JP2016018061A - Optical system and optical device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system that has a wide angle of view, and has lateral chromatic aberration occurring upon attaining the wide angle of view excellently corrected, and has a high optical performance over an entire screen.SOLUTION: In an optical system composed of a first lens group with negative refractive power, an aperture stop and a second lens group with positive refractive power, the second lens group has a negative lens unit. An Abbe number νp of a material of a positive lens constituting the negative lens unit and abnormal portion dispersibility thereof Δθg.F_p, an Abbe number νn of a material of a negative lens constituting the negative lens unit and abnormal portion dispersibility thereof Δθg.F_n, a focal length of the optical system f, a focal length of the negative lens unit fsg, and abnormal portion dispersibility Δθg.F with partial dispersion ratio θg.F for g-and F-lines are appropriately set, respectively.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical system and an optical apparatus having the optical system, and is suitable for, for example, a silver salt film camera, a digital still camera, a video camera, a surveillance camera, a TV camera, a projector, and the like.

  In recent years, a projection optical system such as an imaging optical system such as a digital camera or a liquid crystal projector has been demanded to be an optical system having a wide angle of view and a short total lens length. Here, the total lens length is the distance from the first lens surface to the image plane in the case of the imaging optical system, and the distance from the first lens surface on the screen side to the projection screen in the case of the projection optical system.

  2. Description of the Related Art Conventionally, a retrofocus type (negative lead type) optical system is known as an optical system advantageous for widening the angle (widening the angle of view). In this retrofocus type optical system, a lens group having a negative refractive power or a weak positive refractive power as a whole is disposed in front of the optical system (object side in the case of an imaging optical system) (screen side in the case of a projection optical system). ing. A lens group having a positive refractive power is disposed behind (image plane in the case of an imaging optical system) (projected screen side in the case of a projection optical system). This achieves a long back focus while widening the angle of view of the entire system.

  The retrofocus type optical system has a refractive power arrangement that is asymmetric with respect to the aperture stop. For this reason, various aberrations increase, and in particular, negative distortion (barrel distortion) and lateral chromatic aberration frequently occur.

  Conventionally, an optical system that corrects negative lateral chromatic aberration while correcting distortion in a retrofocus optical system is known (Patent Documents 1 and 2). In Patent Documents 1 and 2, the incident height (distance from the optical axis) h of the pupil paraxial ray to the lens surface is relatively high, and abnormal partial dispersion such as fluorite is applied to the lens group behind the aperture stop. A lens having a positive refractive power (positive lens) made of a low dispersion material is used. As a result, a wide angle of view is achieved while correcting chromatic aberration.

Japanese Patent Application Laid-Open No. 06-082689 JP 2002-287031 A

  In a retrofocus type optical system, a lens group having a negative refractive power or a weak positive refractive power is arranged in front of the aperture stop, and a lens group having a positive refractive power is arranged behind the aperture stop. It is easy to achieve a wide angle of view while maintaining focus. In general, in a retrofocus type optical system, in order to correct chromatic aberration that occurs when trying to shorten the total lens length, a low dispersion and anomalous partial dispersion material having a large Abbe number such as fluorite is used. It is valid.

  However, in a retrofocus type optical system, even when an anomalous partial dispersive material is used, lateral chromatic aberration on the short wavelength side is generated with a curvature as the angle of view increases. For this reason, even if the lateral chromatic aberration is suppressed by using an anomalous partial dispersive material, the lateral chromatic aberration remains at the position where the image height with a large angle of view is high and the lateral chromatic aberration is bent on the short wavelength side.

  In a retro-focus type optical system, in order to correct the lateral chromatic aberration satisfactorily while widening the angle of view, positive refraction closer to the image side than the aperture stop where the incident height of the paraxial ray of the pupil increases to the lens surface It is important to appropriately set the lens configuration of the lens group behind the force. If this configuration is inappropriate, it will be difficult to correct the lateral chromatic aberration well while achieving a wide angle of view and obtain high optical performance over the entire screen.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical system that has a wide angle of view and corrects chromatic aberration of magnification generated when the angle of view is widened and has high optical performance over the entire screen.

