JP7020674B2 - Large aperture lens - Google Patents

Description

The present invention relates to a large-diameter lens particularly suitable for photographing devices such as digital cameras, silver salt cameras and video cameras, in which various aberrations such as spherical aberration and axial chromatic aberration are strongly corrected.

In recent years, with the increase in the number of pixels of photographing devices such as digital cameras, there is a demand for an optical system having high optical performance in which various aberrations are sufficiently corrected.

In particular, there is an increasing demand for high-resolution images that can make use of the blurring before and after the in-focus portion, and in order to obtain such images, the performance of large-diameter lenses with a small F value is being improved.

In general, the smaller the F value of the optical system and the brighter it is, the more various aberrations occur and the lower the optical performance. In particular, when an attempt is made to obtain a bright optical system in the focal range on the telephoto side of the standard range, the deterioration of optical performance due to axial chromatic aberration becomes remarkable.

In order to correct axial chromatic aberration, it is common to use an optical material with a low refractive index and low dispersion, such as fluorite, which has a large positive anomalous dispersibility, for a lens with a positive refractive power. It is difficult to sufficiently suppress chromatic aberration in a small bright optical system.

In order to realize a bright optical system with a small F value, it is necessary to increase the refractive power of each surface and bend the light beam more strongly to form an image. In an optical material having a large low refractive index and low dispersion, it is necessary to further change the curvature in order to obtain the required refractive power. Then, various aberrations such as spherical aberration, coma aberration, and astigmatism worsen due to the influence of increasing the refractive power of the lens surface, and it becomes difficult to correct them.

Patent No. 3254239 Japanese Patent Application Laid-Open No. 2016-21246 Patent No. 5395700

The large-diameter lens described in Patent Document 1 performs floating focus to suppress performance fluctuations during focusing up to a short-distance object having a minimum shooting magnification of about -1/7 times. However, since focusing is performed while the entire lens system is extended along the optical axis, there is a problem that it is difficult to speed up focusing because the weight driven by autofocus increases.

The large-diameter lens described in Patent Document 2 has a three-group configuration, the first group and the third group are fixed, and the inner focus of the two groups is adopted to realize high-speed autofocus. However, there is a problem that the correction of chromatic aberration is not sufficient and the F value is as dark as F1.8.

The large-diameter lens described in Patent Document 3 adopts a rear focus method, and performs high-speed autofocus and good correction of various aberrations. However, since the axial chromatic aberration is not sufficiently corrected, there is a problem that coloring occurs in the peripheral portion of the blur when a high-contrast subject is photographed.

The present invention has been made in view of such a situation, and in addition to strongly correcting various aberrations, especially chromatic aberration, to obtain good image quality over the entire screen, the coloring generated at the peripheral portion of the blurred image is reduced. It is an object of the present invention to provide a large-diameter optical system having high optical performance, achieving miniaturization of a product without omitting an autofocus mechanism, and having a size suitable for an interchangeable lens.

The first invention for solving the above-mentioned problems comprises a first lens group G1 having a positive refractive force and a second lens group G2 having a positive refractive force in order from the object side, and the first lens group. G1 is composed of one or more convex lenses and one concave lens or one junction concave lens component from the object side, and is composed of a first a lens group G1a having a positive refractive force as a whole and a junction concave lens component having a negative refractive force. The first b lens group G1b is composed of a first c lens group G1c having a positive refractive force, and the second lens group G2 is composed of one or more convex lenses and a junction concave lens component having a negative refractive force. It is composed of a 2a lens group G2a, an aperture aperture S, and a second b lens group G2b. When focusing from infinity to a short-range object, the first lens group G1 is fixed to the image plane, and the second lens group is fixed. A large-diameter lens characterized by moving G2 from the image plane side to the object side along the optical axis and satisfying the conditional expression for the following.
(1) -3.8 <ΦG1b / ΦG1 <-0.5
(2) 0.18 <ΦG1 / Φ <0.50
(3) 3.0 <ΦG2 / ΦG1 <7.5
(4) 0.8 <νdL1bp1 × ΔPgFL1bp1
ΦG1: Refractive force of the first lens group G1 ΦG1b: Refractive force of the first b lens group G1b ΦG2: Refractive force of the second lens group G2 Φ: Refractive force of the entire system at infinity νdL1bp1: First b lens group G1b Abbe number ΔPgFL1bp1: of the convex lens constituting the first b lens group G1b of the lens having the highest refractive index Abnormal dispersibility of the lens having the highest refractive index among the convex lenses constituting

The second invention is the large-diameter lens according to the first invention, which satisfies the following conditional expression.
(5) 0.015 <ΔPgFG1Pave
(6) ΔPgFG1Nave <-0.0020
ΔPgFG1Nave: Mean value of the anomalous dispersibility of the concave lens of the first lens group G1 ΔPgFG1Pave: Mean value of the anomalous dispersibility of the convex lens of the first lens group G1

The third invention is the large-diameter lens according to the first invention or the second invention, which is characterized by satisfying the following conditional expression.
(7) 0.010 <ΔPgFG2aPave
ΔPgFG2aPave: Mean value of the anomalous dispersibility of the convex lens of the second a lens group G2a

The fourth invention is the large-diameter lens according to any one of the first invention to the third invention, which is characterized by satisfying the following conditional expression.
(8) 1.85 <NdL2ap1
NdL2ap1: Refractive index of the convex lens located closest to the object among the lenses constituting the second lens group G2.

The fifth invention is the large-diameter lens according to any one of the first invention to the fourth invention, which is characterized by satisfying the following conditional expression.
(9) 0.020 <ΔPgFL2ap1
ΔPgFL2ap1: Abnormal dispersibility of the convex lens located closest to the object among the lenses constituting the second lens group G2.

A sixth invention is the large-diameter lens according to any one of the first to fifth inventions, wherein the second lens group G2 has at least one aspherical lens.

By satisfying the above conditions, the present invention strongly corrects various aberrations, especially chromatic aberration, and obtains good image quality over the entire screen, and also achieves high optical performance in which coloring generated at the peripheral edge of a blurred image is reduced. It is possible to achieve miniaturization of the product without omitting the autofocus mechanism, and to provide an optical system having a large diameter suitable for an interchangeable lens.

