatible with various image sensors (cameras), so it is necessary to secure a certain degree of back focus.

Further, in the basic lens configuration, the rear lens group 102 has the third lens surface (i =) that sequentially contacts the air from the lens surface (i = 9) on the aperture stop STO side of the biconcave lens L5 to the image IMG side. 9,11,13) bending direction (+, +,-) and the third lens surface that sequentially comes into contact with air from the lens surface (i = 15) on the image IMG side of the final lens LE to the aperture stop STO side. The bending direction (-,-, +) of (i = 15, 14, 13) is set in the opposite direction. As a result, a desirable partially symmetric lens group in the entire lens system 100 can be constructed, so that it is possible to further correct the residual aberration with a good balance and reduce the aberration variation.

Further, since the rear lens group 102 has two rear positive lenses L6 and L7, the rear positive lens L6 on the aperture stop STO side is referred to as the rear lens A group 102A on the aperture aperture STO side, and the rear positive lens on the image IMG side. The image IMG side from L7 is set as the rear lens B group 102B. In this case, since the light beam after passing through the rear lens group A 102A is in a state close to that of the afocal lens, the change in the light ray angle can be reduced. Therefore, when the front and rear lens groups including the rear lens group A 102A are used as the moving group for focus adjustment, the lens group becomes the optimum lens group, and the aberration fluctuation can be reduced regardless of whether the fixed interval or the variable interval is set. It will be easier to use as an adjustment point in the assembly process. If the number of positive lenses in the front lens group 101 and the rear lens group 102 is increased by division, various aberrations can be easily corrected, but on the other hand, the optical axis Dc becomes long, so from the viewpoint of compactness. It will be disadvantageous. Further, since the rear lens group 102 constitutes a partially symmetric lens group, the deviation of the optical axis lengths of the rear lens group A 102A and the rear lens group B 102B is large from the viewpoint of ensuring the merit of aberration correction obtained from the symmetry. It is desirable to suppress it as much as possible.

Then, in the entire lens system 100, the rear lens group A 102A is an infinite object, and the lens surface (i = 1) of the frontmost lens LF arranged on the most object OBJ side of the entire lens system 100 on the object OBJ side. When the absolute value of the length from the rear lens A group 102A to the near-axis image position is the largest, the object distance is set to infinity, the F number of the entire system is FNO, and the front lens group 101. When the optical axis length is LF1, the optical axis length of the rear lens group 102 is LF2, the optical axis length of the rear lens group A 102A is TL2A, and the optical axis length of the rear lens group B 102B is TL2B, the following conditions, that is, Set so as to satisfy the conditional expression [4]-[7]. Note that FIG. 2 illustrates some of these condition items.
0.8 <[TLl / TL2] <1.6 ... [4]
0.6 <[TL2A / TL2B] <1.6 ... [5]
1.0 <[TLL / (AFL / FNO)] <1.5 ... [6]
0.3 <[TL2 / (FL2 / FNO)] <0.6 ... [7]

In this case, since the conditional expression [4] indicates the ratio of the optical axis Dc lengths of the front lens group 101 and the rear lens group 102, the number of divisions of each positive lens is biased so as to ensure partial symmetry. It is desirable to set it evenly without occurring. The same applies to the conditional expression [5], and consideration is given so that the partial symmetry of the rear lens group 102 can be ensured. Therefore, if the range of the conditional expression [4] or [5] is not satisfied, the load on either the front lens group 101 or the rear lens group 102 becomes large, the aberration correction becomes unstable, and the large-diameter image pickup lens 1 It becomes impossible to secure the compactness of the lens. Further, the conditional expression [6] sets a constraint in the radial direction of the front lens group 101 and the rear lens group 102, and indicates the aspect ratio in the entire lens system 100 when the entrance pupil diameter is AFL / FNO. .. Further, the conditional expression [7] sets a constraint in the radial direction of the rear lens group 102, and as an alternative to the diameter of the aperture pattern STO, the aspect ratio of the rear lens group 102 when FL2 / FNO is set is set. show. Therefore, when the upper limit of the conditional expressions [6] and [7] is exceeded, the length increases in the optical axis Dc direction, and when the condition falls below the lower limit, the length increases in the radial direction.

On the other hand, when constructing the large-diameter image pickup lens 1, the following points are taken into consideration in the entire lens system 100. First, in all the positive lenses LF, L2 ..., L6, L7 ..., two or more positive lenses using a glass material having a d-line refractive index of 1.75 or more are included, and the average Abbe number is 38.0 or more. The absolute value of the focal lengths of all the positive lenses LF, L2 ..., L6, L7 ... In the whole lens system 100 is 80, which is the absolute value of the focal length of the negative lens having the maximum focal length in the whole lens system 100. Set larger than [%].

The front lenses LF, L2, and L3 in the front lens group 101 use high refraction type glass and obtain positive power due to a weak curvature. In this case, it is possible to configure the lens with two positive lenses, but since the power per lens is increased, the lens thickness becomes large and the aberration cannot be sufficiently corrected. Therefore, if the lens group is divided into three or more lenses, the front lens group 101 can be made compact, and the aberration correction effect can be ensured. Chromatic aberration can be corrected by using a low-refraction and low-dispersion glass material for each of the positive lenses LF, L2 ... Of the front lens group 101, but when the refractive index is low, a predetermined positive power is obtained. Since it is necessary to reduce the radius of curvature, the lens thickness becomes large. In addition, it is necessary to make the shape closer to a plano-convex shape or a biconvex shape in which a refractive power can be obtained, rather than the meniscus shape, which also causes an increase in the lens thickness. Therefore, it is desirable to set the curvature of the front positive lenses LF, L2 ... In the front lens group 101 in combination with the high refractive index glass material. On the other hand, when the glass characteristic used for the junction lens Ja of the rear lens group 102 is a refractive index difference, it is advantageous for correcting axial aberrations, and when it is set to an Abbe number difference, it is advantageous for improving chromatic aberration. Further, by combining the glass characteristics and the shape in a well-balanced manner, there is an effect that the aberration can be finely adjusted in the entire lens system 100.