The optical system of the present invention is an optical system including, in order from the object side to the image side, a first lens group having a positive or negative refractive power, an aperture stop, and a second lens group having a positive refractive power.
The second lens group is a negative lens unit including a cemented lens in which a negative lens and a positive lens are cemented in order from the object side to the image side, or a cemented lens in which the positive lens and the negative lens are cemented in sequence from the object side to the image side. Have
Assuming that the partial dispersion ratio for g-line and F-line is θg.F, the abnormal partial dispersion Δθg.F is
Δθg.F ＝ θg.F- (0.6438-0.001682 × νd)
And
The Abbe number of the positive lens material constituting the negative lens unit is νp, the anomalous partial dispersion is Δθg.F_p, the Abbe number of the material of the negative lens constituting the negative lens unit is νn, and the anomalous partial dispersion is Δθg. .F_n, where f is the focal length of the entire optical system, and fsg is the focal length of the negative lens unit.
0.72 ≦ νp / νn ≦ 1.00
0.005 ≦ Δθg.F_p- Δθg.F_n ≦ 0.050
-0.8 ≦ fsg / f ≦ -0.5
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain an optical system having a wide angle of view and excellently correcting the lateral chromatic aberration generated when the angle of view is widened, and having high optical performance over the entire screen.

FIG. 1 is a lens configuration diagram of Example 1 of the present invention. Various aberration diagrams at infinity of Example 1 of the present invention FIG. 6 is a lens configuration diagram of Example 2 of the present invention. Various aberration diagrams at infinity of Example 2 of the present invention Lens configuration diagram of Embodiment 3 of the present invention Various aberration diagrams at infinity of Example 3 of the present invention Lens configuration diagram of Embodiment 4 of the present invention Various aberration diagrams at infinity of Example 4 of the present invention Lens configuration diagram of Embodiment 5 of the present invention Various aberration diagrams at infinity of Example 5 of the present invention Lens configuration diagram of Embodiment 6 of the present invention Various aberration diagrams at infinity of Example 6 of the present invention Lens configuration diagram of Embodiment 7 of the present invention Various aberration diagrams at infinity of Example 7 of the present invention Explanatory drawing for verifying the optical system of the present invention Explanatory drawing for verifying the optical system of the present invention Schematic diagram of main parts of an imaging apparatus of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The optical system of the present invention includes, in order from the object side to the image side, a first lens group having a positive or negative refractive power, an aperture stop, and a second lens group having a positive refractive power. In the optical system of the present invention, the height from the optical axis of the paraxial light beam passing through the foremost lens surface is behind the intersection of the optical axis and the pupil paraxial light beam. It consists of a retrofocus type that is smaller than the maximum height from the optical axis passing through the surface.

  Note that the paraxial light beam is a paraxial light beam that is incident with the height from the optical axis set to 1 in parallel with the optical axis of the optical system when the focal length of the entire optical system is normalized to 1. is there. The pupil paraxial ray is the intersection of the entrance pupil of the optical system and the optical axis among the rays incident at −45 ° with respect to the optical axis when the focal length of the entire optical system is normalized to 1. Paraxial rays passing through.

  FIG. 1 is a lens cross-sectional view of Example 1 of the optical system of the present invention, and FIG. 2 is an aberration diagram of the optical system of Example 1 in an infinitely focused state. 3 is a lens cross-sectional view of Example 2 of the optical system of the present invention, and FIG. 4 is an aberration diagram of the optical system of Example 2 in an infinitely focused state. FIG. 5 is a lens cross-sectional view of Example 3 of the optical system of the present invention, and FIG. 6 is an aberration diagram of the optical system of Example 3 in an infinitely focused state.