It is a lens block diagram at the time of infinity focusing which concerns on Example 1 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 1 of this invention. FIG. 3 is a longitudinal aberration diagram at a shooting distance of 999 mm according to the first embodiment of the present invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 1 of this invention. FIG. 3 is a lateral aberration diagram at a shooting distance of 999 mm according to the first embodiment of the present invention. It is a lens block diagram at the time of infinity focusing which concerns on Example 2 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 2 of this invention. FIG. 3 is a longitudinal aberration diagram at a shooting distance of 995 mm according to the second embodiment of the present invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 2 of this invention. FIG. 3 is a lateral aberration diagram at a shooting distance of 995 mm according to the second embodiment of the present invention. It is a lens block diagram at the time of infinity focusing which concerns on Example 3 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 3 of this invention. FIG. 3 is a longitudinal aberration diagram at a shooting distance of 994 mm according to the third embodiment of the present invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 3 of this invention. FIG. 3 is a lateral aberration diagram at a shooting distance of 994 mm according to the third embodiment of the present invention. It is a lens block diagram at the time of infinity focusing which concerns on Example 4 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 4 of this invention. FIG. 3 is a longitudinal aberration diagram at a shooting distance of 997 mm according to the fourth embodiment of the present invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 4 of this invention. It is a lateral aberration diagram at a shooting distance 997 mm which concerns on Example 4 of this invention. It is a lens block diagram at the time of infinity focusing which concerns on Example 5 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 5 of this invention. FIG. 3 is a longitudinal aberration diagram at a shooting distance of 995 mm according to the fifth embodiment of the present invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 5 of this invention. FIG. 5 is a lateral aberration diagram at a shooting distance of 995 mm according to the fifth embodiment of the present invention. It is a lens block diagram at the time of infinity focusing which concerns on Example 6 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 6 of this invention. It is a longitudinal aberration diagram at a shooting distance of 1001 mm according to the sixth embodiment of the present invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 6 of this invention. FIG. 3 is a lateral aberration diagram at a shooting distance of 1001 mm according to the sixth embodiment of the present invention. It is a lens block diagram at the time of infinity focusing which concerns on Example 7 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 7 of this invention. It is a longitudinal aberration diagram at a shooting distance of 999 mm according to the seventh embodiment of the present invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 7 of this invention. FIG. 3 is a lateral aberration diagram at a shooting distance of 999 mm according to the seventh embodiment of the present invention. It is a lens block diagram at the time of infinity focusing which concerns on Example 8 of this invention. It is a longitudinal aberration diagram at the time of infinity focusing which concerns on Example 8 of this invention. It is a longitudinal aberration diagram at a photographing distance of 1000 mm which concerns on Example 8 of this invention. It is a lateral aberration diagram at the time of infinity focusing which concerns on Example 8 of this invention. It is a lateral aberration diagram at a shooting distance of 1000 mm which concerns on Example 8 of this invention.

Hereinafter, a large-diameter lens according to an embodiment of the present invention will be described. The refractive indexes of the materials for the g-line (wavelength 435.84 nm), F-line (486.13 nm), d-line (587.56 nm), and C-line (656.27 nm) are Ng, NF, Nd, and NC, respectively. .. Then, the Abbe number νd, the partial dispersion ratio PgF, and the abnormal partial dispersion ΔPgF are determined.
νd = (Nd-1) / (NF-NC)
PgF = (Ng-NF) / (NF-NC)
ΔPgF = PgF-0.64833 + 0.00180 × νd
Expressed as.

The optical system of each embodiment is composed of a first lens group G1 having a positive refractive force and a second lens group G2 having a positive refractive force in order from the object side, and the first lens group G1 is 1 from the object side. A first a lens group G1a consisting of one or more convex lenses and one concave lens or one junction concave lens component having a positive refractive force as a whole, and a first b lens group G1b consisting of a junction lens component having a negative refractive force. The second lens group G1 is composed of a first c lens group G1c having a positive refractive force, and the second lens group G2 is composed of a second a lens group G2a composed of one or more convex lenses and a junction concave lens component having a negative refractive force, and an aperture aperture. It is composed of S and a second b lens group G2b. When focusing from infinity to a short-range object, the first lens group G1 is fixed to an image plane, and the second lens group G2 is imaged along an optical axis. It is characterized by moving from the surface side to the object side and satisfying the conditional expression for the following.
(1) -3.8 <ΦG1b / ΦG1 <-0.5
(2) 0.18 <ΦG1 / Φ <0.50
(3) 3.0 <ΦG2 / ΦG1 <7.5
(4) 0.8 <νdL1bp1 × ΔPgFL1bp1
ΦG1: Refractive force of the first lens group G1 ΦG1b: Refractive force of the first b lens group G1b ΦG2: Refractive force of the second lens group G2 Φ: Refractive force of the entire system at infinity νdL1bp1: First b lens group G1b Abbe number ΔPgFL1bp1: of the convex lens constituting the first b lens group G1b of the lens having the highest refractive index Abnormal dispersibility of the lens having the highest refractive index among the convex lenses constituting

In the lens configuration, when focusing to a short distance, the first lens group G1 having a relatively large lens diameter and weight is fixed to the image plane, and the second lens group G2 having a relatively small lens diameter and weight is illuminated. Since it moves along the axis, it is possible to speed up focusing and simplify the mechanism easily.

In order to correct chromatic aberration in a telescopic lens, it is common to use an optical material with low refractive index and low dispersion and large positive anomalous dispersibility, such as fluorite, for the convex lens. In the optical system frequently used for the convex lens, the Petzval sum is deteriorated, the curvature of field is increased, and the optical performance is deteriorated. Therefore, in the present invention, a subgroup having a negative refractive power is arranged, and an optical material having a low refractive index and a low dispersion and a large positive anomalous dispersibility is arranged in a convex lens in the subgroup to correct chromatic aberration and the Petzval sum. The correction of is compatible. The conditional expression (1) defines the refractive power of the subgroup. By satisfying the conditional equation (1), it is possible to correct the Petzval sum even if an optical material having a low refractive index and a low dispersion is used for the convex lens in the subgroup, and the chromatic aberration correction and the Petzval sum correction are compatible with each other. Contributes to improved performance.

When the negative refractive power of the first b lens group G1b becomes stronger beyond the lower limit of the conditional equation (1), it becomes necessary to increase the positive refractive power of the first c lens group in order to correct it, resulting in spherical aberration. , Astigmatism and other aberrations worsen.

If the negative refraction force of the first b lens group G1b becomes weaker than the upper limit of the conditional expression (1), it leads to deterioration of the Petzval sum of the whole system, and in order to correct it, the first b lens group is configured. It is necessary to select the optical material of the concave lens on the lower refractive index side and the optical material of the convex lens on the higher refractive index side. Since it cannot be done, it leads to deterioration of chromatic aberration.

Regarding the conditional expression (1), in order to make the above effect more reliable, the upper limit value is set to -0.6 and the lower limit value is set to -3.1 to make the above effect more reliable. can do.

