JP2023060137A - Optical system, optical device, and method of manufacturing optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system that is well corrected for various aberrations.

SOLUTION: An optical system LS provided herein comprises an aperture stop S and a negative lens (L15) located on the object side of the aperture stop S and configured to satisfy the following conditional expressions: ndN1+(0.01425×νdN1)<2.12, 18.0<νdN1<35.0, 0.702<θgFN1+(0.00316×νdN1), where ndN1 represents a refractive index of the negative lens for the d-ray, νdN1 represents an Abbe number of the negative lens for the d-ray, and θgFN1 represents a partial dispersion ratio of the negative lens, defined as: θgFN1=(ngN1-nFN1)/(nFN1-nCN1), where ngN1 represents a refractive index of the negative lens for the g-ray, nFN1 represents a refractive index of the negative lens for the F-ray, and nCN1 represents a refractive index of the negative lens for the C-ray.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to optical systems, optical instruments, and methods of manufacturing optical systems.

2. Description of the Related Art In recent years, image pickup elements used in image pickup apparatuses such as digital cameras and video cameras have increasingly high pixel counts. In addition to standard aberrations (single-wavelength aberrations) such as spherical aberration and coma, the photographic lens provided in an imaging device using such an image sensor also has good chromatic aberration so that the color of the image does not blur under a white light source. It is desired that the lens has a high resolving power and is corrected to . In particular, in the correction of chromatic aberration, it is desirable that the secondary spectrum be well corrected in addition to the primary achromatism. As means for correcting chromatic aberration, for example, a method using a resin material having anomalous dispersion is known (see, for example, Patent Document 1). As described above, with the recent increase in the number of pixels of an image sensor, there is a demand for a photographing lens in which various aberrations are well corrected.

JP 2016-194609 A

An optical system according to a first aspect has an aperture stop and a negative lens that satisfies the following conditional expression and is arranged closer to the object side than the aperture stop.
ndN1+(0.01425×νdN1)<2.12
18.0<νdN1<35.0
0.702<θgFN1+(0.00316×νdN1)
where ndN1: the refractive index of the negative lens for the d-line; νdN1: the Abbe number of the negative lens with respect to the d-line; θgFN1=(ngN1−nFN1)/(nFN1−nCN1) where nFN1 is the refractive index of the negative lens for the F line and nCN1 is the refractive index of the negative lens for the C line.

An optical instrument according to a second aspect includes the optical system described above.

In the method for manufacturing an optical system according to the third aspect, each lens is arranged in a lens barrel so as to have an aperture stop and a negative lens disposed on the object side of the aperture stop and satisfying the following conditional expression: Deploy.
ndN1+(0.01425×νdN1)<2.12
18.0<νdN1<35.0
0.702<θgFN1+(0.00316×νdN1)
where ndN1: the refractive index of the negative lens for the d-line; νdN1: the Abbe number of the negative lens with respect to the d-line; θgFN1=(ngN1−nFN1)/(nFN1−nCN1) where nFN1 is the refractive index of the negative lens for the F line and nCN1 is the refractive index of the negative lens for the C line.

FIG. 2 is a lens configuration diagram of the optical system according to the first example in an infinity focused state; 4A and 4B are various aberration diagrams in the infinity focused state of the optical system according to the first example. FIG. 10 is a lens configuration diagram of the optical system according to the second example in an infinity focused state; It is an aberration diagram in the infinity focus state of the optical system which concerns on 2nd Example. FIG. 11 is a lens configuration diagram of the optical system according to the third embodiment in an infinity focused state; 6(A), 6(B), and 6(C) respectively show the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the third embodiment when focusing on infinity. It is an aberration diagram. FIG. 11 is a lens configuration diagram of the optical system according to the fourth example in an infinity focused state; 8(A), 8(B), and 8(C) respectively show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system according to the fourth embodiment when focusing on infinity. It is an aberration diagram. FIG. 11 is a lens configuration diagram of the optical system according to the fifth embodiment in an infinity focused state; 10(A), 10(B), and 10(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the fifth embodiment, respectively, when focusing on infinity. It is an aberration diagram. FIG. 11 is a lens configuration diagram of the optical system according to the sixth embodiment in an infinity focused state; 12(A), 12(B), and 12(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the sixth embodiment, respectively, when focusing on infinity. It is an aberration diagram. FIG. 12 is a lens configuration diagram of the optical system according to the seventh embodiment in an infinity focused state; 14(A), 14(B), and 14(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the seventh embodiment, respectively, when focusing on infinity. It is an aberration diagram. It is a figure showing composition of a camera provided with an optical system concerning this embodiment. It is a flow chart which shows the manufacturing method of the optical system concerning this embodiment.

An optical system and an optical apparatus according to this embodiment will be described below with reference to the drawings. first,
A camera (optical device) having an optical system according to this embodiment will be described with reference to FIG. This camera 1 is a digital camera provided with an optical system according to this embodiment as a taking lens 2 as shown in FIG. In the camera 1 , light from an object (subject) (not shown) is condensed by the photographing lens 2 and reaches the imaging device 3 . As a result, the light from the subject is imaged by the imaging element 3 and recorded in a memory (not shown) as an image of the subject. In this manner, the photographer can photograph the subject with the camera 1. FIG. This camera may be a mirrorless camera or a single-lens reflex type camera having a quick return mirror.

An optical system LS (1) as an example of the optical system (taking lens) LS according to this embodiment is shown in FIG.
, the aperture stop S and the following conditional expressions (1) to
and a negative lens (L15) that satisfies (3).

ndN1+(0.01425×νdN1)<2.12 (1)
18.0<νdN1<35.0 (2)
0.702<θgFN1+(0.00316×νdN1) (3)
where ndN1: the refractive index of the negative lens for the d-line νdN1: the Abbe number of the negative lens with respect to the d-line θgFN1: the partial dispersion ratio of the negative lens, where n is the refractive index of the negative lens for the g-line
θgFN1=(ngN1−nFN1)/(nFN1−nCN1) where gN1, nFN1 is the refractive index of the negative lens for the F line, and nCN1 is the refractive index of the negative lens for the C line.
The Abbe number νdN1 of the negative lens with respect to the d-line is defined by the following equation: νdN1=(ndN1−1)/(nFN1−nCN1)

According to this embodiment, in the correction of chromatic aberration, it is possible to obtain an optical system in which the secondary spectrum is well corrected in addition to the primary achromatization, and an optical apparatus 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, or the optical system LS(4) shown in FIG. Further, the optical system LS according to this embodiment may be the optical system LS(5) shown in FIG. 9, the optical system LS(6) shown in FIG. 11, or the optical system LS(7) shown in FIG. .

Conditional expression (1) defines an appropriate relationship between the refractive index of the negative lens for the d-line and the Abbe number based on the d-line. By satisfying the conditional expression (1), it is possible to satisfactorily correct the reference aberration such as spherical aberration and coma, and correct (achromatic) the first-order chromatic aberration.