  7 is a lens cross-sectional view of Example 4 of the optical system of the present invention, and FIG. 8 is an aberration diagram of the optical system of Example 4 in an infinitely focused state. FIG. 9 is a lens cross-sectional view of Example 5 of the optical system of the present invention, and FIG. 10 is an aberration diagram of the optical system of Example 5 in an infinitely focused state. 11 is a lens cross-sectional view of Example 6 of the optical system according to the present invention, and FIG. 12 is an aberration diagram of the optical system of Example 6 in an infinitely focused state. FIG. 13 is a lens cross-sectional view of Example 7 of the optical system according to the present invention, and FIG. 14 is an aberration diagram of the optical system of Example 7 in an infinite focus state.

  FIG. 15 is an explanatory diagram for verifying the optical system of the present invention. FIG. 16 is an explanatory diagram for verifying the optical system of the present invention. FIG. 17 is a schematic diagram of a main part of the imaging apparatus of the present invention.

  The optical system of each embodiment is a photographing optical system used for an imaging apparatus (optical apparatus) such as a digital still camera, a video camera, and a silver salt film camera. In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). In addition, you may use the optical system of each Example as projection lenses, such as a projector. At this time, the left side is the screen and the right side is the projected image.

  In the lens cross-sectional view, LA is an optical system. The optical system LA includes a first lens unit L1 having a positive or negative refractive power on the object side and a second lens unit L2 having a positive refractive power on the image side with the aperture stop SP interposed therebetween. LF is a focus lens group that moves during focusing.

  In Examples 1 to 4, 6, and 7, the focus lens unit LF includes a part of the first lens unit L1 and the second lens unit L2. In Example 5, the focus lens unit LF includes a partial lens unit (lens unit) of the first lens unit L1. The focus lens group LF moves integrally to the object side as indicated by an arrow during focusing from an infinitely distant object to a close object. LN is a negative lens unit. The negative lens unit LN includes a cemented lens in which a negative lens and a positive lens are cemented in order from the object side to the image side, or a cemented lens in which the positive lens and the negative lens are cemented in order from the object side to the image side.

  IP is an image plane. When the imaging optical system of a video camera or digital still camera is used, the imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is a silver salt film camera. Corresponds to the film surface. In FIG. 15, FP is a flare cut stop.

  Each longitudinal aberration diagram shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration in order from the left. In the diagrams showing spherical aberration and lateral chromatic aberration, the solid line d represents the d line (587.6 nm), and the broken line g represents the g line (435.8 nm). In the diagram showing astigmatism, the solid line S represents the sagittal direction ΔS of the d line, and the broken line M represents the meridional direction ΔM of the d line. Moreover, the figure which shows distortion represents the distortion in d line | wire. Fno is the F number, and ω is the half angle of view (degrees) of the shooting angle of view.

In the optical system LA of each embodiment, the second lens unit L2 includes a negative lens unit LN including a cemented lens in which a negative lens and a positive lens are cemented or a cemented lens in which a positive lens and a negative lens are cemented. The Abbe number of the positive lens material constituting the negative lens unit LN is νp, the anomalous partial dispersion is Δθg.F_p, the Abbe number of the material of the negative lens constituting the negative lens unit LN is νn, and the anomalous partial dispersion is Δθg. .F_n, the focal length of the optical system LA is f. The focal length of the negative lens unit LN is fsg, and the anomalous partial dispersion Δθg.F is the partial dispersion ratio for g-line and F-line is θg.F.
Δθg.F ＝ θg.F- (0.6438-0.001682 × νd)
And At this time,
0.72 ≦ νp / νn ≦ 1.00 (1)
0.005 ≦ Δθg.F_p- Δθg.F_n ≦ 0.050 (2)
-0.8 ≤ fsg / f ≤ -0.5 (3)
The following conditional expression is satisfied.