As described above, in all the positive lenses LF, L2 ..., L6, L7 ... Of the entire lens system 100, two or more positive lenses using a glass material having a d-line refractive index of 1.75 or more are included, and the average. The Abbe number is 38.0 or more, and the absolute value of the focal distances of all the positive lenses LF, L2 ..., L6, L7 ... In the entire lens system 100 is the relevant negative lens having the maximum focal distance in the entire lens system 100. If it is set to be larger than the absolute value of the focal distance of 80 [%], the glass characteristics and the lens shape are combined in a well-balanced manner by considering the glass material characteristics and power distribution of all the positive lenses LF, L2 ..., L6, L7 ... Therefore, it is possible to easily and satisfactorily adjust the aberration including fine adjustment in the entire lens system. In particular, since the power balance of each front lens LF, L2, L3 ... In the front lens group 101 can be selected to the curvature combined with the high refractive index glass material, the front lens group 101 can be made compact and the aberration correction effect can be enhanced. At the same time, it is possible to advantageously correct the axial aberration (chromatic aberration) by the rear lens group 102. In all the positive lenses LF, L2 ..., L6, L7 ..., a more desirable effect can be obtained by including at least one positive lens using a glass material having a refractive index of 1.85 or more of the d-line. Can be done.

Further, in the entire lens system 100, the absolute value of the radius of curvature of the lens surface (i = 8, 9) facing the aperture stop STO is set small on the front lens group 101 side, and the lens surface on the front lens group 101 side is set small. When the radius of curvature of (i = 8) is SR1 and the spatial spacing of the aperture stop STO is TLS,
1.0 <[SR1 / TLS] <1.5 ... [8]
Set to meet the conditions of.

The rear lens group 102 has a stronger positive power than the front lens group 101, but when the radius of curvature on the aperture stop STO side of the rear negative lens L5 of the rear lens group 102 is small, it is a drawback of the modified Gaussian type in the sagittal direction. Since coma is likely to occur, the absolute value of the radius of curvature SR2 on the image IMG side with respect to the aperture stop STO is set larger than the radius of curvature SR1 on the object OBJ side with respect to the aperture pattern STO. Further, in the case of a large diameter, the hemispherical degree increases due to the tendency that the absolute value of the radius of curvature of the lens surface (i = 8, 9) in contact with the space of the aperture stop STO decreases, so this conditional expression [8] is set. .. Therefore, if it is below the lower limit of the conditional expression [8], the hemispherical degree increases and it becomes difficult to process the lens, and if it exceeds the upper limit, it becomes difficult to correct the aberration due to the decrease in partial symmetry.

Therefore, if such a condition is set, the absolute value of the radius of curvature of the lens surface (i = 8, 9) facing the aperture stop STO can be set small on the front lens group 101 side, which is a drawback of the modified Gauss type. The occurrence of sagittal coma aberration can be effectively suppressed. Further, since the conditional expression [8] is set, the processability of the lens can be improved by suppressing the hemispherical degree, and the effectiveness of the aberration correction can be further enhanced by improving the aperture symmetry.

Further, when forming the final lens LE, when a meniscus-shaped aspherical surface is included and the focal length of the final lens LE is set to FLE,
-4.0 <[FLE / AFL] <-0.8 ... [9]
It is formed so as to satisfy the conditions of.

Since the surface shapes of both sides of the aspherical lens constituting the final lens LE face in the same direction from the optical axis Dc to the outer peripheral portion, there are two types, one is a convex shape toward the object OBJ side and the other is a concave shape. There are two types. In the case of a concave shape, since it enters and exits at an angle close to the normal line of the surface through which the main light rays of each angle of view pass, the occurrence of off-axis aberrations is reduced, and the biconcave lens L5 on the opening pattern STO side of the aspherical lens is reduced. However, since it is gradually bounced upward so as to separate the off-axis ray from the on-axis ray, it is advantageous in correcting the aberration from the on-axis aberration to the off-axis aberration. On the other hand, in the case of a convex shape, since the on-axis ray and the off-axis ray have an angle close to equal to the normal of the aspherical position where the light ray enters and exits, the off-axis aberration is similarly corrected from the on-axis aberration. be able to.

The final lens LE of the example has a weak negative power as a component, and aberration correction is performed by an aspherical effect that is slightly deviated from the spherical surface. Since it is a negative meniscus lens, the curve is stronger in the direction of the center of curvature on both sides. Although it is possible to use a biconcave lens, the curve trend may differ between the center and the periphery, so the condition for facing in the same direction is the conditional expression [9]. By using such a final lens LE, the ingress / egress characteristics of the light rays passing through the final lens LE can be set by an aspherical surface, so that off-axis aberrations in the final stage can be effectively suppressed and off-axis aberrations can be suppressed. Aberration correction can also be effectively performed.

In the large-diameter image pickup lens 1 according to the present embodiment, as shown in FIG. 1, four lenses LF, L2, L3, and L4 are arranged in the front lens group 101 when the entire lens system 100 is configured, and the rear lens group 101 is arranged. By arranging four lenses L5, L6, L7, LE in the lens group 102B, the lens group 102B is composed of eight lenses LF, L2 ... L7, LE in total, and the F number is 1.7 or less. Set the half angle of view to 12-25 [°] respectively. As a result, from the viewpoint of setting the number of lenses, it is possible to secure the optical performance that the F number is 1.7 or less and the half angle of view is 12-25 [°] while realizing the compactification. That is, it can be implemented as an optimum embodiment in which the total length of the lens can be shortened while ensuring the necessary and sufficient optical performance (various aberrations) in the large-diameter image pickup lens 1 according to the present embodiment.

Further, as shown in FIG. 1, the large-diameter image pickup lens 1 according to the present embodiment includes a focus adjustment function unit 201. That is, regarding the focus adjustment, the rear lens group 102 is set as the rear lens A group 102A on the object OBJ side between the adjacent front and rear rear lenses L6 and L7 in the plurality of rear regular lenses L6 and L7, and the image IMG side. Is set to the rear lens B group 102B, and if at least one of the air spaces Sf and Fr before and after the rear lens A group 102A is set as an adjustment interval to be changed at the time of focus adjustment, after passing through the rear lens A group 102A. Since the change in the beam angle can be reduced by making the light beam close to that of the afocal lens, it is possible to enhance the correction effect of various aberrations and suppress unnecessary aberration fluctuations at the time of focus adjustment.