If the corresponding value of conditional expression (1) exceeds the upper limit, for example, the Petzval sum becomes small, which makes it difficult to correct curvature of field, which is not preferable. By setting the upper limit of conditional expression (1) to 2.11, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (1) is set to 2.10, 2.09, 2.0
8, 2.07 and even 2.06 are preferred.

Conditional expression (2) defines an appropriate range of the Abbe's number based on the d-line of the negative lens. By satisfying the conditional expression (2), it is possible to satisfactorily correct the reference aberration such as spherical aberration and coma, and correct the first-order chromatic aberration (achromatization).

If the corresponding value of conditional expression (2) exceeds the upper limit, for example, it becomes difficult to correct axial chromatic aberration in the subgroup closer to the object side than the aperture stop S, which is not preferable. Set the upper limit of conditional expression (2) to 32
. By setting it to 5, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (2) is set to 32.0, 31.5,
31.0, 30.5, 30.0, and preferably 29.5.

If the corresponding value of conditional expression (2) is less than the lower limit, for example, it becomes difficult to correct longitudinal chromatic aberration in the subgroup closer to the object side than the aperture stop S, which is not preferable. Set the lower limit of conditional expression (2) to 20
. By setting it to 0, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (2) is set to 23.0, 23.5,
24.0, 24.5, 25.0, 25.5, 26.0, 26.5, 27.0, 27.5, and preferably 27.7.

Conditional expression (3) appropriately defines the anomalous dispersion of the negative lens. By satisfying the conditional expression (3), in the correction of chromatic aberration, in addition to the primary achromatization, the secondary spectrum can be favorably corrected.

When the corresponding value of conditional expression (3) is below the lower limit, the anomalous dispersion of the negative lens becomes small, so
It becomes difficult to correct chromatic aberration. By setting the lower limit of conditional expression (3) to 0.704, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (3) is set to 0.708, 0.710, 0.712, and further to 0.712.
715 is preferred.

In the optical system of this embodiment, the negative lens preferably satisfies the following conditional expression (4).
1.83<ndN1+(0.00787×νdN1) (4)

Conditional expression (4) defines an appropriate relationship between the refractive index of the negative lens for the d-line and the Abbe number based on the d-line. By satisfying the conditional expression (4), it is possible to satisfactorily correct the reference aberration such as spherical aberration and coma, and correct the first-order chromatic aberration (achromatization).

If the corresponding value of conditional expression (4) is less than the lower limit, for example, the refractive index of the negative lens becomes small, which makes it difficult to correct the reference aberration, especially spherical aberration, which is not preferable. By setting the lower limit of conditional expression (4) to 1.84, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (4) is set to 1.85,
Furthermore, it is preferable to set it to 1.86.

In the optical system of this embodiment, the negative lens has the following conditional expressions (2-1) and (4
-1) may be satisfied.
18.0<νdN1<26.5 (2-1)
1.83<ndN1+(0.00787×νdN1) (4-1)

Conditional expression (2-1) is similar to conditional expression (2), and can obtain the same effect as conditional expression (2). By setting the upper limit of conditional expression (2-1) to 26.0, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (2-1) to 25.5, more preferably 25.0. On the other hand, by setting the lower limit of conditional expression (2-1) to 23.5, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the conditional expression (2-
The lower limit of 1) is preferably 24.0, more preferably 24.5.

Conditional expression (4-1) is similar to conditional expression (4), and can provide the same effect as conditional expression (4). By setting the lower limit of conditional expression (4-1) to 1.90, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (4-1) to 1.92, more preferably 1.94.

In the optical system of this embodiment, the negative lens has the following conditional expressions (2-2) and (4
-2) may be satisfied.
25.0<νdN1<35.0 (2-2)
1.83<ndN1+(0.00787×νdN1) (4-2)

Conditional expression (2-2) is similar to conditional expression (2), and can obtain the same effect as conditional expression (2). By setting the upper limit of conditional expression (2-2) to 32.5, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (2-2) to 31.5, more preferably 29.5. On the other hand, by setting the lower limit of conditional expression (2-2) to 26.2, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the conditional expression (2-
The lower limit of 2) is preferably 26.7, more preferably 27.7.

Conditional expression (4-2) is similar to conditional expression (4), and can obtain the same effect as conditional expression (4). By setting the lower limit of conditional expression (4-2) to 1.84, the effects of the present embodiment can be made more reliable. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (4-2) to 1.85.

In the optical system of this embodiment, the negative lens preferably satisfies the following conditional expression (5).
DN1>0.80 (5)
However, DN1: the thickness of the negative lens on the optical axis [mm]

Conditional expression (5) defines an appropriate range for the thickness of the negative lens on the optical axis. By satisfying the conditional expression (5), various aberrations such as coma and chromatic aberration (axial chromatic aberration and chromatic aberration of magnification) can be satisfactorily corrected.

If the corresponding value of conditional expression (5) is less than the lower limit, it becomes difficult to correct various aberrations such as coma and chromatic aberration (axial chromatic aberration and chromatic aberration of magnification), which is not preferable. By setting the lower limit of conditional expression (5) to 0.90, the effect of this embodiment can be made more reliable.
In order to further ensure the effect of this embodiment, the lower limit of conditional expression (5) is set to 1.00, 1.00.
10, 1.20 and even 1.30 are preferred.

The optical system of this embodiment has an object-side lens arranged closest to the object side, an aperture diaphragm S is arranged on the image side of the object-side lens, and the negative lens is on the image side of the object-side lens. It is desirable to arrange it closer to the object side. This makes it possible to satisfactorily correct various aberrations such as coma and chromatic aberration (axial chromatic aberration and chromatic aberration of magnification).

In the optical system of this embodiment, the negative lens is preferably a glass lens. As a result, it is possible to obtain a lens that is resistant to aging and to environmental changes such as temperature changes, as compared with the case where the material is resin.

In the optical system of this embodiment, the negative lens desirably satisfies the following conditional expressions (6) to (7).
ndN1<1.63 (6)
ndN1−(0.040×νdN1−2.470)×νdN1<39.809 (
7)

Conditional expression (6) defines an appropriate range of the refractive index for the d-line of the negative lens.
By satisfying the conditional expression (6), various aberrations such as coma and chromatic aberration (axial chromatic aberration and chromatic aberration of magnification) can be satisfactorily corrected.

If the corresponding value of conditional expression (6) exceeds the upper limit, it becomes difficult to correct various aberrations such as coma and chromatic aberration (axial chromatic aberration and chromatic aberration of magnification), which is not preferable. By setting the upper limit of conditional expression (6) to 1.62, the effect of this embodiment can be made more reliable.

Conditional expression (7) defines an appropriate relationship between the refractive index of the negative lens for the d-line and the Abbe number based on the d-line. By satisfying the conditional expression (7), it is possible to satisfactorily correct the reference aberration such as spherical aberration and coma, and correct the first-order chromatic aberration (achromatization).

