JP2021173954A - Large-diameter imaging lens - Google Patents

Abstract

To cover a satisfactory optical performance in imaging from a semi-wide-angle to middle telephotographic regions, cope with a large high definition image pickup device and make reduction in size.SOLUTION: A large-diameter imaging lens comprises: a first lens group 101 including a lens L11 having a lens surface closest to an object OBJ side and a lens surface closest to an image IMG side which are curved toward the object OBJ; a second lens group 102 that has a second A lens group 102A including positive lenses L21, L22, an air space S2, and a negative lens L23, and a second B lens group 102B including a negative lens L24, and positive lenses L25, L26, and has a double-convex air lens La at an aperture diaphragm STO; and a third lens group 103 including a positive lens L31 with a convex object OBJ-side lens surface, a negative lens L32 with a concave image IMG-side lens surface, an air space S6, and a positive lens L33 with a convex object OBJ-side lens surface.SELECTED DRAWING: Figure 1

Description

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

In recent years, image pickup elements used in digital cameras and the like have become larger and have higher pixels, and as a result, the image pickup lenses have higher optical performance that enables good and sufficient correction of various aberrations. In addition to the demand, an imaging lens having a small F number and enabling a short shooting distance is also required in order to increase the blurring of the foreground and the background of the subject (blurring before and after the focal image).

Conventionally, a so-called Gauss-type or modified Gauss-type image pickup lens is known as a bright image pickup lens having an F number of about 1.0 or less, and this type of image pickup lens is disclosed in Patent Documents 1-3. Has been done. In general, in a Gaussian image pickup lens, two negative lenses are arranged with a concave surface having a strong refractive power facing the aperture side with the aperture in between, and at least one of the two negative lenses on the object side and the image plane side, respectively. It has a configuration in which two positive lenses are arranged. As a result, the concave surface of the negative refractive power toward the aperture side of the two negative lenses arranged across the aperture mainly secures the back focus performance, and the Petzval sum is reduced to flatten the curvature of field. It also corrects coma aberration and the like while trying to improve the performance. However, when the refractive power of the two concave surfaces is increased, sagittal flare occurs around the screen, and the amount generated increases especially when the F number is reduced. Therefore, in the Gauss type imaging lens, the F number is used. The problem is to correct the sagittal flare when the value is reduced. The image pickup lenses of Patent Documents 2 and 3 correct the sagittal coma with an aspherical lens, and add lens groups before and after the Gaussian optical system to correct the aberration with respect to the image pickup lens of Patent Document 1. .. In particular, in the case of Patent Document 2, since each lens group is moved to correct the aberration at the time of focusing, there is a problem that a sufficient imaging magnification cannot be secured.

On the other hand, an imaging lens for solving these problems is also proposed in Patent Document 4-7. The "rear type wide converter lens" of Patent Document 4 is intended to provide a rear type wide converter lens capable of satisfactorily correcting various aberrations, and specifically, is mounted on the image side of a master lens. It is a rear type wide converter lens for reducing the focal distance of the optical system including this master lens, has a positive refractive force as a whole, and has a first positive lens component and a negative one in order from the object side. It consists of a lens component and a second positive lens component. Β is the ratio of the combined focal distance of the master lens and the rear wide converter lens to the focal distance of the master lens, fn is the focal distance of the negative lens component, and fc is When the focal distance of the rear wide converter lens is taken, it is configured so as to simultaneously satisfy the conditional expression of 0.4 <β, 0.10 <(-fn) / fc <0.90. Is a type in which a conversion lens is attached to the rear side (image side) of the image pickup lens.

On the other hand, Patent Document 5 is a type in which a conversion lens is added to the front side (object side) of the image pickup lens. The "wide-angle conversion lens" of Patent Document 5 is intended to provide a high-performance wide-angle conversion lens that is suitable for a high-performance lens having an angle of view at the wide-angle end of about 55 ° to 60 ° and has little change in image quality. Specifically, in a substantially afocal wide-angle conversion lens that is attached to the object side of a photographing lens to shorten the focal distance of the entire lens system, a concave lens with a concave surface having a strong curvature facing the image surface side in order from the object side. It is composed of the first lens of the above, the second lens of the convex lens with the convex surface having a strong curvature facing the image plane side, the third lens of the biconcave lens, and the fourth lens of the biconvex lens, and the angular magnification is about 0.7. When hi is the radius of the effective diameter of the i-th surface, ri is the radius of curvature of the i-th surface, ni is the refractive index of the d-line of the i-th lens, and νi is the Abbe number of the i-th lens. 0.3 << | h2 / r2 | 0.85, 0.15 << | h2 / r4 | <0.45, 0.15 << | h5 / r5 | <0.45, 1 << | r6 / r7 | <1 It is configured to satisfy each condition of .35, 8 <(ν4-ν3) <25.

Further, Patent Document 6 is the same as Patent Document 5 in that a conversion lens is added to the front side (object side) of the image pickup lens, but Patent Document 5 is configured as a wide type, whereas Patent Document 5 is patented. Document 6 is different in that it is configured as a teletype. The "telephoto conversion lens" of Patent Document 6 suppresses the increase of the secondary spectrum as much as possible without disturbing the balance of correction of the chromatic aberration of the main lens, and has a single color such as spherical aberration, coma aberration, nonpoint aberration and distortion. The purpose is to provide a high-performance teleconversion lens with well-corrected aberration and less deterioration in image quality. Specifically, the first lens L1 composed of a convex lens and the first lens L1 composed of a concave lens are arranged in order from the object side. Bonding with 2 lenses L2 By joining a positive lens, a third lens L3 consisting of a convex lens with a convex surface having a strong curvature facing the object side, a fourth lens L4 consisting of a convex lens, and a fifth lens L5 consisting of a concave lens. It is configured, the angular magnification is about 1.35 to 3 times, νi and j are the equivalent Abbe numbers from the i-th lens to the j-th lens, and ΔPi is the deviation of the partial dispersion ratio of the i-lens from the standard line. Then, each of -0.01 <1 / ν1,3 <0.01, -0.01 <l / ν4,5 <0.01, 0.003 <(ΔPI + ΔP3) / 2, and ΔP2 <0.014. It is configured to satisfy the conditions.

On the other hand, Patent Document 7 is a type having a configuration in which several lenses are added to the object side with respect to a general type imaging lens such as a Gaussian type or a Sonnar type. The "large-diameter lens" of Patent Document 7 can satisfactorily correct various aberrations, particularly chromatic aberration, to obtain good image quality over the entire screen, and achieves miniaturization of the product without omitting the autofocus mechanism. The purpose is to provide a large-diameter lens whose size is suitable for an interchangeable lens. Specifically, the first lens group G1 having a positive refractive power and the first lens group G1 having a positive refractive power are provided in this order from the object side. It is composed of a second lens group G2, and the first lens group G1 has a lens having a positive refractive power Lpl, a positive refractive power Lp2, and a negative refractive power, and is from an infinity object to a short-range object. At the time of focusing, the first lens group G1 is fixed to the image plane, and the second lens group G2 is moved from the image plane side to the object side along the optical axis so as to satisfy a predetermined condition. be.

Japanese Unexamined Patent Publication No. 48-88831 Japanese Unexamined Patent Publication No. 9-61708 Japanese Unexamined Patent Publication No. 63-70216 Japanese Unexamined Patent Publication No. 2015-4103 Japanese Unexamined Patent Publication No. 2000-241700 Japanese Unexamined Patent Publication No. 2000-356744 JP-A-2018-005099

However, the conventional imaging lens disclosed in Patent Document 4-7 described above has the following problems.

That is, in the rear type wide converter lens as disclosed in Patent Document 4, the number of lenses is 3- because an additional lens system is added to the rear side (image side) of the Gauss type optical system to increase the aperture. It will be a reduced type of 4 sheets. As a result, the focal length, F number, back focus, image circle, etc. are also reduced, and a master lens having a larger image circle than the camera is used, or a camera smaller than the original image circle of the master lens is used. It is easy for the image lens to become large, such as when it is necessary to do so.

On the other hand, since the front type conversion lens as disclosed in Patent Documents 5 and 6 has an afocal junction, the F number, back focus, and image circle of the combined imaging lens of the entire system remain as they are, and the focal length is maintained. (Shooting angle of view) changes. Therefore, in order to obtain a quasi-wide-angle range, a wide-angle conversion lens as in Patent Document 5 may be added to the image pickup lens in the standard range, while in order to obtain a medium telephoto range, a telephoto lens as in Patent Document 6 may be added. Since the conversion lens may be added to the image pickup lens in the standard range, it is possible to cover the shooting range from the quasi-wide-angle range to the medium telephoto range, but on the other hand, the F number and the shooting magnification depend on the master lens. As a result, in this case as well, the overall length of the image pickup lens after the conversion lens is added becomes long, and the size tends to increase.

On the other hand, in a configuration in which several lenses, which are partial optical systems of the front conversion lens, are added to the object side of a general type imaging lens as disclosed in Patent Document 7, miniaturization can be achieved to some extent. However, on the other hand, sufficient F-number and shooting magnification have not been obtained.

As described above, even with a conventional type such as a conventional Gauss type or a modified Gauss type, and an imaging lens in which several lenses are added before and after the conventional type, it is not easy to perform good and sufficient correction for various aberrations. It is not easy to increase the diameter and reduce the overall size, and further improvement has been requested from the viewpoint of solving these problems.

An object of the present invention is to provide a large-diameter imaging lens that solves the problems existing in such a background technique.

In order to solve the above-mentioned problems, the present invention includes an imaging optical system C in which a first lens group 101, a second lens group 102 including an aperture aperture STO, and a third lens group 103 are sequentially arranged from the object OBJ side. When constructing the large-diameter imaging lens M, a configuration including one lens L11 in which both sides of the lens are curved toward the object OBJ side, or a lens surface (first lens surface (i = 1)) and the most image on the most object OBJ side. The first lens group 101 having a configuration consisting of a plurality of lenses L11, L12 ... With the lens surface on the IMG side curved toward the object OBJ, and the first lens group 101 located on the object OBJ side of the aperture aperture STO, It is located on the image IMG side of the second A lens group 102A in which two positive lenses L21 ... and L22 ..., the air space S2, and the negative lens L23 ... are sequentially arranged, and the aperture aperture STO. The second lens group 102B has a second B lens group 102B in which two positive lenses L25 ... And L26 ... Are sequentially arranged, and has a biconvex air lens La formed by a pair of lens surfaces facing the aperture aperture STO. From the lens group 102 and the object OBJ side, the lens surface on the object OBJ side is a convex positive lens L31 ..., the lens surface on the image IMG side is a concave negative lens L32 ... 3rd lens group 103 in which positive lenses L33 ... The focusing adjustment function unit 301 that changes the interval (focus variable interval Di) of at least one of the air spaces S3 of the above air space S3 at the time of focusing when the object moves from infinity to a short distance is provided. From the lens surface on the most object OBJ side of the second lens group 102 (second lens surface (i = 3 ...)), the optical axis length of the lens surface on the most image IMG side of the second lens group 102 is TL2, the focal point of the entire system. When the distance is AFL, the F number is FNO, and the AFL / FNO is FPD, the imaging optical system C satisfying the conditional expression [1] "0.6 <(TL2 / EPD) <2.1" is provided. And.

In this case, according to a preferred embodiment of the present invention, the imaging optical system C sets the optical axis lengths from the first lens surface (i = 1) to the second lens surface (i = 3 ...) at TL1 and th. The optical axis length of the lens surface (i = 14 ...) on the most image IMG side of the second lens group 102 from the second lens surface (i = 3 ...) is TL2, and the third lens group from the first lens surface (i = 1). In 103, the optical axis length to the lens surface on the most image IMG side is TLL, the optical axis length from the first lens surface (i = 1) to the aperture aperture STO is TLF, and the lens surface on the object OBJ side facing the aperture aperture STO. When the radius of curvature of (i = 8 ...) Is RS1 and the radius of curvature of the lens surface (i = 10 ...) on the image IMG side facing the aperture aperture STO is RS2, the conditional expression [2] "0.1 < (TL1 / TL2) <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) <0.8 ", conditional expression [4]" 0.08 <(TL1 / TLL) <0. 60 ”, conditional expression [5]“ 0.3 <(TLF / TLL) <0.7 ”, conditional expression [6]“ 0.1 <(RS1 / TLL) <0.5 ”, and conditional expression [7] ] It is desirable to satisfy "-0.55 <(RS2 / TLL) <-0.10".