The conditional equation (2) defines the ratio of the refractive power of the entire system at the time of infinity focusing to the refractive power of the first lens group G1 in order to achieve both miniaturization and high performance. Satisfying the conditional expression (2) contributes to achieving both miniaturization and high performance of the optical system.

When the lower limit of the conditional equation (2) is exceeded and the positive refractive power of the first lens group G1 becomes weaker than the refractive power of the entire system at infinity, the total length of the optical system increases, and the first Since the optical system of the lens group G1 becomes large, it becomes difficult to reduce the size and weight.

When the upper limit of the conditional expression (2) is exceeded and the positive refractive power of the first lens group G1 becomes stronger with respect to the refractive power of the entire system at infinity focusing, the F value of the first lens group itself becomes smaller. Therefore, it becomes difficult to correct the aberration of the first lens group. Further, in order to maintain the refractive power of the entire system, the imaging magnification of the second lens group must be increased, and the residual aberration of the first lens group is further increased. Therefore, it becomes difficult to correct various aberrations such as spherical aberration, astigmatism, and coma in the entire system.

Regarding the conditional expression (2), in order to make the above effect more reliable, the upper limit value is set to 0.35 and the lower limit value is set to 0.20 to make the above effect more certain. Can be done.

The conditional expression (3) defines the ratio of the refractive powers of the first lens group G1 and the second lens group G2 in order to achieve both miniaturization and high performance. Satisfying the conditional expression (3) contributes to achieving both miniaturization and high performance of the optical system.

If the positive refractive power of the second lens group G2 becomes weaker than the lower limit of the conditional expression (3), it becomes difficult to secure the back focus, and especially when applying this optical system for a single-lens reflex camera, it is quick. Interference with the return mirror cannot be prevented.

When the positive refractive power of the first lens group G1 becomes weaker than the upper limit of the conditional expression (3), the total length of the optical system is extended, and the optical system of the first lens group G1 is enlarged accordingly, so that the size is small. It becomes difficult to reduce the weight and weight.

Regarding the conditional expression (3), in order to make the above effect more reliable, the upper limit value is set to 6.8 and the lower limit value is set to 3.3 to make the above effect more certain. Can be done.

The conditional expression (4) defines the relationship between the Abbe number of the lens having the highest refractive index among the convex lenses constituting the first b lens group and the anomalous dispersibility in order to effectively correct the chromatic aberration. The larger this value is, the lower the dispersion and the larger the positive anomalous dispersibility of the optical material. Therefore, when used for a convex lens of a junction lens, it is effective for correcting chromatic aberration, particularly a secondary spectrum. Satisfying the conditional expression (4) contributes to higher performance of the optical system.

If the Abbe number of the lens having the highest refractive index among the convex lenses constituting the first b lens group exceeds the lower limit of the conditional expression (4) and the anomalous dispersibility becomes small, the correction effect of chromatic aberration becomes poor, and in particular, When an optical material having a negative anomalous dispersibility is used, it becomes difficult to correct the second-order spectrum and the optical performance deteriorates.

If the value of the conditional expression (4) is 1.2 or more, the effect is more certain.

Further, the large-diameter lens of the present invention is characterized by satisfying the following conditional expression.
(5) 0.015 <ΔPgFG1Pave
(6) ΔPgFG1Nave <-0.0020
ΔPgFG1Pave: Mean value of anomalous dispersibility of the convex lens of the first lens group G1 ΔPgFG1Nave: Mean value of the anomalous dispersibility of the concave lens of the first lens group G1

In a bright optical system having a small F-number on the telephoto side from the standard range, deterioration of optical performance due to axial chromatic aberration becomes a particular problem. Further, the correction of the primary chromatic aberration is not sufficient, and if the correction of the secondary spectrum is not sufficient, the edge of the blurred image may be colored or the edge of a high-brightness subject may have purple fringing. In order to correct the secondary spectrum, it is important to sufficiently correct the primary chromatic aberration and then appropriately select and arrange the optical material in consideration of the anomalous dispersibility of each.

The conditional expression (5) defines the average value of the anomalous dispersibility of the convex lenses constituting the first lens group G1. The convex lens can effectively correct the second-order spectrum by using an optical material having a large positive anomalous dispersibility. Satisfying the conditional expression (5) contributes to higher performance of optical performance.

If the lower limit of the conditional expression (5) is exceeded and the average value of the anomalous dispersibility of the convex lens of the first lens group G1 becomes smaller, it becomes difficult to correct the secondary spectrum and the optical performance deteriorates.

If the value of the conditional expression (5) is 0.02 or more, the effect is more certain.

As shown in the conditional equation (5), if an optical material having a large positive anomalous dispersibility is used for the convex lens, it is possible to correct the second-order spectrum. In the optical system, the correction of the second-order spectrum is insufficient by itself. If the secondary spectrum is corrected by relying on a convex lens using an optical material with a large positive anomalous dispersibility, the number of convex lenses must be increased, which not only increases the size of the optical system but also the Petzval sum of the entire system. It also leads to deterioration of the image plane, which makes it difficult to correct the curvature of field and leads to deterioration of optical performance.

Therefore, by using an optical material having a large negative anomalous dispersibility for the concave lens constituting the first lens group G1, effective correction of the second-order spectrum while minimizing the deterioration of the Petzval sum of the entire system. Is possible.

The conditional expression (6) defines the average value of the anomalous dispersibility of the concave lens of the first lens group G1. The concave lens can effectively correct the second-order spectrum by using an optical material having a large negative anomalous dispersibility. By satisfying the conditional expression (6), it contributes to high performance of optical performance.

If the upper limit of the conditional expression (6) is exceeded and the average value of the anomalous dispersibility of the concave lens of the first lens group G1 becomes large, it becomes difficult to correct the secondary spectrum and the optical performance deteriorates.

If the value of the conditional expression (6) is −0.0030 or less, the effect is more certain.

Further, the large-diameter lens of the present invention is characterized by satisfying the following conditional expression.
(7) 0.010 <ΔPgFG2aPave
ΔPgFG2aPave: Mean value of the anomalous dispersibility of the convex lens of the second a lens group G2a

As described above, by selecting an optical material in consideration of anomalous dispersibility for each lens of the first lens group G1, it is possible to correct axial chromatic aberration, particularly a secondary spectrum. However, in a telephoto optical system as shown in the present invention, which has a particularly small F-number and is bright, the correction of the second-order spectrum is insufficient. It is necessary to select an optical material in consideration of anomalous dispersibility for each lens of the second a lens group G2a that moves when focusing from infinity to a short distance. This is specified by the conditional expression (7).