If the corresponding value of conditional expression (7) exceeds the upper limit, for example, the Petzval sum becomes small, which makes it difficult to correct curvature of field, which is not preferable. The upper limit of conditional expression (7) is set to 39.80
By setting it to 0, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (7) is set to 39.500, 39.0
00, 38.500, 38.000, 37.500 and preferably 36.800.

In the optical system of this embodiment, the negative lens preferably satisfies the following conditional expression (8).
ndN1−(0.020×νdN1−1.080)×νdN1<16.260 (
8)

Conditional expression (8) defines an appropriate relationship between the refractive index of the negative lens for the d-line and the Abbe number based on the d-line. By satisfying the conditional expression (8), it is possible to satisfactorily correct the reference aberration such as spherical aberration and coma, and correct the first-order chromatic aberration (achromatization).

If the corresponding value of conditional expression (8) exceeds the upper limit, for example, the Petzval sum becomes small, making it difficult to correct curvature of field, which is not preferable. The upper limit of conditional expression (8) is set to 16.24
By setting it to 0, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (8) is set to 16.000, 15.8
00, 15.500, 15.300, 15.000, 14.800, 14.500, 14
. 000, preferably 13.500.

Next, a method for manufacturing the above optical system LS will be outlined with reference to FIG. First, an aperture stop S and a negative lens are arranged at least on the object side of the aperture stop S (step ST
1). At this time, each lens is arranged in the lens barrel so that at least one of the negative lenses arranged on the object side of the aperture stop S satisfies the above conditional expressions (1) to (3) (step ST2). According to such a manufacturing method, in the correction of chromatic aberration, it is possible to manufacture an optical system in which the secondary spectrum is well corrected in addition to the primary achromatization.

An optical system LS according to an example of the present embodiment will be described below with reference to the drawings. Figure 1, Figure 3,
5, 7, 9, 11, and 13 show the optical system LS {LS(1) according to the first to seventh examples.
˜LS(7)} and a cross-sectional view showing the distribution of refractive power. In the cross-sectional views of the optical systems LS(1) and LS(2) according to the first and second examples, the direction of movement of the focusing lens group when focusing on a short-distance object from infinity is called "focusing". The characters are indicated by arrows. In the cross-sectional views of the optical systems LS(3) to LS(7) according to the third to seventh examples, from the wide-angle end state (W) to the telephoto end state (T
), the direction of movement of each lens group along the optical axis is indicated by an arrow.

1, 3, 5, 7, 9, 11 and 13, each lens group is denoted by G
Each lens is represented by a combination of the symbol L and a number. In this case, in order to prevent complication due to a large number of types and numbers of symbols and numerals, the lens groups and the like are represented independently using combinations of symbols and numerals for each embodiment. For this reason, even if the same combination of symbols and numerals is used between examples,
It does not mean that they have the same configuration.

Tables 1 to 7 are shown below, of which Table 1 is the first embodiment, Table 2 is the second embodiment, Table 3 is the third embodiment, Table 4 is the fourth embodiment, and Table 5 is the third embodiment. Table 6 is a table showing each specification data in the fifth embodiment, Table 6 is the sixth embodiment, and Table 7 is the seventh embodiment. In each embodiment, the d-line (
wavelength λ = 587.6 nm), g-line (wavelength λ = 435.8 nm), C-line (wavelength λ = 656.8 nm).
3 nm) and the 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 ° (degrees), ω is the half angle of view), and Y is the image height. show. TL indicates the distance obtained by adding BF to the distance from the foremost lens surface to the last lens surface on the optical axis when focusing on infinity, and BF is the distance from the last lens surface on the optical axis when focusing on infinity. The distance to plane I (back focus) is shown. If the optical system is a variable power optical system, these values are shown for each variable power state of the wide-angle end (W), the intermediate focal length (M), and the 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 in which light rays travel, and R is the radius of curvature of each optical surface (the surface whose center of curvature is located on the image side). positive value), D is the distance on the optical axis from each optical surface to the next optical surface (or image plane), n
d is the refractive index of the material of the optical member for the d-line, νd is the Abbe number of the material of the optical member with respect to the d-line, and θgF is 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 of air nd=1.00000 is omitted. When the optical surface is an aspherical surface, the surface number is marked with *a, and the column of radius of curvature R indicates the paraxial radius of curvature.

Let ng be the refractive index of the material of the optical member for the g-line (wavelength λ = 435.8 nm), let nF be the refractive index of the material of the optical member for the F-line (wavelength λ = 486.1 nm), and let C be the material of the optical member. Let nC be the refractive index for a ray (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 equation (A).

θgF=(ng−nF)/(nF−nC) (A)

In the table of [aspheric surface data], the shape of the aspheric surface shown in [lens specifications] is shown by the following equation (B). X(y) is the distance (zag amount) along the optical axis from the tangent plane at the vertex of the aspherical surface to the position on the aspherical 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 order aspheric coefficient. “E-n” indicates “×10 ⁻ⁿ ”. For example, 1.234E-05 = 1.234 x ^10-5 . Note that the second-order aspheric coefficient A2 is 0,
The description is omitted.

X(y)=(y ² /R)/{1+(1−κ×y ² /R ² ) ^1/2 }+A4×y ⁴ +A6×y ⁶ +A
8× ^y8 +A10× ^y10 (B)

If the optical system is not a variable-magnification optical system, f indicates the focal length of the entire lens system and β indicates the photographing magnification as [variable interval data for short-distance photographing]. In addition, in the [Variable distance data for close-range shooting] table, the surface distance in [Lens specifications] corresponding to each focal length and shooting magnification is "
Shows the surface spacing at the surface number that is "variable".

When the optical system is a variable magnification optical system, the wide-angle end (W) is set as [Variable interval data for variable magnification shooting]
, intermediate focal length (M), and telephoto end (T). The [lens group data] table shows the starting surface (surface closest to the object side) and focal length of each lens group.

The [value corresponding to conditional expression] table shows the value corresponding to each conditional expression.

Unless otherwise specified, "mm" is generally used for the focal length f, radius of curvature R, surface spacing D, and other lengths in all specifications below, but the optical system is proportionally enlarged. Alternatively, it is not limited to this because equivalent optical performance can be obtained even if it is proportionally reduced.

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

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. FIG. 1 is a diagram showing the lens configuration of the optical system according to Example 1 of the present embodiment in an infinity focused state. The optical system LS(1) according to the first embodiment is composed of a first lens group G1 having negative refractive power and a second lens group G2 having positive refractive power, which are arranged in order from the object side. there is The second lens group G2 moves along the optical axis toward the object when focusing from an infinite object to a close (finite) object. An aperture stop S is arranged in the second lens group G2. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this is the same for all the following examples.

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 biconvex positive lens L12, a biconcave negative lens L13, and a biconvex positive lens L13. and a cemented lens composed of a lens L14 and a biconcave negative lens L15.
In this embodiment, the negative meniscus lens L11 of the first lens group G1 corresponds to the object side lens,
The negative lens L15 of the first lens group G1 corresponds to a negative lens that satisfies conditional expressions (1) to (3). The negative lens L13 has an aspheric lens surface on the image side.