Further, according to a preferred embodiment of another invention, when the focusing adjustment function unit 301 is configured, a configuration including at least one moving lens group Gm1 ... That moves during focusing, or a lens surface on the most object OBJ side of the entire system ( A configuration including a fixed lens group Gc that fixes i = 1) with respect to the image position, and at least one moving lens group Gm1 that moves during focusing, or a lens surface (i = 1) on the most object OBJ side of the entire system. A configuration including two fixed lens groups Gc ... that fix the lens surface (i = 21 ...) on the most image IMG side with respect to the image position, and one moving lens group Gm1 or one lens Gm1 that moves during focusing. In, from the lens surface (i = 14 ...) On the image IMG side of the moving lens group Gm1 located on the object OBJ side with respect to the focus variable interval Di existing on the most object OBJ side at the time of an infinite object to the image position. Image of the moving lens group Gm1 located on the object OBJ side with respect to the focus variable interval Di that exists most on the object IMG side when the distance is FP1 and the shooting magnification is 0.1 times. When the distance from the lens to the image position is FP2, it can be configured to satisfy the conditional expression [8] "0.005 << {│ (FP2-FP1) / FP1│} <0.5".

Further, according to a preferred embodiment of another invention, the imaging optical system C has five lenses L24 ... Arranged on the image IMG side with respect to the aperture aperture STO, and the object OBJ side has a concave shape from the object OBJ side. Partial symmetry consisting of a negative lens L24 having a lens surface (i = 10 ...), three positive lenses L25, L26, L31, and a negative lens L32 having a lens surface (i = 17 ...) having a concave shape on the image IMG side. It is composed of a lens group Gs, and the partially symmetric lens group Gs includes at least one positive lens L25 having a convex shape on both sides and at least one negative lens L24 having a concave shape on both sides. be able to. The focusing adjustment function unit 301 can make the air spaces S4 and S5 located on one side or both sides of the positive lens L26 whose both sides are air contact surfaces in the partially symmetrical lens group Gs function as the focus variable interval Di. ..

In addition, according to a preferred embodiment of another invention, when the focal length of the entire system is AFL and the focal length of the second lens group is FL2, the imaging optical system C has the conditional equation [9] "0" as the power distribution. It can be set so as to satisfy .1 <(AFL / FL2) ≦ 1.0 ”. Further, in the imaging optical system C, the distance from the image point of the first lens group 101 of the infinite object point to the lens surface (i = 3 ...) On the object OBJ side of the second lens group 102 is defined as OB2, and this OB2 is defined as the object distance. The distance of the image IMG position from the lens surface (i = 14 ...) On the image IMG side of the second lens group 102 is IM2, and the combined focal distance of the first lens group 101 and the second lens group 102 is FLM. Then, the conjugate relationship of the second lens group 102 is set to the conditional expression [10] "0.0 <(│IM2 / OB2│) ≤ 0.8" and the conditional expression [11] "0.45 <(FLM / AFL)". It can be set to satisfy according to <4.9 ". On the other hand, in the imaging optical system C, the first lens group 101 is composed of two or less lenses L11 having negative power, and all the lens surfaces (i = 3,) in air contact of the lenses in the second A lens group 102A. 5, 7, 8 ...), And all the air-contacting lens surfaces (i = 15, 18 ...) located on the object OBJ side of each lens in the third lens group 103 can be curved and formed on the object OBJ side, respectively. can. Further, in the imaging optical system C, the first lens group 101 is composed of six or less lenses, and the difference between the number of positive lenses and the number of negative lenses can be set within one. In addition, the imaging optical system C can include a negative lens L23 using a low refractive index low dispersion glass material having an absolute partial dispersion value dPgF of 0.02 or more in the second lens group 102. , At least the lens surface (i = 19 ...) On the image IMG side of the lens (L33 ...) located closest to the image IMG side of the third lens group 103 can be formed into an aspherical shape.

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

(1) A configuration in which both sides of the lens include one lens L11 curved toward the object OBJ, or a lens surface on the most object OBJ side (first lens surface (i = 1)) and a lens surface on the most image IMG side, respectively. The first lens group 101 having a configuration consisting of a plurality of lenses L11, L12 ... Curved toward the object OBJ side, and two positive lenses L21 ... And L22 ..., the air space S2, the negative lens L23 ..., the second A lens group 102A, and the image of the aperture aperture STO are located on the IMG side. A second lens group 102 having a second B lens group 102B in which L25 ... And L26 ... Are sequentially arranged, and a second lens group 102 having a biconvex air lens La formed by a pair of lens surfaces facing the aperture aperture STO, and an object OBJ. From the side, a positive lens L31 with a convex lens surface on the object OBJ side, a negative lens L32 with a concave lens surface on the image IMG side, an air space S6, and a positive lens L33 with a convex lens surface on the object OBJ side. At least of the third lens group 103 in which ... An imaging optical system that has a focusing adjustment function unit 301 that changes the distance between one air space (variable focus interval Di) during focusing when an object moves from infinity to a short distance, and satisfies the above-mentioned conditional equation [1]. Since C is provided, while securing the focusing adjustment function unit 301 that can use various focusing methods, the entire system can be miniaturized, various aberrations can be corrected well and sufficiently, and the F number is small (1.0). Below) A bright, large-diameter lens can be obtained. As a result, it covers sufficient optical performance for shooting in the quasi-wide-angle to medium-telephoto range, and is compatible with large high-definition imaging elements. It can be used as a caliber image pickup lens M.

(2) According to a preferred embodiment, when the imaging optical system C is configured, the optical axis lengths from the first lens surface (i = 1) to the second lens surface (i = 3 ...) at the time of an infinite object point are set to TL1,. The optical axis length of the lens surface (i = 14 ...) on the most image IMG side of the second lens group 102 from the second lens surface (i = 3 ...) is TL2, and the third lens from the first lens surface (i = 1). In group 103, the optical axis length to the lens surface on the most image IMG side is TLL, the optical axis length from the first lens surface (i = 1) to the aperture aperture STO is TLF, and the lens on the object OBJ side facing the aperture aperture STO. When the radius of curvature of the surface (i = 8 ...) Is RS1, and the radius of curvature of the lens surface (i = 10 ...) on the image IMG side facing the aperture aperture STO is RS2, the conditional equation [2] "0.1. <(TL1 / TL2) <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) <0.8 ", conditional expression [4]" 0.08 <(TL1 / TLL) <0 .60 ”, conditional expression [5]“ 0.3 <(TLF / TLL) <0.7 ”, conditional expression [6]“ 0.1 <(RS1 / TLL) <0.5 ”, and conditional expression [ 7] If the lens is configured to satisfy "-0.55 <(RS2 / TLL) <-0.10", the dimensions of the imaging optical system C can be optimized, and thus correction for coma and other lenses can be achieved. And it can be implemented as the most desirable form from the viewpoint of reducing the overall size.

(3) According to a preferred embodiment, when the focusing adjustment function unit 301 is configured, if at least one moving lens group Gm1 ... That moves during focusing is provided and configured so as to satisfy the above-mentioned conditional expression [8], multi-group focusing. Since the focusing adjustment mechanism based on the method can be constructed, the focusing adjustment function unit 301 having higher focusing performance can be obtained.

(4) According to a preferred embodiment, when the focusing adjustment function unit 301 is configured, the fixed lens group Gc that fixes the lens surface (i = 1) on the most object OBJ side of the entire system with respect to the image position, and the fixed lens group Gc that is moved during focusing. If at least one moving lens group Gm1 ... Since the focusing adjustment function unit 301 based on the method can be constructed, it is possible to contribute to further weight reduction and miniaturization of the large-diameter imaging lens M.

(5) According to a preferred embodiment, when the focusing adjustment function unit 301 is configured, the lens surface (i = 1) on the most object OBJ side and the lens surface (i = 21 ...) On the most image IMG side of the entire system are image positions. If two fixed lens groups Gc ... Fixed to the lens and one moving lens group Gm1 or one lens Gm1 that move during focusing are provided and configured to satisfy the above-mentioned conditional expression [8], they are arranged in the middle. Since the focusing adjustment function unit 301 based on the inner focus method for moving one focus lens group Fm can be constructed, it can be implemented as an optimum form from the viewpoint of reducing the weight and size of the large-diameter imaging lens M.

(6) According to a preferred embodiment, when the imaging optical system C is configured, the five lenses L24 ... Arranged on the image IMG side are concave from the object OBJ side to the object OBJ side with respect to the aperture aperture STO. Partial symmetry consisting of a negative lens L24 having a lens surface (i = 10 ...), three positive lenses L25, L26, L31, and a negative lens L32 having a lens surface (i = 17 ...) having a concave shape on the image IMG side. It is composed of a lens group Gs, and the partially symmetric lens group Gs includes at least one positive lens L25 having a convex shape on both sides and at least one negative lens L24 having a concave shape on both sides. Then, since another lens can be combined with the partially symmetric lens group Gs configured by the double gauss type, it is possible to suppress abrupt refraction of the ingress / egress angle of the light beam, and the occurrence of aberration due to this can be suppressed. Can be effectively suppressed.

(7) According to a preferred embodiment, when the focusing adjustment function unit 301 is configured, the air spaces S4 and S5 located on one side or both sides of the positive lens L26 whose both sides are air contact surfaces in the partially symmetrical lens group Gs are focused. If it is made to function as a variable interval Di, the focus variable interval Di can be set inside the partially symmetrical lens group Gs, so that the occurrence of aberration during focusing can be suppressed and the aberration can be stabilized (stabilized). Can be done.

(8) According to a preferred embodiment, when the imaging optical system C is configured, if the power distribution is set so as to satisfy the above conditional expression [9], the power distribution in the second lens group 102 is particularly within an appropriate range. Since it can be set to, a good power balance can be ensured.

(9) According to a preferred embodiment, when the imaging optical system C is configured, if the conjugate relationship of the second lens group 102 is set so as to satisfy the above-mentioned conditional equations [10] and [11], it is based on the double gauss type. Since the second lens group 102 can be constructed in a so-called aperture-symmetrical conjugate relationship, aberration correction can be particularly well performed.

(10) According to a preferred embodiment, when the imaging optical system C is configured, the first lens group 101 is composed of two or less lenses L11 having negative power, and the air contact of the lenses in the second A lens group 102A. All lens surfaces (i = 3, 5, 7, 8 ...) And all air-contacting lens surfaces (i = 15, 18 ...) located on the object OBJ side of each lens in the third lens group 103, respectively. If the curved shape is formed on the object OBJ side, the length of the imaging optical system C in the optical axis direction can be shortened due to the weight compression effect of the lens. Even if it is M, the weight can be reduced.

(11) According to a preferred embodiment, when the imaging optical system C is configured, the first lens group 101 is composed of six or less lenses, and the difference between the number of positive lenses and the number of negative lenses is set within one. By doing so, the total number of the first lens group 101 is suppressed to 6 or less, and the difference between the number of positive lenses and the number of negative lenses is set to 1 or less, so that well-balanced aberration correction can be performed. can.

(12) According to a preferred embodiment, when the imaging optical system C is configured, a negative lens using a low refractive index low dispersion glass material in which the absolute value of the abnormal partial dispersion value dPgF is 0.02 or more in the second lens group 102. If L23 is included, good and effective correction for axial chromatic aberration can be performed by selecting an appropriate abnormal partial dispersion value dPgF.

(13) According to a preferred embodiment, when the imaging optical system C is configured, at least the lens surface (i = 19 ...) On the image IMG side of the lens (L33 ...) located closest to the image IMG side of the third lens group 103. If it is formed into an aspherical shape, the lens used on the image IMG side, which has a relatively small diameter, can be made aspherical, so that the advantages in terms of processing surface and cost can be enhanced, and in particular, it becomes a drawback of the Gauss type. Since the correction of the sagittal coma can be borne, it is possible to realize aberration correction different from other lenses.

A block diagram of a large-diameter imaging lens according to a first embodiment of a preferred embodiment of the present invention. List of each optical condition of Example 1-6 according to the preferred embodiment of the present invention, List of each optical condition of Examples 7-12 according to the preferred embodiment of the present invention, The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the first embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the second embodiment of the preferred embodiment, A longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the second embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the third embodiment of the preferred embodiment, A longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the third embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the fourth embodiment of the preferred embodiment, The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the fourth embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the fifth embodiment of the preferred embodiment, The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the fifth embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the sixth embodiment of the preferred embodiment, FIG. 6 is a longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the sixth embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the seventh embodiment of the preferred embodiment, The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the seventh embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to Example 8 of the preferred embodiment, The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the eighth embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the ninth embodiment of the preferred embodiment, Configuration diagram of the large-diameter imaging lens according to the tenth embodiment of the preferred embodiment, A longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the ninth embodiment is used as a parameter. The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the tenth embodiment is used as a parameter. Configuration diagram of the large-diameter imaging lens according to the eleventh embodiment of the preferred embodiment, Configuration diagram of the large-diameter imaging lens according to the twelfth embodiment of the preferred embodiment, The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the eleventh embodiment is used as a parameter. The longitudinal aberration diagram when the imaging magnification of the large-diameter imaging lens according to the twelfth embodiment is used as a parameter.

Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.

First, the basic configuration (essential configuration) of the large-diameter imaging lens M according to the present embodiment will be described with reference to FIG. Note that FIG. 1 also serves as a configuration of the large-diameter imaging lens M according to the first embodiment described later. It can be assumed that the large-diameter imaging lens M according to the present embodiment is 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 in the rear of the optical axis Dc direction. Reference numeral 302 indicates a glass flat plate face plate in which the total thickness of parallel flat plates such as a face plate, an infrared cut filter, and a low-pass filter arranged on the front surface of the image sensor is given as an optically equivalent thickness. This glass flat plate face plate does not affect the configuration of the large-diameter imaging lens M according to the present embodiment.

The large-diameter imaging lens M includes an imaging optical system C that constitutes a main part of the lens M. As shown in FIG. 1, the imaging optical system C includes a first lens group 101, a second lens group 102, and a third lens group 103 arranged sequentially from the object OBJ side to the image IMG side. Further, the second lens group 102 includes an aperture diaphragm STO in the middle portion, and the second A lens group 102A and the aperture diaphragm STO arranged before and after the aperture diaphragm STO, that is, on the object OBJ side with respect to the aperture diaphragm STO. On the other hand, it is composed of a second B lens group 102B arranged on the image IMG side.

The first lens group 101 includes a single lens L11 in which both sides of the lens are curved toward the object OBJ side, or the lens surface (first lens surface (i = 1)) on the most object OBJ side and the most image IMG side. It can be configured by any one of a plurality of lenses L11, L12 ... In which the lens surface is curved toward the object OBJ side. With this configuration, the length of the lens group in the optical axis Dc direction can be compressed by the compression effect of the overlapping lenses, and in particular, if a meniscus lens is used as one lens L11, the volume of the lens can be reduced. Therefore, it is possible to reduce the weight of a large-diameter lens having a large outer diameter. The first lens group 101 in FIG. 1 includes a single lens L11 in which both sides of the lens are curved toward the object OBJ.

The first lens group 101 can be configured by a single lens L11 having a minimum number of lenses, whereby the length of the imaging optical system C can be shortened. On the other hand, if a plurality of lenses L11, L12 ... Are combined, the action of the conversion lens makes it possible to correspond to the imaging angle of view and image performance in the quasi-wide-angle to medium-telephoto region, and higher-performance aberration correction. It can be performed.

The second lens group 102 is located on the object OBJ side of the aperture aperture STO, and two positive lenses L21 ... And L22 ..., an air space S2 ..., and a negative lens L23 ... Are sequentially arranged from the object OBJ side. It has a second B lens group 102B, which is located on the image IMG side of the lens group 102A and the aperture aperture STO, and has a negative lens L24 ..., two positive lenses L25 ... And L26 ... in that order from the object OBJ side. It is configured to include a biconvex air lens La formed by a pair of lens surfaces facing the aperture aperture STO.

The second lens group 102 constitutes a so-called double gauss type. The double gauss type having aperture symmetry is suitable for a large-diameter imaging lens having a small F number because it has a high ability to correct aberrations that cancel each other before and after the aperture aperture STO. Further, a lens can be added to the air spaces S1 and S5 before and after the second lens group 102 and the air space S3 of the aperture stop STO to function as an optical system that can easily share the refractive power and aberration correction. However, in the case of the large-diameter imaging lens M, if the radius of curvature of the lens surface before and after facing the aperture diaphragm STO is reduced, coma aberration in the sagittal direction peculiar to the Gauss type increases. In this case, the aberration may be corrected in other parts.

From the object OBJ side, the third lens group 103 includes a positive lens L31 ... with a convex lens surface on the object OBJ side, a negative lens L32 ... A positive lens L33 ... With a convex lens surface is sequentially arranged.

In the third lens group 103, the lens diameter on the image IMG side is made smaller as the lens on the image IMG side is used, in order to constrain the emission light flux diameter on the image IMG side with respect to the incident luminous flux diameter on the object OBJ side that has passed through the second lens group 102. .. When used as an interchangeable lens, it is necessary to make the outer diameter on the image IMG side smaller than the inner diameter of the mounting mechanism in the image pickup device main body (camera body) and set it to a specific distance (flange back) or more. In the case of a large-diameter imaging lens having a small F-number, the size of the diameter of the final lens is set to be larger than the size determined by the F-number and the back focus.

Further, in the above basic lens configuration, at least one of the air space S1 on the object OBJ side of the second lens group 102, the air space S5 on the image IMG side of the second lens group 102, and the air space S3 of the aperture stop STO. It is provided with a focusing adjustment function unit 301 that changes the distance between the two air spaces (variable focus interval Di) at the time of focusing when the object point moves from infinity to a short distance.

The adjustment of the focus variable interval Di in the focusing adjustment function unit 301 reduces fluctuations in various aberrations by utilizing the double gauss type aperture symmetry. In particular, various focusing modes can be realized by including the air spaces S1, S3, and S5 located on both sides of the second A lens group 102A or the second B lens group 102B. That is, it is possible to realize a multi-group moving focusing method in which the total length changes by moving the lens group or a single lens on the optical axis Dc, or a rear focusing method or an inner focusing method in which the total length does not change. In this case, moving a plurality of lens groups or a single lens is advantageous in terms of performance. On the other hand, when it is desired to avoid the movement of a large and heavy lens group such as a large-diameter lens having a small F number, a focusing method with a small number of lenses is advantageous, and if the moving portion is mechanically reduced, It is possible to avoid complication and reduce the weight.

FIG. 1 shows a case where the interval of the air space S5 on the image IMG side of the second lens group 102 is changed. That is, the moving lens group Gm1 in which the first lens group 101 and the second lens group 102 are integrated moves on the optical axis Dc, and the moving lens group Gm2 in which the third lens group 103 is a single unit moves on the optical axis Dc. This is a two-group moving focusing method in which the moving lens groups Gm1 and Gm2 move by different amounts as they move.

Further, in this basic lens configuration, the following conditional expression [1] is set to be satisfied.
[1] 0.6 <(TL2 / EPD) <2.1

However, EPD is AFL / FNO, AFL is the focal length of the entire system at the time of an infinite object point, and FNO is the F number. By satisfying the conditional expression [1], it can be confirmed that the F number of the entire system can be set to 1.0 or less, specifically, the F number can be set to about 0.8-0.95. rice field.

In this case, the smaller the F-number, the larger the axial luminous flux incident on the entire system, so that the entire lens tends to be larger. The second lens group 102 has a function of converging the axial luminous flux by positive power while suppressing and correcting the occurrence of aberration, and condensing the luminous flux to one point on the image plane by passing through the third lens group 103. There is. That is, the second lens group 102 has an aberration correction property in which aberrations are canceled by the second A lens group 102A and the second B lens group 102B due to the symmetry before and after the double gauss type aperture pattern STO. In this case, the axial luminous flux when the light enters the second lens group 102 diverges and increases when the power of the first lens group 101 is negative, and converges when the power of the first lens group 101 is positive. And become smaller. The luminous flux incident on the second lens group 102 is once converged by the second A lens group 102A, passes through the aperture stop STO that controls the amount of light, and then diverged by the second B lens group 102B.

The diameter and length of the second lens group 102 are basic factors for determining the size of the entire system in order to determine the aberration correction and power balance by the first lens group 101 and the third lens group 103 arranged in the front-rear direction. Since the conditional expression [1] is the ratio of the axially incident luminous flux of the entire system to the second lens group 102, the EPD increases as the F number decreases. Therefore, when the value of the conditional expression [1] becomes small and exceeds the range of the conditional expression [1], a predetermined F number in the entire system is obtained unless the length of the second lens group 102 is increased. I can't do it.

According to the large-diameter imaging lens M according to the present embodiment including such an imaging optical system C, as a basic configuration, a configuration including a single lens L11 in which both sides of the lens are curved toward the object OBJ, or the most object. A first lens group having a configuration consisting of a plurality of lenses L11, L12 ... in which the lens surface on the OBJ side (first lens surface (i = 1)) and the lens surface on the most image IMG side are curved toward the object OBJ, respectively. The second A lens group 102A, which is located on the object OBJ side of the aperture aperture STO and sequentially arranges two positive lenses L21 ... And L22 ..., an air space S2, and a negative lens L23 ... From the object OBJ side, and The image of the aperture aperture STO is located on the IMG side, and has a second B lens group 102B in which a negative lens L24 ..., two positive lenses L25 ... And L26 ... are sequentially arranged from the object OBJ side, and faces the aperture aperture STO. A second lens group 102 having a biconvex air lens La formed by a pair of lens surfaces, a positive lens L31 having a convex lens surface on the object OBJ side from the object OBJ side, and a lens surface on the image IMG side. The third lens group 103 in which the concave negative lens L32 ..., the air space S6, and the positive lens L33 with the convex lens surface on the object OBJ side are sequentially arranged, and the air space on the object OBJ side of the second lens group 102. S1, image of the second lens group 102 The distance between at least one air space (variable focus interval Di) of the air space S5 on the IMG side and the air space S3 of the aperture aperture STO, the object point moves from infinity to a short distance. Since it has a focusing adjustment function unit 301 that changes during focusing and an imaging optical system C that satisfies the above-mentioned conditional expression [1], all the focusing adjustment function units 301 that can use various focusing methods are secured. It is possible to reduce the size of the system, correct various aberrations satisfactorily and sufficiently, and obtain a bright large-diameter lens having a small F number (1.0 or less). As a result, it is possible to cover sufficient optical performance for shooting in the quasi-wide-angle to medium-telephoto range, and it is compatible with large high-definition imaging elements, and it is a large interchangeable lens that is optimal for use in digital cameras that are compact and compact. It can be provided as a caliber image pickup lens M.

On the other hand, it is desirable that the image pickup optical system C provided in the large-diameter image pickup lens M according to the present embodiment is further set so as to satisfy the following conditional expressions [2]-[7].
[2] 0.1 <(TL1 / TL2) <1.5
[3] 0.3 <(TL2 / TLL) <0.8
[4] 0.08 <(TL1 / TLL) <0.60
[5] 0.3 <(TLF / TLL) <0.7
[6] 0.1 <(RS1 / TLL) <0.5
[7] -0.55 <(RS2 / TLL) <-0.10

However, TL1 is the optical axis length from the first lens surface (i = 1) at the time of an infinite object point to the lens surface (second lens surface (i = 3 ...)) On the most object OBJ side of the second lens group 102. TL2 is the optical axis length from the second lens surface (i = 3 ...) to the lens surface (i = 14 ...) on the most image IMG side of the second lens group 102, and TL is from the first lens surface (i = 1). The optical axis length of the fifth lens surface (i = 19 ...), TLF is the optical axis length from the first lens surface (i = 1) to the aperture aperture STO, and RS1 is the curvature of the third lens surface (i = 8 ...). The radius, RS2, is the radius of curvature of the fourth lens surface (i = 10 ...).

In this case, the conditional expression [2] is the ratio of the length from the first lens group 101 to the second lens group 102 to the length of the second lens group 102 on the optical axis Dc. Therefore, the length of the optical system can be set by selecting the number of lenses in the first lens group 101. Further, when the negative power divergence system is converged by the positive power, the air space on the optical axis Dc between the first lens group 101 and the second lens group 102 can be made shorter. Regarding the length relationship between the first lens group 101 and the second lens group 102, if the numerical value of the conditional expression [2] is increased and the number of lenses in the first lens group 101 is increased, the length of the second lens group 102 is shortened. On the contrary, if the numerical value of the conditional expression [2] is reduced and the number of lenses in the first lens group 101 is reduced, the length of the second lens group 102 becomes longer.

The conditional expression [3] is the ratio of the length of the second lens group 102 to the total lens length, and the length of the second lens group 102 is preferably 0.3 to 0.8 times the total lens length. .. When the length of the first lens group 101 is long, the length of the second lens group 102 is short. The multiplication value of the conditional expression [2] and the conditional expression [3] is the value of the conditional expression [4], and includes a length of 60% or less with respect to the entire system from the length that can be configured by one lens. When each embodiment described later is taken into consideration, the maximum number of lenses in the first lens group 101 is five, but the number of lenses can be increased or decreased within a range satisfying the conditional expression [4]. The lower limit of the conditional expression [4] is determined by the length when the first lens group 101 is composed of one lens L11, and when the upper limit is exceeded, the total lens length becomes longer.