The focus adjustment function unit 201 mainly enhances the effect of capturing spherical aberration by varying the space of the aperture stop STO. Further, by varying the space between the two rear lenses L6 and L7 of the rear lens group 102, the effect of correcting astigmatism is mainly enhanced. By moving (Gm1, Gm2, Gm3) three lens groups (front lens group 101, rear lens A group 102A, rear lens B group 102B) as in the focus method of [F11] shown in FIG. It is possible to reduce the change in aberration during focusing from a long distance to a short distance. Further, in the case of the focus method of [F12] in which the two lens groups (front lens group 101 + rear lens A group 102A, rear lens B group 102B) are moved (Gm4, Gm3), astigmatism is mainly suppressed. In the case of the focus method of [F13] in which two lens groups (front lens group 101, rear lens A group 102A + rear lens B group 102B) are moved (Gm1, Gm5), spherical aberration is mainly suppressed. Thereby, the fluctuation of the focus aberration can be reduced.

In the large-diameter image pickup lens which is the object of the present invention, since the three-dimensional space which is the subject is imaged by the plane image pickup element, the image gradually becomes blurred as the distance from the focal space increases. In particular, since the depth of focus becomes shallow when shooting from a medium distance to a short distance, there are many shooting methods that focus on the vicinity of one subject and blur the surroundings instead of copying a flat subject. In this case, it is more effective in shooting to leave the curvature of field around the screen by the focus method of [F14], that is, the whole extension method of moving the entire lens system 100 (Gm6).

Regarding the adjustment interval to be changed at the time of focus adjustment, the air space Sf on the object OBJ side with respect to the rear lens group A 102A, the air space Sr on the image IMG side with respect to the rear lens group A 102A, and the rear lens group A 102A. On the other hand, since any one of the front and rear air spaces Sf and Sr is included, a maximum of three lens groups 101, 102A and 102B can be configured to be movable.

As described above, the relationship between the variable spacing and the aberration is that the spherical aberration mainly changes by changing the spatial spacing of the aperture stop STO, and the space of the two rear positive lenses L6 and L7 of the rear lens group 102. By changing the interval, astigmatism mainly changes. As a result, the spherical aberration changes by changing the spatial interval of the aperture stop STO, resulting in soft focus. Further, if the spatial spacing between the two rear positive lenses L6 and L7 of the rear lens group 102 is changed, the curvature of field changes. In this case, since the blur caused by the curvature of field is defocused, the amount of blur in the peripheral image can be increased or decreased. That is, since the upper part of the spherical aberration, which is an area with a large F number, slightly changes before and after the focal position, the soft focus effect due to the spherical aberration has a focus core and the surroundings become blurred. Further, the aberration adjustment by this interval has an effect that it can be used for correcting the curvature of field caused by the variation at the time of assembly.

Hereinafter, this aberration adjustment, particularly the aberration adjustment using the variable spacing of the shaft upper surface spacing ZD9 and ZD12, and the adjustment that can be used at the time of manufacturing to which this aberration adjustment is applied will be described.

Image pickup devices (optical devices) such as cameras have various functions such as focus detection by sensors, lens performance storage by memory, and lens group movement by arithmetic devices and actuators, so normal lens performance is maintained. At the same time, it is possible to obtain an image in which the lens performance is impaired by changing the distance between the lens groups during shooting. In addition, since it is difficult to check the focus and composition (distance of objects in the screen, etc.) with the naked eye when the lens performance is impaired, the spatial information on the subject side changes in a complicated manner due to the various functions of the image pickup device. Can be quickly and accurately grasped, and the operation can be accurately performed according to the characteristics of the image pickup device.

First, the adjustment of "curvature of field" will be described. The focus method [F12A] shown in FIG. 5 (f) is a longitudinal aberration diagram when the shaft upper surface spacing (ZD12) is changed with respect to the focus method [F12] of the image pickup lens 1 according to the first embodiment (FIG. 1). Is shown. That is, it shows a state in which the variable interval ZD12 is excessively moved by "−0.20 mm" from the state in which the short-distance aberration correction of the focus method [F12] is performed. In this case, it can be confirmed that the "astigmatism" moves in the negative direction as compared with the longitudinal aberration diagram of [F12] shown in FIG. 4 (c). The curvature of field is a blur caused by defocusing, and when the center of the screen is in focus, the periphery of the screen is blurred, and when the periphery of the screen is in focus, the center of the screen is blurred. That is, when the astigmatism moves in the negative direction, the object corresponding to the focus plane around the screen is in the infinity direction from the focus plane corresponding to the center of the screen, and when the astigmatism moves in the positive direction. The object corresponding to the focus plane around the screen is closer to the lens side than the focus plane corresponding to the center of the screen.

Therefore, it can be applied to, for example, projection resolution inspection in the manufacturing process. That is, when the resolution is centered on the projection plane, the variable spacing ZD12 is widened if the resolution around the projection plane is on the lens side, while the variable spacing is widened if the resolution is not on the lens side around the projection plane. By narrowing the ZD12, a flat image plane can be obtained. Further, the inclination of the resolution surface can be corrected by making the whole or a part of the rear lens group B 102B on the image side of the ZD 12 into an eccentric state.

Next, the adjustment of "spherical aberration" will be described. The focus method [F13A] shown in FIG. 5 (g) is a longitudinal aberration diagram when the shaft upper surface spacing (ZD9) is changed with respect to the focus method [F13] of the image pickup lens 1 according to the first embodiment (FIG. 1). Is shown. That is, the case where the variable interval ZD9 is excessively moved by "−0.50 mm" from the state where the short-distance aberration correction of the focus method [F13] is performed is shown. In this case, it can be confirmed that the "spherical aberration" moves in the negative direction from the longitudinal aberration diagram of [F13] shown in FIG. 4 (d). As for spherical aberration, the direction in which the lens diameter is large is above the vertical axis of the aberration diagram. Therefore, on the lens surface on the image IMG side of the aperture stop STO, the entry / exit angle of the light beam formed around the image plane becomes gentle, while the light beam formed on the center of the image plane is the center of the lens surface (light). Since it becomes steeper toward the periphery with respect to the axis Dc), if the spatial spacing of the aperture stop STO is changed, the change in the spherical aberration above the vertical axis in the aberration diagram becomes large.