  According to the present invention, in a retrofocus type optical system, two lenses made of materials different from each other are bonded, the Abbe number being smaller on the image side than the aperture stop SP, the partial dispersion ratio θg.F of the g line and the F line being large. A cemented lens is provided. This improves the curvature of lateral chromatic aberration on the short wavelength side. Thereby, the lateral chromatic aberration is corrected satisfactorily.

  FIG. 15A is a lens cross-sectional view of a retrofocus type wide-angle lens for comparison with the optical system of the present invention. As shown in FIG. 15A, the retrofocus-type wide-angle lens LA has a negative lens G21, a positive lens G22, and a positive lens G23 in order from the object side to the image side from the aperture stop SP to the image side. The negative lens G21 and the positive lens G22 are often marginal contacts. On the other hand, in such a lens type wide-angle lens, the lateral chromatic aberration on the short wavelength side is often bent as shown in FIG.

  FIG. 15C is an explanatory diagram in which the difference between the g-line and the d-line in each lens surface and the entire system is plotted for the distortion third-order aberration coefficient V and fifth-order aberration coefficient V ^ (lens design method written by Naoya Matsui). reference). From FIG. 15C, the distorted fifth-order aberration coefficient is large on both lens surfaces forming the above-described marginal contact. Here, the relationship between the distortion, the distortion third-order aberration coefficient, and the distortion fifth-order aberration coefficient is based on the following equation (X1) (see the lens design method, P102 equation by Naoya Matsui, equation (4.22)) under the condition that the chromatic aberration of magnification disappears.

Where V: distortion third-order aberration coefficient V ^: distortion fifth-order aberration coefficient N1: refractive power of the medium closest to the object ω: half angle of view.

  From this, in order to eliminate the curvature of the chromatic aberration of magnification of the g-line at the image height y in consideration of y = ftanθ where the image height is y, the shooting half angle of view is θ, and the focal length is f, It is only necessary that the differential values of the expression (X1) regarding the d-line are equal (conditional expression (X2)).

From formula (X1) and formula (X2)

Can be summarized.

  Formula (X3) is an arbitrary ratio of the difference between the difference in the wavelength g and d of the fifth-order aberration coefficient V ^ of the distortion and the difference in the wavelength g and d of the third-order aberration coefficient V of the distortion opposite to the positive and negative and the focal length f. It is determined by the image height y. Here, for example, if f = 24 mm and y = 20 mm, the expression (X3) may be −2.9.

  This is the optical system shown in FIG. 16 (a). This optical system has, on the image side from the aperture stop SP, a cemented lens in which a difference between the Abbe numbers of materials is relatively small and anomalous partial dispersibility is greatly different, and a positive lens is cemented. It has a large negative lens unit G22a. Further, a positive lens G23 and a positive lens G24 are provided. As a result, the ratio of the third-order aberration coefficient to the fifth-order aberration coefficient in the entire system in FIG. FIG. 16B shows chromatic aberration of magnification. As shown in FIG. 16B, the lateral chromatic aberration at the position where the image height is high is canceled out by the low-order and high-order lateral chromatic aberration.

  As described above, the optical system having the negative lens G21, the positive lens G22, and the positive lens G23 in order from the object side to the image side from the aperture stop SP to the marginal contact between the negative lens G21 and the positive lens G22. The chromatic aberration of magnification increases with respect to the image height. Further, lateral chromatic aberration often occurs with a bend.

  In such a case, it is preferable to use a negative lens in which the difference in Abbe number is relatively small and the anomalous partial dispersibility is greatly different. A negative lens unit is better than a cemented lens obtained by cementing the negative lens and the positive lens. Alternatively, a negative lens unit including a cemented lens in which a positive lens and a negative lens are cemented is preferable. This makes it easy to control the bending of the chromatic aberration of magnification. The optical system of the present invention is configured as described above to satisfactorily correct chromatic aberration and obtain high optical performance.