The conditional expression [5] indicates the position of the aperture stop STO in the length of the entire system, and when the numerical value is "0.5", the aperture stop STO is located at the center of the entire system. In the case of the standard photographing region as in Example 1-9 described later, the aperture stop STO is within "0.5 ± 0.1" which is almost the center position. Even when the imaging angle of view is changed to wide-angle or telephoto by changing the configuration of the first lens group 101, the aperture of the second lens group 102 is within the range of the conditional expression [5]. The aberration correction effect due to symmetry can be utilized. However, when the range of the conditional expression [5] is exceeded, it becomes difficult to correct the occurrence of aberration.

The range of the conditional expressions [6] and [7] is a range in which the generated coma aberration can be corrected by the entire optical system. Therefore, when the range of the conditional expressions [6] and [7] is exceeded, the radius of curvature of either "RSl" or "RS2" becomes too small, and the balance between the occurrence of aberration and the correction is lost. This makes it difficult to correct coma and other aberrations.
If the conditional expression [2]-[7] is satisfied, the dimensions of the imaging optical system C can be optimized, so that the coma aberration and other aberrations can be corrected and the overall size can be reduced. It can be implemented as the most desirable form from the viewpoint.

In addition, it is desirable that the image pickup optical system C provided in the large-diameter image pickup lens M according to the present embodiment is set so as to satisfy the following conditional expressions [9]-[11].
[9] 0.1 <(AFL / FL2) ≤ 1.0
[10] 0.0 <(│IM2 / OB2│) ≤ 1.0
[11] 0.45 <(FLM / AFL) <4.9

However, FL2 is the focal distance of the second lens group 102, and OB2 is the distance from the image point of the first lens group 101 of the infinite object point to the lens surface (i = 3 ...) On the object OBJ side of the second lens group 102. , IM2 is the distance of the image position from the lens surface (i = 14 ...) On the IMG side of the image of the second lens group 102 when OB2 is the object distance, and FLM is the first lens group 101 and the second lens group 102. The combined focal distance of.

The conditional expressions [9]-[11] indicate the optimum range of the power balance of the first lens group 101 to the third lens group 103. Normally, in an optical system having positive power, when the distance to the object OBJ is short, the position of the image IMG becomes longer in the positive direction, so that the position of the focal length of the optical system from the principal point on the front side becomes infinity. On the other hand, if it is shorter than that, there is a conjugate relationship in which the position of the image IMG becomes longer in the negative direction. The second lens group 102 in the embodiment is a double gauss type by keeping a good power balance within the range satisfying the conditional expression [9] and further keeping it within the range of the conditional equations [10] and [11]. Since the aperture symmetry conjugate relationship of the second lens group 102 can be configured, better aberration correction is possible. It is ideal if the point from the object point to the image point is almost symmetrical with respect to the aperture stop STO.

The first lens group 101 can have an image point at infinity due to its characteristics as a front conversion lens, but the first lens group 101 is a retrofocus type when the lens on the object OBJ side is composed of a negative lens. It becomes an optical system and can advantageously correct off-axis aberrations. By setting the object point of the second lens group 102 (the image point of the first lens group 101) in an appropriate range, the on-axis and off-axis aberrations of the properties of the two lens types can be satisfactorily corrected.

Since the image point of the first lens group 101 can be at infinity, the value of the conditional expression [10] is 0.0 when OB2 becomes infinity. Therefore, when the value falls below the lower limit of 0.0, the negative power of the first lens group 101 becomes weaker and the OB2 becomes larger. Becomes difficult. Further, when the image point IM2 of the second lens group 102 becomes small and the negative power of the first lens group 101 becomes too strong, the power of the second lens group 102 also becomes too strong, and the near point in the second lens group 102 Set the object point to a long image position. For this reason, in particular, spherical aberration is often generated due to a large aperture having a small F number, and it is difficult to correct this by using the third lens group 103.

On the other hand, since OB2 is set to the value of IM2 or more, the value of the conditional expression [10] is 1.0 or less. Therefore, when the upper limit value of 1.0 is exceeded, the negative power of the first lens group 101 becomes too strong and the OB2 becomes small, so that off-axis aberrations occur more frequently, and the second lens group 102 and later. Correction by the optical system becomes difficult. Further, when the negative power of the first lens group 101 becomes weaker, the OB2 becomes longer, so that it becomes difficult to correct the off-axis aberration due to the advantage of the retrofocus type off-axis aberration correction.

In this way, by satisfying the conditional expression [9] in the conditional expression [9]-[11], the power distribution in the second lens group 102 can be set in an appropriate range, so that a good power balance can be achieved. Can be secured. In addition, by satisfying the conditional expressions [10] and [11], the second lens group 102 based on the double gauss type can be constructed in a so-called aperture-symmetrical conjugate relationship, so that aberration correction can be particularly well performed. can.

Next, various examples (Examples 1-12) in this embodiment will be described with reference to FIGS. 1 to 26.

First, the large-diameter image pickup lens M according to the first embodiment will be described with reference to FIGS. 1 to 2, 4 and 1.

FIG. 1 shows the configuration of the large-diameter imaging lens M according to the first embodiment. As described in the above-described embodiment, the large-diameter imaging lens M shown in the first embodiment includes a first lens group 101, a second lens group 102 including an aperture diaphragm STO, and a third lens group 103 from the object OBJ side. An imaging optical system C arranged in sequence is provided.

In the imaging optical system C, the first lens group 101 includes a single lens L11 in which both sides of the lens are curved toward the object OBJ. The lens L11 used is a negative meniscus lens having a negative power. Then, the second lens group 102 is arranged on the image IMG side of the lens L11 via the air space S1.

The second lens group 102 is composed of a second A lens group 102A located on the object OBJ side of the aperture stop STO and a second B lens group 102B located on the image IMG side of the aperture stop STO. The second A lens group 102A is composed of a total of three lenses in which a positive meniscus lens L21, a positive meniscus lens L22, an air space S2, and a negative meniscus lens L23 are sequentially arranged from the object OBJ side, and the second B lens group 102B. From the object OBJ side, a junction lens Ja in which a biconcave lens (negative lens) L24 and a biconvex lens (positive lens) L25 are joined, an air space S4, and a biconvex lens (positive lens) L26 having an aspherical shape are sequentially arranged. It consists of a total of three lenses. In this case, a pair of lens surfaces facing the aperture stop STO, that is, a lens surface on the image IMG side of the negative meniscus lens L23 located on the object OBJ side with respect to the aperture stop STO (third lens surface (i = 8)). A biconvex air lens La is formed by the air space S3 between the lens surface (fourth lens surface (i = 10)) on the object OBJ side of the biconcave lens L24 located on the image IMG side with respect to the aperture stop STO. Will be done.

In particular, the negative meniscus lens L23 of the second A lens group 102A is formed by using a low refractive index low dispersion glass material having an absolute partial dispersion value dPgF of 0.02 or more. Since the low refractive index low dispersion glass material is distributed with a refractive index of 1.57 or less and an Abbe number of 75 or more, axial chromatic aberration can be corrected by selectively using an appropriate glass material. As described above, when the second lens group 102 is formed, if the negative lens L23 using the low refractive index low dispersion glass material having the absolute value of the abnormal partial dispersion value dPgF of 0.02 or more is included, an appropriate abnormal partial dispersion is included. By selecting the dispersion value dPgF, there is an advantage that good and effective correction for axial chromatic aberration can be performed.

Then, the third lens group 103 is arranged on the image IMG side of the biconvex lens L26 via the air space S5. The third lens group 103 includes a junction lens Jb in which a positive meniscus lens L31 having a convex lens surface on the object OBJ side and a negative meniscus lens L32 having a concave lens surface on the image IMG side are joined from the object OBJ side. It is composed of a total of three lenses in which S6 and a biconvex lens (positive lens) L33 having an aspherical shape are sequentially arranged. In this case, the biconvex lens L33 is set so that the lens surface (i = 18) on the object OBJ side has a smaller radius of curvature than the lens surface (fifth lens surface (i = 19)) on the image IMG side.

When a lens surface having an aspherical shape is used, the nature of the aberration correction depends on which part of the aspherical shape the light flux passes through, which is advantageous when performing finer aberration correction. With a large-diameter lens, the lens diameter becomes large, which affects ease of processing and cost. Therefore, it is advantageous to asphericize the lens on the image IMG side (final lens) or a small-diameter lens located closest to this. It becomes. In particular, in the case of an interchangeable lens, the final lens is restricted by the inner diameter of the mount, so the lens diameter is adjusted to substantially match the imaging size (image circle). Therefore, in a large-diameter imaging lens, the diameter of the final lens is often the smallest.

As described above, if at least the lens surface (i = 19) on the image IMG side of the biconvex lens L33 located on the image IMG side of the third lens group 103 is made into an aspherical shape, the image IMG side having a relatively small diameter can be obtained. Since the lens to be used can be made aspherical, it is possible to enhance the advantages in terms of processing surface and cost, and in particular, it is possible to bear the correction of the sagittal coma, which is a drawback of the Gauss type, so that aberration correction different from other lenses can be performed. realizable.

In the above imaging optical system C, in particular, the five lenses L24 ... Arranged on the image IMG side with respect to the aperture diaphragm STO have a lens surface (i = 10) having a concave shape on the object OBJ side from the object OBJ side. Since it is composed of a negative lens L24, three positive lenses L25, L26, L31, and a negative lens L32 having a lens surface (i = 17) having a concave shape on the image IMG side, it is configured as a partially symmetric lens group Gs.

The partially symmetric lens group Gs includes two lenses, a second B lens group 102B and a third lens group 103 following the second B lens group 102B, and bears the ejection function of a large-diameter lens having a small F number. The second lens group 102 is a double gauss type and is a basic part of the partially symmetric lens group Gs, and the second lens group 102 is superposed on the partially symmetric lens group Gs to construct a partially symmetric optical system. The focusing adjustment function unit 301, which will be described later, has a function of keeping the aberration constant while suppressing the aberration generated at the time of focusing by setting the focus variable interval in the lens group. With this configuration, the luminous flux converged by the aperture stop STO diverges when it is incident on the partially symmetric optical system, and is gradually converged by the three positive lenses while being focused on the image plane by the final lens on the image IMG side. do. The biconvex lens and the biconcave lens suppress sudden refraction and the accompanying aberration generation while balancing the entrance / exit angles of light rays by curves with different directions on both sides.

In this way, the five lenses L24 ... Arranged on the image IMG side with respect to the aperture aperture STO are negative lenses L24 having a lens surface (i = 10) in which the object OBJ side has a concave shape from the object OBJ side. It is composed of three positive lenses L25, L26, L31, and a partially symmetric lens group Gs composed of a negative lens L32 having a lens surface (i = 17) having a concave shape on the image IMG side, and the partially symmetric lens group Gs. If at least one positive lens L25, L26 having a convex shape on both sides and at least one negative lens L24 having a concave shape on both sides are included, the partially symmetric optical system that is the basis of the double gauss type can be added to other lenses. Since the lens can be added, it is possible to suppress abrupt refraction of the light entering / exiting angle, and it is possible to effectively suppress the occurrence of aberrations associated therewith.

Further, on the air-contacting all lens surfaces (i = 3, 5, 7, 8) of the lenses L21, L22, L23 in the second A lens group 102A, and on the object OBJ side of each lens L31, L33 in the third lens group 103. All the lens surfaces (i = 15, 18) that are in air contact with each other are curved toward the object OBJ side. In this way, the first lens group 101 is composed of two or less lenses L11 having negative power, and all the air-contacting lens surfaces (i = 3, 5, 7, of the lenses in the second A lens group 102A) are in contact with each other. 8), and if all the air-contacting lens surfaces (i = 15, 18) located on the object OBJ side of each lens in the third lens group 103 are curved toward the object OBJ side, the lens weight compression effect can be obtained. As a result, the length of the imaging optical system C in the optical axis Dc direction can be shortened, so that even a large-diameter imaging lens M having a large outer diameter, including a lens having a meniscus shape with a small volume, can be reduced in weight.

On the other hand, reference numeral 301 denotes a focusing adjustment function unit. In the case of the first embodiment, at least one moving lens group Gm1 ... That moves during focusing is provided, and the distance between the air spaces S5 on the image IMG side of the second lens group 102 changes. That is, the moving lens group Gm1 in which the first lens group 101 and the second lens group 102 are integrated moves on the optical axis Dc, and the moving lens group Gm2 in which the third lens group 103 is a single unit moves on the optical axis Dc. A focusing adjustment function unit 301 is configured by a two-group moving focusing method in which the moving lens groups Gm1 and Gm2 move by different amounts as they move.

In this case, in the partially symmetrical lens group Gs, the air space S5 located on one side of the positive lens L26 whose both sides are air contact surfaces functions as the focus variable interval Di when the object point moves. In this way, the focus is variable when the object moves in the air space S5 (and / or S4) located on one side (or both sides) of the positive lens L26 whose both sides provided in the partially symmetrical lens group Gs are air contact surfaces. If it functions as the interval Di, the variable focus interval Di can be set inside the partially symmetrical lens group Gs, so that the occurrence of aberration during focusing can be suppressed and the aberration can be stabilized (stabilized).