The second lens group G2 is a cemented lens composed of a biconvex positive lens L21, a positive meniscus lens L22 with a convex surface facing the object side, and a negative meniscus lens L23 with a convex surface facing the object side, arranged in order from the object side. , a biconcave negative lens L24 and a biconvex positive lens L2
5, a single flat positive lens L26 with a convex surface facing the image side, and a positive meniscus lens L27 with a concave surface facing the object side. on the image side of the second lens group G2,
An image plane I is arranged. Positive lens L21 and positive meniscus lens L in second lens group G2
22, an aperture stop S is arranged. The positive lens L26 has an aspheric lens surface on the image side.

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

(Table 1)
[Overall specifications]
f28.773
FNO 1.8796
2ω 75.3311
Y 21.60
TL 131.9655
BF 36.457
[Lens specifications]
Surface number R D nd νd θgF
1 57.6700 1.7000 1.713000 53.94 0.5441
2 23.6385 10.630
3 360.0000 3.4200 1.846660 23.78
4 -149.5844 2.1000
5 -91.6110 1.7000 1.487490 70.31
6 34.8169 0.1000 1.520500 51.02
7*a 31.0734 7.4700
8 54.5000 8.5700 1.834000 37.18
9 -43.5000 1.7000 1.749714 24.66 0.6272
10 475.5646 D10 (variable)
11 41.6500 6.2000 1.589130 61.24
12 -79.7342 8.8800
13 ∞ 1.0000 (Aperture S)
14 71.7000 1.3000 1.659398 26.87 0.6323
15 165.1470 1.0000 1.672700 32.19
16 41.0000 6.0900
17 -19.3844 1.5200 1.805180 25.46
18 400.0000 2.4200 1.772500 49.65
19 -67.0000 0.6000
20 ∞ 3.0800 1.729160 54.66
21 -50.8920 0.2000 1.520500 51.02
22*a -37.6986 1.1400
23 -98.0000 5.2100 1.834810 42.72 0.5651
24 -26.8452 2.3629
25∞BF
[Aspheric data]
7th surface κ=0.0000
A4=-2.99E-06, A6=-2.39E-08, A8=1.13E-10, A10=-3.69E-13
22nd surface κ=0.0000
A4=2.03E-05, A6=4.37E-09, A8=1.85E-10, A10=-1.33E-12
[Variable interval data for close-up shooting]
Focused at infinity Focused at close range
f = 28.7734 β = -0.2174
D10 9.5660 2.3031
[Value corresponding to conditional expression]
Conditional expression (1)
ndN1 + (0.01425 x vdN1) = 2.101
Conditional expressions (2), (2-1), (2-2)
νdN1 = 24.66
Conditional expression (3)
θgFN1+(0.00316×νdN1)=0.7051
Conditional expressions (4), (4-1), (4-2)
ndN1 + (0.00787 x vdN1) = 1.944
Conditional expression (5)
DN1 = 1.7000
Conditional expression (6)
ndN1 = 1.749714
Conditional expression (7)
ndN1−(0.040×νdN1−2.470)×νdN1=34.836
Conditional expression (8)
ndN1−(0.020×νdN1−1.080)×νdN1=12.721

FIG. 2 is a diagram of various aberrations in the infinity focused state of the optical system according to the first embodiment. In each aberration diagram, FNO indicates F number and Y indicates image height. The spherical aberration diagram shows the F-number or numerical aperture corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the coma aberration diagram shows the value of each image height. . d is the d-line (wavelength λ=587
. 6 nm), g is g-line (wavelength λ = 435.8 nm), C is C-line (wavelength λ = 656.3 nm
) and F indicate the F line (wavelength λ=486.1 nm). In the astigmatism diagrams, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. In the aberration diagrams of each example shown below, the same reference numerals as in the present example are used, and redundant description is 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 embodiment)
A second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. FIG. 3 is a diagram showing the lens configuration in the infinity focused state of the optical system according to the second example of the present embodiment. The optical system LS(2) according to the second embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a positive refractive power. Powerful third lens group G3
It consists of When focusing from an infinity object to a short distance (finite distance) object, the second lens group G2 and the third lens group G3 move by different amounts of movement toward the object side along the optical axis. An aperture stop S is disposed between the second lens group G2 and the third lens group G3, and moves along the optical axis together with the third lens group G3 during focusing.

The first lens group G1 is a cemented lens composed of a positive meniscus lens L11 having a convex surface facing the object side and a negative meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side;
It is composed of a cemented lens composed of a positive meniscus lens L13 having a concave surface facing the object side and a biconcave negative lens L14, and a biconvex positive lens L15. In this embodiment, the positive meniscus lens L11 of the first lens group G1 corresponds to the object side lens.

The second lens group G2 is composed of, in order from the object side, a biconvex positive lens L21 and a cemented lens composed of a biconvex positive lens L22 and a biconcave negative lens L23. In this embodiment, the negative lens L23 of the second lens group G2 corresponds to a negative lens that satisfies the conditional expressions (1) to (3).

The third lens group G3 includes a cemented lens composed of a positive meniscus lens L31 having a concave surface facing the object side and a biconcave negative lens L32 arranged in order from the object side, and a biconvex positive lens L.
33 and a biconcave negative lens L34, and a biconvex positive lens L35.
and consists of An image plane I is arranged on the image side of the third lens group G3. positive lens L35
has an aspherical surface on the image side.

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

(Table 2)
[Overall specifications]
f48.500
FNO 1.400
2ω 48.226
Y 21.60
TL 142.000
BF 38.800
[Lens specifications]
Surface number R D nd νd θgF
1 53.65780 7.000 2.00100 29.13 0.599
2 129.86950 2.500 1.54814 45.78 0.569
3 27.02480 13.200
4 -55.86860 6.000 1.49700 81.61 0.539
5 -29.50270 2.000 1.61266 44.46 0.564
6 89.74970 2.918
7 90.14640 7.500 1.72916 54.61 0.544
8 -57.19860 D8 (Variable)
9 124.11860 5.000 2.00100 29.13 0.599
10 -235.55950 0.100
11 75.56290 6.500 1.49700 81.61 0.539
12 -80.97560 1.800 1.65940 26.87 0.633
13 114.37760 D13 (variable)
14 ∞ 4.463 (Aperture S)
15 -79.86500 5.000 1.49782 82.57 0.539
16 -30.16300 1.600 1.64769 33.72 0.593
17 68.03140 7.392
18 54.19340 9.000 1.80420 46.50 0.558
19 -36.68930 1.800 1.54814 45.78 0.569
20 39.60550 1.830
21 87.27070 4.500 1.77250 49.62 0.550
22*a-64.82140 BF
[Aspheric data]
22nd surface κ=-14.6003
A4=-3.46E-06, A6=7.41E-09, A8=0.00E+00, A10=0.00E+00
[Variable interval data for close-up shooting]
Focused at infinity Focused at close range
f = 48.500 β = -0.181
D8 11.787 0.477
D13 1.310 5.731
[Value corresponding to conditional expression]
Conditional expression (1)
ndN1 + (0.01425 x vdN1) = 2.042
Conditional expressions (2), (2-1), (2-2)
νdN1 = 26.87
Conditional expression (3)
θgFN1+(0.00316×νdN1)=0.7179
Conditional expressions (4), (4-1), (4-2)
ndN1 + (0.00787 x vdN1) = 1.871
Conditional expression (5)
DN1 = 1.800
Conditional expression (6)
ndN1 = 1.65940
Conditional expression (7)
ndN1−(0.040×νdN1−2.470)×νdN1=35.830
Conditional expression (8)
ndN1−(0.020×νdN1−1.080)×νdN1=12.920

