JP2024029243A - Optical system and optical device - Google Patents

Abstract

To provide an optical system which is well corrected for the secondary spectrum in addition to the primary achromaticity in chromatic aberration correction.SOLUTION: An optical system LS provided herein comprises an aperture stop S and a positive lens L6 disposed on the image side of the aperture stop S and configured to satisfy the following conditional expressions: 0.000<ndP2-(2.015-0.0068×νdP2), 52.40<νdP2<65.00, 0.545<θgFP2, 0.0004≤θgFP2-(0.6418-0.00168×νdP2), Dp2≥3.500[mm], where ndP2 represents a refractive index of the positive lens for the d-ray, νdP2 represents an Abbe number of the positive lens for the d-ray, and θgFP2 represents a partial dispersion ratio of the positive lens. A lens located on the most image side has negative refractive power.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to optical systems and optical instruments.

In recent years, imaging elements used in imaging devices such as digital cameras and video cameras have been increasing in number of pixels. In addition to standard aberrations (single-wavelength aberrations) such as spherical aberration and coma, the photographing lens installed in an imaging device using such an image sensor has good chromatic aberration so that there is no color fringing in the image under a white light source. It is desired that the lens be corrected to have high resolving power. In particular, when correcting chromatic aberration, it is desirable that not only the first-order achromatization but also the second-order spectrum be well corrected. As a means for correcting chromatic aberration, for example, a method using a resin material having anomalous dispersion (see, for example, Patent Document 1) is known. As described above, with the increase in the number of pixels in image sensors in recent years, there is a demand for photographic lenses in which various aberrations are well corrected.

Japanese Patent Application Publication No. 2016-194609

The optical system according to the present invention includes an aperture stop and a positive lens disposed on the image side of the aperture stop and satisfying the following conditional expression,
0.000<ndP2-(2.015-0.0068×νdP2)
52.40<νdP2<65.00
0.545<θgFP2
0.0004≦θgFP2-(0.6418-0.00168×νdP2)
DP2≧3.500 [mm]
However, ndP2: the refractive index of the positive lens for the d-line νdP2: the Abbe number of the positive lens with respect to the d-line θgFP2: the partial dispersion ratio of the positive lens, and the refractive index of the positive lens for the g-line is ngP2 When the refractive index of the positive lens for the F-line is nFP2, and the refractive index of the positive lens for the C-line is nCP2, it is defined by the following formula: θgFP2=(ngP2-nFP2)/(nFP2-nCP2)
DP2: Thickness of the positive lens on the optical axis The lens located closest to the image side has negative refractive power.

An optical device according to the present invention includes the optical system described above.

FIG. 2 is a lens configuration diagram of the optical system according to the first example in an infinity focused state. FIGS. 2(A), 2(B), and 2(C) show various aberrations of the optical system according to the first embodiment when focusing at infinity, when focusing at intermediate distance, and when focusing at short distance, respectively. It is a diagram. FIG. 7 is a lens configuration diagram of an optical system according to a second example in an infinity focused state. 4(A), FIG. 4(B), and FIG. 4(C) show various aberrations of the optical system according to the second embodiment when focusing at infinity, when focusing at intermediate distance, and when focusing at short distance, respectively. It is a diagram. FIG. 7 is a lens configuration diagram of an optical system according to a third example in a focused state at infinity. FIG. 6(A), FIG. 6(B), and FIG. 6(C) show various aberrations of the optical system according to the third embodiment when focusing at infinity, when focusing at intermediate distance, and when focusing at short distance, respectively. It is a diagram. FIG. 7 is a lens configuration diagram of an optical system according to a fourth example in an infinity focused state. FIG. 8(A), FIG. 8(B), and FIG. 8(C) show various aberrations of the optical system according to the fourth embodiment when focusing at infinity, when focusing at intermediate distance, and when focusing at short distance, respectively. It is a diagram. FIG. 7 is a lens configuration diagram of an optical system according to a fifth embodiment in an infinity focused state. FIG. 10(A), FIG. 10(B), and FIG. 10(C) show various aberrations of the optical system according to the fifth embodiment when focusing at infinity, when focusing at intermediate distance, and when focusing at short distance, respectively. It is a diagram. FIG. 7 is a lens configuration diagram of an optical system according to a sixth embodiment in an infinity focused state. FIGS. 12(A), 12(B), and 12(C) show various aspects of the optical system according to the sixth embodiment when focusing at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is an aberration diagram. FIG. 7 is a lens configuration diagram of an optical system according to a seventh embodiment in an infinity focused state. 14(A), FIG. 14(B), and FIG. 14(C) show various aspects of the optical system according to the seventh embodiment when focusing at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is an aberration diagram. FIG. 9 is a lens configuration diagram of an optical system according to an eighth embodiment in an infinity focused state. 16(A), FIG. 16(B), and FIG. 16(C) show various aspects of the optical system according to the eighth embodiment when focusing at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is an aberration diagram. FIG. 9 is a lens configuration diagram of an optical system according to a ninth embodiment in an infinity focused state. FIG. 18(A), FIG. 18(B), and FIG. 18(C) show various aberrations of the optical system according to the ninth embodiment at infinity focus, intermediate distance focus, and short distance focus, respectively. It is a diagram. FIG. 7 is a lens configuration diagram of the optical system according to the tenth embodiment in an infinity focused state. 20(A), FIG. 20(B), and FIG. 20(C) show various aspects of the optical system according to the tenth embodiment when focusing at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is an aberration diagram. FIG. 1 is a diagram showing the configuration of a camera including an optical system according to the present embodiment. 3 is a flowchart showing a method for manufacturing an optical system according to the present embodiment.

Preferred embodiments of the present invention will be described below. First, a camera (optical device) equipped with an optical system according to this embodiment will be described based on FIG. 21. This camera 1 is a digital camera equipped with an optical system according to this embodiment as a photographic lens 2, as shown in FIG. In the camera 1 , light from an object (subject) (not shown) is collected by a photographing lens 2 and reaches an image sensor 3 . Thereby, light from the subject is captured by the image sensor 3 and recorded in a memory (not shown) as a subject image. In this way, the photographer can photograph the subject using the camera 1. Note that this camera may be a mirrorless camera or a single-lens reflex camera with a quick return mirror.

As shown in FIG. 1, the optical system LS (1) as an example of the optical system (taking lens) LS according to the present embodiment includes an aperture stop S and the following conditional expression arranged on the image side of the aperture stop S. It has a positive lens (L6) that satisfies (1) to (4).

-0.010<ndP2-(2.015-0.0068×νdP2)...(1)
50.00<νdP2<65.00...(2)
0.545<θgFP2...(3)
-0.010<θgFP2-(0.6418-0.00168×νdP2)
...(4)
However, ndP2: refractive index for the d-line of the positive lens, νdP2: Abbe number with reference to the d-line of the positive lens, θgFP2: partial dispersion ratio of the positive lens, and the refractive index for the g-line of the positive lens is n.
gP2, the refractive index of the positive lens for the F-line is nFP2, and the refractive index of the positive lens for the C-line is nCP2, then it is defined by the following formula: θgFP2=(ngP2-nFP2)/(nFP2-nCP2)
The Abbe number νdP2 based on the d-line of the positive lens is defined by the following formula: νdP2=(ndP2-1)/(nFP2-nCP2)

According to this embodiment, in the correction of chromatic aberration, it is possible to obtain an optical system in which not only the first-order achromatization but also the secondary spectrum is well corrected, and an optical device equipped with this optical system. The optical system LS according to this embodiment may be the optical system LS(2) shown in FIG. 3, the optical system LS(3) shown in FIG. 5, the optical system LS(4) shown in FIG. The optical system LS(5) shown in FIG. 9 may be used, or the optical system LS(6) shown in FIG. 11 may be used. Further, the optical system LS according to the present embodiment may be the optical system LS (7) shown in FIG. 13, the optical system LS (8) shown in FIG. 15, or the optical system LS (9) shown in FIG. , an optical system LS (10) shown in FIG. 19 may be used.

Conditional expression (1) defines an appropriate relationship between the refractive index of the positive lens for the d-line and the Abbe number with the d-line as a reference. By satisfying conditional expression (1), it is possible to satisfactorily correct reference aberrations such as spherical aberration and coma aberration, and correct primary chromatic aberration (achromatism).

If the corresponding value of conditional expression (1) falls outside the above range, it becomes difficult to correct chromatic aberration. By setting the lower limit of conditional expression (1) to -0.005, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit value of conditional expression (1) is set to -0.001, 0.000, 0.003, 0.005, 0.007, and further 0.008. It may be set to

Note that the upper limit of conditional expression (1) may be set to less than 0.150. Thereby, it is possible to satisfactorily correct reference aberrations such as spherical aberration and coma aberration, and correct primary chromatic aberration (achromatism). In this case, by setting the upper limit of conditional expression (1) to 0.100, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the upper limit of conditional expression (1) may be set to 0.080, 0.060, 0.050, or even 0.045.

Conditional expression (2) defines an appropriate range of the Abbe number based on the d-line of the positive lens. By satisfying conditional expression (2), it is possible to satisfactorily correct reference aberrations such as spherical aberration and coma aberration, and correct primary chromatic aberration (achromatism).

If the corresponding value of conditional expression (2) falls outside the above range, it becomes difficult to correct chromatic aberration. By setting the lower limit of conditional expression (2) to 50.50, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the lower limit value of conditional expression (2) may be set to 51.00, 51.50, 52.00, or even 52.40.

By setting the upper limit of conditional expression (2) to 64.00, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit value of conditional expression (2) is set to 63.00, 62.50, 62.00, 61.50, 61.00, 60.00, and It may be set to 59.50.

Conditional expression (3) appropriately defines the anomalous dispersion of the positive lens. By satisfying conditional expression (3), in the correction of chromatic aberration, it is possible to satisfactorily correct the secondary spectrum in addition to the primary achromatization.

If the corresponding value of conditional expression (3) falls outside the above range, it becomes difficult to correct chromatic aberration. By setting the lower limit of conditional expression (3) to 0.547, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the lower limit value of conditional expression (3) may be set to 0.548, 0.549, or even 0.550.