For this reason, the soft focus effect due to normal spherical aberration becomes the "focus core" when the aperture diameter is small, and the spherical aberration changes around the aperture diameter "bleeding around the focus core". It becomes. The side where the spherical aberration is negative, that is, the side where the air spacing of ZD9 is narrowed is the object side from the paraxial focal position, and the side where the spherical aberration is positive, that is, the side where the air spacing of ZD9 is widened is the opposite. In addition, when these are applied to the above-mentioned projection resolution inspection, it is difficult to focus when the effect of soft focus is large. If the spatial spacing ZD9 of the aperture stop STO is adjusted after opening the aperture, a clear image plane can be obtained. As for the adjustment at the time of manufacture, the spherical aberration can be adjusted by ZD9 and the curvature of field can be adjusted by ZD12 also in Example 2-4 described later.

In this way, the focus adjustment function unit 201 sets the adjustment interval to be changed at the time of focus adjustment in the air space Sf on the object OBJ side with respect to the rear lens group A 102A and the air space on the image IMG side with respect to the rear lens group A 102A. Since any one of the front and rear air spaces Sf and Sr is included with respect to the Sr and the rear lens A group 102A, and a maximum of three lens groups 101, 102A and 102B can be configured to be movable, the softness due to the change in spherical aberration It is possible to enhance the versatility and functionality of focus photography, increase / decrease in the amount of blurring of peripheral images due to changes in curvature of field, and correction of curvature of field. In addition, by controlling the actuator (not shown) that moves each lens group 101, 102A, 102B and using the image sensor as a sensor, in addition to the original focus adjustment, spherical aberration and curvature of field can be controlled. Furthermore, it can be used for adjustment processes during manufacturing, and can further enhance diversity and expandability.

Therefore, according to such a large-diameter imaging lens according to the present embodiment, as a basic configuration, a plurality of front positive lenses LF, L2 ... Continuously from the object OBJ side and a front negative lens L4 on the most open pattern STO side. All lenses LF, L2 ... The front lens group 101, which is smaller and the lens surfaces (i = 1, 2, ...) Of all lenses LF, L2 ... Are in contact with air, the biconcave lens L5 arranged on the most aperture aperture STO side, and the most image IMG side. A plurality of posterior positive lenses L6, L7 sandwiched by a final lens LE having a negative power whose both sides are curved in the same direction on the optical axis Dc are included, and at least one of the posterior positive lenses L6, L7. This is because the entire lens system 100 having a rear lens group 102 including two biconvex lenses (L6, L7) is provided, the object distance is set to infinity, and the above-mentioned conditional equations [1]-[3] are satisfied. The constructed front lens group 101 can shorten the length in the optical axis Dc direction, and the entrance / exit angle of each lens surface is loosened to suppress the occurrence of aberrations. In addition, the rear lens group 102 functions as a partially symmetric lens group. By doing so, the residual aberration generated in the previous stage can be corrected in a well-balanced manner. As a result, it is possible to realize a bright interchangeable lens that is optimal for digital cameras, etc. that can fully meet consumer needs, such as being able to cover sufficient optical performance even in short-distance photography, and to reduce the size and compactness of the entire optical system. At the same time, it is possible to obtain a single-focus large-diameter image pickup lens 1 that is compatible with a large-scale high-definition image pickup element and is particularly suitable for a quasi-wide-angle to medium-television shooting range.

Table 1 shows the lens data of the entire lens system 100 in the large-diameter image pickup lens 1 according to the first embodiment. The entire lens system 100 at the time of an infinite object has a focal length of 49.60 mm, an F number of 1.43, a half angle of view: 23.31 °, and an image height of 21.63 mm.

The "plane data" in Table 1 indicates the surface number of the lens surface counted from the object OBJ side by i, and this surface number i corresponds to the reference numeral (number) shown in FIG. Correspondingly, the radius of curvature R (i) of the lens surface, the axis top surface distance D (i), the refractive index nd (i) of the lens, the Abbe number νd (i) of the lens, and the abnormal partial dispersion value ΔPgF (i). The absolute values of are shown respectively. nd (i) and νd (i) are numerical values for the d line (587.56 [nm]). The shaft upper surface distance D (i) indicates the lens thickness or the air space between the facing surfaces. The unit of the radius of curvature R (i) and the surface spacing D (i) is [mm]. The surface number OBJ indicates an object, STO indicates an aperture stop, and IMG indicates the position of an image. The Infinity of the radius of curvature R (i) is a plane, and the surface with A after the surface number i indicates that the surface shape is aspherical. The blanks of the refractive index nd (i) and the Abbe number νd (i) indicate that it is air.

The "aspherical coefficient" in Table 1 is based on the case where the ASP is an aspherical surface number in a Cartesian coordinate system (X, Y, Z) with the center of the surface as the origin and the optical axis Dc direction as Z. Z is represented by the number 1. In Equation 1, R is the central radius of curvature, A4, A6, A8, and A10 are the aspherical coefficients of the 4th, 6th, 8th, and 10th orders, respectively, and H is the distance from the origin on the optical axis. In Table 2, "E" means "x10".

As shown in FIG. 6, since AFL is 49.60 mm and TLL is 40.69 mm, TLL / AFL is “0.82”, and the conditional expression [1] (0.68 <[TLL / AFL] <1. .00) is satisfied. Since TLi is 65.00 mm, TLi / AFL becomes "1.31" and satisfies the conditional expression [2] (0.8 <[TLi / AFL] <1.4). Since the IMD is 24.31 mm, the IMD / AFL is "0.49", which satisfies the conditional expression [3] (0.2 << [IMD / AFL]).

Further, since TL1 is 15.44 mm and TL2 is 14.33 mm, TLl / TL2 is "1.08", which satisfies the conditional expression [4] (0.8 <[TLl / TL2] <1.6). .. Since TL2A is 5.28 mm and TL2B is 7.80 mm, TL2A / TL2B is "0.68", and the conditional expression [5] (0.6 <[TL2A / TL2B] <1.6) is satisfied. Since FNO is 1.43, TLL / (AFL / FNO) is 1.17, which satisfies the conditional expression [6] (1.0 << [TLL / (AFL / FNO)] <1.5). Since FL2 is 44.15 mm, TL2 / (FL2 / FNO) becomes "0.46", which satisfies the conditional expression [7] (0.3 <[TL2 / (FL2 / FNO)] <0.6). ..