  Conditional expression (1) is the Abbe number of the materials of the positive lens and the negative lens constituting the negative lens and the positive lens in the second lens unit L2 or the cemented lens (negative lens unit LN) including the positive lens and the negative lens. Specify the ratio. If the upper limit of conditional expression (1) is exceeded, a large balance of chromatic aberration occurs, making it difficult to maintain optical performance. When the lower limit of conditional expression (1) is exceeded, the power of the cemented lens surface becomes weak, and the ability to correct the curvature of lateral chromatic aberration on the short wavelength side is weakened. More preferably, the numerical value of conditional expression (1) is set as follows.

0.78 ≦ νp / νn ≦ 1.00 (1a)
Conditional expression (2) defines the difference in anomalous partial dispersion between the materials of the positive lens and the negative lens that constitute the negative lens unit LN in the second lens unit L2. When the upper limit of conditional expression (2) is exceeded, the correction of lateral chromatic aberration on the short wavelength side on the cemented lens surface becomes excessive, and the optical performance deteriorates. If the lower limit of conditional expression (2) is exceeded, the ability to correct lateral chromatic aberration on the short wavelength side on the cemented lens surface will be weakened, making it difficult to obtain the desired effect. More preferably, the numerical range of conditional expression (2) is set as follows.

0.005 ≦ Δθg.F_p- Δθg.F_n ≦ 0.030 (2a)
Conditional expression (2a) is preferably set as follows in order to achieve more effect.

0.005 ≦ Δθg.F_p- Δθg.F_n ≦ 0.020 (2b)
Conditional expression (3) defines the power of the negative lens unit LN in the second lens unit L2. If the upper limit of conditional expression (3) is exceeded, the correction of lateral chromatic aberration on the short wavelength side of the negative lens unit LN becomes excessive, resulting in a decrease in chromatic aberration and a decrease in optical performance. When the lower limit of conditional expression (3) is exceeded, the negative lens unit LN has a weak ability to correct short-wavelength side chromatic aberration, and it becomes difficult to obtain a desired effect. More preferably, the numerical range of conditional expression (3) is set as follows.

-0.80 ≤ fsg / f ≤ -0.56 (3a)
In each embodiment, on the image side of the negative lens unit LN, a first positive lens unit made of a single lens or a cemented lens and a second positive lens unit made of a single lens or a cemented lens are provided.

The negative lens unit LN and the first positive lens unit are in marginal contact. The radius of curvature of the lens surface on the image side of the negative lens unit LN is R1a, and the radius of curvature of the lens surface on the object side of the first positive lens unit is R2a. At this time,
| R1a / R2a | ≦ 1.7 (4)
The following conditional expression is satisfied.

  Conditional expression (4) defines the shape of the air lens formed by the negative lens unit and the first positive lens unit in the second lens unit L2. If the upper limit of conditional expression (4) is exceeded, the power of the lens surface before and after the marginal contact is formed becomes strong, causing a chromatic aberration of magnification on the short wavelength side, astigmatism, etc., and maintaining good optical performance. It becomes difficult. More preferably, the numerical range of conditional expression (4) is set as follows.

0.10 ≦ | R1a / R2a | ≦ 1.55 (4a)
As described above, in each of the embodiments, in the retrofocus type optical system, the negative lens unit LN having a relatively close Abbe number closer to the image side than the aperture stop SP and having a large partial dispersion ratio between the g line and the F line is provided. . This improves the bending of lateral chromatic aberration on the short wavelength side. Thereby, the residual aberration of lateral chromatic aberration is remarkably reduced, and an optical system having high optical performance is obtained.

  In each embodiment, the material of the lens constituting the negative lens unit LN may be a glass material or a resin. In each embodiment, the first lens unit L1 includes a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a negative lens in order from the object side to the image side.