Further, when configuring the focusing adjustment function unit 301 of the first embodiment, it is set so as to satisfy the conditional expression [8]. Specific set values related to the conditional expression [8] are shown in FIG.
[8] 0.009 << {│ (FP2-FP1) / FP1│} <0.5

However, the FP1 is from the lens surface (i = 14) on the image IMG side of the moving lens group Gm1 located on the object OBJ side with respect to the focus variable interval Di existing on the most object OBJ side at the time of an infinite object to the image position. The distance, FP2, is the lens surface on the image IMG side (i = 14 ... ) To the image position.

In this way, when the focusing adjustment function unit 301 is configured, if at least one moving lens group Gm1 ... That moves during focusing is provided and configured so as to satisfy the above-mentioned conditional expression [8], focusing based on the multi-group focusing method Since the adjustment mechanism can be constructed, the focusing adjustment function unit 301 having higher focusing performance can be obtained.

Further, the optical characteristics (optical conditions) in the optical imaging system C in such a lens configuration are set so as to satisfy all of the above-mentioned conditional expressions [1]-[11]. Specific setting values related to each conditional expression are shown in FIG.

Table 1 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 1. The large-diameter imaging lens M at an infinite object point has a focal length of 28.91 mm, an F number of 0.84, and a half angle of view of 21.41 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown. In this case, the shooting magnification of "0.00" indicates that the subject is at an infinite object point. In the optical horizontal magnification, the image height is inverted with respect to the object height, so that it is a negative value. However, this photographing magnification is expressed as the image height / (-object height).

In the "plane data" of Table 1, the surface number of the lens surface counted from the object OBJ side is indicated by i. This surface number i corresponds to a part of the reference numerals (some numbers) shown in FIG. Correspondingly, the radius of curvature R (i) of the lens surface, the axial top surface distance D (i), the refractive index nd (i) of the glass material, the Abbe number νd (i) of the glass material, and the low refractive index low dispersion glass material are used. The anomalous partial dispersion value dPgF (i) of the existing lens and the focal length FL (i) of the single lens (treated as a plurality of bonded lenses) placed in the air are shown. 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), the surface spacing D (i), and the focal length FL (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.

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

Further, in the "variable focus interval" in Table 1, "VD0", "VD2", "VD8" ... Indicated by VD + surface number indicate the variable interval in which the focus can be adjusted, and the second A lens group 102A and the second lens group 102A. The 2B lens group 102B includes the division of the adjacent air spaces S1, S3, and S5. The same numerical value of "shooting magnification" indicates that the lens groups before and after the same value move on the optical axis Dc at the same time.

As shown in FIG. 2, since AFL is 28.91 mm and FNO is 0.84, EPD = AFL / FNO is “34.50” and TL2 / EPD is “1.62”, and the conditional expression [1] Satisfy "0.6 <(TL2 / EPD) = 1.62 <2.1". Since TL1 is 12.68 mm and TL2 is 55.80 mm, TL1 / TL2 is "0.23", and the conditional expression [2] "0.1 <(TL1 / TL2) = 0.23 <1.5". Since the TLL is 86.89 mm, the TL2 / TLL becomes "0.64", and the conditional expression [3] "0.3 <(TL2 / TLL) = 0.64 <0.8" is satisfied. .. Since TL1 / TLL is "0.15", the conditional expression [4] "0.08 <(TL1 / TLL) = 0.15 <0.60" is satisfied, and TLF is 40.79 mm, TLF / The TLL becomes “0.47” and satisfies the conditional expression [5] “0.3 <(TLF / TLL) = 0.47 <0.7”. Further, since RS1 is 17.23 mm and RS2 is -23.79 mm, RS1 / TLL is "0.20", and the conditional expression [6] "0.1 <(RS1 / TLL) = 0.20 <0". While satisfying ".5", RS2 / TLL becomes "-0.27", and the conditional expression [7] "-0.55 <(RS2 / TLL) = -0.27 <-0.10" is satisfied.

Further, since FP1 is 52.34 mm and FP2 is 62.62 mm, │ (FP2-FP1) / FP1│ becomes "0.196", and the conditional expression [8] "0.009 << {│ (FP2-FP1) ) / FP1│} = 0.196 <0.5 ”. Since FL2 is 54.82 mm, AFL / FL2 becomes “0.53” and satisfies the conditional expression [9] “0.1 <(AFL / FL2) = 0.53 ≦ 1.0”. OB2 is -93.00 mm, IM2 is 52.34 mm. Since the FLM is 52.61 mm, │IM2 / OB2│ becomes “0.56” and satisfies the conditional expression [10] “0.0 <(│IM2 / OB2│) = 0.56 ≦ 1.0”. At the same time, FLM / AFL becomes "1.82" and satisfies the conditional expression [11] "0.45 <(FLM / AFL) = 1.82 <4.9".

On the other hand, FIG. 4 shows a longitudinal aberration diagram in which the imaging magnification of the large-diameter imaging lens M of Example 1 is set as a parameter (“0.00”, “0.10”). From the left side, 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). Each scale is ± 0.50 mm, ± 0.50 mm, ± 3.0%. As shown in FIG. 4, it can be confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is “0.00” or “0.10”.

Next, the large-diameter imaging lens M according to the second embodiment will be described with reference to FIGS. 2, 5, 6, and 2.

FIG. 5 shows the configuration of the large-diameter imaging lens M according to the second embodiment. Also in the second embodiment, as the basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between the second embodiment and the first embodiment is that the lens configuration of the first lens group 101 and the lens configuration of the third lens group 103 are changed, and the other basic configurations are those of the first embodiment. Is the same as. Therefore, in FIG. 5, except for the surface numbers (i = 1,2,3 ... 21,22), the same parts as those in FIG. 1 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted.

The first lens group 101 consists of two lenses (first lens surface (i = 1)) on the most object OBJ side and two lenses (i = 3) on the most image IMG side curved toward the object OBJ side. It is provided with lenses L11 and L12 (generally a plurality of lenses). In this case, as the lenses L11 and L12, a junction lens Jc in which a biconvex lens (positive lens) L11 and a biconcave lens (negative lens) L12 are joined is used. The second lens group 102 is composed of a second A lens group 102A located on the object OBJ side of the aperture stop STO and a second B lens group 102B located on the image IMG side of the aperture stop STO, and has a basic lens configuration. Is the same as in Example 1. However, since the number of lenses in the first lens group 101 is different, the surface number (i) in FIG. 5 is moved up. On the other hand, the third lens group 103 is a junction lens Jb in which a biconvex lens (positive lens) L31 and a biconcave lens (negative lens) L32 are joined from the object OBJ side, an air space S6, and a biconvex lens (positive lens) having an aspherical shape. It is composed of a total of three lenses in which L33 is sequentially arranged.

Table 2 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 2. The large-diameter image pickup lens M at the time of an infinite object has a focal length of 29.00 mm, an F number of 0.84, and a half angle of view: 21.26 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 2, the large-diameter imaging lens M of the second embodiment also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.60 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.27 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.64 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.17 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.47 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.19 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.23 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.149 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.63 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.41 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 1.35 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIG. 6 shows a longitudinal aberration diagram in which the imaging magnification in the large-diameter imaging optical system C of Example 2 is a parameter (“0.00”, “0.10”). As shown in FIG. 6, it can be confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10".

Next, the large-diameter imaging lens M according to the third embodiment will be described with reference to FIGS. 2, 7, 8, and 3.

FIG. 7 shows the configuration of the large-diameter imaging lens M according to the third embodiment. In Example 3, as a basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between the third embodiment and the second embodiment is that the lens configuration of the first lens group 101, the lens configuration of the second A lens group 102A, and the configuration of the focusing adjustment function unit 301 are changed. The basic configuration of is the same as that of the second embodiment. Therefore, in FIG. 7, except for the surface numbers (i = 1, 2, 3 ... 22, 23), the same parts as those in FIG. 5 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted. In Example 3 (the same applies to Example 4-12), the lens (L23) made of a low refractive index low dispersion glass material used in the second lens group 102 in Examples 1 and 2 is not used.

The first lens group 101 consists of two lenses in which the lens surface on the most object OBJ side (first lens surface (i = 1)) and the lens surface on the most image IMG side (i = 3) are curved toward the object OBJ, respectively. The point that the lenses L11 and L12 are provided is the same as in the second embodiment, but the lenses L11 and L12 use two single lenses, a biconvex lens (positive lens) L11 and a biconcave lens (negative lens) L12, respectively.

The second lens group 102 is composed of a second A lens group 102A located on the object OBJ side of the aperture aperture STO and a second B lens group 102B located on the image IMG side of the aperture aperture STO, and has a basic lens configuration. Is the same as in Example 2, but in the second A lens group 102A of Example 3, the biconvex lens (positive lens) L21, the positive meniscus lens L22 curved from the object OBJ side to the object OBJ side, the air space S2, and the object It is composed of a total of three single lenses in which a biconcave lens L23 whose lens surface on the OBJ side is close to a flat surface is sequentially arranged. In this case, since the lens configuration of the first lens group 101 is different, the surface number (i) in FIG. 7 is moved up. The basic configuration of the third lens group 103 is the same as that of the second embodiment, but the lens surface on the image IMG side of the biconvex lens (normal lens) L33 having an aspherical shape located closest to the image IMG side. (I = 21) is set to a convex surface close to a flat surface.

Further, as shown in FIG. 7, the focusing adjustment function unit 301 fixes (immobilizes) the position of the first lens group 101 with respect to the image position, and at the same time, the air space S1 on the object OBJ side of the second lens group 102. The air space S5 on the image IMG side is changed as the focus variable interval Di.

That is, the position of the first lens group 101 is fixed (immobile) as a fixed lens group Gc located on the object OBJ side, and the second lens group 102 and the third lens group 103 are designated as independent moving lens groups Gm1 and Gm2, respectively. It is configured as a two-group moving rear focus method in which each of them moves to the object OBJ side on the optical axis Dc by a different amount by making it function.

In this way, when configuring the focusing adjustment function unit 301, the fixed lens group Gc that fixes the lens surface (i = 1) on the most object OBJ side of the entire system with respect to the image position, and at least one that moves during focusing. If the moving lens group Gm1 ... Is provided and the condition formula [8] is set to be satisfied, in particular, the first lens group 101 on the OBJ side of the object in which the large-diameter lens is arranged is immobile, and the focusing adjustment based on the rear focus method is performed. Since the functional unit 301 can be constructed, it can contribute to further weight reduction and miniaturization of the large-diameter imaging lens M.

Table 3 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 3. The large-diameter imaging lens M at an infinite object point has a focal length of 28.00 mm, an F number of 0.84, and a half angle of view of 21.92 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 2, the large-diameter imaging lens M of the third embodiment also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.69 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.38 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.62 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.24 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.50 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.29 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.21 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.137 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.68 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.28 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 0.97 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIGS. 8A and 8B show longitudinal aberration diagrams in which the imaging magnification in the large-diameter imaging optical system C of Example 3 is a parameter (“0.00”, “0.10”). As shown in FIGS. 8A and 8B, it was confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10". can.

Next, the large-diameter imaging lens M according to the fourth embodiment will be described with reference to FIGS. 2, 9, 10, and 4.

FIG. 9 shows the configuration of the large-diameter imaging lens M according to the fourth embodiment. In Example 4, as a basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between the fourth embodiment and the third embodiment is that the lens configuration of the first lens group 101 and the configuration of the focusing adjustment function unit 301 are changed, and the other basic configurations are the same as those of the third embodiment. It is the same. Therefore, in FIG. 9, the same parts as those in FIG. 7 are designated by the same reference numerals to clarify their configurations, and detailed description thereof will be omitted.

The first lens group 101 includes a single lens L11 in which both sides of the lens are curved toward the object OBJ side, and the lens surface (first lens surface (i = 1)) on the most object OBJ side and the most image IMG side. The configuration satisfies any of a configuration including a plurality of lenses L11, L12 ... In which the lens surface is curved toward the object OBJ, respectively. Specifically, two single lenses, a negative meniscus lens L11 curved from the object OBJ side to the object OBJ side and a negative meniscus lens L12 curved toward the object OBJ side, were used.

Further, as shown in FIG. 9, the focusing adjustment function unit 301 fixes (immobilizes) the positions of the first lens group 101 and the second A lens group 102A with respect to the image position, and sets the air space S3 of the aperture stop STO and the air space S3. The air space S5 on the image IMG side of the second B lens group 102B is changed as the focus variable interval Di.