Conditional expression (4) appropriately defines the anomalous dispersion of the positive lens. By satisfying conditional expression (4), in correction of chromatic aberration, it is possible to satisfactorily correct the secondary spectrum in addition to primary achromatization.

If the corresponding value of conditional expression (4) falls outside the above range, it becomes difficult to correct chromatic aberration. By setting the lower limit of conditional expression (4) to -0.005, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the lower limit value of conditional expression (4) may be set to -0.001.

Note that the upper limit of conditional expression (4) may be set to less than 0.040. Thereby, it is possible to satisfactorily correct reference aberrations such as spherical aberration and coma aberration, and correct primary chromatic aberration (achromatism). In this case, by setting the upper limit of conditional expression (4) to 0.030, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the upper limit of conditional expression (4) may be set to 0.025, and further to 0.020.

The optical system LS according to the present embodiment includes an aperture stop S, a front group GF arranged closer to the object side than the aperture stop S, and a rear group GR arranged closer to the image side than the aperture stop S. It is desirable that the lens has the positive lens and satisfies the following conditional expression (5).
-10.00<fP2/fR<10.00...(5)
However, fP2: focal length of the positive lens, fR: focal length of the rear group GR, and if the optical system LS is a variable magnification optical system, the focal length of the rear group GR in the wide-angle end state.

Conditional expression (5) defines an appropriate relationship between the focal length of the positive lens and the focal length of the rear group GR. By satisfying conditional expression (5), reference aberrations such as spherical aberration and comatic aberration can be favorably corrected.

If the corresponding value of conditional expression (5) falls outside the above range, it becomes difficult to correct reference aberrations such as spherical aberration and coma aberration. By setting the lower limit of conditional expression (5) to -9.50, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit value of conditional expression (5) is set to -9.00, -8.50, -8.00, -7.00, -5.00, It may be set to -3.00, -1.50, -0.05, 0.05, or even 0.10.

By setting the upper limit of conditional expression (5) to 8.50, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the upper limit of conditional expression (5) may be set to 7.50, 6.50, 5.00, 4.00, or even 3.00. good.

In the optical system LS according to the present embodiment, it is desirable that the positive lens satisfy the following conditional expression (6).
0.10<fP2/f<15.00 (6)
However, fP2: focal length of the positive lens f: focal length of the optical system LS; if the optical system LS is a variable power optical system, the focal length of the optical system LS in the wide-angle end state

Conditional expression (6) defines an appropriate relationship between the focal length of the positive lens and the focal length of the optical system LS. By satisfying conditional expression (6), reference aberrations such as spherical aberration and comatic aberration can be favorably corrected.

If the corresponding value of conditional expression (6) falls outside the above range, it becomes difficult to correct reference aberrations such as spherical aberration and coma aberration. By setting the lower limit of conditional expression (6) to 0.20, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the lower limit value of conditional expression (6) may be set to 0.30, 0.40, 0.45, or even 0.50.

By setting the upper limit of conditional expression (6) to 14.20, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the upper limit of conditional expression (6) may be set to 12.00, 10.00, 8.50, or even 7.50.

In the optical system LS according to the present embodiment, the positive lens may satisfy the following conditional expression (3-1).
0.555<θgFP2...(3-1)

Conditional expression (3-1) is the same expression as conditional expression (3), and can obtain the same effect as conditional expression (3). By setting the lower limit of conditional expression (3-1) to 0.556, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (3-1) to 0.557.

In the optical system LS according to the present embodiment, the positive lens may satisfy the following conditional expression (4-1).
0.010<θgFP2-(0.6418-0.00168×νdP2)
...(4-1)

Conditional expression (4-1) is the same expression as conditional expression (4), and can obtain the same effect as conditional expression (4). By setting the lower limit of conditional expression (4-1) to 0.011, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (4-1) to 0.012.

Note that the upper limit of conditional expression (4-1) may be set to less than 0.030. Thereby, the same effect as conditional expression (4) can be obtained. In this case, by setting the upper limit of conditional expression (4-1) to 0.028, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, the upper limit of conditional expression (4-1) may be set to 0.025, 0.023, or even 0.020.

In the optical system LS according to the present embodiment, it is desirable that the positive lens satisfy the following conditional expression (7).
DP2>0.400[mm]...(7)
However, DP2: Thickness on the optical axis of the positive lens

Conditional expression (7) appropriately defines the thickness of the positive lens on the optical axis. By satisfying conditional expression (7), various aberrations such as comatic aberration and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be favorably corrected.

If the corresponding value of conditional expression (7) falls outside the above range, it becomes difficult to correct various aberrations such as comatic aberration and chromatic aberration (axial chromatic aberration and lateral chromatic aberration). By setting the lower limit of conditional expression (7) to 0.450 [mm], the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (7) is set to 0.490 [mm], 0.550 [mm], 0.580 [mm], and 0.650 [mm]. mm], 0.680 [mm], 0.750 [mm], 0.800 [mm], 0.850 [mm], 0.880 [mm], 0.950 [mm], 0.980 [mm] ], 1.050 [mm], 1.100 [mm], 1.140 [mm], 1.250 [mm], and further may be set to 1.350 [mm].

In the optical system LS according to the present embodiment, the positive lens is preferably a single lens or one of the two lenses in a cemented lens made of two lenses cemented together. When glass is used as the lens material, the optical properties change less due to temperature than resin. In this embodiment, since glass can be used as the material of the positive lens, the positive lens is a lens whose lens surface is in contact with air (i.e., a single lens or a cemented lens made of two lenses). Even if it is one of the two lenses, it is preferable because the optical characteristics change little due to temperature.

In the optical system LS according to the present embodiment, it is desirable that at least one lens surface of the object-side lens surface and the image-side lens surface of the positive lens be in contact with air. When glass is used as the lens material, the optical properties change less due to temperature than resin. In this embodiment, glass can be used as the material of the positive lens, so even if the lens surface of the positive lens is in contact with air, there is little change in optical characteristics due to temperature, which is preferable.

In the optical system LS according to this embodiment, the positive lens is preferably a glass lens. As for the positive lens, it is preferable to use a glass lens rather than a resin lens because it has less deterioration over time and less change in optical properties due to temperature.

Next, with reference to FIG. 22, a method for manufacturing the above-mentioned optical system LS will be outlined. First, an aperture stop S and a positive lens are arranged at least on the image side of the aperture stop S (step ST1). At this time, each lens is arranged in the lens barrel so that at least one of the positive lenses arranged on the image side of the aperture stop S satisfies the above conditional expressions (1) to (4), etc. (step ST2). According to such a manufacturing method, in correcting chromatic aberration, it is possible to manufacture an optical system in which not only the first-order achromatization but also the secondary spectrum is well corrected.

Hereinafter, the optical system LS according to an example of this embodiment will be explained based on the drawings. 1, FIG. 3, FIG. 5, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 15, FIG. 17, and FIG. (10)} is a cross-sectional view showing the configuration and refractive power distribution. In the cross-sectional views of the optical systems LS(1) to LS(10) according to the first to tenth embodiments, the moving direction when the focusing lens group focuses from infinity to a short-distance object is referred to as "focusing". The characters are indicated by arrows. In the cross-sectional views of the optical systems LS(6) to LS(8) according to the sixth to eighth embodiments and the optical system LS(10) according to the tenth embodiment, from the wide-angle end state (W) to the telephoto end state (T ) The arrows indicate the direction of movement of each lens group along the optical axis when changing the magnification.

1, FIG. 3, FIG. 5, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 15, FIG. 17, and FIG. Each is represented by a combination of numbers. In this case, in order to prevent the types and numbers of codes and numbers from becoming large and complicated, lens groups and the like are expressed using combinations of codes and numbers independently for each embodiment. Therefore, even if the same combination of symbols and numbers is used between the embodiments, it does not mean that they have the same configuration.

Tables 1 to 10 are shown below, of which Table 1 is the first example, Table 2 is the second example, Table 3 is the third example, Table 4 is the fourth example, and Table 5 is the fourth example. 5 Example, Table 6 shows the 6th example, Table 7 shows the 7th example, Table 8 shows the 8th example, Table 9 shows the 9th example, and Table 10 shows each specification data in the 10th example. It is a table. In each example, the aberration characteristics are calculated as d-line (wavelength λ = 587.6 nm), g-line (wavelength λ = 435.8 nm), C-line (wavelength λ = 656.3 nm), and F-line (wavelength λ = 486.1 nm).

In the [Overall Specifications] table, f is the focal length of the entire lens system, FNO is the F number, 2ω is the angle of view (unit is ° (degree), ω is the half angle of view), and Y is the image height. show. TL is the distance obtained by adding BF to the distance from the frontmost surface of the lens on the optical axis to the final surface of the lens when focusing on infinity, and BF is the distance from the final surface of the lens on the optical axis when focusing on infinity. The distance to surface I (back focus) is shown. fF indicates the focal length of the front group, and fR indicates the focal length of the rear group. Note that when the optical system is a variable power optical system, these values are shown for each variable power state of wide-angle end (W), intermediate focal length (M), and telephoto end (T).

In the [Lens specifications] table, the surface number indicates the order of the optical surfaces from the object side along the direction of propagation of the light ray, and R is the radius of curvature of each optical surface (the surface whose center of curvature is located on the image side). ), D is the surface spacing that is the distance on the optical axis from each optical surface to the next optical surface (or image surface), nd is the refractive index of the material of the optical member for the d-line, and νd is the optical θgF represents the Abbe number of the material of the member based on the d-line, and θgF represents the partial dispersion ratio of the material of the optical member. The radius of curvature "∞" indicates a plane or an aperture, and (diaphragm S) indicates an aperture diaphragm S, respectively. The description of the refractive index nd=1.00000 of air is omitted. When the optical surface is an aspherical surface, the surface number is marked with *, and the radius of curvature R column indicates the paraxial radius of curvature.

The refractive index of the material of the optical member for the g-line (wavelength λ = 435.8 nm) is ng, the refractive index of the material of the optical member for the F-line (wavelength λ = 486.1 nm) is nF, and the C of the material of the optical member is Let nC be the refractive index for a line (wavelength λ=656.3 nm). At this time, the partial dispersion ratio θgF of the material of the optical member is defined by the following formula (A).