FIG. 4 is a diagram of various aberrations in the infinity focused state of the optical system according to the second embodiment. From the various aberration diagrams, it can be seen that the optical system according to Example 2 is well corrected for various aberrations and has excellent imaging performance.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 5 to 6 and Table 3. FIG. FIG. 5 is a diagram showing the lens configuration in the infinity focused state of the optical system according to the third example of the present embodiment. The optical system LS(3) according to the third embodiment includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a negative refractive power. Powerful third lens group G3
and a fourth lens group G4 having positive refractive power. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to fourth lens groups G1 to G4 move in directions indicated by arrows in FIG. An aperture stop S is disposed between the second lens group G2 and the third lens group G3, and moves along the optical axis together with the third lens group G3 during zooming.

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, and a biconcave negative lens L.
13 and a biconvex positive lens L14. In this embodiment, the first lens group G
1 of the negative meniscus lens L11 corresponds to the object side lens. Both lens surfaces of the negative meniscus lens L11 are aspheric. The negative lens L13 has an aspheric lens surface on the image side.

The second lens group G2 is a cemented lens composed of a negative meniscus lens L21 with a convex surface facing the object side and a positive meniscus lens L22 with a convex surface facing the object side, arranged in order from the object side;
and a biconvex positive lens L23. In this embodiment, the negative meniscus lens L21 of the second lens group G2 corresponds to a negative lens that satisfies conditional expressions (1) to (3).

The third lens group G3 includes a cemented lens composed of a biconvex positive lens L31 and a biconcave negative lens L32 arranged in order from the object side, and a negative meniscus lens L having a concave surface facing the object side.
33 and a biconvex positive lens L34. In this embodiment, the negative meniscus lens L33 and the positive lens L34 of the third lens group G3 move toward the image side along the optical axis when focusing from an infinity object to a short (finite) distance object.

The fourth lens group G4 includes a cemented lens composed of a biconvex positive lens L41 and a biconcave negative lens L42, a biconvex positive lens L43, and a biconvex positive lens arranged in order from the object side. and a cemented lens composed of L44 and a biconcave negative lens L45.
An image plane I is arranged on the image side of the fourth lens group G4. The negative lens L45 has an aspheric lens surface on the image side.

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

(Table 3)
[Overall specifications]
Zoom ratio 2.07
WMT
f 16.65 24.00 34.44
FNO 4.12 4.12 4.18
2ω 53.80 41.66 31.60
Y 21.60 21.60 21.60
TL 168.91 164.50 169.42
BF 39.00 48.25 65.00
[Lens specifications]
Surface number R D nd νd θgF
1*a 157.02850 3.000 1.76684 46.78 0.5576
2*a 19.73150 8.955
3 397.62390 1.550 1.88300 40.66 0.5668
4 51.01700 5.065
5 -57.91430 1.500 1.88300 40.66 0.5668
6 51.94950 0.400 1.55389 38.09 0.5928
7*a 70.15770 1.237
8 44.62150 6.911 1.69895 30.13 0.6021
9 -47.20650 D9 (Variable)
10 42.61580 1.050 1.74971 24.66 0.6272
11 17.74250 4.132 1.59154 39.29 0.5779
12 75.16900 0.100
13 34.28950 4.194 1.53404 48.26 0.5617
14 -63.55520 D14 (Variable)
15 ∞ 3.263 (Aperture S)
16 151.28780 2.518 1.62004 36.40 0.5833
17 -33.01780 1.000 1.88300 40.66 0.5668
18 44.83300 2.756
19 -20.44030 0.800 1.88300 40.66 0.5668
20 -59.69050 0.150
21 151.29690 3.966 1.84666 23.80 0.6215
22 -32.91290 D22 (Variable)
23 34.01270 10.039 1.49782 82.57 0.5386
24 -29.32300 1.100 1.83400 37.18 0.5778
25 71.52300 0.100
26 34.90120 10.548 1.49782 82.57 0.5386
27 -38.97720 0.100
28 40.26640 11.985 1.50377 63.91 0.536
29 -23.35670 1.600 1.80610 40.97 0.5688
30*a-1764.39570 BF
[Aspheric data]
First surface κ=1.0000
A4=3.00E-06, A6=3.39E-09, A8=0.00E+00, A10=0.00E+00
2nd surface κ=1.0000
A4=-2.11E-05, A6=0.00E+00, A8=0.00E+00, A10=0.00E+00
7th surface κ=1.0000
A4=1.75E-05, A6=-2.74E-08, A8=1.77E-11, A10=0.00E+00
30th surface κ=1.0000
A4=1.53E-05, A6=8.95E-09, A8=0.00E+00, A10=0.00E+00
[Variable interval data for zooming]
WMT
D9 29.355 13.227 2.000
D14 3.000 9.342 13.197
D22 9.534 5.666 1.200
[Lens group data]
Group Starting surface Focal length
G1 1 -23.700
G2 10 41.700
G3 15 -62.000
G4 23 49.100
[Value corresponding to conditional expression]
Conditional expression (1)
ndN1 + (0.01425 x vdN1) = 2.101
Conditional expressions (2), (2-1), (2-2)
νdN1 = 24.66
Conditional expression (3)
θgFN1+(0.00316×νdN1)=0.7051
Conditional expressions (4), (4-1), (4-2)
ndN1 + (0.00787 x vdN1) = 1.944
Conditional expression (5)
DN1 = 1.050
Conditional expression (6)
ndN1 = 1.74971
Conditional expression (7)
ndN1−(0.040×νdN1−2.470)×νdN1=34.836
Conditional expression (8)
ndN1−(0.020×νdN1−1.080)×νdN1=12.721

6(A), 6(B), and 6(C) respectively show the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the third embodiment when focusing on infinity. It is an aberration diagram. From the various aberration diagrams, it can be seen that the optical system according to the third example is well corrected for various aberrations and has excellent imaging performance.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 7 to 8 and Table 4. FIG. FIG. 7 is a diagram showing the lens configuration in the infinity focused state of the optical system according to the fourth example of this embodiment. The optical system LS(4) according to the fourth example includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a positive refractive power. Powerful third lens group G3
and a fourth lens group G4 having positive refractive power. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to fourth lens groups G1 to G4 move in directions indicated by arrows in FIG. An aperture stop S is arranged in the fourth lens group G4.