The conditional expression (7) defines the average value of the anomalous dispersibility of the convex lens of the second a lens group G2a. The secondary spectrum can be effectively corrected by using an optical material having a large positive anomalous dispersibility for the convex lens of the second a lens group G2a. By satisfying the conditional expression (7), it contributes to the correction of axial chromatic aberration.

If the lower limit of the conditional expression (7) is exceeded and the anomalous dispersibility of the convex lens of the second a lens group G2a becomes small, it becomes difficult to sufficiently correct the secondary spectrum.

If the value of the conditional expression (7) is 0.014 or more, the effect is more certain.

Further, the large-diameter lens of the present invention is characterized by satisfying the following conditional expression.
(8) 1.85 <NdL2ap1
NdL2ap1: Refractive index of the convex lens located closest to the object among the lenses constituting the second lens group G2.

The conditional expression (8) defines the refractive index of the convex lens located closest to the object among the lenses constituting the second lens group G2. The second lens group G2 is a focus group that moves from infinity to a short-distance object when focusing, and it is essential to reduce the size of the focus group in order to realize autofocus and automatic aperture with a practical lens barrel size. be. In particular, the diameter of the lens on the image side of the aperture is limited by the camera mount, so further miniaturization is required. By using a high-refractive index material for the convex lens located closest to the object among the lenses constituting the second lens group G2, it is possible to correct astigmatism and curvature of field and to reduce the size of the focus group at the same time. By satisfying the conditional expression (8), it contributes to the miniaturization of the product while satisfactorily correcting the aberration.

When the refractive index of the convex lens located closest to the object among the lenses constituting the second lens group G2 becomes low beyond the lower limit of the conditional expression (8), the Petzval sum deteriorates, astigmatism, and curvature of field. Is difficult to correct.

If the value of the conditional expression (8) is 1.90 or more, the effect is more certain.

Further, the large-diameter lens of the present invention is characterized by satisfying the following conditional expression.
(9) 0.020 <ΔPgFL2ap1
ΔPgFL2ap1: Abnormal dispersibility of the convex lens located closest to the object among the lenses constituting the second lens group G2.

Conditional expression (9) defines the anomalous dispersibility of the convex lens located closest to the object among the lenses constituting the second lens group G2. For the convex lens located closest to the object among the lenses constituting the second lens group G2 in the conditional equation (8), an optical material having a high refraction coefficient is effective for facilitating correction of non-point aberration and curvature of field. On the other hand, among the lenses constituting the second lens group G2, the convex lens located on the object side is an optical material having a refractive index of about 1.90 or more, but the positive anomalous dispersibility is relatively small. Exists, and when such optical materials are used, the correction of the secondary spectrum is inadequate. An optical material having a large positive anomalous dispersibility is suitable for the secondary spectrum to be sufficiently corrected. The conditional expression (9) defines this. By satisfying the conditional expression (9), it contributes to the correction of axial chromatic aberration.

If the lower limit of the conditional expression (9) is exceeded and the anomalous dispersibility of the convex lens located closest to the object among the lenses constituting the second lens group G2 becomes small, it becomes difficult to sufficiently correct the secondary spectrum.

If the value of the conditional expression (9) is 0.025 or more, the effect is more certain.

In order to improve the optical performance of the large-diameter lens of the present invention, it is desirable to use at least one aspherical lens in the second lens group G2.

It is desirable to arrange this aspherical lens for the purpose of correcting spherical aberration. By adopting an aspherical lens, it is possible to reduce the burden of aberration correction when correcting spherical aberration generated by a positive refractive power with a negative refractive power.

As a result, the negative refractive power for correcting the spherical aberration generated by the positive refractive power can be weakened, and the curvature of the concave surface on the most object side of the second b lens group G2b can be relaxed. It is possible to suppress the occurrence of sagittal coma flare.

It is even better to arrange this aspherical lens on the image side of the aperture. Since the height of the axial ray is higher on the object side than the aperture, a large-diameter aspherical lens is required, which is not preferable because it increases the processing cost. If this aspherical lens is arranged on the image side of the diaphragm, the diameter of the lens can be reduced, which is advantageous in terms of workability.

In addition, since this aspherical surface corrects spherical aberration generated by a positive refractive power, it is either an aspherical lens that weakens the positive refractive power as it moves away from the optical axis, or a non-spherical surface that strengthens the negative refractive power as it moves away from the optical axis. It is preferably spherical.

Next, the lens configuration of the embodiment according to the imaging optical system of the present invention will be described.
In the following description, the lens configuration will be described in order from the object side to the image side.

In [plane data], the surface number is the number of the lens surface or aperture stop counted from the object side, r is the radius of curvature of each lens surface, d is the distance between each lens surface, and nd is the d line (wavelength 587.56 nm). The refractive index, vd is the Abbe number with respect to the d line, and PgF is the partial dispersion ratio.

* (Asterisk) attached to the surface number indicates that the lens surface shape is aspherical. Further, BF represents back focus.

The (aperture) attached to the surface number indicates that the aperture diaphragm is located at that position. ∞ (infinity) is entered for the radius of curvature for a plane or aperture stop.

In [Aspherical surface data], the value of each coefficient that gives the aspherical surface shape of the lens surface marked with * in [Surface data] is shown. The shape of the aspherical surface is expressed by the following formula. In the following equation, the displacement from the optical axis in the direction orthogonal to the optical axis is y, the displacement from the intersection of the aspherical surface and the optical axis in the optical axis direction (sag amount) is z, and the radius of curvature of the reference spherical surface is r. The cornic coefficient is represented by K. Further, the 4th, 6th, and 8th order aspherical coefficients are represented by A4, A6, and A8, respectively.

[Various data] shows the values such as the focal length at the time of focusing at infinity.

[Variable interval data] shows the variable interval and the BF value in each shooting distance state.

[Lens group data] shows the lens surface number on the most object side constituting each lens group and the combined focal length of the entire lens group.

In all the following specification values, the focal length f, the radius of curvature r, the lens surface spacing d, and other length units are described in millimeters (mm) unless otherwise specified, but optics. The system is not limited to this because the same optical performance can be obtained in the proportional expansion and the proportional reduction.

FIG. 1 is a lens configuration diagram of the large-diameter lens according to the first embodiment at infinity focusing.