θgF=(ng-nF)/(nF-nC)...(A)

In the table of [Aspheric data], the shape of the aspheric surface shown in [Lens specifications] is shown by the following formula (B). X(y) is the distance (sag amount) along the optical axis from the tangent plane at the apex of the aspheric surface to the position on the aspheric surface at height y, and R is the radius of curvature of the reference sphere (paraxial radius of curvature) , κ is the conic constant, and Ai is the i-th aspherical coefficient. "E-n" indicates "×10 ^-n ". For example, 1.234E-05=1.234×10 ⁻⁵ . Note that the second-order aspheric coefficient A2 is 0, and its description is omitted.

X(y)=(y ² /R)/{1+(1-κ×y ² /R ² ) ^1/2 }+A4×y ⁴ +A6×y ⁶ +A8×y ⁸ +A10×y ¹⁰ +A12×y ¹² ... (B)

When the optical system is not a variable magnification optical system, f represents the focal length of the entire lens system, and β represents the imaging magnification as [variable interval data during close-range photography]. In addition, the [Variable spacing data for close-up shooting] table shows the surface spacing for surface numbers for which surface spacing is "variable" in [Lens specifications], corresponding to each focal length and shooting magnification. .

When the optical system is a variable magnification optical system, [variable interval data during variable magnification shooting] corresponds to each variable magnification state of wide-angle end (W), intermediate focal length (M), and telephoto end (T). Indicates the surface spacing for surface numbers where the surface spacing is "variable" in "Lens Specifications".

The [Lens Group Data] table shows the starting surface (the surface closest to the object) and focal length of each lens group.

The table of [Values corresponding to conditional expressions] shows values corresponding to each conditional expression.

Below, in all specification values, the focal length f, radius of curvature R, surface spacing D, and other lengths are generally expressed in mm unless otherwise specified, but the optical system is proportionally enlarged. Alternatively, even if the optical performance is proportionally reduced, the same optical performance can be obtained, so the present invention is not limited to this.

The description of the tables up to this point is common to all embodiments, and repeated description below will be omitted.

(First example)
A first example will be explained using FIGS. 1 to 2 and Table 1. FIG. 1 is a diagram showing a lens configuration of an optical system according to a first example of the present embodiment in a focused state at infinity. The optical system LS (1) according to the first embodiment includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a biconvex positive lens L2, and a negative meniscus lens L2 with a concave surface facing the object side. It is composed of a cemented lens consisting of a meniscus lens L3, a biconcave negative lens L4, a positive meniscus lens L5 with a concave surface facing the object side, and a biconvex positive lens L6. When focusing from an object at infinity to an object at a short distance (finite distance), the entire optical system LS(1) moves toward the object along the optical axis. The aperture stop S is disposed between the negative meniscus lens L3 and the negative lens L4 (of the cemented lens).

In this embodiment, the positive lens L6 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like. The negative meniscus lens L1 and a cemented lens including the positive lens L2 and the negative meniscus lens L3 constitute a front group GF arranged closer to the object side than the aperture stop S. The negative lens L4, the positive meniscus lens L5, and the positive lens L6 constitute a rear group GR arranged closer to the image side than the aperture stop S.

Table 1 below lists the values of the specifications of the optical system according to the first example.

(Table 1)
[Overall specifications]
f 36.000
FNO 2.006
2ω 63.245
Y 21.700
TL 87.738
BF 37.938
fF 39.703
fR 101.311
[Lens specifications]
Surface number R D nd νd θgF
1 37.66140 1.500 1.51680 64.12 0.5360
2 16.40870 16.000
3 34.41050 9.000 1.78797 47.17 0.5548
4 -25.79160 5.500 1.53172 48.96 0.5599
5 -369.88120 2.000
6 ∞ 4.000 (Aperture S)
7 -24.44630 1.900 1.80518 25.35 0.6115
8 61.36910 2.200
9 -73.89840 4.000 1.74810 52.28 0.5465
10 -21.51350 0.100
11 94.80860 3.600 1.68348 54.80 0.5501
12 -60.08020 D12 (variable)
[Variable interval data for close-up shooting]
Infinity focus state Intermediate distance focus state Close range focus state
f=36.000 β=-0.033 β=-0.237
D12 37.938 39.138 46.457
[Conditional expression corresponding value]
<Positive lens L6 (fP2=54.319)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.041
Conditional expression (2) νdP2=54.80
Conditional expression (3), (3-1) θgFP2=0.5501
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0004
Conditional expression (5) fP2/fR=0.536
Conditional expression (6) fP2/f=1.509
Conditional expression (7) DP2=3.600

FIG. 2(A) is a diagram showing various aberrations of the optical system according to the first embodiment when focusing on infinity. FIG. 2(B) is a diagram showing various aberrations of the optical system according to the first embodiment when focusing on an intermediate distance. FIG. 2C is a diagram showing various aberrations when the optical system according to the first example is focused at a short distance (close range). In each aberration diagram when focusing at infinity, FNO indicates the F number and Y indicates the image height. In each aberration diagram at the time of intermediate distance focusing or short distance focusing, NA indicates the numerical aperture, and Y indicates the image height. In addition, spherical aberration diagrams show the F number or numerical aperture value corresponding to the maximum aperture, astigmatism diagrams and distortion aberration diagrams each show the maximum image height, and coma aberration diagrams show the value of each image height. . d is the d-line (wavelength λ = 587.6 nm), g is the g-line (wavelength λ = 435.8 nm), C is the C-line (wavelength λ = 6
56.3 nm) and F indicate the F line (wavelength λ=486.1 nm), respectively. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Note that in the aberration diagrams of each example shown below, the same symbols as in this example are used, and overlapping explanations will be omitted.

From the various aberration diagrams, it can be seen that the optical system according to the first example has various aberrations well corrected and has excellent imaging performance.

(Second example)
A second example will be described using FIGS. 3 to 4 and Table 2. FIG. 3 is a diagram showing a lens configuration of the optical system according to the second example of the present embodiment in a focused state at infinity. The optical system LS(2) according to the second embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power, which are arranged in order from the object side. There is. When focusing from an object at infinity to an object at a short distance (finite distance), the first lens group G1 moves toward the object along the optical axis. The aperture stop S is arranged within the first lens group G1. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this is the same in all the examples below.

The first lens group G1 includes a cemented lens consisting of a positive meniscus lens L1 with a convex surface facing the object side and a negative meniscus lens L2 with a convex surface facing the object side, arranged in order from the object side, and a biconcave negative lens L3 and a cemented lens consisting of a biconvex positive lens L4, a biconvex positive lens L5, a biconvex positive lens L6, a biconcave negative lens L7, and a biconcave negative lens. A cemented lens consisting of L8 and a biconvex positive lens L9, a biconvex positive lens L10, a biconvex positive lens L11, a positive meniscus lens L12 with a concave surface facing the object side, and a biconcave negative lens. It consists of a cemented lens consisting of lens L13. An aperture stop S is arranged between the negative lens L7 (of the cemented lens) and the negative lens L8 (of the cemented lens) in the first lens group G1. In this embodiment, the positive lens L9 of the first lens group G1 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like. The positive lens L5 has an aspherical lens surface on the image side. The positive lens L11 has an aspherical lens surface on the image side.

The second lens group G2 is composed of a cemented lens consisting of a biconvex positive lens L21 and a biconcave negative lens L22, which are arranged in order from the object side. An image plane I is arranged on the image side of the second lens group G2. The negative lens L22 has an aspherical lens surface on the image side.

In this example, a cemented lens consisting of a positive meniscus lens L1 and a negative meniscus lens L2, a cemented lens consisting of a negative lens L3 and a positive lens L4, a cemented lens consisting of a positive lens L5, a positive lens L6 and a negative lens L7 are used. constitutes a front group GF arranged closer to the object side than the aperture stop S. A cemented lens consisting of a negative lens L8 and a positive lens L9, a cemented lens consisting of a positive lens L10, a positive lens L11, a positive meniscus lens L12 and a negative lens L13, and a cemented lens consisting of a positive lens L21 and a negative lens L22. , constitutes a rear group GR arranged closer to the image side than the aperture stop S.

Table 2 below lists the values of the specifications of the optical system according to the second example.

(Table 2)
[Overall specifications]
f 51.600
FNO 1.230
2ω 45.915
Y 21.600
TL 144.475
BF 18.202
fF 180.913
fR 55.423
[Lens specifications]
Surface number R D nd νd θgF
1 59.68690 4.896 2.00100 29.13 0.5995
2 127.45590 1.800 1.55298 55.07 0.5446
3 33.65140 13.918
4 -52.00000 1.804 1.64769 33.72 0.5930
5 57.35910 7.146 1.75500 52.33 0.5475
6 -851.07300 0.500
7 78.83350 10.000 1.95375 32.32 0.5901
8* -87.59360 0.500
9 126.23440 10.526 1.59319 67.90 0.5440
10 -38.27230 1.800 1.64769 33.72 0.5930
11 55.47370 6.250
12 ∞ 8.720 (Aperture S)
13 -35.23580 1.800 1.67300 38.26 0.5758
14 105.56420 7.874 1.67769 52.63 0.5546
15 -71.87010 0.500
16 75.31740 8.082 1.61800 63.34 0.5410
17 -80.32620 0.500
18 103.59820 10.000 1.95375 32.32 0.5901
19* -75.78570 0.500
20 -170.20920 3.978 1.59319 67.90 0.5440
21 -58.93950 1.800 1.67270 32.18 0.5973
22 45.31050 D22 (variable)
23 128.40960 10.000 2.00100 29.13 0.5995
24 -62.62500 10.000 1.80301 25.53 0.6153
25* 100.00000BF
[Aspheric data]
8th side κ=1.000,A4=1.07815E-06,A6=-1.82829E-10
A8=6.45395E-15,A10=-3.23669E-17,A12=0.00000E+00
Side 19 κ=1.000,A4=3.25607E-06,A6=-7.96761E-10
A8=2.82282E-14,A10=5.01296E-16,A12=0.00000E+00
25th side κ=1.000,A4=1.89064E-06,A6=-9.12196E-10
A8=1.33056E-11,A10=-3.29589E-14,A12=3.54880E-17
[Variable interval data for close-up shooting]
Infinity focus state Intermediate distance focus state Close range focus state
f=51.600 β=-0.033 β=-0.150
D22 3.379 5.843 14.468
[Lens group data]
Group starting plane focal length
G1 1 61.764
G2 23 277.853
[Conditional expression corresponding value]
<Positive lens L9 (fP2=64.247)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.021
Conditional expression (2) νdP2=52.63
Conditional expression (3), (3-1) θgFP2=0.5546
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0012
Conditional expression (5) fP2/fR=1.159
Conditional expression (6) fP2/f=1.245
Conditional expression (7) DP2=7.874

FIG. 4(A) is a diagram showing various aberrations of the optical system according to the second embodiment when focusing on infinity. FIG. 4(B) is a diagram showing various aberrations of the optical system according to the second embodiment when focusing on an intermediate distance. FIG. 4C is a diagram showing various aberrations when the optical system according to the second embodiment is focused at a short distance (close range). From the various aberration diagrams, it can be seen that the optical system according to the second example has various aberrations well corrected and has excellent imaging performance.