The first lens group G1 is a cemented lens composed of a biconvex positive lens L11, a negative meniscus lens L12 with a convex surface facing the object side, and a positive meniscus lens L13 with a convex surface facing the object side, arranged in order from the object side. and consists of In this embodiment, the positive lens L11 of the first lens group G1 corresponds to the object side lens, and the negative meniscus lens L12 of the first lens group G1 corresponds to the negative lens that satisfies the conditional expressions (1) to (3). do.

The second lens group G2 includes a cemented lens composed of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side, arranged in order from the object side, and a biconcave negative lens L.
23.

The third lens group G3 is composed of a biconvex positive lens L31. In this embodiment, the entire third lens group G3 moves along the optical axis toward the object side when focusing from an infinite distance object to a close (finite distance) object.

The fourth lens group G4 includes a cemented lens composed of a biconvex positive lens L41 and a biconcave negative lens L42 arranged in order from the object side, a biconvex positive lens L43, and a concave surface facing the object side. A cemented lens composed of a positive meniscus lens L44 and a biconcave negative lens L45, a biconvex positive lens L46, a negative meniscus lens L47 with a concave surface facing the object side,
consists of An image plane I is arranged on the image side of the fourth lens group G4. An aperture stop S is arranged between the positive lens L43 and the positive meniscus lens L44 in the fourth lens group G4.

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

(Table 4)
[Overall specifications]
Zoom ratio 4.05
WMT
f 72.1 135.0 292.1
FNO 4.707 4.863 6.494
2ω 23.341 12.218 5.684
Y 14.75 14.75 14.75
TL 168.674 197.816 220.732
BF 43.294 45.652 70.374
[Lens specifications]
Surface number R D nd νd θgF
1 93.841 5.6 1.51680 63.88 0.536
2 -447.915 0.2
3 112.303 1.7 1.61155 31.26 0.618
4 39.024 8 1.51742 52.20 0.558
5 262.500 D5 (Variable)
6 -239.035 1.3 1.69680 55.52 0.543
7 20.159 4 1.80809 22.74 0.629
8 61.046 2.038
9 -54.537 1.4 1.85026 32.35 0.595
10 167.455 D10 (variable)
11 102.636 3.4 1.58913 61.22 0.540
12 -68.899 D12 (Variable)
13 39.218 5.5 1.49700 81.73 0.537
14 -39.212 1.3 1.85026 32.35 0.595
15 207.543 0.2
16 51.630 3.7 1.48749 70.31 0.529
17 -98.216 0.9
18 ∞ 23.297 (Aperture S)
19 -79.941 3.3 1.80 100 34.92 0.585
20 -17.991 1 1.70000 48.11 0.560
21 29.977 2
22 35.573 3.5 1.60342 38.03 0.583
23 -52.781 6.6996
24 -20.538 1.2 1.77250 49.62 0.552
25 -34.657 BF
[Variable interval data for zooming]
WMT
D5 2.306 36.768 51.599
D10 32.727 21.603 2.157
D12 10.112 13.560 16.367
[Lens group data]
Group Starting surface Focal length
G1 1 127.677
G2 6 -31.532
G3 11 70.494
G4 13 147.512
[Value corresponding to conditional expression]
Conditional expression (1)
ndN1 + (0.01425 x vdN1) = 2.057
Conditional expressions (2), (2-1), (2-2)
νdN1 = 31.26
Conditional expression (3)
θgFN1+(0.00316×νdN1)=0.7168
Conditional expressions (4), (4-1), (4-2)
ndN1 + (0.00787 x vdN1) = 1.858
Conditional expression (5)
DN1 = 1.7
Conditional expression (6)
ndN1 = 1.61155
Conditional expression (7)
ndN1−(0.040×νdN1−2.470)×νdN1=36.513
Conditional expression (8)
ndN1−(0.020×νdN1−1.080)×νdN1=12.605

8(A), 8(B), and 8(C) respectively show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system according to the fourth embodiment when focusing on infinity. It is an aberration diagram. From the various aberration diagrams, it can be seen that the optical system according to the fourth example is well corrected for various aberrations and has excellent imaging performance.

(Fifth embodiment)
A fifth embodiment will be described with reference to FIGS. 9 to 10 and Table 5. FIG. FIG. 9 is a diagram showing the lens configuration in the infinity focused state of the optical system according to the fifth example of this embodiment. The optical system LS(5) according to the fifth embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a positive refractive power. third lens group G with power
3. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to
The third lens groups G1 to G3 move in directions indicated by arrows in FIG. An aperture stop S is disposed between the second lens group G2 and the third lens group G3, and moves along the optical axis together with the third lens group G3 during zooming.

The first lens group G1 is a cemented lens composed of a biconvex positive lens L11, a negative meniscus lens L12 with a convex surface facing the object side, and a positive meniscus lens L13 with a convex surface facing the object side, arranged in order from the object side. and consists of In this embodiment, the positive lens L11 of the first lens group G1 corresponds to the object side lens, and the negative meniscus lens L12 of the first lens group G1 corresponds to the negative lens that satisfies the conditional expressions (1) to (3). do.

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

The third lens group G3 is a cemented lens composed of a biconvex positive lens L31, a biconvex positive lens L32, and a negative meniscus lens L33 with a concave surface facing the object side, arranged in order from the object side. A positive meniscus lens L34 with a convex surface facing toward and a biconcave negative lens L35
and a biconvex positive lens L36, a cemented lens composed of a positive meniscus lens L37 having a concave surface facing the object side and a biconcave negative lens L38, a biconvex positive lens L39, and an object side It is composed of a positive meniscus lens L40 with a convex surface facing toward and a negative meniscus lens L41 with a concave surface facing. An image plane I is arranged on the image side of the third lens group G3. In this embodiment, the positive lens L31 of the third lens group G3 moves toward the image side along the optical axis when focusing from an infinite object to a short (finite) distance object.