Further, since SR1 is 14.41 mm and TLS is 10.92 mm, SR1 / TLS is "1.32" and the conditional expression [8] (1.0 << [SR1 / TLS] <1.5) is satisfied. .. Since the FLE is −73.00 mm, the FLE / AFL is “-1.47” and the conditional expression [9] (-4.0 <[FLE / AFL] <−0.8) is satisfied. In addition, as shown in FIG. 6, various other physical quantities and the range of conditional expressions in Example 1 also satisfy the constituent requirements required by the present invention.

On the other hand, in the "variable focus interval" in Table 1, F10 corresponds to the focus method [F11]-[F14] shown in FIG. 1 at infinity, and F12A corresponds to the axis with respect to F12. F13A shows a case where the upper surface spacing (ZD12) is changed and the shaft upper surface spacing (ZD9) is changed with respect to F13. The ZD16 of the "focus variable interval" is the optical axis length from the final lens surface (i = 15) to the image IMG, and particularly indicates the above-mentioned IMD at infinity.

In the case of the first embodiment, the focus adjustment when the distance of the object OBJ changes from infinity to a short distance can be performed by any one of the four types of focus methods [F11]-[F14]. In [F11], each of the three lens groups in which the front lens group 101, the rear lens A group 102A, and the rear lens B group 102B are integrated is moved to the object OBJ side by different amounts, and the air spacing including the aperture throttle STO, [F12 (F12A)], a method of changing the air spacing between the rear positive lenses L6 and L7 in the rear lens group 102 and the air spacing on the image IMG side, integrates the front lens group 101 and the rear lens group A 102A. The two lens groups, which are the integrated lens group and the rear lens group B 102B, are moved to the object OBJ side by different amounts, and the air gap between the rear positive lenses L6 and L7 in the rear lens group 102, the image IMG side. [F13 (F13A)] is a method of changing the air spacing of the two lenses, in which the front lens group 101 and the rear lens group 102 are integrated, and the two lens groups are moved to the object OBJ side by different amounts to open the lens. The method of changing the air spacing including the aperture STO and the air spacing on the image IMG side, respectively, [F14] is a method of moving the entire lens system 100 to the object OBJ side as a unit and changing the air spacing on the image IMG side. ..

3 and 5 show the focus methods [F12A] and [F13A] at infinity [F10], the focus method [F11]-[F14], and the shaft upper surface spacing in the image pickup lens 1 of the first embodiment. The corresponding longitudinal aberration diagrams are shown. Each longitudinal aberration diagram shows spherical aberration (656.27 nm, 587.56 nm, 435.83 nm), astigmatism (587.56 nm), and distortion (587.56 nm) from the left side. Each scale is ± 0.50 mm, ± 0.50 mm, ± 3.0%.

As is clear from FIG. 3-FIG. 5, good aberration, that is, imaging performance is obtained regardless of the focus method ([F10], [F11]-[F14], [F12A] and [F13A]). It can be confirmed that it can be obtained.

An image sensor is arranged on the image plane (IMG), and a face plate, an infrared cut filter, a parallel flat plate such as a low-pass filter, etc. are usually arranged on the front surface of the image sensor. , The total thickness is converted into an optically equivalent air spacing and added to the back focus of the entire system.

Next, the large-diameter image pickup lens 1 of the second embodiment according to the present embodiment will be described with reference to FIGS. 6-8.

As shown in FIG. 7, the large-diameter image pickup lens 1 of the second embodiment has the same basic lens configuration as the first embodiment described above, but the focus variable intervals ZD9 and ZD12 are unchanged. The whole extension method of moving (Gm6) the entire lens system 100, which is the same as the focus method [F14] of Example 1, is adopted.

Table 2 shows the lens data of the entire lens system 100 in the large-diameter image pickup lens 1 according to the second embodiment. The image pickup lens 1 at an infinite object point has a focal length of 49.60 mm, an F number of 1.43, a half angle of view: 23.29 °, and an image height of 21.63 mm.

As shown in FIG. 6, since AFL is 49.60 mm and TLL is 40.00 mm, TLL / AFL is “0.81”, and the conditional expression [1] (0.68 <[TLL / AFL] <1. .00) is satisfied. Since TLi is 65.00 mm, TLi / AFL becomes "1.31" and satisfies the conditional expression [2] (0.8 <[TLi / AFL] <1.4). Since the IMD is 25.00 mm, the IMD / AFL is "0.50", which satisfies the conditional expression [3] (0.2 << [IMD / AFL]).

Further, since TL1 is 15.23 mm and TL2 is 12.87 mm, TLl / TL2 is "1.18", which satisfies the conditional expression [4] (0.8 <[TLl / TL2] <1.6). .. Since TL2A is 5.55 mm and TL2B is 7.17 mm, TL2A / TL2B is “0.77” and the conditional expression [5] (0.6 << [TL2A / TL2B] <1.6) is satisfied. Since FNO is 1.43, TLL / (AFL / FNO) is 1.15, which satisfies the conditional expression [6] (1.0 << [TLL / (AFL / FNO)] <1.5). Since FL2 is 44.84 mm, TL2 / (FL2 / FNO) becomes "0.41" and satisfies the conditional expression [7] (0.3 <[TL2 / (FL2 / FNO)] <0.6). ..

Further, since SR1 is 14.62 mm and TLS is 11.90 mm, SR1 / TLS is "1.23" and the conditional expression [8] (1.0 << [SR1 / TLS] <1.5) is satisfied. .. Since the FLE is -127.32 mm, the FLE / AFL is "-2.57", which satisfies the conditional expression [9] (-4.0 <[FLE / AFL] <-0.8). In addition, as shown in FIG. 6, various other physical quantities and the range of conditional expressions in Example 2 also satisfy the constituent requirements required by the present invention.

FIG. 8 shows a longitudinal aberration diagram corresponding to the point at infinity [F10] and the focus method [F14] in the image pickup lens 1 of the second embodiment, respectively. As is clear from FIG. 8, it can be confirmed that good aberration, that is, imaging performance can be obtained regardless of the focus method ([F10], [F14]).

Next, the large-diameter image pickup lens 1 of the third embodiment according to the present embodiment will be described with reference to FIGS. 6, 9 and 10.