The large-diameter lens of FIG. 1 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of three regular meniscus lenses having a convex surface facing the object side and a concave lens having a convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a concave surface facing the object side and having a negative refractive power.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, the specification values of the large-diameter lens according to the first embodiment are shown below.
Numerical Example 1
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 115.7436 5.4407 1.65844 50.85 0.5575
2 180.1804 0.3000
3 74.5000 6.0183 1.43700 95.10 0.5334
4 100.3863 0.3000
5 63.4310 12.3856 1.43700 95.10 0.5334
6 249.4535 2.9002
7 216.1665 2.2000 1.61310 44.36 0.5604
8 49.5173 15.8891
9 -248.4001 4.6130 1.43700 95.10 0.5334
10 -95.8446 1.8000 1.61340 44.27 0.5633
11 -500.0000 1.0000
12 67.9843 10.4346 1.83481 42.72 0.5648
13 -211.9683 1.8000 1.61340 44.27 0.5633
14 67.2983 (d14)
15 53.7906 4.5962 1.92286 20.88 0.6388
16 94.6373 0.3000
17 46.5373 4.1734 1.61997 63.88 0.5425
18 66.7867 0.3000
19 40.7185 6.9541 1.59282 68.63 0.5441
20 275.0000 1.3000 1.85478 24.80 0.6122
21 28.4253 7.5444
(Aperture) ∞ 5.4041
23 -50.8188 0.9000 1.65412 39.68 0.5737
24 29.5160 7.5115 1.87071 40.73 0.5682
25 -196.5287 2.2670
26 -76.2095 3.5767 1.91082 35.25 0.5821
27 -35.1809 0.9000 1.64769 33.84 0.5923
28 124.7179 0.3000
29 * 68.8532 4.9326 1.84915 40.00 0.5694
30 * -92.2688 (d30)
31 ∞ 1.4500 1.52301 58.59 0.5449
32 ∞ BF


[Aspherical data]
29 faces 30 faces
K 0 0
A4 -1.27386E-06 1.98113E-06
A6 -1.15209E-10 1.20129E-10
A8 0 1.65076E-12

[Various data]
INF
Focal length 101.85
F number 1.46
Full angle of view 2ω 23.85
Image height Y 21.63
Lens total length 171.92

[Variable interval data]
Shooting distance INF 999
d0 ∞ 826.8724
d14 15.8705 3.0000
d30 37.5626 50.4932
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 334.47
G2 15 90.25
G1a 1 1015.80
G1b 9 -421.69
G1c 12 203.76
G2a 15 355.09
G2b 23 83.54

FIG. 6 is a lens configuration diagram of the large-diameter lens according to the second embodiment at infinity focusing.

The large-diameter lens of FIG. 6 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of two positive meniscus lenses having a convex surface facing the object side and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a concave surface facing the object side and having a negative refractive power.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, various values of the large-diameter lens according to the second embodiment are shown below.
Numerical Example 2
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 148.8937 6.3628 1.65844 50.85 0.5575
2 400.8029 0.3000
3 88.8052 7.7121 1.43700 95.10 0.5334
4 186.3141 0.3000
5 63.4922 10.2180 1.43700 95.10 0.5334
6 179.5482 3.1552 1.61340 44.27 0.5633
7 53.6846 13.1608
8-2496.1579 4.3228 1.43700 95.10 0.5334
9 -155.5309 1.8000 1.61340 44.27 0.5633
10 96.9720 1.0000
11 67.3521 9.7521 1.83481 42.72 0.5648
12 -262.9426 1.8000 1.61340 44.27 0.5633
13 87.8711 (d13)
14 55.9775 4.3603 1.92286 20.88 0.6388
15 94.4046 0.3000
16 51.4948 4.2937 1.55032 75.50 0.5400
17 81.4925 0.3000
18 40.6596 7.9142 1.59282 68.63 0.5441
19 -3711.1109 1.3000 1.74077 27.76 0.6076
20 27.5023 7.7790
(Aperture) ∞ 4.3136
22 -57.0428 0.9000 1.65412 39.68 0.5737
23 27.2148 7.7486 1.87071 40.73 0.5682
24-358.4172 2.5557
25 -76.1439 2.9982 1.91082 35.25 0.5821
26 -41.1144 0.9000 1.64769 33.84 0.5923
27 114.8214 0.3000
28 * 64.8502 5.9302 1.84915 40.00 0.5694
29 * -84.3052 (d29)
30 ∞ 1.4500 1.52301 58.59 0.5449
31 ∞ BF

[Aspherical data]
28 faces 29 faces
K 0 0
A4 -1.83614E-0 1.84629E-06
A6 -1.50424E-1 4.19931E-11
A8 0 1.92462 E-12

[Various data]
INF
Focal length 102.38
F number 1.46
Full angle of view 2ω 23.63
Image height Y 21.63
Lens total length 167.66

[Variable interval data]
Shooting distance INF 995
d0 ∞ 826.8724
d13 15.8705 3.0000
d29 37.5626 50.5468
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 402.35
G2 14 86.34
G1a 1 307.15
G1b 8 -130.75
G1c 11 147.86
G2a 14 271.98
G2b 22 84.30

FIG. 11 is a lens configuration diagram of the large-diameter lens according to the third embodiment at infinity focusing.

The large-diameter lens of FIG. 11 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of three positive meniscus lenses having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a convex surface facing the object side and having a negative refractive power.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, the specification values of the large-diameter lens according to the third embodiment are shown below.
Numerical Example 3
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 140.0817 6.2300 1.65844 50.85 0.5574
2 323.3865 0.3000
3 96.3564 7.1418 1.43700 95.10 0.5335
4 195.4487 0.3000
5 70.7786 9.1061 1.43700 95.10 0.5335
6 177.0092 4.7886
7 292.1758 2.2000 1.61340 44.27 0.5633
8 59.1273 9.0589
9 162.9902 5.9737 1.43700 95.10 0.5335
10 -301.6999 1.8000 1.72047 34.71 0.5834
11 98.6498 1.0000
12 65.5095 9.9061 1.91082 35.25 0.5821
13 -308.8045 1.8000 1.65412 39.68 0.5737
14 73.0064 (d14)
15 54.7872 4.3652 1.92286 20.88 0.6388
16 90.6572 0.3000
17 51.3497 4.2449 1.55032 75.50 0.5400
18 80.0374 0.3000
19 42.4911 8.0775 1.59282 68.63 0.5441
20 -424.2628 1.3000 1.72825 28.32 0.6058
21 27.7117 7.7161
(Aperture) ∞ 4.7515
23 -54.7992 0.9000 1.65412 39.68 0.5736
24 27.4844 7.9729 1.87071 40.73 0.5681
25 -237.1687 2.2922
26 -80.2746 3.1419 1.91082 35.25 0.5821
27 -40.3204 0.9000 1.64769 33.84 0.5923
28 136.8587 0.3000
29 * 71.5761 4.9376 1.84915 40.00 0.5695
30 * -93.0490 (d30)
31 ∞ 1.4500 1.52301 58.59 0.5449
32 ∞ BF

[Aspherical data]
29 faces 30 faces
K 0 0
A4 -1.49036E-06 1.82324E-06
A6 4.11465E-10 8.11154E-10
A8 0 2.20680E-12

[Various data]
INF
Focal length 103.31
F number 1.46
Full angle of view 2ω 23.43
Image height Y 21.63
Lens total length 167.37

[Variable interval data]
Shooting distance INF 994
d0 ∞ 826.8724
d14 16.2501 3.0000
d30 37.5630 50.8731
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 379.36
G2 15 87.79
G1a 1 511.83
G1b 9 -183.27
G1c 12 153.75
G2a 15 308.63
G2b 23 83.62

FIG. 16 is a lens configuration diagram of the large-diameter lens according to the fourth embodiment at infinity focusing.