  Alternatively, the first lens unit L1 includes a negative lens, a positive lens, a negative lens, a positive lens, and a negative lens in order from the object side to the image side. Alternatively, the first lens unit L1 includes a negative lens and a cemented lens in which a positive lens and a negative lens are cemented in order from the object side to the image side. Alternatively, the first lens unit L1 includes a negative lens, a positive lens, a negative lens, a positive lens, and a cemented lens in which the negative lens and the positive lens are cemented in order from the object side to the image side. In each embodiment, the second lens unit L2 includes, in order from the object side to the image side, a positive lens, a cemented lens in which a negative lens and a positive lens are cemented, a meniscus positive lens having a concave object side, and a positive lens. The

  Alternatively, the second lens unit L2 includes, in order from the object side to the image side, a cemented lens in which a negative lens and a positive lens are cemented, a cemented lens in which a negative lens and a positive lens are cemented, and a positive lens. Alternatively, the second lens unit L2 includes, in order from the object side to the image side, a positive lens, a cemented lens in which a positive lens and a negative lens are cemented, a positive meniscus lens having a concave object side, and a positive lens.

  Next, specific lens configurations of the first lens unit L1 and the second lens unit L2 of each embodiment will be described. The optical system according to the first exemplary embodiment includes, in order from the object side to the image side, a first lens unit L1 having a negative refractive power, an aperture stop SP, and a second lens unit L2 having a positive refractive power. The first lens unit L1 is as follows in order from the object side to the image side. Positive lens with convex object side, negative meniscus lens with convex object side, positive lens with biconvex shape, negative lens with convex meniscus with object side, positive lens with biconvex shape, negative meniscus shape with convex on image side It consists of a lens. The second lens unit L2 on the image side from the aperture stop SP is as follows in order from the object side to the image side.

  The lens includes a biconvex positive lens, a cemented lens in which a negative lens and a positive lens are cemented, a meniscus positive lens having a concave object side, and a positive lens.

  In the optical system of Example 2, the refractive power arrangement of each lens group and the position of the aperture stop SP are the same as those of Example 1. The first lens unit L1 is as follows in order from the object side to the image side. Convex positive lens on the object side, negative meniscus lens on the object side convex, biconvex positive lens, negative meniscus lens on the object side convex, biconvex positive lens, negative meniscus negative on the image side It consists of a lens. The lens configuration of the second lens unit L2 on the image side from the aperture stop SP is the same as that of the first embodiment.

  In the optical system of the third embodiment, the refractive power arrangement of each lens group and the position of the aperture stop SP are the same as those of the first embodiment. The first lens unit L1 is as follows in order from the object side to the image side. Convex positive lens on the object side, negative meniscus lens on the object side convex, biconvex positive lens, negative meniscus lens on the object side convex, biconvex positive lens, negative meniscus negative on the image side It consists of a lens. The lens configuration of the second lens unit L2 on the image side from the aperture stop SP is the same as that of the first embodiment.

  In the optical system of the fourth embodiment, the refractive power arrangement of each lens group and the position of the aperture stop SP are the same as those of the first embodiment. The first lens unit L1 is as follows in order from the object side to the image side. The lens is composed of a negative meniscus lens having a convex surface on the object side, a positive lens having a biconvex shape, a negative lens having a convex surface on the object side and a meniscus shape, a positive lens having a biconvex shape, and a negative lens having a convex shape on the image side and a meniscus shape. The lens configuration of the second lens unit L2 located on the image side from the aperture stop SP is the same as that of the first embodiment.

  The optical system of Example 5 includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, an aperture stop SP, and a second lens unit L2 having a positive refractive power.

  The first lens unit L1 is as follows in order from the object side to the image side. It is composed of a meniscus negative lens having a convex object side and a cemented lens in which a positive lens and a negative lens are cemented. The second lens unit L2 located on the image side from the aperture stop SP is as follows in order from the object side to the image side. The lens includes a cemented lens in which a negative lens and a positive lens are cemented, a cemented lens in which a negative lens and a positive lens are cemented, and a biconvex positive lens.