As shown in FIG. 9, the large-diameter image pickup lens 1 of Example 3 has the same basic lens configuration as that of Example 1 described above, but as a focus method, the focus variable interval ZD9 is unchanged, and Example 1 is used. The same method as the focus method [F12] of the above, that is, the focus adjustment at a close distance is performed at the variable interval of the ZD12. Specifically, the lens group in which the front lens group 101 and the rear lens group A 102A are integrated, and the two lens groups in which the rear lens group B 102B is integrated are moved to the object OBJ side by different amounts, and the rear lens group B is moved to the rear. A method of changing the air spacing between the posterior positive lenses L6 and L7 in the lens group 102 and the air spacing on the image IMG side, that is, two lens groups (front lens group 101 + rear lens A group 102A, rear lens B group 102B). ) Is moved (Gm4, Gm3) [F12], and the focus method is adopted.

Further, in the third embodiment, when the rear lens group 102 is configured, the junction lens Ja is configured by the biconcave lens L5 arranged on the most aperture stop STO side and the rear positive lens L6 arranged on the image IMG side of the biconcave lens L5. In this case, the biconcave lens L5 is formed by using a glass material having an abnormal partial dispersion value dPgf of 0.02 or more, and the posterior positive lens L6 has a high refractive index of 1.75 or more. Formed using refracted glass. If the rear lens group 102 is configured in this way, it is possible to further enhance the correction effect on spherical aberration and axial chromatic aberration, in particular by utilizing glass having a large Abbe number and the difference in refractive index.

Table 3 shows the lens data of the entire lens system 100 in the large-diameter image pickup lens 1 according to the third embodiment. The image pickup lens 1 at an infinite object point has a focal length of 49.60 mm, an F number of 1.40, a half angle of view: 23.29 °, and an image height of 21.63 mm.

As shown in FIG. 6, since AFL is 49.60 mm and TLL is 40.06 mm, TLL / AFL is “0.81”, and the conditional expression [1] (0.68 <[TLL / AFL] <1. .00) is satisfied. Since TLi is 65.00 mm, TLi / AFL becomes "1.31" and satisfies the conditional expression [2] (0.8 <[TLi / AFL] <1.4). Since the IMD is 24.94 mm, the IMD / AFL is "0.50", which satisfies the conditional expression [3] (0.2 << [IMD / AFL]).

Further, since TL1 is 15.56 mm and TL2 is 13.59 mm, TLl / TL2 is "1.15", which satisfies the conditional expression [4] (0.8 <[TLl / TL2] <1.6). .. Since TL2A is 5.30 mm and TL2B is 7.72 mm, TL2A / TL2B is "0.69", and the conditional expression [5] (0.6 <[TL2A / TL2B] <1.6) is satisfied. Since FNO is 1.43, TLL / (AFL / FNO) is 1.16, which satisfies the conditional expression [6] (1.0 << [TLL / (AFL / FNO)] <1.5). Since FL2 is 41.94 mm, TL2 / (FL2 / FNO) becomes "0.46", which satisfies the conditional expression [7] (0.3 <[TL2 / (FL2 / FNO)] <0.6). ..

Further, since SR1 is 14.77 mm and TLS is 10.91 mm, SR1 / TLS is "1.35", which satisfies the conditional expression [8] (1.0 << [SR1 / TLS] <1.5). .. Since the FLE is −58.42 mm, the FLE / AFL becomes “-1.18” and the conditional expression [9] (-4.0 <[FLE / AFL] <−0.8) is satisfied. In addition, as shown in FIG. 6, various other physical quantities and the range of conditional expressions in Example 3 also satisfy the constituent requirements required by the present invention.

FIG. 10 shows a longitudinal aberration diagram corresponding to the point at infinity [F10] and the focus method [F12] in the image pickup lens 1 of the third embodiment, respectively. As is clear from FIG. 10, it can be confirmed that good aberration, that is, imaging performance can be obtained regardless of the focus method ([F10], [F12]).

Next, the large-diameter image pickup lens 1 of the fourth embodiment according to the present embodiment will be described with reference to FIGS. 6, 11 and 12.

As shown in FIG. 11, the large-diameter image pickup lens 1 of Example 4 has the same basic lens configuration as that of Example 1 described above, but as a focus method, the focus variable interval ZD9 is unchanged, and Example 1 is used. The same method as the focus method [F12] of the above (the same method as in the third embodiment), that is, the focus adjustment at a close distance is performed at variable intervals of the ZD12. Specifically, the lens group in which the front lens group 101 and the rear lens group A 102A are integrated, and the two lens groups in which the rear lens group B 102B is integrated are moved to the object OBJ side by different amounts, and the rear lens group B is moved to the rear. A method of changing the air spacing between the posterior positive lenses L6 and L7 in the lens group 102 and the air spacing on the image IMG side, that is, two lens groups (front lens group 101 + rear lens A group 102A, rear lens B group 102B). ) Is moved (Gm4, Gm3) by the focus method of [F12], and the shooting area is set to the medium telephoto area.

Further, in Example 4, when constructing the front lens group 101, at least one lens using a low refractive index low dispersion glass material having an absolute partial dispersion value dPgf of 0.02 or more (example is the front lens). It was configured to include a positive lens L3). When the front lens group 101 is configured in this way, in particular, by including a positive lens using a low-refractive index low-dispersion glass material, the effect of correcting chromatic aberration in the medium telephoto shooting region where chromatic aberration tends to be conspicuous can be obtained. Can be enhanced.

The lens to which this condition is applied can be any of the front positive lenses LF, L2, and L3, but since the low refractive index low dispersion glass material has the characteristic of low hardness, it can be applied to the foremost lens LF. It is desirable to avoid it, and it is desirable to apply it to small-diameter lenses in terms of processing. Further, when a low-dispersion glass material is used for the front positive lens L3 of the front lens group 101, chromatic aberration can be corrected, but when the refractive index is low, it is necessary to reduce the radius of curvature in order to obtain a predetermined positive power. At the same time, it is necessary to make the shape closer to a plano-convex shape or a biconvex shape where power can be obtained, rather than the meniscus shape. In this case, since the lens thickness becomes large, it is necessary to consider the balance with the lens thickness.

Table 4 shows the lens data of the entire lens system 100 in the large-diameter image pickup lens 1 according to the fourth embodiment. The image pickup lens 1 at the time of an infinite object has a focal length: 73.00 mm, an F number: 1.55, a half angle of view: 16.35 °, and an image height: 21.63 mm.