The large-diameter lens of FIG. 16 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of two positive meniscus lenses having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a concave surface facing the object side and having a negative refractive power.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, the specification values of the large-diameter lens according to the fourth embodiment are shown below.
Numerical Example 4
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 85.6120 12.3160 1.59282 68.63 0.5441
2 458.7719 0.3000
3 64.4906 7.5979 1.43700 95.10 0.5335
4 102.3846 6.2369
5 167.7157 2.2000 1.61340 44.27 0.5633
6 53.1815 15.5839
7 -182.2473 4.5069 1.43700 95.10 0.5335
8 -85.4275 1.8000 1.61340 44.27 0.5633
9 -9376.1589 1.0000
10 73.7526 10.2373 1.81600 46.62 0.5567
11 -154.9000 1.8000 1.61340 44.27 0.5633
12 76.2067 (d12)
13 75.5345 3.7216 1.92286 20.88 0.6388
14 130.7918 0.3000
15 49.6854 4.5433 1.72916 54.67 0.5452
16 80.6570 0.3000
17 37.9275 8.1019 1.59282 68.63 0.5441
18 579.3915 1.3000 1.69895 30.05 0.6028
19 27.4914 7.8083
(Aperture) ∞ 6.0049
21 -41.7222 3.2790 1.59282 68.63 0.5441
22 -30.2996 0.9000 1.65412 39.68 0.5736
23 -161.8290 1.4463
24 -134.8107 4.7768 1.95375 32.32 0.5900
25 -31.5815 0.9000 1.68893 31.16 0.5989
26 92.3257 0.3000
27 * 58.7797 7.0365 1.84915 40.00 0.5695
28 * -76.4136 (d28)
29 ∞ 1.4500 1.52301 58.59 0.5449
30 ∞ BF

[Aspherical data]
27 faces 28 faces
K 0 0
A4 -1.34538E-06 7.95788E-07
A6 7.16339E-10 6.26328E-10
A8 0 -1.26638E-13

[Various data]
INF
Focal length 101.85
F number 1.45
Full angle of view 2ω 23.87
Image height Y 21.63
Lens total length 170.09

[Variable interval data]
Shooting distance INF 997
d0 ∞ 826.8724
d12 15.7659 3.0000
d28 37.5800 50.2088
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 435.00
G2 16 84.82
G1a 1 501.13
G1b 9 -226.65
G1c 13 206.03
G2a 16 160.12
G2b 24 99.95

FIG. 21 is a lens configuration diagram of the large-diameter lens according to the fifth embodiment at infinity focusing.

The large-diameter lens of FIG. 21 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of three positive meniscus lenses having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a convex surface facing the object side and having a negative refractive power.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, the specification values of the large-diameter lens according to the fifth embodiment are shown below.
Numerical Example 5
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 128.0780 7.5613 1.65844 50.85 0.5574
2 403.3458 0.3000
3 88.1573 5.9855 1.43700 95.10 0.5335
4 134.9147 0.3000
5 67.9896 7.6133 1.43700 95.10 0.5335
6 119.9000 5.8068
7 209.5511 2.2000 1.61340 44.27 0.5633
8 58.6284 10.9201
9 415.7584 5.2502 1.59282 68.63 0.5441
10 -183.1569 1.8000 1.61340 44.27 0.5633
11 92.9849 1.0000
12 60.5606 9.1444 1.83481 42.72 0.5648
13 4282.4046 1.8000 1.63775 42.41 0.5605
14 73.3355 (d14)
15 68.7996 3.8932 1.92286 20.88 0.6388
16 118.4362 0.3000
17 51.0869 4.6608 1.55032 75.50 0.5400
18 89.6048 0.3000
19 45.0701 8.0241 1.59282 68.63 0.5441
20 739.4855 3.9890 1.85478 24.80 0.6122
21 31.9388 6.7882
(Aperture) ∞ 4.1526
23 -61.9917 0.9000 1.60342 38.01 0.5827
24 30.9854 6.5784 1.95375 32.32 0.5900
25 1717.1833 2.8655
26 -82.2138 3.3632 1.91082 35.25 0.5821
27 -38.8028 0.9000 1.68893 31.16 0.5989
28 138.4029 0.3000
29 * 70.0089 5.6683 1.84915 40.00 0.5695
30 * -91.0116 (d30)
31 ∞ 1.4500 1.52301 58.59 0.5449
32 ∞ BF

[Aspherical data]
29 faces 30 faces
K 0 0
A4 -2.55803E-06 1.23327E-06
A6 2.30151E-10 9.20080E-10
A8 0 4.57577E-13

[Various data]
INF
Focal length 103.75
F number 1.46
Full angle of view 2ω 23.33
Image height Y 21.63
Lens total length 168.75

[Variable interval data]
Shooting distance INF 995
d0 ∞ 826.8724
d14 16.3846 3.0000
d30 37.5495 50.9341
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 423.53
G2 15 87.44
G1a 1 486.54
G1b 9 -190.77
G1c 12 173.18
G2a 15 357.58
G2b 23 79.61

FIG. 26 is a lens configuration diagram of the large-diameter lens according to the sixth embodiment at infinity focusing.