(Third example)
The third example will be explained using FIGS. 5 to 6 and Table 3. FIG. 5 is a diagram showing the lens configuration of the optical system according to the third example of the present embodiment in a focused state at infinity. The optical system LS (3) according to the third embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power, which are arranged in order from the object side. There is. When focusing from an object at infinity to an object at a short distance (finite distance), the first lens group G1 moves toward the object along the optical axis. The aperture stop S is arranged within the first lens group G1.

The first lens group G1 includes a cemented lens consisting of a positive meniscus lens L1 with a convex surface facing the object side and a negative meniscus lens L2 with a convex surface facing the object side, arranged in order from the object side, and a biconcave negative lens L3 and a cemented lens consisting of a positive meniscus lens L4 with a convex surface facing the object side, a double-convex positive lens L5, a double-convex positive lens L6, a double-concave negative lens L7, and a double-concave positive lens L5. A cemented lens consisting of a negative lens L8 having a negative shape and a positive lens L9 having a double convex shape, a positive lens L10 having a double convex shape, a positive lens L11 having a double convex shape, a positive meniscus lens L12 having a concave surface facing the object side, and a double convex positive lens L10; and a cemented lens consisting of a concave negative lens L13. An aperture stop S is arranged between the negative lens L7 (of the cemented lens) and the negative lens L8 (of the cemented lens) in the first lens group G1. In this embodiment, the positive lens L9 of the first lens group G1 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like. The positive lens L5 has an aspherical lens surface on the image side. The positive lens L11 has an aspherical lens surface on the image side.

The second lens group G2 is composed of a cemented lens consisting of a biconvex positive lens L21 and a biconcave negative lens L22, which are arranged in order from the object side. An image plane I is arranged on the image side of the second lens group G2. The negative lens L22 has an aspherical lens surface on the image side.

In this example, a cemented lens consisting of a positive meniscus lens L1 and a negative meniscus lens L2, a cemented lens consisting of a negative lens L3 and a positive meniscus lens L4, a cemented lens consisting of a positive lens L5, a positive lens L6 and a negative lens L7 are used. constitutes a front group GF arranged closer to the object side than the aperture stop S. A cemented lens consisting of a negative lens L8 and a positive lens L9, a cemented lens consisting of a positive lens L10, a positive lens L11, a positive meniscus lens L12 and a negative lens L13, and a cemented lens consisting of a positive lens L21 and a negative lens L22. , constitutes a rear group GR arranged closer to the image side than the aperture stop S.

Table 3 below lists the values of the specifications of the optical system according to the third example.

(Table 3)
[Overall specifications]
f 51.600
FNO 1.234
2ω 45.915
Y 21.600
TL 144.475
BF 16.971
fF 137.280
fR 57.798
[Lens specifications]
Surface number R D nd νd θgF
1 59.91640 4.946 2.00100 29.13 0.5995
2 122.25270 1.800 1.55298 55.07 0.5446
3 34.65300 14.326
4 -52.14650 1.800 1.64769 33.72 0.5930
5 52.31690 7.062 1.75500 52.33 0.5475
6 1455.56290 0.500
7 82.68170 10.000 1.95375 32.32 0.5901
8* -81.45860 0.500
9 107.20010 10.172 1.59319 67.90 0.5440
10 -41.90310 1.800 1.64769 33.72 0.5930
11 65.19340 5.776
12 ∞ 11.584 (Aperture S)
13 -36.98690 1.800 1.67300 38.26 0.5758
14 42.28040 10.320 1.63687 56.92 0.5592
15 -69.87670 0.500
16 91.14440 6.243 1.61800 63.34 0.5410
17 -132.47670 0.500
18 76.35240 7.378 1.95375 32.32 0.5901
19* -73.70530 0.500
20 -279.36470 4.064 1.59319 67.90 0.5440
21 -67.85000 1.800 1.67270 32.18 0.5973
22 39.74260 D22 (variable)
23 132.84640 10.000 2.00100 29.13 0.5995
24 -57.20730 10.000 1.80301 25.53 0.6153
25* 100.00000BF
[Aspheric data]
8th side κ=1.000,A4=1.11430E-06,A6=-9.64894E-11
A8=-4.80566E-14,A10=3.68135E-17,A12=0.00000E+00
Side 19 κ=1.000,A4=3.12049E-06,A6=-1.16045E-09
A8=1.85421E-13,A10=2.55320E-16,A12=0.00000E+00
25th side κ=1.000,A4=2.37837E-06,A6=-2.95041E-10
A8=1.26641E-11,A10=-2.67596E-14,A12=2.67579E-17
[Variable interval data for close-up shooting]
Infinity focus state Intermediate distance focus state Close range focus state
f=51.600 β=-0.033 β=-0.151
D22 4.133 6.498 15.209
[Lens group data]
Group starting plane focal length
G1 1 61.384
G2 23 276.098
[Conditional expression corresponding value]
<Positive lens L9 (fP2=42.897)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.009
Conditional expression (2) νdP2=56.92
Conditional expression (3), (3-1) θgFP2=0.5592
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0130
Conditional expression (5) fP2/fR=0.742
Conditional expression (6) fP2/f=0.831
Conditional expression (7) DP2=10.320

FIG. 6(A) is a diagram showing various aberrations of the optical system according to the third example when focusing on infinity. FIG. 6(B) is a diagram showing various aberrations of the optical system according to the third embodiment when focusing on an intermediate distance. FIG. 6C is a diagram showing various aberrations when the optical system according to the third example is focused at a short distance (close range). From the various aberration diagrams, it can be seen that the optical system according to the third example has various aberrations well corrected and has excellent imaging performance.

(Fourth example)
A fourth example will be described using FIGS. 7 to 8 and Table 4. FIG. 7 is a diagram showing the lens configuration of the optical system according to the fourth example of the present embodiment in an infinity focused state. The optical system LS (4) according to the fourth embodiment is composed of a first lens group G1 having a positive refractive power and a second lens group G2 having a positive refractive power, which are arranged in order from the object side. There is. When focusing from an object at infinity to an object at a short distance (finite distance), the second lens group G2 moves toward the object along the optical axis. The aperture stop S is arranged within the second lens group G2.

The first lens group G1 includes, in order from the object side, a positive meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, and a positive meniscus lens with a concave surface facing the object side. L13, a cemented lens consisting of a biconcave negative lens L14 and a biconvex positive lens L15, and a positive meniscus lens L16 with a convex surface facing the object side.

The second lens group G2 includes, in order from the object side, a positive meniscus lens L21 with a convex surface facing the object side, a cemented lens consisting of a biconvex positive lens L22, a biconcave negative lens L23, and a biconcave A cemented lens consisting of a negative lens L24 having a negative shape and a positive lens L25 having a double convex shape, a cemented lens consisting of a positive lens L26 having a double convex shape and a negative lens L27 having a double concave shape, a positive lens L28 having a double convex shape, It is composed of a concave negative lens L29. An aperture stop S is arranged between the negative lens L23 (of the cemented lens) and the negative lens L24 (of the cemented lens) in the second lens group G2. An image plane I is arranged on the image side of the second lens group G2. In this embodiment, the positive lens L25 of the second lens group G2 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like. The positive lens L28 has an aspherical lens surface on the image side. The negative lens L29 has an aspherical lens surface on the image side.

In this embodiment, a positive meniscus lens L11, a negative meniscus lens L12, a positive meniscus lens L13, a cemented lens consisting of a negative lens L14 and a positive lens L15, a positive meniscus lens L16, a positive meniscus lens L21, and a positive lens are used. The cemented lens L22 and the negative lens L23 constitute a front group GF arranged closer to the object side than the aperture stop S. A rear group in which a cemented lens consisting of a negative lens L24 and a positive lens L25, a cemented lens consisting of a positive lens L26 and a negative lens L27, a positive lens L28, and a negative lens L29 are arranged closer to the image side than the aperture stop S. Configure GR.

Table 4 below lists the values of the specifications of the optical system according to the fourth example.