As shown in FIG. 6, since AFL is 73.00 mm and TLL is 54.29 mm, TLL / AFL is “0.74”, and the conditional expression [1] (0.68 <[TLL / AFL] <1. .00) is satisfied. Since TLi is 89.25 mm, TLi / AFL becomes "1.22" and satisfies the conditional expression [2] (0.8 <[TLi / AFL] <1.4). Since the IMD is 34.96 mm, the IMD / AFL is "0.48", which satisfies the conditional expression [3] (0.2 << [IMD / AFL]).

Further, since TL1 is 22.92 mm and TL2 is 15.84 mm, TLl / TL2 is "1.45", which satisfies the conditional expression [4] (0.8 <[TLl / TL2] <1.6). .. Since TL2A is 7.28 mm and TL2B is 8.36 mm, TL2A / TL2B is “0.87”, which satisfies the conditional expression [5] (0.6 << [TL2A / TL2B] <1.6). Since FNO is 1.55, TLL / (AFL / FNO) is 1.15, which satisfies the conditional expression [6] (1.0 << [TLL / (AFL / FNO)] <1.5). Since FL2 is 68.46 mm, TL2 / (FL2 / FNO) becomes "0.36", which satisfies the conditional expression [7] (0.3 <[TL2 / (FL2 / FNO)] <0.6). ..

Further, since SR1 is 19.63 mm and TLS is 15.53 mm, SR1 / TLS is "1.26" and the conditional expression [8] (1.0 << [SR1 / TLS] <1.5) is satisfied. .. Since the FLE is −81.98 mm, the FLE / AFL becomes “-1.12” and the conditional expression [9] (-4.0 <[FLE / AFL] <−0.8) is satisfied. In addition, as shown in FIG. 6, the range of various other physical quantities and conditional expressions in Example 4 also satisfy the constituent requirements required by the present invention.

FIG. 12 shows a longitudinal aberration diagram corresponding to the point at infinity [F10] and the focus method [F12] in the image pickup lens 1 of the fourth embodiment, respectively. As is clear from FIG. 12, it can be confirmed that good aberration, that is, imaging performance can be obtained regardless of the focus method ([F10], [F12]).

Although the preferred embodiments including the first and fourth embodiments have been described in detail above, the present invention is not limited to such an embodiment, and the present invention is not limited to such an embodiment, and the detailed configuration, shape, material, quantity, numerical value, and the like are used. It may be arbitrarily changed, added or deleted without departing from the gist of the present invention.

For example, an example is shown in which the front lens group 101 includes three continuous front lenses LF, L2, and L3 from the object OBJ side, but two front lenses LF ... Or four or more front lenses. It does not exclude the case where the lens LF ... Is included. Further, an example is shown in which the rear lens group 102 includes two posterior positive lenses L6 and L7 sandwiched between the biconcave lens L5 and the final lens LE, but if necessary, three or more posterior positive lenses L6 ... It does not exclude the case of inclusion. By using a known aberration correction technique by lens division, an arbitrary number of these can be selected within a range in which the restriction of the optical axis length in the lens group can be tolerated. On the other hand, when constructing the rear lens group 102, the bending direction of the third lens surface that sequentially contacts the air from the lens surface (i = 9) on the aperture stop STO side of the biconcave lens L5 to the image IMG side, and the final lens. It is desirable to set the bending direction of the third lens surface that comes into contact with air sequentially from the lens surface (i = 15) on the image IMG side of the LE to the aperture stop STO side in the opposite direction, but this is an essential configuration requirement. It does not become. Similarly, when the rear lens group 102 is configured, by having two rear positive lenses L6 and L7, the rear lens group A 102A on the aperture aperture STO side, the rear lens group A 102A on the aperture aperture STO side, and the image The rearmost lens B group 102B on the image IMG side is provided from the rear positive lens L7 on the IMG side, and the rear lens group A 102A is the earliest lens arranged on the most object OBJ side of the entire lens system 100 when the rear lens group A 102A is an infinite object. When the absolute value of the length from the lens surface (i = 1) on the LB object OBJ side to the near-axis image position after the exit of the rear lens group A 102A is the largest, the object distance is set to infinity and the object distance is set to infinity. The F number of the entire system is FNO, the optical axis length of the front lens group 101 is LF1, the optical axis length of the rear lens group 102 is LF2, the optical axis length of the rear lens group A 102A is TL2A, and the optical axis length of the rear lens group B 102B. When the length is TL2B, it is desirable to set it so as to satisfy the conditional expressions [4]-[7], but it is not an indispensable constituent requirement.

Further, in the entire lens system 100, the d-line refractive index is 1. The absolute value of the focal distances of all the positive lenses LF ..., L6 ... The refractive index of the d-line is 1. Including at least one positive lens using a glass material having an abnormal partial dispersion value of 85 or more, and at least 1 using a low refractive index low dispersion glass material having an absolute partial dispersion value dPgf of 0.02 or more in the front lens group 101. It is equipped with a biconcave lens L5 in which the rear lens group 102 is arranged on the most aperture aperture STO side and a junction lens Ja by a rear positive lens L6 in which the rear lens group 102 is arranged on the image IMG side of the biconcave lens L5. The concave lens L5 is formed by using a glass material having an abnormal partial dispersion value dPgf of 0.02 or more, and the rear positive lens L6 is made of a highly refracting glass having a d-line refractive index of 1.75 or more. It is desirable to implement it according to each configuration of use, but none of them is an essential configuration requirement.

The large-diameter image pickup lens according to the present invention can be used as a dedicated lens or an interchangeable lens in various optical devices such as digital cameras and video cameras.