That is, the position is fixed (immovable) as a fixed lens group Gc located on the object OBJ side in which the first lens group 101 and the second A lens group 102A are integrated, and the second B lens group 102B and the third lens group 103 are respectively. By functioning as independent moving lens groups Gm1 and Gm2, they are configured to move to the object OBJ side on the optical axis Dc by different amounts.

As described above, in the fourth embodiment, when the focusing adjustment function unit 301 is configured, the fixed lens group Gc for fixing the lens surface (i = 1) on the most object OBJ side of the entire system with respect to the image position, and the fixed lens group Gc at the time of focusing The moving moving lens groups Gm1 and Gm2 are provided and set so as to satisfy the conditional expression [8], and the two-group moving rear focus method is configured as in the third embodiment.

Table 4 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 4. The large-diameter image pickup lens M at the time of an infinite object has a focal length of 28.00 mm, an F number of 0.84, and a half angle of view of 21.77 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 2, the large-diameter imaging lens M of the fourth embodiment also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.83 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.27 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.67 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.18 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.51 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.22 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.21 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.128 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.48 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.55 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 1.14 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIGS. 10A and 10B show longitudinal aberration diagrams in which the imaging magnification in the large-diameter imaging optical system C of Example 4 is set as a parameter (“0.00”, “0.10”). As shown in FIGS. 10A and 10B, it was confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10". can.

Next, the large-diameter imaging lens M according to the fifth embodiment will be described with reference to FIGS. 2, 11, 12, and 5.

FIG. 11 shows the configuration of the large-diameter imaging lens M according to the fifth embodiment. In Example 5, as a basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between Example 5 and Example 4 is that the lens configuration of the first lens group 101 and the configuration of the focusing adjustment function unit 301 are changed, and the other basic configurations are the same as those of the fourth embodiment. It is the same. Therefore, in FIG. 11, the same parts as those in FIG. 9 are designated by the same reference numerals to clarify their configurations, and detailed description thereof will be omitted.

The first lens group 101 includes two lenses L11 in which the lens surface on the most object OBJ side (first lens surface (i = 1)) and the lens surface on the most image IMG side (i = 3) are curved toward the object OBJ side. And L12 are provided, and each is composed of two single lenses, a biconvex lens (positive lens) L11 and a biconcave lens (negative lens) L12.

Further, as shown in FIG. 11, the focusing adjustment function unit 301 fixes (immobilizes) the first lens group 101 and the third lens group 103 with respect to the image position, and the air on the object OBJ side of the second lens group 102. The space S1 and the air space S5 on the image IMG side are changed as the focus variable interval Di.

That is, in the focusing adjustment function unit 301 of the fifth embodiment, the first lens group 101 is a fixed lens group Gc located on the object OBJ side, and the third lens group 103 is a fixed lens group Gc located on the image IMG side. It is configured to have two fixed lens groups Gc ..., and the second lens group 102 located in the middle as one independent moving lens group Gm1 so as to move on the optical axis Dc toward the object OBJ side. It is an inner focus method.

In this way, two fixed lens groups Gc ... That fix the lens surface (i = 1) on the most object OBJ side and the lens surface (i = 21) on the image IMG side of the entire system with respect to the image position, and focusing. If one moving lens group (including one lens) Gm1 that moves occasionally is provided and the condition formula [8] is set to be satisfied, one focus lens group Fm arranged in the middle can be moved as an inner focus method. Since the focusing adjustment function unit 301 based on the above can be constructed, it can be implemented as an optimum form from the viewpoint of reducing the weight and size of the large-diameter imaging lens M.

Table 5 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 5. The large-diameter image pickup lens M at the time of an infinite object has a focal length of 28.00 mm, an F number of 0.84, and a half angle of view of 21.91 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 2, the large-diameter imaging lens M of the fifth embodiment also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.71 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.39 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.62 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.24 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.51 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.35 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.21 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.138 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.68 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.27 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 0.98 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIGS. 12A and 12B show longitudinal aberration diagrams in which the imaging magnification in the large-diameter imaging optical system C of Example 5 is a parameter (“0.00”, “0.10”). As shown in FIGS. 12A and 12B, it was confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10". can.

Next, the large-diameter imaging lens M according to the sixth embodiment will be described with reference to FIGS. 2, 13, 14, and 6.

FIG. 13 shows the configuration of the large-diameter imaging lens M according to the sixth embodiment. In Example 6, as a basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between Example 6 and Example 5 is that the configuration of the first lens group 101, the second A lens group 102A, the third lens group 103, and the focusing adjustment function unit 301 are changed. Other basic configurations are the same as in the fifth embodiment. Therefore, in FIG. 13, except for the surface numbers (i = 1, 2, 3 ... 23, 24), the same parts as those in FIG. 11 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted.

The first lens group 101 includes a single single lens L11 in which both sides of the lens are curved toward the object OBJ side, and the lens surface (first lens surface (i = 1)) on the most object OBJ side and the most image IMG side. The lens surface (i = 4) of the lens surface (i = 4) satisfies any of the two single lenses L11 and L12 curved toward the object OBJ. In this case, the two single lenses L11 and L12 are each composed of a negative meniscus lens curved toward the object OBJ side.

Further, the second A lens group 102A is different in that the negative meniscus lens L23 curved toward the object OBJ side is used in Example 6 instead of the biconcave lens L23 in Example 5, and the third lens group 103 is an object. From the OBJ side, the positive meniscus lens L31 curved toward the object OBJ side, the negative meniscus lens L32 curved toward the object OBJ side, the air space S6, and the lens surface (i = 22) on the image IMG side have an aspherical shape. It is composed of a total of three single lenses in which biconvex lenses (positive lenses) L33, which are close to a flat surface, are sequentially arranged.

Further, as shown in FIG. 13, the focusing adjustment function unit 301 fixes (immobilizes) the first lens group 101, the second A lens group 102A, and the third lens group 103 with respect to the image position, and sets the aperture aperture STO. The air space S3 and the air space S5 on the image IMG side of the second B lens group 102B are configured to be changed as the focus variable interval Di, respectively.

That is, the focusing adjustment function unit 301 of the sixth embodiment is a fixed lens group Gc located on the object OBJ side in which the first lens group 101 and the second A lens group 102A are integrated, and the third lens group 103 is on the image IMG side. The fixed lens group Gc to be located and the second B lens group 102B as one independent moving lens group Gm1 are configured to move on the optical axis Dc toward the object OBJ side. Although the lens group to be moved is different, the same group movement inner focus method as in the fifth embodiment is adopted.

Table 6 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 6. The large-diameter imaging lens M at an infinite object point has a focal length of 28.01 mm, an F number of 0.84, and a half angle of view of 21.67 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 2, the large-diameter imaging lens M of Example 6 also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.92 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.23 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.70 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.16 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.52 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.21 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.21 <-0.10 ", conditional expression [8] ] "0.009 << {│ (FP2-FP1) / FP1│} = 0.127 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.42 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.47 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 1.09 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIGS. 14A and 14B show longitudinal aberration diagrams in which the imaging magnification in the large-diameter imaging optical system C of Example 6 is a parameter (“0.00”, “0.10”). As shown in FIGS. 14 (a) and 14 (b), it was confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10". can.

Next, the large-diameter imaging lens M according to the seventh embodiment will be described with reference to FIGS. 3, 15, 16, and 7.

FIG. 15 shows the configuration of the large-diameter imaging lens M according to the seventh embodiment. In Example 7, as the basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between Example 7 and Example 6 is that the lens configuration of the first lens group 101 and the configuration of the focusing adjustment function unit 301 are changed, and the other basic configurations are the same as those of the sixth embodiment. It is the same. Therefore, in FIG. 15, the same parts as those in FIG. 13 are designated by the same reference numerals to clarify their configurations, and detailed description thereof will be omitted.

The first lens group 101 is configured to include a single single lens L11 whose both sides are curved toward the object OBJ side. Specifically, a negative meniscus lens curved from the object OBJ side to the object OBJ side. L11, a positive meniscus lens L12 curved toward the image IMG side is provided.

Further, as shown in FIG. 15, the focusing adjustment function unit 301 images the two lenses L32 and L33 located on the image IMG side of the first lens group 101, the second lens group 102, and the third lens group 103. It is fixed (immovable) with respect to the position, and the air space S5 on the image IMG side of the second lens group 102 is changed as the focus variable interval Di.

That is, the first lens group 101 and the second lens group 102 are integrated into the fixed lens group Gc on the object OBJ side, and the two lenses L32 and L33 located on the image IMG side of the third lens group 103 are on the image IMG side. The fixed lens group Gc of the third lens group 103, and one lens (positive meniscus lens) L31 located on the object OBJ side of the third lens group 103 is used as the moving lens group Gm1 to move on the optical axis Dc to the object OBJ side. It is configured in.

Therefore, although the fixed lens group and the moving lens group are different, the same group movement inner focus method as in the sixth embodiment is used. In particular, in the case of the seventh embodiment, since the moving lens group Gm1 is only one single lens, it is a single moving inner focus method in which only one single lens is moved.

Table 7 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 7. The large-diameter image pickup lens M at the time of an infinite object has a focal length of 25.00 mm, an F number of 0.84, and a half angle of view of 23.90 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 3, the large-diameter imaging lens M of the seventh embodiment also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.68 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.47 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.55 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.25 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.53 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.27 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.24 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.117 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.43 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.72 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 2.62 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIGS. 16A and 16B show longitudinal aberration diagrams in which the imaging magnification in the large-diameter imaging optical system C of Example 7 is set as a parameter (“0.00”, “0.10”). As shown in FIGS. 16A and 16B, it was confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10". can.

Next, the large-diameter imaging lens M according to the eighth embodiment will be described with reference to FIGS. 3, 17, 18, and Table 8.

FIG. 17 shows the configuration of the large-diameter imaging lens M according to the eighth embodiment. In Example 8, as a basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between Example 8 and Example 7 is that the configurations of the first lens group 101, the second A lens group 102A, the third lens group 103, and the focusing adjustment function unit 301 are changed, and other basics. The configuration is the same as that of the seventh embodiment. Therefore, in FIG. 17, except for the surface numbers (i = 1, 2, 3 ... 22, 23), the same parts as those in FIG. 15 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted.

In the eighth embodiment, the lens L12 arranged on the image IMG side of the first lens group 101 in the first lens group 101 is configured by a negative meniscus lens L12 curved toward the image IMG side and formed by an aspherical shape, and is also an embodiment. The lens L23 arranged on the most aperture aperture STO side of the second A lens group 102A in No. 7 is composed of a biconcave lens (negative lens). Further, when constructing the third lens group 103 of the eighth embodiment, the junction lens Jb in which the biconvex lens (positive lens) L31 and the biconcave lens (negative lens) L32 are joined from the object OBJ side, the air space S6, and the aspherical surface are formed. It is composed of a total of three lenses in which biconvex lenses (positive lenses) L33 having a shape are sequentially arranged.

On the other hand, as shown in FIG. 17, the focusing adjustment function unit 301 has two positive lenses L21 and L22 located on the object OBJ side in the first lens group 101 and the second A lens group 102A, the second B lens group 102B, and the second lens group 102B. The third lens group 103 is fixed (immovable) with respect to the image position, and the air space S3 of the aperture stop STO is changed as the focus variable interval Di.

That is, the fixed lens group Gc located on the object OBJ side in which the two positive lenses L21 and L22 located on the object OBJ side in the first lens group 101 and the second A lens group 102A are integrated is used as the second A lens group 102A. One negative lens L23 arranged most on the image IMG side is configured as one moving lens group Gm1 so as to move on the optical axis Dc toward the image IMG side. Therefore, although the fixed lens group and the moving lens group are different, the one-element moving inner focus method similar to that of the seventh embodiment is adopted.

Table 8 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 8. The large-diameter image pickup lens M at the time of an infinite object has a focal length of 26.34 mm, an F number of 0.84, and a half angle of view: 23.30 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 3, the large-diameter imaging lens M of Example 8 also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.73 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.29 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.63 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.18 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.50 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.29 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.22 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.010 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.66 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.29 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 1.03 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIGS. 18A and 18B show longitudinal aberration diagrams in which the imaging magnification in the large-diameter imaging optical system C of Example 8 is a parameter (“0.00”, “0.10”). As shown in FIGS. 18A and 18B, it was confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10". can.

Next, the large-diameter imaging lens M according to the ninth embodiment will be described with reference to FIGS. 3, 19, 21, and 9.

FIG. 19 shows the configuration of the large-diameter imaging lens M according to the ninth embodiment. In Example 9, as the basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between Example 9 and Example 8 is that the configurations of the first lens group 101, the second A lens group 102A, the third lens group 103, and the focusing adjustment function unit 301 are changed, and other basics. The configuration is the same as that of the eighth embodiment. Therefore, in FIG. 19, except for the surface numbers (i = 1,2,3 ... 27,28), the same parts as those in FIG. 17 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted.