  In the optical system of Example 6, the refractive power arrangement of each lens group and the position of the aperture stop SP are the same as those of Example 5. The first lens unit L1 is as follows in order from the object side to the image side. It is composed of a negative meniscus lens having a convex object side, a biconvex positive lens, a biconcave negative lens, a biconvex positive lens, and a cemented lens in which a negative lens and a positive lens are cemented. The lens configuration of the second lens unit L2 located on the image side from the aperture stop SP is the same as that of the first embodiment.

  In the optical system of the seventh embodiment, the refractive power arrangement of each lens group and the position of the aperture stop SP are the same as those of the first embodiment. The lens configuration of the first lens unit L1 is the same as that of the first embodiment. The second lens unit L2 located on the image side from the aperture stop SP is as follows in order from the object side to the image side. The lens includes a biconvex positive lens, a cemented lens in which a positive lens and a negative lens are cemented, a meniscus positive lens having a concave object side, and a positive lens.

  FIG. 17 is a schematic diagram of a main part of a digital still camera using the optical system of each embodiment. In FIG. 17, reference numeral 20 denotes a camera body, and reference numeral 21 denotes a photographing optical system constituted by any one of the optical systems described in each embodiment. Reference numeral 22 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 21 and is built in the camera body 20.

  The present embodiment can be applied to a single-lens reflex camera with a quick return mirror, a mirrorless single-lens reflex camera without a quick return mirror, and an imaging apparatus such as a lens shutter camera. In addition, the present invention can be similarly applied to an optical apparatus such as a projector.

  Hereinafter, Numerical Examples 1 to 7 corresponding to Examples 1 to 7, respectively, are shown. In each numerical example, i indicates the order from the object side, ri is the radius of curvature of each surface, di is the member thickness or air spacing between the i-th surface and the i + 1-th surface, and ndi and νdi are d Indicates the refractive index and Abbe number for the line. BF is a back focus, which is a distance from the final lens surface to the image plane.

(Numerical example 1)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 109.958 3.55 1.51633 64.1 42.70
2 3199.111 0.10 40.88
3 83.973 1.30 1.59522 67.7 35.99
4 18.954 4.19 28.08
5 43.283 3.67 1.51633 64.1 27.81
6 -882.410 4.70 26.63
7 33.350 0.90 1.59522 67.7 16.80
8 10.118 3.10 13.83
9 43.024 3.08 1.74950 35.3 13.13
10 -156.256 0.50 11.68
11 -84.624 8.24 1.76182 26.5 11.31
12 -99.021 1.00 13.18
13 (Aperture) ∞ 1.00 13.55
14 100.462 7.37 1.81600 46.6 13.92
15 -18.742 1.59 14.49
16 -22.434 0.80 1.80518 25.4 13.38
17 15.184 2.16 1.80809 22.8 13.75
18 40.066 1.38 14.39
19 -44.734 2.25 1.69680 55.5 14.61
20 -20.085 0.15 15.87
21 -3928.597 3.08 1.59282 68.6 17.94
22 -26.351 38.04 18.84
Image plane ∞

Various data focal length 24.50
F number 2.86
Half angle of view (degrees) 41.45
Statue height 21.64
Total lens length 92.15
BF 38.04
Entrance pupil position 20.39
Exit pupil position -21.13
Front principal point position 34.74
Rear principal point position 13.54

Lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -43.29 33.32 5.97 -20.61
2 13 27.18 19.78 10.31 -4.52

Single lens Data lens Start surface Focal length
1 1 220.46
2 3 -41.44
3 5 80.02
4 7 -24.76
5 9 45.31
6 11 -1015.33
7 14 19.91
8 16 -11.14
9 17 29.13
10 19 50.42
11 21 44.74