The large-diameter lens of FIG. 26 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of three positive meniscus lenses having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a negative refractive power as a whole, with a concave surface facing the object side and three lenses of a convex lens, a concave lens, and a convex lens joined from the object side.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, the specification values of the large-diameter lens according to the sixth embodiment are shown below.
Numerical Example 6
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 118.9921 9.1465 1.65844 50.85 0.5574
2 656.7877 0.3000
3 83.3810 5.3723 1.43700 95.10 0.5335
4 115.1062 0.3000
5 78.9460 5.8885 1.43700 95.10 0.5335
6 121.6933 5.5440
7 197.8334 2.2000 1.61310 44.36 0.5604
8 58.7612 12.5360
9 -792.9935 3.7355 1.43700 95.10 0.5335
10 -168.2895 1.0000 1.61310 44.36 0.5604
11 76.1452 5.1013 1.59282 68.63 0.5441
12 200.5086 1.0000
13 65.1634 9.4130 1.80420 46.50 0.5571
14 -455.9270 1.8000 1.63775 42.41 0.5605
15 81.5353 (d15)
16 57.9913 3.8042 1.94595 17.98 0.6544
17 85.7121 0.3000
18 51.9245 4.4942 1.59282 68.63 0.5441
19 88.4075 0.3000
20 41.6033 8.5657 1.59282 68.63 0.5441
21 5998.9072 1.3000 1.74077 27.76 0.6076
22 27.3712 7.7711
(Aperture) ∞ 4.2715
24-59.8055 0.9000 1.56732 42.84 0.5742
25 28.9313 7.0145 1.87071 40.73 0.5681
26 10064.4349 2.8390
27 -81.6714 2.6665 1.91082 35.25 0.5821
28 -44.4966 0.9000 1.69895 30.05 0.6028
29 161.7882 0.3000
30 * 75.8764 9.2642 1.88202 37.22 0.5768
31 * -8.55E + 01 (d31)
32 ∞ 1.4500 1.52301 58.59 0.5449
33 ∞ BF

[Aspherical data]
30 faces 31 faces
K 0 0
A4 -2.53189E-06 9.94955E-07
A6 0 2.18739 E-10
A8 0 1.07296E-12

[Various data]
INF
Focal length 102.18
F number 1.46
Full angle of view 2ω 23.71
Image height Y 21.63
Lens total length 173.83

[Variable interval data]
Shooting distance INF 1001
d0 ∞ 826.8724
d15 15.7872 3.0000
d31 37.5630 50.4102
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 399.50
G2 16 87.42
G1a 1 484.04
G1b 9 -206.30
G1c 13 182.69
G2a 16 373.38
G2b 24 79.93

FIG. 31 is a lens configuration diagram of the large-diameter lens according to the seventh embodiment at infinity focusing.

The large-diameter lens of FIG. 31 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of three positive meniscus lenses having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a concave surface facing the object side and having a negative refractive power.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, the specification values of the large-diameter lens according to the seventh embodiment are shown below.
Numerical Example 7
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 102.4036 5.5582 1.65844 50.85 0.5574
2 149.2820 0.3000
3 74.5000 9.4445 1.43700 95.10 0.5335
4 158.9528 0.3000
5 79.5482 9.0637 1.43700 95.10 0.5335
6 241.3612 4.3160
7 387.4299 2.2000 1.61340 44.27 0.5633
8 53.8748 14.6956
9 -265.8666 4.3917 1.43700 95.10 0.5335
10 -103.1399 1.8000 1.61340 44.27 0.5633
11 -500.0000 1.0000
12 73.5443 10.6775 1.83481 42.72 0.5648
13 -149.8448 1.8000 1.61340 44.27 0.5633
14 73.8135 (d14)
15 69.4099 3.7022 1.92286 20.88 0.6388
16 114.7865 0.3000
17 47.6366 4.6001 1.55032 75.50 0.5400
18 79.7832 0.3000
19 43.6382 7.2273 1.59282 68.63 0.5441
20 3165.0277 1.5512 1.71736 29.50 0.6034
21 29.3287 7.3681
(Aperture) ∞ 4.6152
23 -50.6131 0.9000 1.65412 39.68 0.5737
24 28.8753 7.8896 1.87071 40.73 0.5681
25 -471.6988 2.4139
26 -88.4472 3.8604 1.91082 35.25 0.5821
27 -34.6117 0.9000 1.67270 32.17 0.5962
28 121.0744 0.3000
29 * 68.0671 5.0259 1.84915 40.00 0.5695
30 * -88.4873 (d30)
31 ∞ 1.4500 1.52301 58.59 0.5449
32 ∞ BF

[Aspherical data]
29 faces 30 faces
K 0 0
A4 -1.16039E-06 2.13317E-06
A6 7.86933E-11 4.73264E-10
A8 0 1.59334E-12

[Various data]
INF
Focal length 101.85
F number 1.46
Full angle of view 2ω 23.85
Image height Y 21.63
Lens total length 172.51

[Variable interval data]
Shooting distance INF 999
d0 ∞ 826.8724
d15 15.9931 3.0000
d30 37.5630 50.6161
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 305.79
G2 15 91.08
G1a 1 1067.88
G1b 9 -470.59
G1c 12 196.54
G2a 15 294.36
G2b 23 91.54

FIG. 36 is a lens configuration diagram of the large-diameter lens according to the eighth embodiment at infinity focusing.

The large-diameter lens of FIG. 36 has a first lens group G1 having a fixed positive refractive power with respect to the image plane when focusing from an infinity object to a short-distance object, and the image plane side to the object side when focusing. It is composed of a second lens group G2 having a positive refractive power that moves to.

The first lens group G1 is composed of a first a lens group G1a having a positive refractive power, a first b lens group G1b having a negative refractive power, and a firstc lens group G1c having a positive refractive power from the object side.

The first a lens group G1a is composed of three positive meniscus lenses having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side from the object side.

The first b lens group G1b is composed of a bonded lens having a concave surface facing the object side and having a negative refractive power.

The first c lens group G1c is composed of a bonded lens having a positive refractive power with a convex surface facing the object side.

The second lens group G2 is composed of a second a lens group G2a having a positive refractive power from the object side, an aperture stop S, and a second b lens group G2b having a positive refractive power.

The second a lens group G2a is composed of two positive meniscus lenses having a convex surface facing the object surface and a bonded lens having a negative refractive power with the convex surface facing the object side from the object side.

The second b lens group G2b is composed of two bonded lenses having a negative refractive power with a concave surface facing the object side from the object side, and a biconvex lens having both lens surfaces having an aspherical shape.