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

(Table 5)
[Overall specifications]
Zoom ratio 3.57
WMT
f 30.000 59.940 107.000
FNO 4.157 4.736 5.827
2ω 30.234 14.934 8.432
Y 8.00 8.00 8.00
TL 89.680 100.710 108.178
BF 16.903 21.915 31.403
[Lens specifications]
Surface number R D nd νd θgF
1 178.2059 2 1.48749 70.31 0.529
2 -102.9382 0.1
3 40.9521 1.1 1.6594 26.87 0.633
4 26.794 3.7 1.49782 82.57 0.539
5 524.5344 D5 (variable)
6 -179.0703 0.95 1.58913 61.22 0.540
7 35.2576 2.05
8 -91.3148 1 1.79952 42.09 0.567
9 13.7881 2.5 1.84666 23.80 0.622
10 147.6289 1.1
11 -23.3693 0.9 1.65844 50.84 0.558
12 -2639.1346 D12 (variable)
13 ∞ 1.9 (Aperture S)
14 53.8539 2.5 1.48749 70.31 0.529
15 -33.3149 4
16 21.2882 4.1 1.49782 82.57 0.539
17 -21.1608 1 1.85026 32.35 0.595
18 -101.3728 0.1
19 18.5545 1.8 1.618 63.34 0.541
20 52.4369 1.7
21 -64.7204 1 1.85026 32.35 0.595
22 26.092 2.7 1.58144 40.98 0.576
23 -25.9027 5.9
24 -247.1286 1.9 1.84666 23.8 0.622
25 -13.9553 0.9 1.8061 40.97 0.569
26 17.4014 2.45
27 41.2181 1.6 1.51823 58.82 0.545
28 -68.4047 0.2
29 22.2413 1.6 1.57957 53.74 0.552
30 110.775 2.2
31 -11.7986 1 1.755 52.34 0.548
32 -25.0879 BF
[Variable interval data for zooming]
WMT
D5 1.557 15.183 20.452
D12 17.269 9.662 2.373
[Lens group data]
Group Starting surface Focal length
G1 1 59.932
G2 6 -15.790
G3 13 19.347
[Value corresponding to conditional expression]
Conditional expression (1)
ndN1 + (0.01425 x vdN1) = 2.042
Conditional expressions (2), (2-1), (2-2)
νdN1 = 26.87
Conditional expression (3)
θgFN1+(0.00316×νdN1)=0.7179
Conditional expressions (4), (4-1), (4-2)
ndN1 + (0.00787 x vdN1) = 1.871
Conditional expression (5)
DN1 = 1.1
Conditional expression (6)
ndN1 = 1.6594
Conditional expression (7)
ndN1−(0.040×νdN1−2.470)×νdN1=35.830
Conditional expression (8)
ndN1−(0.020×νdN1−1.080)×νdN1=12.920

10(A), 10(B), and 10(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the fifth embodiment, respectively, when focusing on infinity. It is an aberration diagram. From the various aberration diagrams, it can be seen that the optical system according to the fifth example is well corrected for various aberrations and has excellent imaging performance.

(Sixth embodiment)
A sixth embodiment will be described with reference to FIGS. 11 to 12 and Table 6. FIG. FIG. 11 is a diagram showing the lens configuration of the optical system according to the sixth example of the present embodiment in the infinity focused state. The optical system LS(6) according to the sixth embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a positive refractive power. It is composed of a third lens group G3 having power and a fourth lens group G4 having positive refractive power. Wide-angle end state (W
) to the telephoto end state (T), the first to fourth lens groups G1 to G4 are respectively shown in FIG.
Move in the direction indicated by the arrow in . An aperture stop S is disposed between the second lens group G2 and the third lens group G3, and moves along the optical axis together with the third lens group G3 during zooming.

The first lens group G1 is a cemented lens composed of a biconvex positive lens L11, a negative meniscus lens L12 with a convex surface facing the object side, and a positive meniscus lens L13 with a convex surface facing the object side, arranged in order from the object side. and consists of In this embodiment, the positive lens L11 of the first lens group G1 corresponds to the object side lens, and the negative meniscus lens L12 of the first lens group G1 corresponds to the negative lens that satisfies the conditional expressions (1) to (3). do.

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

The third lens group G3 is composed of a biconvex positive lens L31. In this embodiment, the positive lens L31 of the third lens group G3 moves toward the image side along the optical axis when focusing from an infinite object to a short (finite) distance object.

The fourth lens group G4 includes a cemented lens composed of a biconvex positive lens L41 and a negative meniscus lens L42 having a concave surface facing the object side, arranged in order from the object side, and a positive meniscus lens L43 having a convex surface facing the object side. , a biconcave negative lens L44 and a biconvex positive lens L4
5, a cemented lens consisting of a positive meniscus lens L46 with a concave surface facing the object side and a biconcave negative lens L47, a biconvex positive lens L48, and a positive meniscus with a convex surface facing the object side. A lens L49 and a negative meniscus lens L50 with a concave surface facing the object side.
and consists of An image plane I is arranged on the image side of the fourth lens group G4.

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

(Table 6)
[Overall specifications]
Zoom ratio 3.52
WMT
f 30.100 59.788 106.000
FNO 4.106 4.674 5.725
2ω 30.235 14.845 8.432
Y 8.00 8.00 8.00
TL 90.060 101.674 110.030
BF 16.808 21.810 31.307
[Lens specifications]
Surface number R D nd νd θgF
1 294.5432 2 1.48749 70.31 0.529
2 -99.5097 0.1
3 40.4843 1.1 1.65940 26.87 0.633
4 26.4411 3.85 1.49782 82.57 0.539
5 1915.7525 D5 (variable)
6 404.1207 1 1.58913 61.22 0.540
7 40.8600 2
8 -52.6340 1 1.75500 52.34 0.548
9 13.7205 2.45 1.80518 25.45 0.616
10 99.1283 1.1
11 -25.0678 1 1.65844 50.84 0.558
12 730.2077 D12 (variable)
13 ∞ 2 (Aperture S)
14 136.6029 2.4 1.48749 70.31 0.529
15 -27.8885 D15 (Variable)
16 19.5350 4 1.49782 82.57 0.539
17 -21.4130 1 1.85026 32.35 0.595
18 -135.5857 0.1
19 17.3373 2.3 1.59319 67.90 0.544
20 60.8703 1.5
21 -60.0857 1 1.85026 32.35 0.595
22 18.8912 2.7 1.62004 36.40 0.588
23 -25.1939 5.9514
24 -232.9076 1.85 1.84666 23.80 0.622
25 -14.2871 0.95 1.80610 40.97 0.569
26 17.4635 2.41564
27 27.9840 1.6 1.51742 52.20 0.558
28 -86.7410 0.2
29 25.3750 1.6 1.57957 53.74 0.552
30 87.3640 2.1481
31 -11.0308 1 1.77250 49.62 0.552
32 -22.0573 BF
[Variable interval data for zooming]
WMT
D5 1.302 14.928 20.197
D12 16.994 9.386 2.097
D15 4.642 5.234 6.113
[Lens group data]
Group Starting surface Focal length
G1 1 60.463
G2 6 -15.943
G3 13 47.737
G4 16 47.764
[Value corresponding to conditional expression]
Conditional expression (1)
ndN1 + (0.01425 x vdN1) = 2.042
Conditional expressions (2), (2-1), (2-2)
νdN1 = 26.87
Conditional expression (3)
θgFN1+(0.00316×νdN1)=0.7179
Conditional expressions (4), (4-1), (4-2)
ndN1 + (0.00787 x vdN1) = 1.871
Conditional expression (5)
DN1 = 1.1
Conditional expression (6)
ndN1 = 1.65940
Conditional expression (7)
ndN1−(0.040×νdN1−2.470)×νdN1=35.830
Conditional expression (8)
ndN1−(0.020×νdN1−1.080)×νdN1=12.920

12(A), 12(B), and 12(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the sixth embodiment, respectively, when focusing on infinity. It is an aberration diagram. 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 embodiment)
A seventh embodiment will be described with reference to FIGS. 13 to 14 and Table 7. FIG. FIG. 13 is a diagram showing the lens configuration in the infinity focused state of the optical system according to the seventh example of this embodiment. The optical system LS(7) according to the seventh embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a positive refractive power. A third lens group G3 having power, a fourth lens group G4 having negative refractive power, and a fifth lens group G having positive refractive power
5. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to
The fifth lens groups G1 to G5 move in directions indicated by arrows in FIG. The aperture diaphragm S is
It is arranged between the second lens group G2 and the third lens group G3, and moves along the optical axis together with the third lens group G3 during zooming.