1: Large-diameter image pickup lens, 100: Whole lens system, 101: Front lens group, 102: Rear lens group, 102A: Rear lens A group, 102B: Rear lens B group, STO: Aperture aperture, OBJ: Object, IMG: Image, LF: front positive lens, L2: front positive lens, L3: front positive lens, L4: front negative lens, L5: biconcave lens, L6: back positive lens (biconvex lens), L7: back positive lens (biconvex lens) , LE: final lens, (i = 1,2,3,4,5,6,7,8): lens surface, Dc: optical axis, AFL: whole system focal distance, TLL: optical axis length of the whole lens system , TLi: optical axis length from the lens surface on the most object side to the image, IMD: optical axis length from the lens surface on the image side of the final lens to the image, FNO: F number, LF1: optical axis length of the front lens group, LF2: optical axis length of rear lens group, TL2A: optical axis length of rear lens A group, TL2B: optical axis length of rear lens B group, Ja: junction lens, dPgf: abnormal partial dispersion value, SR1: radius of curvature, TLS : Spatial spacing of aperture aperture, FLE: Focus distance of final lens, Sf: Air space, Sr: Air space

Claims (12)

In a large-diameter imaging lens having a front lens group having a positive power arranged on the object side and a rear lens group having a positive power arranged on the image side with respect to the aperture aperture in the entire lens system, from the object side. It includes a plurality of continuous front positive lenses and a front negative lens on the most aperture pattern side, and all lenses are composed of meniscus lenses with a convex shape on the object side, and the radius of curvature of each lens surface on the aperture aperture side is on the object side. The front lens group, which gradually decreases from the lens surface to the aperture aperture side and the lens surfaces of all lenses come into contact with air, and the biconcave lenses arranged on the most aperture aperture side and the most image side, both sides are in the same direction on the optical axis. It comprises a whole lens system including a plurality of posterior positive lenses sandwiched between a final lens having a curved negative power and a posterior lens group including at least one biconvex lens in the posterior positive lens. , The object distance is set to infinity, the focal distance of the entire system is AFL, the optical axis length of the entire lens system is TLL, the optical axis length from the lens surface on the most object side to the image is TLi, and the lens surface on the image side of the final lens. When the optical axis length from to the image is IMD,
0.68 <[TLL / AFL] <1.00 ... (conditional expression 1)
0.8 <[TLi / AFL] <1.4 ... (Conditional expression 2)
0.2 <[IMD / AFL] ... (Conditional expression 3)
A large-diameter imaging lens characterized by satisfying the above conditions. The rear lens group includes the bending direction of the third lens surface that sequentially contacts the air from the lens surface on the aperture diaphragm side of the biconcave lens to the image side, and from the lens surface on the image side of the final lens to the aperture diaphragm side. The large-diameter imaging lens according to claim 1, wherein the bending direction of the third lens surface that sequentially comes into contact with air is set in the opposite direction. By having the two posterior positive lenses, the rear lens group includes the rear lens group A from the posterior positive lens on the aperture aperture side to the rear lens group A on the aperture aperture side, and the rear lens on the image side from the posterior positive lens on the image side. A near axis after emission of the rear lens group A from the lens surface on the object side of the earliest lens arranged on the object side of the entire lens system when the rear lens group A is an infinite object and has group B. When the absolute value of the length to the image position is the largest, the object distance is set to infinity, the F number of the entire system is FNO, the optical axis length of the front lens group is LF1, and the optical axis of the rear lens group. When the length is LF2, the optical axis length of the rear lens A group is TL2A, and the optical axis length of the rear lens B group is TL2B.
0.8 <[TLl / TL2] <1.6 ... (conditional expression 4)
0.6 <[TL2A / TL2B] <1.6 ... (Conditional expression 5)
1.0 <[TLL / (AFL / FNO)] <1.5 ... (conditional expression 6)
0.3 <[TL2 / (FL2 / FNO)] <0.6 ... (Conditional expression 7)
The large-diameter image pickup lens according to claim 1 or 2, wherein the condition of the above is satisfied. The entire lens system includes three or more front positive lenses and two or more rear positive lenses, and all positive lenses are made of a glass material having a d-line refractive index of 1.75 or more. The absolute value of the focal distances of all positive lenses in the entire lens system is the focal distance of the negative lens having the maximum focal distance in the entire lens system, including two or more lenses and having an average Abbe number of 38.0 or more. The large-diameter image pickup lens according to claim 1, 2, or 3, wherein the absolute value of is set to be larger than 80 [%]. The large-diameter imaging lens according to claim 4, wherein the entire lens system includes at least one positive lens using a glass material having a refractive index of 1.85 or more for the d-line in all the positive lenses. The large diameter according to claim 4 or 5, wherein the front lens group includes at least one lens using a low refractive index low dispersion glass material having an absolute value of an abnormal partial dispersion value of 0.02 or more. Imaging lens. The rear lens group includes a biconcave lens arranged on the most aperture aperture side and a junction lens composed of a rear positive lens arranged on the image side of the biconcave lens, and the biconcave lens has an absolute partial dispersion value of 0.02. The large according to claim 4 or 5, wherein the positive lens is formed by using the above-mentioned glass material and the high-refractive-index glass having a refractive index of 1.75 or more of the d-line. Aperture imaging lens. In the entire lens system, the absolute value of the radius of curvature of the lens surface facing the aperture diaphragm is set small on the front lens group side, and the radius of curvature of the lens surface on the front lens group side is set to SR1 and the aperture diaphragm. When the space spacing is TLS,
1.0 <[SR1 / TLS] <1.5 ... (Conditional expression 8)
The large-diameter image pickup lens according to any one of claims 1-7, wherein the large-diameter image pickup lens is characterized by satisfying the condition of. When the final lens includes a meniscus-shaped aspherical surface and the focal length of the final lens is FLE,
-4.0 <[FLE / AFL] <-0.8 ... (conditional expression 9)
The large-diameter image pickup lens according to claim 1, wherein the condition of the above is satisfied. The entire lens system is composed of eight lenses in total by arranging four lenses in the front lens group and four lenses in the rear lens group, and has an F number of 1.7. The large-diameter image pickup lens according to claim 1, wherein the half angle of view is set to 12-25 [°], respectively. In the rear lens group, the object side between the adjacent front and rear rear lenses in the plurality of rear lenses is the rear lens A group, the image side is the rear lens B group, and the rear lens group A is the rear lens group. The large-diameter imaging lens according to claim 1, wherein at least one of the air spaces before and after the lens is set as an adjustment interval to be changed at the time of focus adjustment. The adjustment interval is any one of the air space on the object side with respect to the rear lens A group, the air space on the image side with respect to the rear lens A group, and the air space before and after the rear lens A group. The large-diameter imaging lens according to claim 11, wherein a maximum of three lens groups can be moved.

Images