(Table 4)
[Overall specifications]
f 50.353
FNO 1.250
2ω 46.020
Y 21.600
TL 144.455
BF 18.783
fF 136.780
fR 60.662
[Lens specifications]
Surface number R D nd νd θgF
1 174.78740 4.000 1.95375 32.32 0.5901
2 833.52260 0.581
3 1000.00000 1.800 1.48749 70.32 0.5291
4 44.92860 11.540
5 -84.24150 4.890 1.49700 81.61 0.5389
6 -42.86770 0.738
7 -41.24460 1.500 1.67300 38.26 0.5758
8 49.18950 10.179 1.76385 48.49 0.5589
9 -140.64700 0.300
10 76.99070 5.967 1.88100 40.14 0.5700
11 39076.81600 D11 (variable)
12 67.65610 3.852 1.95375 32.32 0.5901
13 150.44840 0.300
14 49.50840 9.073 1.49782 82.57 0.5386
15 -105.39230 1.500 1.65412 39.68 0.5738
16 36.84600 6.335
17 ∞ 8.194 (Aperture S)
18 -34.40800 1.500 1.72047 34.71 0.5834
19 42.48130 10.628 1.63353 57.98 0.5571
20 -47.42670 0.300
21 49.31990 10.689 1.76385 48.49 0.5589
22 -47.46320 1.500 1.61266 44.46 0.5640
23 89.59080 0.300
24 53.88640 7.000 1.88202 37.22 0.5770
25* -1746.44720 12.139
26 -103.22090 1.500 1.82115 24.06 0.6237
27* 179.50540BF
[Aspheric data]
25th side κ=1.000,A4=-7.41276E-07,A6=1.64174E-09
A8=-9.05962E-13,A10=1.71045E-15,A12=0.00000E+00
Side 27 κ=1.000,A4=1.28875E-05,A6=4.32796E-10
A8=1.14166E-11,A10=-1.22201E-14,A12=0.00000E+00
[Variable interval data for close-up shooting]
Infinity focus state Intermediate distance focus state Close range focus state
f=50.353 β=-0.033 β=-0.135
D11 9.368 7.591 2.315
[Lens group data]
Group starting plane focal length
G1 1 201.517
G2 12 67.247
[Conditional expression corresponding value]
<Positive lens L25 (fP2=37.071)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.013
Conditional expression (2) νdP2=57.98
Conditional expression (3), (3-1) θgFP2=0.5571
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0127
Conditional expression (5) fP2/fR=0.611
Conditional expression (6) fP2/f=0.736
Conditional expression (7) DP2=10.628

FIG. 8(A) is a diagram showing various aberrations of the optical system according to the fourth example when focusing on infinity. FIG. 8(B) is a diagram showing various aberrations of the optical system according to the fourth example when focusing on an intermediate distance. FIG. 8C is a diagram showing various aberrations when the optical system according to the fourth example is focused at a short distance (close range). From the various aberration diagrams, it can be seen that the optical system according to the fourth example has various aberrations well corrected and has excellent imaging performance.

(Fifth example)
The fifth example will be explained using FIGS. 9 to 10 and Table 5. FIG. 9 is a diagram showing the lens configuration of the optical system according to the fifth example of the present embodiment in a focused state at infinity. The optical system LS (5) according to the fifth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. and a third lens group G3 having a high power. When focusing from an object at infinity to an object at a short distance (finite distance), the second lens group G2 moves toward the object along the optical axis. The aperture stop S is arranged within the third lens group G3.

The first lens group G1 includes, in order from the object side, a positive meniscus lens L11 with a convex surface facing the object side, a biconvex positive lens L12, a biconvex positive lens L13, and a biconcave negative lens. A cemented lens consisting of L14.

The second lens group G2 is composed of a cemented lens consisting of a positive meniscus lens L21 with a concave surface facing the object side and a biconcave negative lens L22 arranged in order from the object side.

The third lens group G3 includes a cemented lens consisting of a biconvex positive lens L31, a biconvex positive lens L32, a biconcave negative lens L33, and a biconvex positive lens arranged in order from the object side. L34, a cemented lens consisting of a biconcave negative lens L35 and a biconvex positive lens L36, and a cemented lens consisting of a biconcave negative lens L37 and a biconvex positive lens L38. An aperture stop S is arranged between the negative lens L33 (of the cemented lens) and the positive lens L34 in the third lens group G3. An image plane I is arranged on the image side of the third lens group G3. In this embodiment, the positive lens L34 of the third lens group G3 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like.

In this example, a positive meniscus lens L11, a positive lens L12, a cemented lens consisting of a positive lens L13 and a negative lens L14, a cemented lens consisting of a positive meniscus lens L21 and a negative lens L22, a positive lens L31, and a positive lens The cemented lens L32 and the negative lens L33 constitute a front group GF arranged closer to the object side than the aperture stop S. A positive lens L34, a cemented lens including a negative lens L35 and a positive lens L36, and a cemented lens including a negative lens L37 and a positive lens L38 constitute a rear group GR disposed closer to the image side than the aperture stop S.

Table 5 below lists the values of the specifications of the optical system according to the fifth example.

(Table 5)
[Overall specifications]
f 101.665
FNO 1.449
2ω 23.912
Y 21.600
TL 150.819
BF 39.283
fF 279.420
fR 68.576
[Lens specifications]
Surface number R D nd νd θgF
1 203.34970 5.072 1.59349 67.00 0.5366
2 2438.74280 0.100
3 111.38720 8.451 1.49782 82.57 0.5386
4 -626.28530 0.100
5 68.22960 12.204 1.49782 82.57 0.5386
6 -226.28870 3.500 1.72047 34.71 0.5834
7 187.96140 D7 (variable)
8 -152.19040 4.000 1.65940 26.87 0.6327
9 -79.15420 2.500 1.48749 70.32 0.5291
10 48.04460 D10 (variable)
11 63.07640 7.100 2.00100 29.13 0.5995
12 -434.36210 0.100
13 186.16830 7.516 1.65160 58.57 0.5416
14 -54.90260 1.800 1.69895 30.13 0.6021
15 29.45820 5.586
16 ∞ 1.600 (Aperture S)
17 130.39990 6.550 1.65240 55.27 0.5607
18 -42.75690 0.100
19 -42.89830 1.600 1.72047 34.71 0.5834
20 24.60610 7.766 1.77250 49.62 0.5518
21 -2376.38190 4.130
22 -48.65100 1.800 1.58144 40.98 0.5763
23 117.70920 5.197 2.00100 29.13 0.5995
24 -57.07940BF
[Variable interval data for close-up shooting]
Infinity focus state Intermediate distance focus state Close range focus state
f=101.66538 β=-0.03333 β=-0.13367
D7 7.73518 10.65475 19.73518
D10 17.02913 14.10956 5.02913
[Lens group data]
Group starting plane focal length
G1 1 91.71758
G2 8 -80.46818
G3 11 78.44227
[Conditional expression corresponding value]
<Positive lens L34 (fP2=50.103)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.013
Conditional expression (2) νdP2=55.27
Conditional expression (3), (3-1) θgFP2=0.5607
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0118
Conditional expression (5) fP2/fR=0.731
Conditional expression (6) fP2/f=0.493
Conditional expression (7) DP2=6.550

FIG. 10(A) is a diagram showing various aberrations of the optical system according to the fifth embodiment when focusing on infinity. FIG. 10(B) is a diagram showing various aberrations of the optical system according to the fifth embodiment when focusing on an intermediate distance. FIG. 10C is a diagram showing various aberrations when the optical system according to the fifth example is focused at a short distance (close range). From the various aberration diagrams, it can be seen that the optical system according to the fifth example has various aberrations well corrected and has excellent imaging performance.

(6th example)
The sixth example will be explained using FIGS. 11 to 12 and Table 6. FIG. 11 is a diagram showing the lens configuration of the optical system according to the sixth example of the present embodiment in an infinity focused state. The optical system LS (6) according to the sixth embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a strong refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a negative refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions indicated by arrows in FIG. 11, respectively. The aperture stop S is arranged between the second lens group G2 and the third lens group G3.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, a biconcave negative lens L13, and a negative meniscus lens L12 with a convex surface facing the object side. It is composed of a convex positive lens L14. The negative meniscus lens L11 has an aspherical lens surface on the image side. The negative meniscus lens L12 has an aspherical lens surface on the image side.

The second lens group G2 is a cemented lens consisting of a biconvex positive lens L21, a negative meniscus lens L22 with a convex surface facing the object side, and a positive meniscus lens L23 with a convex surface facing the object side, arranged in order from the object side. It consists of and. The aperture stop S is arranged near the image side of the positive meniscus lens L23, and moves together with the second lens group G2 during zooming.

The third lens group G3 is composed of a cemented lens consisting of a negative meniscus lens L31 with a convex surface facing the object side and a biconvex positive lens L32, arranged in order from the object side, and a biconvex positive lens L33. be done. In this embodiment, the positive lens L33 of the third lens group G3 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like. The positive lens L32 has an aspherical lens surface on the image side.

The fourth lens group G4 is composed of a biconcave negative lens L41. When focusing from an object at infinity to an object at a short distance (finite distance), the fourth lens group G4 moves toward the image side along the optical axis.

The fifth lens group G5 is composed of a negative meniscus lens L51 with a concave surface facing the object side. An image plane I is arranged on the image side of the fifth lens group G5. The negative meniscus lens L51 has an aspherical lens surface on the image side.

In this embodiment, a cemented lens consisting of a negative meniscus lens L11, a negative meniscus lens L12, a negative lens L13, a positive lens L14, a positive lens L21, a negative meniscus lens L22, and a positive meniscus lens L23 has an aperture diaphragm. A front group GF is arranged closer to the object than S. A cemented lens consisting of a negative meniscus lens L31 and a positive lens L32, a positive lens L33, a negative lens L41, and a negative meniscus lens L51 constitute a rear group GR arranged closer to the image side than the aperture stop S.

Table 6 below lists the values of the specifications of the optical system according to the sixth embodiment.