The first lens group G1 is composed of a biconvex positive lens L11 arranged in order from the object side, and a cemented lens composed of a negative meniscus lens L12 having a convex surface facing the object side and a biconvex positive lens L13. be done. In this embodiment, the positive lens L11 of the first lens group G1 corresponds to the object side lens, and the negative meniscus lens L12 of the first lens group G1 corresponds to the negative lens that satisfies the conditional expressions (1) to (3). do.

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

The third lens group G3 is a cemented lens composed of a biconvex positive lens L31, a biconvex positive lens L32, and a negative meniscus lens L33 with a concave surface facing the object side, arranged in order from the object side. A positive meniscus lens L34 with a convex surface facing toward and a biconcave negative lens L35
and a cemented lens composed of a biconvex positive lens L36. In this embodiment, when focusing from an infinity object to a short (finite) distance object, the positive lens L of the third lens group G3
31 moves to the image side along the optical axis.

The fourth lens group G4 is composed of a cemented lens composed of a biconvex positive lens L41 and a biconcave negative lens L42 arranged in order from the object side.

The fifth lens group G5 includes, in order from the object side, a biconvex positive lens L51, a positive meniscus lens L52 with a convex surface facing the object side, and a negative meniscus lens L with a concave surface facing the object side.
53 and . An image plane I is arranged on the image side of the fifth lens group G5.

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

(Table 7)
[Overall specifications]
Zoom ratio 3.52
WMT
f 30.100 59.504 106.001
FNO 4.041 4.562 5.598
2ω 30.234 14.934 8.432
Y 8.00 8.00 8.00
TL 88.887 99.454 106.507
BF 16.347 21.044 30.352
[Lens specifications]
Surface number R D nd νd θgF
1 95.9846 2.1 1.48749 70.31 0.529
2 -454.2540 0.1
3 45.5603 1.1 1.65940 26.87 0.633
4 28.7400 3.85 1.49782 82.57 0.539
5 -318.9670 D5 (Variable)
6 327.3606 0.95 1.61800 63.34 0.541
7 51.7855 2
8 -97.4754 1 1.79952 42.09 0.567
9 11.8221 2.45 1.84666 23.80 0.622
10 55.5836 1.1
11 -24.3651 1 1.62280 57.10 0.546
12 138.3758 D12 (variable)
13 ∞ 1.91 (Aperture S)
14 32.3232 2.4 1.48749 70.31 0.529
15 -32.6054 3.9
16 25.0507 4.05 1.49782 82.57 0.539
17 -17.3527 1 1.85026 32.35 0.595
18 -213.4595 0.1
19 20.2400 2.1 1.61800 63.34 0.541
20 44.3529 1.5
21 -39.3759 1 1.85026 32.35 0.595
22 95.8451 2.65 1.58144 40.98 0.576
23 -21.4429 D23 (variable)
24 16.6140 1.85 1.84666 23.80 0.622
25 -1932.8218 0.95 1.90265 35.73 0.580
26 12.0007 D26 (variable)
27 87.5432 1.55 1.51823 58.82 0.545
28 -285.3654 0.2
29 17.0944 1.6 1.57957 53.74 0.552
30 24.0117 2.2
31 -10.6962 1.1 1.75500 52.34 0.548
32 -17.6042 BF
[Variable interval data for zooming]
WMT
D5 1.310 14.930 20.200
D12 17.000 9.380 2.105
D23 5.520 5.890 6.110
D26 3.000 2.500 2.030
[Lens group data]
Group Starting surface Focal length
G1 1 60.716
G2 6 -15.893
G3 13 21.225
G4 24 -53.965
G5 27 -180.378
[Value corresponding to conditional expression]
Conditional expression (1)
ndN1 + (0.01425 x vdN1) = 2.042
Conditional expressions (2), (2-1), (2-2)
νdN1 = 26.87
Conditional expression (3)
θgFN1+(0.00316×νdN1)=0.7179
Conditional expressions (4), (4-1), (4-2)
ndN1 + (0.00787 x vdN1) = 1.871
Conditional expression (5)
DN1 = 1.1
Conditional expression (6)
ndN1 = 1.65940
Conditional expression (7)
ndN1−(0.040×νdN1−2.470)×νdN1=35.830
Conditional expression (8)
ndN1−(0.020×νdN1−1.080)×νdN1=12.920

14(A), 14(B), and 14(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system according to the seventh embodiment, respectively, when focusing on infinity. It is an aberration diagram. From the various aberration diagrams, it can be seen that the optical system according to Example 7 is well corrected for various aberrations and has excellent imaging performance.

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

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

It should be noted that the following content can be appropriately employed within a range that does not impair the optical performance of the optical system of this embodiment.

Focusing lens group shall refer to a portion having at least one lens separated by an air gap that varies 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 performs focusing 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 motor drive (using an ultrasonic motor or the like) for autofocus.

Although each example of the optical system of the present embodiment has been shown to have a configuration that does not have a vibration isolation function, the present application is not limited to this, and a configuration having a vibration isolation function is also possible.

The lens surface may be spherical, planar, or aspherical. A spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment and prevents degradation of optical performance due to errors in processing and assembly adjustment. Also, even if the image plane is deviated, there is little deterioration in rendering performance, which is preferable.

If the lens surface is aspherical, the aspherical surface can be ground aspherical, glass-molded aspherical, which is formed into an aspherical shape from glass, or composite aspherical, which is formed into an aspherical shape from resin on the surface of glass. It doesn't matter which one. 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 provided with an anti-reflection film having high transmittance over a wide wavelength range in order to reduce flare and ghost and achieve high-contrast optical performance. As a result, flare and ghost can be reduced, and high contrast and high optical performance can be achieved.

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 (1)

An optical system having an aperture stop and a negative lens disposed on the object side of the aperture stop and satisfying the following conditional expression.
ndN1+(0.01425×νdN1)<2.12
18.0<νdN1<35.0
0.702<θgFN1+(0.00316×νdN1)
where ndN1: the refractive index of the negative lens for the d-line; νdN1: the Abbe number of the negative lens with respect to the d-line; θgFN1=(ngN1−nFN1)/(nFN1−nCN1) where nFN1 is the refractive index of the negative lens for the F line and nCN1 is the refractive index of the negative lens for the C line.

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