The first lens group 101 includes a single lens L11 in which both sides of the lens are curved toward the object OBJ side, and the lens surface (first lens surface (i = 1)) on the most object OBJ side and the most image IMG side. The lens surface (i = 8) is configured to satisfy all of the four lenses L11, L12, L13, and L14 curved toward the object OBJ side. In the example, the negative meniscus lens L11 curved toward the object OBJ side, the biconcave lens L12, the positive meniscus lens L13 curved toward the image IMG side, and the positive meniscus lens L14 curved toward the object OBJ side are provided from the object OBJ side.

In this case, in the ninth embodiment, the first lens group 101 is composed of six or less lenses, and the difference between the number of positive lenses and the number of negative lenses is one or less. When configuring the first lens group 101, as in Example 9 (the same applies to Example 10), it is composed of six or less lenses, and the difference between the number of positive lenses and the number of negative lenses is set within one. By doing so, the total number of the first lens group 101 is suppressed to 6 or less, and the difference between the number of positive lenses and the number of negative lenses is set to 1 or less, so that well-balanced aberration correction can be performed. can.

The second A lens group 102A is configured by using a negative meniscus lens L23 in which the lens L23 arranged on the most aperture aperture STO side is curved toward the object OBJ side, and the third lens group 103 is a biconvex lens (biconvex lens) from the object OBJ side. It is composed of a total of three lenses in which a positive lens) L31, a negative meniscus lens L32 curved toward the object OBJ side, an air space S6, and a biconvex lens (positive lens) L33 having an aspherical shape are sequentially arranged.

On the other hand, as shown in FIG. 19, the focusing adjustment function unit 301 includes the negative lens L32 and the positive lens L33 located closest to the image IMG in the first lens group 101, the second lens group 102, and the third lens group 103. Each of the two lenses is fixed (immovable) with respect to the image position, and the air space S5 on the image IMG side of the second lens group 102 is changed as the focus variable interval Di.

That is, the fixed lens group Gc located on the object OBJ side in which the first lens group 101 and the second lens group 102 are integrated is used, and the two lenses L32 and L33 located closest to the image IMG side in the third lens group 103 are used. A fixed lens group Gc located on the image IMG side, and only one positive lens L31 located on the image OBJ side of the third lens group 103 as one moving lens group Gm1, and an object OBJ on the optical axis Dc. It is configured to move to the side. Therefore, although the fixed lens group and the moving lens group are different, the one-element moving inner focus method similar to that of the eighth embodiment is adopted.

Table 9 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 9. The large-diameter imaging lens M at an infinite object point has a focal length of 25.02 mm, an F number of 0.93, and a half angle of view of 23.82 °. Further, data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”, “0.15”) is shown.

As shown in FIG. 3, the large-diameter imaging lens M of the ninth embodiment also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.53 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.71 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.45 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.32 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.56 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.37 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.42 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.108 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.29 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.12 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 2.74 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, in FIGS. 21A, 21B, and 21C, the imaging magnification in the large-diameter imaging optical system C of Example 9 is set as parameters (“0.00”, “0.10”, “0.15”. ”) Is shown in the longitudinal aberration diagram. As shown in FIGS. 21 (a), 21 (b), and 21 (c), good aberration is obtained regardless of the shooting magnifications of "0.00", "0.10", and "0.15". That is, it can be confirmed that the imaging performance can be obtained.

Next, the large-diameter imaging lens M according to the tenth embodiment will be described with reference to FIGS. 3, 20, 22, and 10.

FIG. 20 shows the configuration of the large-diameter imaging lens M according to the tenth embodiment. In Example 10, as the basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between Example 10 and Example 9 is that the configurations of the first lens group 101, the second A lens group 102A, the third lens group 103, and the focusing adjustment function unit 301 are changed, and other basics. The configuration is the same as that of the ninth embodiment. Therefore, in FIG. 20, except for the surface numbers (i = 1, 2, 3 ... 28, 29), the same parts as those in FIG. 19 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted.

The first lens group 101 includes a single lens L11 in which both sides of the lens are curved toward the object OBJ side, and the lens surface (first lens surface (i = 1)) on the most object OBJ side and the most image IMG side. The lens surface (i = 8) is configured to satisfy all of the four lenses L11, L12, L13, and L14 curved toward the object OBJ side. In the example, three negative meniscus lenses L11, L12, L13 curved from the object OBJ side to the object OBJ side, a positive meniscus lens L14 curved toward the image IMG side, and a positive meniscus lens L15 curved toward the object OBJ side. Equipped with a total of five single lenses. Therefore, similarly to the ninth embodiment, the first embodiment 101 is composed of six or less lenses, and the difference between the number of positive lenses and the number of negative lenses is set to one or less.

Further, the second A lens group 102A is configured by using biconvex lenses (positive lenses) L21 and L22 from the object OBJ side and a negative meniscus lens L23 curved toward the object OBJ side. In the case of Example 10, the biconvex lens (normal lens) L26 in the second B lens group 102B has a spherical shape, and unlike other examples, it is not formed into an aspherical shape.

Further, the third lens group 103 has a bonded lens Jb, an air space S6, and an aspherical shape formed by joining a positive meniscus lens L31 curved toward the object OBJ side and a negative meniscus lens L32 curved toward the object OBJ side from the object OBJ side. It is composed of a total of three lenses in which the biconvex lens (positive lens) L33 is sequentially arranged.

On the other hand, as shown in FIG. 20, the focusing adjustment function unit 301 fixes (immobilizes) the first lens group 101 with respect to the image position, and focuses the air space S1 on the object OBJ side of the second lens group 102 with a variable focus interval. It is configured to be changed as Di. That is, the first lens group 101 is a fixed lens group Gc, the second lens group 102 and the third lens group 103 are integrated as a movable lens group Gm1, and the lens group 101 is configured to move toward the object OBJ on the optical axis Dc. It is provided with a fixed lens group Gc that fixes the lens surface (i = 1) on the most object OBJ side of the entire system with respect to the image position, and one moving lens group Gm1 that moves during focusing. It is a group movement rear focus system configured to satisfy 8].

In this way, when configuring the focusing adjustment function unit 301, the fixed lens group Gc that fixes the lens surface (i = 1) on the most object OBJ side of the entire system with respect to the image position, and at least one that moves during focusing. By providing the moving lens group Gm1 ... Since the adjustment function unit 301 can be constructed, it is possible to contribute to further weight reduction and miniaturization of the large-diameter imaging lens M.

Table 10 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 10. The large-diameter imaging lens M at an infinite object point has a focal length of 17.52 mm, an F number of 0.93, and a half angle of view of 32.88 °. Further, data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”, “0.15”) is shown.

As shown in FIG. 3, the large-diameter imaging lens M of Example 10 also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.85 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 1.30 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.38 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.49 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.64 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.32 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.18 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.111 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.14 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.61 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 2.48 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, in FIGS. 22 (a), 22 (b), and (c), the imaging magnification in the large-diameter imaging optical system C of Example 10 is set as parameters (“0.00”, “0.10”, “0.15”. ”) Is shown in the longitudinal aberration diagram. As shown in FIGS. 22 (a), 22 (b), and (c), good aberration is obtained regardless of the shooting magnifications of "0.00", "0.10", and "0.15". That is, it can be confirmed that the imaging performance can be obtained.

Next, the large-diameter imaging lens M according to the eleventh embodiment will be described with reference to FIGS. 3, 23, 25 and 11.

FIG. 23 shows the configuration of the large-diameter imaging lens M according to the eleventh embodiment. In Example 11, as a basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between Example 11 and Example 10 is that the configurations of the first lens group 101, the second A lens group 102A, and the third lens group 103 are changed, and the other basic configurations are implemented. Same as Example 10. Therefore, in FIG. 23, except for the surface numbers (i = 1,2,3 ... 24,25), the same parts as those in FIG. 20 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted.

The first lens group 101 is composed of three lenses L11, L12, and L13 as a whole including one lens L13 in which both sides of the lens are curved toward the object OBJ side. In the example, a total of three single lenses are provided, from the object OBJ side, a biconcave lens (negative lens) L11, a biconvex lens (positive lens) L12, and a positive meniscus lens L13 curved toward the object OBJ side. Further, the second A lens group 102A is configured by using two positive meniscus lenses L21 and L22 curved from the object OBJ side to the object OBJ side and a negative meniscus lens L23 curved toward the object OBJ side. Further, the third lens group 103 is curved from the object OBJ side to the junction lens Jb in which the biconvex lens (positive lens) L31 and the biconcave lens (negative lens) L32 are joined, the air space S6, and the object OBJ side, and the image IMG. It is composed of a total of three lenses in which a positive meniscus lens L33 whose lens surface on the side is close to a flat surface is sequentially arranged.

In the case of Example 11, the positive meniscus lens L33 in the third lens group 103 has a spherical shape, and unlike other examples, it is not formed into an aspherical shape. Further, in the eleventh embodiment, as in the tenth embodiment, the biconvex lens (normal lens) L26 of the second B lens group 102B has a spherical shape. Therefore, in the case of Example 11, there is no lens formed in an aspherical shape.

Further, the focusing adjustment function unit 301 has a fixed lens group Gc that fixes (immobilizes) the first lens group 101 with respect to the image position, and a moving lens group that integrally moves the second lens group 102 and the third lens group 103. Although Gm1 is used and the fixed lens group and the moving lens group are different, the air space S1 on the object OBJ side of the second lens group 102 is changed as the focus variable interval Di as in the tenth embodiment. It becomes a group movement rear focus system.

Table 11 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 11. The large-diameter imaging lens M at an infinite object point has a focal length of 58.02 mm, an F number of 0.93, and a half angle of view of 10.82 °. Further, data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”, “0.15”) is shown.

As shown in FIG. 3, the large-diameter imaging lens M of the eleventh embodiment also has the conditional expression [1] “0.6 <(TL2 / EPD) = 0.73 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.76 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.50 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.38 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.65 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.21 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.26 <-0.10 ", conditional expression [8] ] "0.009 <{│ (FP2-FP1) / FP1│} = 0.403 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.79 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.26 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 1.17 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, in FIGS. 25 (a), 25 (b), and 25 (c), the imaging magnification in the large-diameter imaging optical system C of Example 11 is set as parameters (“0.00”, “0.10”, “0.15”. ”) Is shown in the longitudinal aberration diagram. As shown in FIGS. 25 (a), 25 (b), and (c), good aberration is obtained regardless of the shooting magnifications of "0.00", "0.10", and "0.15". That is, it can be confirmed that the imaging performance can be obtained.

Next, the large-diameter imaging lens M according to the twelfth embodiment will be described with reference to FIGS. 3, 24, 26 and 12.

FIG. 24 shows the configuration of the large-diameter imaging lens M according to the twelfth embodiment. In Example 12, as the basic configuration, as described in the above-described embodiment, the first lens group 101, the second lens group 102 including the aperture stop STO, and the third lens group 103 are sequentially arranged from the object OBJ side. An imaging optical system C is provided.

The main difference between the 12th embodiment and the 11th embodiment is that the configurations of the first lens group 101, the third lens group 103, and the focusing adjustment function unit 301 are changed, and the other basic configurations are implemented. Same as Example 11. Therefore, in FIG. 24, except for the surface numbers (i = 1, 2, 3 ... 20, 21), the same parts as those in FIG. 23 are designated by the same reference numerals to clarify their configurations and their detailed description. Is omitted.

The first lens group 101 includes a single single lens L11 whose both sides are curved toward the object OBJ, specifically, a single positive meniscus lens L11 which is curved toward the object OBJ and is formed into an aspherical shape. It has the configuration used. Further, the third lens group 103 has a bonded lens Jb, an air space S6, and an aspherical shape formed by joining a positive meniscus lens L31 curved toward the object OBJ side and a negative meniscus lens L32 curved toward the object OBJ side from the object OBJ side. It is composed of a total of three lenses in which a positive meniscus lens L33, which is curved toward the object OBJ side and whose lens surface on the image IMG side is close to a flat surface, is sequentially arranged.

On the other hand, as shown in FIG. 24, the focusing adjustment function unit 301 fixes (immobilizes) the first lens group 101, the second A lens group 102A, and the third lens group 103 with respect to the image position, and sets the aperture aperture STO. The air space S3 and the air space S5 on the image IMG side of the second lens group 102 are changed as the focus variable interval Di, respectively.