(Table 6)
[Overall specifications]
Magnification ratio = 2.018
WMT
f 14.420 20.000 29.100
FNO 4.079 4.079 4.079
2ω 115.788 91.418 67.717
Y 20.500 20.500 20.500
TL 108.287 100.728 97.082
BF 15.000 20.785 26.388
fF 11.448 16.095 25.109
fR -147.070 -170.944 -261.654
[Lens specifications]
Surface number R D nd νd θgF
1 62.74780 3.000 1.69370 53.32 0.5474
2* 15.93720 5.662
3 31.45490 2.900 1.69370 53.32 0.5474
4* 21.64240 10.575
5 -79.52230 1.900 1.49782 82.57 0.5386
6 28.83090 0.100
7 27.92810 5.864 1.60094 35.56 0.5849
8 -574.63420 D8 (variable)
9 25.01930 3.831 1.59349 67.00 0.5358
10 -1097.79190 0.352
11 14.26720 1.200 1.88300 40.66 0.5668
12 9.29540 4.520 1.52529 49.41 0.5596
13 79.41400 2.500
14 ∞ D14 (variable) (aperture S)
15 270.87700 1.100 1.82561 36.05 0.5840
16 9.81980 3.786 1.49782 82.57 0.5386
17* -596.39240 3.148
18 34.32010 5.700 1.68348 54.80 0.5501
19 -19.72160 D19 (variable)
20 -21.48630 1.000 1.58502 55.62 0.5488
21 62.03200 D21 (variable)
22 -63.98190 1.200 1.51680 63.88 0.5360
23* -71.49970BF
[Aspheric data]
2nd side κ=0.000,A4=2.99E-06,A6=1.56E-08
A8=-1.09E-10,A10=1.79E-13,A12=0.00E+00
4th side κ=0.000,A4=3.29E-05,A6=1.10E-08
A8=4.63E-10,A10=-1.24E-12,A12=3.11E-15
Side 17 κ=1.000,A4=7.88E-06,A6=-6.14E-07
A8=1.05E-08,A10=-2.69E-10,A12=0.00E+00
23rd side κ=1.000,A4=3.06E-05,A6=2.73E-08
A8=-4.72E-11,A10=7.08E-13,A12=0.00E+00
[Variable interval data during variable magnification shooting]
WMT
D8 26.267 13.125 1.5
D14 1.500 1.618 1.697
D19 2.000 2.718 4.261
D21 5.182 4.144 4.897
[Lens group data]
Group starting plane focal length
G1 1 -22.500
G2 9 23.100
G3 15 28.500
G4 20 -27.200
G5 22 -1245.200
[Conditional expression corresponding value]
<Positive lens L33 (fP2=19.145)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.041
Conditional expression (2) νdP2=54.80
Conditional expression (3), (3-1) θgFP2=0.5501
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0004
Conditional expression (5) fP2/fR=-0.130
Conditional expression (6) fP2/f=1.328
Conditional expression (7) DP2=5.700

FIG. 12(A) is a diagram of various aberrations when focusing on infinity in the wide-angle end state of the optical system according to the sixth embodiment. FIG. 12(B) is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of the optical system according to the sixth embodiment. FIG. 12C is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the optical system according to the sixth embodiment. From the various aberration diagrams, it can be seen that the optical system according to the sixth example has various aberrations well corrected and has excellent imaging performance.

(Seventh Example)
The seventh example will be explained using FIGS. 13 to 14 and Table 7. FIG. 13 is a diagram showing a lens configuration of the optical system according to the seventh example of the present embodiment in an infinity focused state. The optical system LS (7) according to the seventh embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions shown by the arrows in FIG. 13, respectively. The aperture stop S is arranged between the second lens group G2 and the third lens group G3.

The first lens group G1 is composed of a cemented lens consisting of a negative meniscus lens L11 with a convex surface facing the object side and a positive meniscus lens L12 with a convex surface facing the object side, which are arranged in order from the object side.

The second lens group G2 includes, in order from the object side, a biconcave negative lens L21, a biconcave negative lens L22, and a positive meniscus lens L23 with a convex surface facing the object side. The negative meniscus lens L21 has an aspherical lens surface on the object side. The negative lens L21 has an aspherical lens surface on the image side.

The third lens group G3 includes a cemented lens consisting of a biconvex positive lens L31, a biconvex positive lens L32, and a biconcave negative lens L33 arranged in order from the object side, and a cemented lens with the convex surface facing the object side. It is composed of a cemented lens consisting of a negative meniscus lens L34 and a positive meniscus lens L35 with a convex surface facing the object side. The aperture stop S is arranged near the object side of the positive lens L31, and moves together with the third lens group G3 during zooming. In this embodiment, the positive lens L31 of the third lens group G3 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like. The positive lens L31 has an aspherical lens surface on the object side.

The fourth lens group G4 includes a negative meniscus lens L41 with a concave surface facing the object side and a biconvex positive lens L42, which are arranged in order from the object side. When focusing from an object at infinity to a short distance (finite distance) object, the fourth lens group G4 moves along the optical axis toward the object side, and the fifth lens group G5 moves along the optical axis toward the image side. do. The positive lens L42 has an aspherical lens surface on the image side.

The fifth lens group G5 is composed of a biconcave negative lens L51. An image plane I is arranged on the image side of the fifth lens group G5. The positive lens L51 has an aspherical lens surface on the image side.

In this embodiment, a cemented lens consisting of a negative meniscus lens L11 and a positive meniscus lens L12, a negative lens L21, a negative lens L22, and a positive meniscus lens L23 are arranged in a front group disposed closer to the object side than the aperture stop S. Configure GF. A cemented lens consisting of a positive lens L31, a positive lens L32 and a negative lens L33, a cemented lens consisting of a negative meniscus lens L34 and a positive meniscus lens L35, a negative meniscus lens L41, a positive lens L42, and a negative lens L51, A rear group GR is arranged closer to the image side than the aperture stop S.

Table 7 below lists the values of the specifications of the optical system according to the seventh example.

(Table 7)
[Overall specifications]
Magnification ratio = 2.747
WMT
f 24.720 50.011 67.898
FNO 4.074 4.107 4.075
2ω 84.838 44.346 32.369
Y 20.735 21.600 21.600
TL 122.000 132.823 150.965
BF 24.245 49.372 55.721
fF -35.120 -41.087 -52.774
fR 32.395 33.090 34.250
[Lens specifications]
Surface number R D nd νd θgF
1 79.38040 2.150 1.84666 23.80 0.6215
2 51.02390 8.034 1.75500 52.33 0.5475
3 1073.05060 D3 (variable)
4 -787.39720 1.800 1.65550 46.34 0.5651
5* 15.02170 8.908
6 -58.26290 1.350 1.49782 82.57 0.5138
7 54.06630 0.100
8 30.99440 4.650 1.77396 24.31 0.6142
9 194.90020 D9 (variable)
10 ∞ 1.500 (Aperture S)
11* 32.88300 3.765 1.68348 54.80 0.5501
12 -482.16640 0.102
13 20.12780 4.081 1.59319 67.90 0.5440
14 -99.80710 1.500 1.76634 38.61 0.5791
15 25.27260 0.342
16 34.24310 2.000 1.95375 32.33 0.5916
17 14.97810 3.842 1.56992 38.72 0.5789
18 73.96770 D9 (variable)
19 -17.50130 0.900 1.80415 28.31 0.6015
20 -23.09180 0.100
21 77.91830 6.224 1.59201 67.02 0.5358
22* -22.62830 D22 (variable)
23 -344.21280 0.900 1.63563 48.44 0.5614
24* 92.95460BF
[Aspheric data]
5th side κ=0.000,A4=2.68E-05,A6=3.48E-08
A8=1.69E-10,A10=0.00E+00,A12=0.00E+00
Side 11 κ=1.000,A4=-9.83E-07,A6=-4.69E-09
A8=2.28E-10,A10=-1.34E-12,A12=0.00E+00
Side 22 κ=1.000,A4=2.57E-05,A6=-7.85E-09
A8=1.82E-10,A10=-5.72E-13,A12=0.00E+00
24th side κ=1.000,A4=-2.86E-06,A6=3.10E-08
A8=-9.24E-11,A10=2.91E-13,A12=0.00E+00
[Variable interval data during variable magnification shooting]
WMT
D3 2.143 14.848 31.406
D9 24.905 6.054 3.035
D18 8.153 5.745 6.556
D22 10.307 4.557 2.000
[Lens group data]
Group starting plane focal length
G1 1 121.600
G2 4 -25.300
G3 10 43.600
G4 19 40.800
G5 23 -115.100
[Conditional expression corresponding value]
<Positive lens L31 (fP2=45.174)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.041
Conditional expression (2) νdP2=54.80
Conditional expression (3), (3-1) θgFP2=0.5501
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0004
Conditional expression (5) fP2/fR=1.394
Conditional expression (6) fP2/f=1.827
Conditional expression (7) DP2=3.765

FIG. 14(A) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the optical system according to the seventh embodiment. FIG. 14(B) is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of the optical system according to the seventh embodiment. FIG. 14C is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the optical system according to the seventh embodiment. From the various aberration diagrams, it can be seen that the optical system according to the seventh example has various aberrations well corrected and has excellent imaging performance.

(Eighth example)
The eighth example will be explained using FIGS. 15 to 16 and Table 8. FIG. 15 is a diagram showing the lens configuration of the optical system according to the eighth example of the present embodiment in a focused state at infinity. The optical system LS (8) according to the eighth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the second lens group G2 and the fourth lens group G4 move in the directions shown by the arrows in FIG. 15, respectively. The aperture stop S is arranged between the second lens group G2 and the third lens group G3.

The first lens group G1 includes a cemented lens consisting of a negative meniscus lens L11 with a convex surface facing the object side and a positive biconvex lens L12 arranged in order from the object side, and a positive meniscus lens L13 with a convex surface facing the object side. It consists of and.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a positive meniscus lens L23 with a convex surface facing the object side, and a biconcave negative lens L22 with a convex surface facing the object side. It is composed of a concave negative lens L24.

The third lens group G3 includes, in order from the object side, a biconvex positive lens L31, a positive meniscus lens L32 with a convex surface facing the object side, a positive meniscus lens L33 with a convex surface facing the object side, and a positive meniscus lens L33 with a convex surface facing the object side. It is composed of a concave negative lens L34, and a cemented lens consisting of a biconvex positive lens L35 and a biconcave negative lens L36. The aperture stop S is arranged near the object side of the positive lens L31, and is fixed to the image plane I together with the third lens group G3 during zooming.
In this embodiment, the positive meniscus lens L32 of the third lens group G3 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like.

The fourth lens group G4 is a cemented lens consisting of a biconvex positive lens L41, a negative meniscus lens L42 with a convex surface facing the object side, and a positive meniscus lens L43 with a convex surface facing the object side, arranged in order from the object side. It consists of and. When focusing from an object at infinity to an object at a short distance (finite distance), the fourth lens group G4 moves toward the object side along the optical axis.

The fifth lens group G5 includes, in order from the object side, a negative meniscus lens L51 with a convex surface facing the object side, a cemented lens consisting of a biconvex positive lens L52, a biconcave negative lens L53, and a cemented lens on the image side. It is composed of a plano-concave negative lens L54 with a concave surface facing toward the object side, a positive biconvex lens L55, and a positive meniscus lens L56 with a convex surface facing the object side. The cemented lens consisting of the positive lens L52 and the negative lens L53 of the fifth lens group G5 and the plano-concave negative lens L54 constitute an anti-vibration lens group that is movable in a direction perpendicular to the optical axis. The displacement of the imaging position (image blur on the image plane I) is corrected. An image plane I is arranged on the image side of the fifth lens group G5.