Subsequently, the specification values of the large-diameter lens according to the eighth embodiment are shown below.
Numerical Example 8
Unit: mm
[Surface data]
Face number rd nd vd PgF
Paraboloid ∞ (d0)
1 90.2454 7.8712 1.65844 50.85 0.5574
2 167.6210 0.3000
3 76.2920 5.6698 1.43700 95.10 0.5335
4 100.7741 0.3000
5 72.9762 10.0895 1.43700 95.10 0.5335
6 231.4844 2.0000
7 157.4610 2.2000 1.63775 42.41 0.5605
8 46.8356 17.1883
9 -182.8104 3.7870 1.43700 95.10 0.5335
10 -98.0729 1.8000 1.63775 42.41 0.5605
11 -500.0000 1.0000
12 59.9826 10.5828 1.80420 46.50 0.5571
13 -343.9519 1.8000 1.63775 42.41 0.5605
14 66.2039 (d14)
15 62.9670 4.3362 1.92286 20.88 0.6388
16 118.1340 0.3000
17 54.1666 3.9883 1.59282 68.63 0.5441
18 81.0490 0.3000
19 43.7504 8.4873 1.59282 68.63 0.5441
20 -207.2733 1.3000 1.69895 30.05 0.6028
21 28.3650 7.5794
(Aperture) ∞ 4.9939
23 -49.6245 0.9000 1.65412 39.68 0.5737
24 30.7397 8.5593 1.87071 40.73 0.5681
25 -229.5974 2.1096
26 -90.0548 3.7067 1.91082 35.25 0.5821
27 -36.1967 0.9000 1.67270 32.17 0.5962
28 127.5561 0.3000
29 * 70.3380 4.9106 1.84915 40.00 0.5695
30 * -91.4394 (d30)
31 ∞ 1.4500 1.52301 58.59 0.5449
32 ∞ BF

[Aspherical data]
29 faces 30 faces
K 0 0
A4 -1.05290E-06 1.94516E-06
A6 2.36212E-10 6.27849E-10
A8 0 7.62259 E-13

[Various data]
INF
Focal length 101.85
F number 1.46
Full angle of view 2ω 23.76
Image height Y 21.63
Lens total length 173.00

[Variable interval data]
Shooting distance INF 1000
d0 ∞ 826.8724
d15 15.7304 3.0000
d30 37.5626 50.3245
BF 1.0000 1.0000

[Lens group data]
Focal length of group origin
G1 1 371.80
G2 15 87.20
G1a 1 849.37
G1b 9 -316.40
G1c 12 195.15
G2a 15 259.88
G2b 23 86.77

The values corresponding to the conditional expressions corresponding to each of the above embodiments are shown below.
ex1 ex2 ex3 ex4
(1) -3.8 <ΦG1b / ΦG1 <-0.5 -0.793 -3.077 -2.070 -1.919
(2) 0.18 <ΦG1 / Φ <0.50 0.305 0.254 0.272 0.234
(3) 3.0 <ΦG2 / ΦG1 <7.5 3.706 4.660 4.321 5.129
(4) 0.8 <νdL1bp1 * ΔPgFL1bp 5.35 5.35 5.35 5.35
(5) 0.015 <ΔPgFG1Pave 0.0326 0.0326 0.0333 0.0310
(6) ΔPgFG1Nave <-0.0020 -0.0063 -0.0053 -0.0037 -0.0053
(7) 0.010 <ΔPgFG2aPave 0.0188 0.0250 0.0250 0.0142
(8) 1.85 <NdL2ap1 1.92286 1.92286 1.92286 1.92286
(9) 0.02 <ΔPgFL2ap1 0.0281 0.0281 0.0281 0.0281

ex5 ex6 ex7 ex8
(1) -3.8 <ΦG1b / ΦG1 <-0.5 -2.220 -1.937 -0.650 -1.175
(2) 0.18 <ΦG1 / Φ <0.50 0.245 0.256 0.333 0.274
(3) 3.0 <ΦG2 / ΦG1 <7.5 4.844 4.570 3.358 4.263
(4) 0.8 <νdL1bp1 * ΔPgFL1bp 1.32 1.32 5.35 5.35
(5) 0.015 <ΔPgFG1Pave 0.0252 0.0302 0.0326 0.0324
(6) ΔPgFG1Nave <-0.0020 -0.0074 -0.0092 -0.0053 -0.0115
(7) 0.010 <ΔPgFG2aPave 0.0250 0.0257 0.0250 0.0222
(8) 1.85 <NdL2ap1 1.92286 1.94595 1.92286 1.92286
(9) 0.02 <ΔPgFL2ap1 0.0281 0.0384 0.0281 0.0281

G1 1st lens group G2 2nd lens group G1a 1a lens group G1b 1b lens group G1c 1c lens group G2a 2a lens group G2b 2b lens group LPF low pass filter I image plane S aperture aperture

Claims (6)

From the object side, it is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power.
The first lens group G1 has a first a lens group G1a which is composed of one or more convex lenses and one concave lens or one junction concave lens component from the object side and has a positive refractive power as a whole, and has a negative refractive power. It is composed of a first b lens group G1b composed of a junction concave lens component and a first c lens group G1c having a positive refractive power.
The second lens group G2 is composed of a second a lens group G2a composed of one or more convex lenses and a junction concave lens component having a negative refractive power, an aperture diaphragm S, and a second b lens group G2b.
When focusing from infinity to a short-range object, 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. A large-diameter lens characterized by satisfying.
(1) -3.8 <ΦG1b / ΦG1 <-0.5
(2) 0.18 <ΦG1 / Φ <0.50
(3) 3.0 <ΦG2 / ΦG1 <7.5
(4) 0.8 <νdL1bp1 × ΔPgFL1bp1
ΦG1: Refractive force of the first lens group G1 ΦG1b: Refractive force of the first b lens group G1b ΦG2: Refractive force of the second lens group G2 Φ: Refractive force of the entire system at infinity νdL1bp1: First b lens group G1b Abbe number ΔPgFL1bp1: of the convex lens constituting the first b lens group G1b of the lens having the highest refractive index Abnormal dispersibility of the lens having the highest refractive index among the convex lenses constituting The large-diameter lens according to claim 1, wherein the large-diameter lens satisfies the following conditional expression.
(5) 0.015 <ΔPgFG1Pave
(6) ΔPgFG1Nave <-0.0020
ΔPgFG1Nave: Mean value of the anomalous dispersibility of the concave lens of the first lens group G1 ΔPgFG1Pave: Mean value of the anomalous dispersibility of the convex lens of the first lens group G1
The large-diameter lens according to claim 1 or 2, wherein the large-diameter lens satisfies the following conditional expression.
(7) 0.010 <ΔPgFG2aPave
ΔPgFG2aPave: Mean value of the anomalous dispersibility of the convex lens of the second a lens group G2a
The large-diameter lens according to any one of claims 1 to 3, wherein the large-diameter lens satisfies the following conditional expression.
(8) 1.85 <NdL2ap1
NdL2ap1: Refractive index of the convex lens located closest to the object among the lenses constituting the second lens group G2.
The large-diameter lens according to any one of claims 1 to 4, wherein the large-diameter lens satisfies the following conditional expression.
(9) 0.020 <ΔPgFL2ap1
ΔPgFL2ap1: Abnormal dispersibility of the convex lens located closest to the object among the lenses constituting the second lens group G2.
The large-diameter lens according to any one of claims 1 to 5 , wherein the second lens group G2 has at least one aspherical lens.

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