That is, the first lens group 101 and the second A lens group 102A are integrated into a fixed lens group Gc located on the object OBJ side, and the second B lens group 102B is a fixed lens group Gc located on the image IMG side. The 2B lens group 102B is set as one moving lens group Gm1 and is configured to move on the optical axis Dc toward the object OBJ side. Although the fixed lens group and the moving lens group are different, the above-described Example 5 It becomes a group movement rear focus method similar to the above.

Table 12 shows the lens data of the entire lens system in the large-diameter imaging lens M of Example 12. The large-diameter image pickup lens M at the time of an infinite object has a focal length of 42.30 mm, an F number of 0.93, and a half angle of view of 14.74 °. Further, the data (variable focus interval) in which the shooting magnification is used as a parameter (“0.00”, “0.05”, “0.10”) is shown.

As shown in FIG. 3, the large-diameter imaging lens M of Example 12 also has the conditional expression [1] “0.6 <(TL2 / EPD) = 1.09 <2.1” and the conditional expression [2] “0”. .1 <(TL1 / TL2) = 0.14 <1.5 ", conditional expression [3]" 0.3 <(TL2 / TLL) = 0.71 <0.8 ", conditional expression [4]" 0 " .08 <(TL1 / TLL) = 0.10 <0.60 ", conditional expression [5]" 0.3 <(TLF / TLL) = 0.36 <0.7 ", conditional expression [6]" 0 " .1 <(RS1 / TLL) = 0.28 <0.5 ", conditional expression [7]" -0.55 <(RS2 / TLL) = -0.28 <-0.10 ", conditional expression [8] ] "0.009 << {│ (FP2-FP1) / FP1│} = 0.236 <0.5", conditional expression [9] "0.1 <(AFL / FL2) = 0.71 ≦ 1.0" , Conditional expression [10] "0.0 <(│IM2 / OB2│) = 0.55 ≤ 1.0", Conditional expression [11] "0.45 <(FLM / AFL) = 1.40 <4" Each conditional expression [1]-[11] of ".9" is satisfied.

On the other hand, FIGS. 26A and 26B show longitudinal aberration diagrams in which the imaging magnification in the large-diameter imaging optical system C of Example 12 is set as a parameter (“0.00”, “0.10”). As shown in FIGS. 26 (a) and 26 (b), it was confirmed that good aberration, that is, imaging performance can be obtained regardless of whether the photographing magnification is "0.00" or "0.10". can.

Although preferred embodiments including Examples 1-12 have been described in detail above, the present invention is not limited to such embodiments, and the present invention is not limited to such embodiments, and the detailed configuration, shape, material, quantity, numerical value, etc. It may be arbitrarily changed, added or deleted without departing from the gist of the present invention.

For example, it is desirable that all of the conditional expressions [2]-[11] are satisfied, but it does not exclude cases where only one or two or more are satisfied or none of them are satisfied. Further, various forms have been exemplified as a specific focusing method of the focusing adjustment function unit 301, but the point is that the air space S1 on the object OBJ side of the second lens group 102 and the image of the image IMG side of the second lens group 102. Various other forms can be applied as long as the distance between at least one air space of the space S5 and the air space S3 of the aperture stop STO can be changed during focusing when the object point moves from infinity to a short distance. Is. On the other hand, as the imaging optical system C, the five lenses L24 ... Arranged on the image IMG side with respect to the aperture stop STO, and the lens surface (i = 10 ...) in which the object OBJ side has a concave shape from the object OBJ side. An example is provided of a configuration in which a partially symmetric lens group Gs including a negative lens L24, three positive lenses L25, L26, L31, and a negative lens L32 having a lens surface (i = 17 ...) With a concave image IMG side is provided. However, it is not an essential component. In this case, as the configuration of the partially symmetrical lens group Gs, an example is shown in which at least one positive lens L25 and L26 having a convex shape on both sides and at least one negative lens L24 having a concave shape on both sides are included. It does not exclude other configurations. Further, as a preferable configuration example of the imaging optical system C, it is composed of two or less lenses L11 having negative power, and all lens surfaces (i = 3, 5,) in air contact of the lenses in the second A lens group 102A. 7, 8 ...), and the first lens group in which all the air-contacting lens surfaces (i = 15, 18 ...) located on the object OBJ side of each lens in the third lens group 103 are curved and formed on the object OBJ side, respectively. The configuration of the first lens group 101, which is composed of six or less lenses and sets the difference between the number of positive lenses and the number of negative lenses within one, and the absolute partial dispersion value dPgF. The configuration of the second lens group 102 including the negative lens L23 using the low refractive index low dispersion glass material having a value of 0.02 or more, and the lens (L33) located closest to the image IMG side of the third lens group 103. It is desirable to adopt the configuration of the imaging optical system C in which at least the lens surface (i = 19 ...) On the image IMG side has an aspherical shape, but it can be replaced by another configuration and is an indispensable component. It's not a thing.

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

M: Large-diameter imaging lens, C: Imaging optical system, OBJ: Object, STO: Aperture aperture, IMG: Image, 101: First lens group, 102: Second lens group, 102A: Second A lens group, 102B: First 2B lens group, 103: 3rd lens group, L11: lens, L12 ...: lens, L21 ...: positive lens, L22 ...: positive lens, L23 ...: negative lens, L24 ...: negative lens, L25 ...: positive lens, L26 ...: Positive lens, L31 ...: Positive lens, L32 ...: Negative lens, L33 ...: Positive lens, S1: Air space, S2: Air space, S3: Air space, S4: Air space, S5: Air space, S6 : Air space, (i = 1): First lens surface, (i = 3 ...): Second lens surface, La: Air lens, Di: Focus variable interval, 301: Focusing adjustment function unit, Gs: Partially symmetric lens Group, Gc: Fixed lens group, Gm1 ...: Moving lens group, TL1: Optical axis length, TL2: Optical axis length, TLL: Optical axis length, TLF: Optical axis length, AFL: Focus distance of all systems, FLM: Synthesis Optical axis distance, FNO: F number, FP1: Distance, FP2: Distance, RS1: Radius of curvature, RS2: Radius of curvature, OB2: Distance, IM2: Distance, dPgF: Abnormal partial dispersion value

Claims (13)

In a large-diameter imaging lens equipped with an imaging optical system in which a first lens group, a second lens group including an aperture aperture, and a third lens group are sequentially arranged from the object side, one lens with both lens surfaces curved toward the object side. The first lens group having a configuration including, or a configuration consisting of a plurality of lenses in which the lens surface on the most object side (first lens surface) and the lens surface on the most image side are curved toward the object side, and the aperture. Located on the object side of the aperture, from the object side, the second A lens group in which two positive lenses, air space, and negative lens are arranged in sequence, and on the image side of the aperture aperture, from the object side, the negative lens, A second lens group having a second B lens group in which two positive lenses are sequentially arranged, and a second lens group having a biconvex air lens formed by a pair of lens surfaces facing the aperture aperture, and an object from the object side. A third lens group in which a positive lens having a convex lens surface on the side, a negative lens having a concave lens surface on the image side, an air space, and a positive lens having a convex lens surface on the object side are sequentially arranged, and the second lens. The distance between at least one air space (hereinafter, variable focus spacing) of the air space on the object side of the lens group, the air space on the image side of the second lens group, and the air space of the aperture aperture is set from infinity. It is equipped with a focusing adjustment function that changes during focusing that moves to a short distance, and is located from the lens surface (second lens surface) on the most object side of the second lens group to the most image side of the second lens group at the time of an infinite object point. When the optical axis length of the lens surface is TL2, the focal distance of the entire system is AFL, the F number is FNO, and AFL / FNO is FPD, the imaging optical system C satisfying the following conditional expression [1] is provided. Large-diameter imaging lens.
[1] 0.6 <(TL2 / EPD) <2.1 The imaging optical system C sets the length (optical axis length) of the optical axis from the first lens surface to the second lens surface at the time of an infinite object point to TL1, and is the most from the second lens surface to the second lens group. The optical axis length of the lens surface on the image side is TL2, the optical axis length from the first lens surface to the fifth lens surface is TLL, the optical axis length from the first lens surface to the aperture aperture is TLF, and the aperture aperture is the aperture aperture. When the radius of curvature of the lens surface on the object side facing the lens surface is RS1 and the radius of curvature of the lens surface on the image side facing the aperture aperture is RS2, the following conditional equations [2]-[7] are satisfied. The large-diameter imaging lens according to claim 1.
[2] 0.1 <(TL1 / TL2) <1.5
[3] 0.3 <(TL2 / TLL) <0.8
[4] 0.08 <(TL1 / TLL) <0.60
[5] 0.3 <(TLF / TLL) <0.7
[6] 0.1 <(RS1 / TLL) <0.5
[7] -0.55 <(RS2 / TLL) <-0.10 The focusing adjustment function unit includes at least one moving lens group that moves during focusing, and is located on the image side of the moving lens group located on the object side with respect to the focus variable interval existing on the most object side at the time of an infinite object. The distance from the lens surface to the image position is from the lens surface on the image side of the moving lens group located on the object side with respect to the variable focus interval existing on the object side most at FP1 and the imaging magnification of 0.1 times. The large-diameter imaging lens according to claim 1, wherein the following conditional expression [8] is satisfied when the distance to the image position is FP2.
[8] 0.005 << {│ (FP2-FP1) / FP1│} <0.5 The focusing adjustment function unit includes a fixed lens group that fixes the lens surface on the most object side of the entire system with respect to the image position, and at least one moving lens group that moves during focusing, and is located on the most object side at the time of an infinite object. The distance from the lens surface on the image side to the image position in the fixed lens group located on the object side with respect to the existing variable focus interval is FP1, and the distance existing on the most object side when the imaging magnification is 0.1 times. The claim is characterized in that the following conditional expression [8] is satisfied when the distance from the lens surface on the image side to the image position in the moving lens group located on the object side with respect to the variable focus interval is FP2. The large-diameter imaging lens according to 1.
[8] 0.005 << {│ (FP2-FP1) / FP1│} <0.5 The focusing adjustment function unit includes two fixed lens groups that fix the most object-side lens surface and the most image-side lens surface of the entire system with respect to the image position, and one moving lens group or one lens that moves during focusing. The distance from the lens surface on the image side to the image position in the fixed lens group located on the object side with respect to the focus variable interval existing on the most object side at the time of an infinite object is FP1 and the imaging magnification. When the distance from the lens surface on the image side to the image position in the fixed lens group located on the object side with respect to the focus variable interval existing on the object side most at 0.1 times is FP2, the following conditions are satisfied. The large-diameter imaging lens according to claim 1, wherein the large-diameter imaging lens satisfies the formula [8].
[8] 0.005 << {│ (FP2-FP1) / FP1│} <0.5 The imaging optical system has five lenses arranged on the image side with respect to the aperture aperture, a negative lens having a lens surface having a concave shape on the object side, three positive lenses, and a concave on the image side from the object side. It is composed of a partially symmetric lens group consisting of a negative lens having a lens surface having a shape, and the partially symmetric lens group includes at least one positive lens having a convex shape on both sides and at least one lens having a concave shape on both sides. The large-diameter imaging lens according to claim 1, wherein the negative lens of the above is included. 6. The focusing adjustment function unit is characterized in that the air space located on one side or both sides of a positive lens whose both sides are air contact surfaces in the partially symmetrical lens group functions as the focus variable interval. Large-diameter imaging lens. The first aspect of the present invention, wherein the imaging optical system satisfies the following conditional expression [9] as the power distribution when the focal length of the entire system is AFL and the focal length of the second lens group is FL2. Large-diameter imaging lens.
[9] 0.1 <(AFL / FL2) ≤ 1.0 In the imaging optical system, the distance of the lens surface on the object side of the second lens group from the image point of the first lens group of an infinite object point is OB2, and the distance of the second lens group when this OB2 is the object distance. When the distance of the image position from the lens surface on the image side is IM2 and the combined focal distance between the first lens group and the second lens group is FLM, the conjugate relationship of the second lens group is determined by the following conditional expression [10. ] And [11], the large-diameter imaging lens according to claim 1 or 8.
[10] 0.0 <(│IM2 / OB2│) ≤ 0.8
[11] 0.45 <(FLM / AFL) <4.9 In the imaging optical system, the first lens group is composed of two or less lenses having negative power, all lens surfaces in air contact of the lenses in the second A lens group, and the third lens group. The large-diameter imaging lens according to claim 1, wherein all the air-contacting lens surfaces located on the object side of each lens are curved toward the object side. The imaging optical system according to claim 1, wherein the first lens group is composed of six or less lenses, and the difference between the number of positive lenses and the number of negative lenses is set to one or less. Large-diameter imaging lens. The imaging optical system is characterized in that the second lens group includes a negative 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. The large-diameter imaging lens according to 1. The large-diameter imaging lens according to claim 1, wherein the imaging optical system forms at least the lens surface on the image side of the lens located on the image side of the third lens group in an aspherical shape.

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