In this embodiment, a cemented lens consisting of a negative meniscus lens L11 and a positive lens L12, a positive meniscus lens L13, a negative meniscus lens L21, a negative lens L22, a positive meniscus lens L23, and a negative lens L24 are an aperture diaphragm. A front group GF is arranged closer to the object than S. From a positive lens L31, a positive meniscus lens L32, a positive meniscus lens L33, a negative lens L34, a cemented lens consisting of a positive lens L35 and a negative lens L36, a positive lens L41, a negative meniscus lens L42, and a positive meniscus lens L43. A cemented lens consisting of a negative meniscus lens L51, a cemented lens consisting of a positive lens L52 and a negative lens L53, a negative lens L54, a positive lens L55, and a positive meniscus lens L56 are arranged on the image side of the aperture stop S. This constitutes the rear group GR.

Table 8 below lists the values of the specifications of the optical system according to the eighth example.

(Table 8)
[Overall specifications]
Magnification ratio = 2.745
WMT
f 71.400 140.000 196.000
FNO 2.865 2.937 2.862
2ω 33.690 17.104 12.209
Y 21.600 21.600 21.600
TL 245.885 245.885 245.885
BF 53.818 53.818 53.818
fF -86.916 -153.374 -238.593
fR 66.539 63.400 66.539
[Lens specifications]
Surface number R D nd νd θgF
1 126.09970 2.800 1.95000 29.37 0.6002
2 88.80350 9.900 1.49782 82.57 0.5386
3 -1065.60390 0.100
4 92.38010 7.700 1.43385 95.23 0.5386
5 704.74520 D5 (variable)
6 67.87460 2.400 1.71999 50.27 0.5527
7 33.37900 10.250
8 -126.53630 2.000 1.61800 63.34 0.5410
9 103.06580 2.000
10 55.28910 4.400 1.84666 23.78 0.6192
11 196.15270 3.550
12 -72.78480 2.200 1.60300 65.44 0.5389
13 375.90450 D13 (variable)
14 ∞ 2.500 (Aperture S)
15 554.79490 3.700 1.83481 42.73 0.5648
16 -131.90030 0.200
17 87.53050 3.850 1.68348 54.80 0.5501
18 700.00000 0.200
19 57.26450 4.900 1.49782 82.57 0.5386
20 1785.19150 1.814
21 -113.79650 2.200 2.00100 29.13 0.5995
22 163.75720 4.550
23 106.94210 5.750 1.90265 35.72 0.5804
24 -66.90690 2.200 1.58144 40.98 0.5763
25 41.94060 D25 (variable)
26 56.09740 4.800 1.49782 82.57 0.5386
27 -194.54090 0.100
28 44.63960 2.000 1.95000 29.37 0.6002
29 28.18890 5.550 1.59319 67.90 0.5440
30 159.43210 D30 (variable)
31 53.09320 1.800 1.80400 46.60 0.5575
32 31.35420 5.150
33 105.97250 3.350 1.84666 23.78 0.6192
34 -105.97280 1.600 1.71999 50.27 0.5527
35 42.82450 2.546
36 ∞ 1.600 1.95375 32.32 0.5901
37 69.08980 3.750
38 103.22750 3.850 1.59319 67.90 0.5440
39 -174.73470 0.150
40 48.66080 3.900 1.71999 50.27 0.5527
41 148.20170 BF
[Variable interval data during variable magnification shooting]
WMT
D5 3.100 35.817 51.100
D13 50.493 17.776 2.493
D25 17.135 14.346 17.135
D30 2.030 4.819 2.030
[Lens group data]
Group starting plane focal length
G1 1 144.006
G2 6 -45.572
G3 14 93.764
G4 26 59.111
G5 31 -110.599
[Conditional expression corresponding value]
<Positive meniscus lens L32 (fP2=145.997)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.041
Conditional expression (2) νdP2=54.80
Conditional expression (3), (3-1) θgFP2=0.5501
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0004
Conditional expression (5) fP2/fR=2.194
Conditional expression (6) fP2/f=2.045
Conditional expression (7) DP2=3.850

FIG. 16(A) is a diagram of various aberrations when focusing on infinity in the wide-angle end state of the optical system according to the eighth embodiment. FIG. 16(B) is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of the optical system according to the eighth embodiment. FIG. 16C is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the optical system according to the eighth embodiment. From the various aberration diagrams, it can be seen that the optical system according to the eighth example has various aberrations well corrected and has excellent imaging performance.

(9th example)
A ninth example will be described using FIGS. 17 to 18 and Table 9. FIG. 17 is a diagram showing the lens configuration of the optical system according to the ninth example of the present embodiment in a focused state at infinity. The optical system LS (9) according to the ninth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a negative refractive power, which are arranged in order from the object side. and a third lens group G3 having a high power. When focusing from an object at infinity to an object at a short distance (finite distance), the first lens group G1 and the second lens group G2 move toward the object side along the optical axis by different amounts of movement. The aperture stop S is disposed between the first lens group G1 and the second lens group G2.

The first lens group G1 is a junction consisting of a biconcave negative lens L11, a biconvex positive lens L12, a biconvex positive lens L13, and a biconcave negative lens L14, arranged in order from the object side. and a negative meniscus lens L15 with a convex surface facing the object side. The aperture stop S is arranged near the image side of the negative meniscus lens L15, and moves together with the first lens group G1 during focusing. The negative lens L11 has an aspherical lens surface on the image side.

The second lens group G2 includes a biconvex positive lens L21 and a negative meniscus lens L22 with a convex surface facing the object side, which are arranged in order from the object side. In this embodiment, the positive lens L21 of the second lens group G2 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like.

The third lens group G3 includes a positive meniscus lens L31 with a convex surface facing the object side, a negative meniscus lens L32 with a concave surface facing the object side, and a biconvex positive lens L33, which are arranged in order from the object side. configured. An image plane I is arranged on the image side of the third lens group G3. The positive meniscus lens L31 has an aspherical lens surface on the image side. A cover glass CV is disposed between the third lens group G3 and the image plane I.

In this embodiment, a negative lens L11, a positive lens L12, a cemented lens consisting of a positive lens L13 and a negative lens L14, and a negative meniscus lens L15 connect the front group GF, which is arranged closer to the object side than the aperture stop S. Configure. The positive lens L21, the negative meniscus lens L22, the positive meniscus lens L31, the negative meniscus lens L32, and the positive lens L33 constitute a rear group GR arranged closer to the image side than the aperture stop S.

Table 9 below lists the values of the specifications of the optical system according to the ninth embodiment.

(Table 9)
[Overall specifications]
f 58.200
FNO 2.834
2ω 40.540
Y 21.700
TL 71.504
BF 0.100
fF 185.637
fR 41.887
[Lens specifications]
Surface number R D nd νd θgF
1 -54.41680 1.200 1.73077 40.51 0.5727
2* 93.79380 1.000
3 49.58010 3.982 1.95375 32.33 0.5905
4 -46.84640 1.409
5 58.45600 4.042 1.59319 67.90 0.5440
6 -28.62670 1.200 1.73800 32.26 0.5899
7 65.78940 0.557
8 42.63400 1.200 1.80518 25.45 0.6157
9 26.81180 4.439
10 ∞ D10 (variable) (aperture S)
11 65.15670 3.538 1.62731 59.30 0.5583
12 -33.71110 0.200
13 32.99860 1.200 1.68893 31.16 0.5993
14 23.75820 D14 (variable)
15 40.89980 1.702 1.51680 64.13 0.5357
16* 41.52740 17.999
17 -17.43560 1.512 1.72916 54.61 0.5443
18 -156.01360 0.200
19 164.98860 4.192 1.95375 32.33 0.5905
20 -80.90270 12.307
21 ∞ 1.600 1.51680 64.13 0.5357
22 ∞ BF
[Aspheric data]
2nd side κ=1.000,A4=1.38723E-05,A6=1.77268E-09
A8=-8.41163E-12,A10=0.00000E+00,A12=0.00000E+00
Side 16 κ=1.000,A4=-1.13951E-05,A6=-7.02007E-09
A8=-1.01527E-10,A10=0.00000E+00,A12=0.00000E+00
[Variable interval data for close-up shooting]
Infinity focus state Intermediate distance focus state Close range focus state
f=58.200 β=-0.500 β=-1.000
D10 6.636 6.762 7.025
D14 1.292 18.125 34.903
[Lens group data]
Group starting plane focal length
G1 1 185.637
G2 11 47.768
[Conditional expression corresponding value]
<Positive lens L21 (fP2=35.911)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.016
Conditional expression (2) νdP2=59.30
Conditional expression (3), (3-1) θgFP2=0.5583
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0161
Conditional expression (5) fP2/fR=0.857
Conditional expression (6) fP2/f=0.617
Conditional expression (7) DP2=3.538

FIG. 18(A) is a diagram showing various aberrations of the optical system according to the ninth embodiment when focusing on infinity. FIG. 18(B) is a diagram showing various aberrations of the optical system according to the ninth embodiment when focusing on an intermediate distance. FIG. 18C is a diagram showing various aberrations when the optical system according to the ninth embodiment is focused at a short distance (close range). From the various aberration diagrams, it can be seen that the optical system according to the ninth example has various aberrations well corrected and has excellent imaging performance.

(10th example)
A tenth example will be described using FIGS. 19 to 20 and Table 10. FIG. 19 is a diagram showing the lens configuration of the optical system according to the tenth example of the present embodiment in the infinity focus state. The optical system LS (10) according to the tenth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a strong refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions shown by the arrows in FIG. 19, respectively. The aperture stop S is arranged between the second lens group G2 and the third lens group G3.

The first lens group G1 includes a cemented lens consisting of a negative meniscus lens L11 with a convex surface facing the object side and a positive biconvex lens L12 arranged in order from the object side, and a positive meniscus lens L13 with a convex surface facing the object side. and a positive meniscus lens L14 with a convex surface facing the object side.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a biconcave positive lens L23, and a biconcave negative lens L21. It is composed of a lens L24.

The third lens group G3 includes, in order from the object side, a biconvex positive lens L31, a negative meniscus lens L32 with a convex surface facing the object side, a negative meniscus lens L33 with a convex surface facing the object side, and a biconvex lens L31. and a cemented lens consisting of a positive lens L34 having a shape. The third lens group G3 constitutes an anti-vibration lens group that is movable in a direction perpendicular to the optical axis, and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like. The aperture stop S is arranged near the object side of the positive lens L31, and moves together with the third lens group G3 during zooming. In this embodiment, the positive lens L34 of the third lens group G3 corresponds to a positive lens that satisfies conditional expressions (1) to (4) and the like. The positive lens L31 has aspherical lens surfaces on both sides.

The fourth lens group G4 is composed of a cemented lens consisting of a biconvex positive lens L41 and a biconcave negative lens L42, which are arranged in order from the object side. When focusing from an object at infinity to an object at a short distance (finite distance), the fourth lens group G4 moves toward the image side along the optical axis.

The fifth lens group G5 is composed of a cemented lens consisting of a biconvex positive lens L51 and a negative meniscus lens L52 with a concave surface facing the object side, which are arranged in order from the object side. An image plane I is arranged on the image side of the fifth lens group G5. The positive lens L51 has an aspherical lens surface on the object side. An optical filter FL is disposed between the fifth lens group G5 and the image plane I. As the optical filter FL, for example, an NC filter (neutral color filter), a color filter, a polarizing filter, an ND filter (neutral density filter), an IR filter (infrared cut filter), etc. are used.

In this embodiment, a cemented lens consisting of a negative meniscus lens L11 and a positive lens L12, a positive meniscus lens L13, a positive meniscus lens L14, a negative meniscus lens L21, a negative lens L22, a positive lens L23, and a negative lens L24 are used. constitutes a front group GF arranged closer to the object side than the aperture stop S. A cemented lens consisting of a positive lens L31, a negative meniscus lens L32, a negative meniscus lens L33 and a positive lens L34, a cemented lens consisting of a positive lens L41 and a negative lens L42, and a cemented lens consisting of a positive lens L51 and a negative meniscus lens L52. constitute a rear group GR arranged closer to the image side than the aperture stop S.

Table 10 below lists the values of the specifications of the optical system according to the tenth example.

(Table 10)
[Overall specifications]
Variable power ratio = 78.219
WMT
f 4.430 13.187 346.510
FNO 2.776 3.514 6.427
2ω 86.496 33.453 1.299
Y 3.350 4.000 4.000
TL 131.989 135.543 198.671
BF 0.400 0.400 0.400
fF -12.060 -16.645 -173.557
fR 25.234 30.446 -82.441
[Lens specifications]
Surface number R D nd νd θgF
1 568.78065 2.300 1.78590 44.17 0.5629
2 86.67383 7.500 1.43700 95.10 0.5353
3 -310.32964 0.100
4 85.84592 6.100 1.49782 82.57 0.5409
5 1850.64210 0.100
6 91.59441 4.700 1.49782 82.57 0.5409
7 305.14505 D7 (variable)
8 63.54828 1.000 1.83481 42.73 0.5651
9 11.98416 5.700
10 -21.15154 0.800 1.83481 42.73 0.5651
11 213.93350 0.100
12 27.96942 3.150 1.92286 20.88 0.6391
13 -40.84385 1.090
14 -19.86982 0.700 1.69680 55.52 0.5436
15 106.15599 1.750
16 ∞ D16 (variable) (aperture S)
17* 12.12280 3.000 1.55332 71.68 0.5404
18* -88.75564 2.600
19 23.32880 1.000 1.90366 31.31 0.5952
20 11.81128 1.750
21 17.35800 0.500 1.83400 37.18 0.5783
22 9.64416 3.500 1.62731 59.30 0.5583
23 -62.13514 D23 (variable)
24 292.73551 2.500 1.53172 48.78 0.5626
25 -90.00320 0.500 1.49782 82.57 0.5409
26 16.96477 D26 (variable)
27* 19.66824 2.100 1.58913 61.22 0.5407
28 -27.01885 0.500 1.71736 29.57 0.6039
29 -58.11835 D29 (variable)
30 ∞ 0.210 1.51680 63.88 0.5369
31 ∞ 0.850
32 ∞ 0.500 1.51680 63.88 0.5369
33 ∞ BF
[Aspheric data]
Side 17 κ=1.000,A4=-3.31986E-05,A6=-5.33039E-07
A8=1.22245E-08,A10=0.00000E+00,A12=0.00000E+00
Side 18 κ=1.000,A4=4.28536E-05,A6=-5.76368E-07
A8=2.04479E-08,A10=-7.59709E-11,A12=0.00000E+00
Page 27 κ=1.000,A4=-2.40095E-05,A6=4.06551E-07
A8=-7.66459E-09,A10=0.00000E+00,A12=0.00000E+00
[Variable interval data during variable magnification shooting]
WMT
D7 0.750 29.140 96.663
D16 59.086 27.196 1.750
D23 1.000 10.405 20.470
D26 9.956 8.504 23.313
D29 7.197 6.298 2.475
[Lens group data]
Group starting plane focal length
G1 1 121.707
G2 8 -10.214
G3 17 20.075
G4 24 -36.977
G5 27 26.912
[Conditional expression corresponding value]
<Positive lens L34 (fP2=13.563)>
Conditional expression (1)
ndP2-(2.015-0.0068×νdP2)=0.016
Conditional expression (2) νdP2=59.30
Conditional expression (3), (3-1) θgFP2=0.5583
Conditional expression (4), (4-1)
θgFP2-(0.6418-0.00168×νdP2)=0.0161
Conditional expression (5) fP2/fR=0.537
Conditional expression (6) fP2/f=3.062
Conditional expression (7) DP2=3.500

FIG. 20(A) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the optical system according to the tenth embodiment. FIG. 20(B) is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of the optical system according to the tenth embodiment. FIG. 20C is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the optical system according to the tenth embodiment. From the various aberration diagrams, it can be seen that the optical system according to the tenth example has various aberrations well corrected and has excellent imaging performance.

According to each of the embodiments described above, in correcting chromatic aberration, it is possible to realize an optical system in which the secondary spectrum is well corrected in addition to the primary achromatization.

Here, each of the above embodiments shows one specific example of the present invention, and the present invention is not limited thereto.

Note that the following content can be appropriately adopted within a range that does not impair the optical performance of the optical system of this embodiment.

A focusing lens group shall refer to a portion having at least one lens separated by an air gap that changes during focusing. That is, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to form a focusing lens group that focuses from an object at infinity to an object at a short distance. This focusing lens group can also be applied to autofocus, and is also suitable for driving a motor (using an ultrasonic motor or the like) for autofocus.

In the eighth embodiment and the tenth embodiment, configurations having an anti-vibration function are shown, but the present application is not limited to this, and a configuration without an anti-vibration function is also possible. Furthermore, other embodiments that do not have a vibration-proofing function can also be configured to have a vibration-proofing function.

The lens surface may be formed as a spherical surface, a flat surface, or an aspherical surface. It is preferable that the lens surface is spherical or flat because it facilitates lens processing and assembly adjustment and prevents deterioration of optical performance due to errors in processing and assembly adjustment. Further, even if the image plane shifts, there is little deterioration in depiction performance, which is preferable.

When the lens surface is aspherical, the aspherical surface can be an aspherical surface made by grinding, a glass molded aspherical surface made by molding glass into an aspherical shape, or a composite aspherical surface made by molding resin into an aspherical shape on the glass surface. Either is fine. Further, the lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

Each lens surface may be coated with an antireflection film having high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve optical performance with high contrast. This reduces flare and ghosting, making it possible to achieve high optical performance with high contrast.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group I Image plane S Aperture diaphragm

Claims (9)

It has an aperture stop and a positive lens that is placed on the image side of the aperture stop and satisfies the following conditional expression,
0.000<ndP2-(2.015-0.0068×νdP2)
52.40<νdP2<65.00
0.545<θgFP2
0.0004≦θgFP2-(0.6418-0.00168×νdP2)
DP2≧3.500 [mm]
However, ndP2: the refractive index of the positive lens for the d-line νdP2: the Abbe number of the positive lens with respect to the d-line θgFP2: the partial dispersion ratio of the positive lens, and the refractive index of the positive lens for the g-line is ngP2 When the refractive index of the positive lens for the F-line is nFP2, and the refractive index of the positive lens for the C-line is nCP2, it is defined by the following formula: θgFP2=(ngP2-nFP2)/(nFP2-nCP2)
DP2: Thickness of the positive lens on the optical axis In an optical system, the lens disposed closest to the image side has negative refractive power. consisting of the aperture stop, a front group arranged on the object side of the aperture stop, and a rear group arranged on the image side of the aperture stop,
The optical system according to claim 1, wherein the rear group includes the positive lens and satisfies the following conditional expression.
-10.00<fP2/fR<10.00
However, fP2: Focal length of the positive lens; fR: Focal length of the rear group; if the optical system is a variable magnification optical system, the focal length of the rear group in the wide-angle end state; The optical system according to claim 1 or 2, wherein the positive lens satisfies the following conditional expression.
0.10<fP2/f<15.00
However, fP2: focal length of the positive lens f: focal length of the optical system; if the optical system is a variable magnification optical system, the focal length of the optical system in the wide-angle end state The optical system according to claim 1, wherein the positive lens satisfies the following conditional expression.
0.555<θgFP2 The optical system according to claim 1, wherein the positive lens satisfies the following conditional expression.
0.010<θgFP2-(0.6418-0.00168×νdP2) The optical system according to any one of claims 1 to 5, wherein the positive lens is a single lens or one of the two lenses in a cemented lens made by cementing two lenses. 7. The optical system according to claim 1, wherein at least one lens surface of the object-side lens surface and the image-side lens surface of the positive lens is in contact with air. The optical system according to claim 1, wherein the positive lens is a glass lens. An optical device comprising the optical system according to claim 1.

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