(Numerical example 2)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 116.520 3.95 1.51633 64.1 42.34
2 -14258.963 0.10 39.97
3 82.458 1.30 1.59522 67.7 35.07
4 18.397 5.26 27.32
5 84.116 2.92 1.51633 64.1 27.03
6 -158.001 4.70 26.03
7 72.333 0.90 1.59522 67.7 17.46
8 11.751 2.33 14.70
9 34.094 3.77 1.74950 35.3 14.39
10 -504.438 0.53 12.84
11 353.782 9.91 1.75520 27.5 12.21
12 147.728 1.14 13.64
13 (Aperture) ∞ 1.00 14.02
14 26.268 4.21 1.67790 55.3 14.82
15 -19.396 2.06 14.79
16 -17.784 0.73 1.74950 35.3 13.30
17 18.000 1.55 1.74950 35.3 13.33
18 29.639 1.25 13.34
19 -59.498 2.43 1.59282 68.6 13.38
20 -17.358 0.32 14.44
21 -369.332 2.96 1.59282 68.6 16.62
22 -23.379 38.02 17.56
Image plane ∞

Various data focal length 24.50
F number 2.86
Half angle of view (degrees) 41.45
Statue height 21.64
Total lens length 91.34
BF 38.02
Entrance pupil position 20.49
Exit pupil position -18.15
Front principal point position 34.31
Rear principal point position 13.52

Lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -30.12 35.68 9.74 -15.59
2 13 24.56 16.50 7.90 -6.51

Single lens Data lens Start surface Focal length
1 1 223.86
2 3 -40.09
3 5 106.75
4 7 -23.70
5 9 42.74
6 11 -342.95
7 14 17.10
8 16 -11.83
9 17 57.86
10 19 40.47
11 21 41.97

(Numerical example 3)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 111.058 3.87 1.51633 64.1 42.69
2 -1161.681 0.10 40.75
3 80.808 1.30 1.59522 67.7 35.06
4 18.000 5.34 27.04
5 85.605 2.75 1.51633 64.1 26.74
6 -200.052 4.70 25.72
7 189.224 0.90 1.59522 67.7 17.76
8 12.712 2.99 15.05
9 32.286 4.01 1.74950 35.3 14.33
10 -123.628 0.61 12.79
11 351.950 9.60 1.75520 27.5 12.47
12 107.959 1.00 13.74
13 (Aperture) ∞ 1.00 14.00
14 23.099 4.27 1.56907 71.3 14.73
15 -18.114 1.98 14.66
16 -16.301 0.70 1.65412 39.7 13.30
17 22.000 1.23 1.59551 39.2 13.33
18 28.094 1.28 13.37
19 -61.127 2.39 1.59282 68.6 13.41
20 -17.946 0.15 14.45
21 3033.223 2.93 1.59282 68.6 16.49
22 -24.969 38.01 17.42
Image plane ∞

Various data focal length 24.50
F number 2.86
Half angle of view (degrees) 41.45
Statue height 21.64
Total lens length 91.13
BF 38.01
Entrance pupil position 20.51
Exit pupil position -17.73
Front principal point position 34.24
Rear principal point position 13.51

Lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -34.31 36.18 8.22 -18.14
2 13 25.64 15.94 8.08 -5.93

Single lens Data lens Start surface Focal length
1 1 196.53
2 3 -39.21
3 5 116.49
4 7 -22.94
5 9 34.54
6 11 -209.76
7 14 18.54
8 16 -14.21
9 17 158.36
10 19 41.99
11 21 41.79

(Numerical example 4)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 130.274 1.49 1.59522 67.7 40.29
2 25.550 3.13 33.87
3 41.730 6.40 1.51633 64.1 33.71
4 -90.455 5.37 32.74
5 59.607 1.03 1.59522 67.7 20.12
6 11.734 4.24 16.42
7 35.285 3.70 1.74950 35.3 15.35
8 -109.611 0.50 13.92
9 -50.738 7.63 1.76182 26.5 13.60
10 -102.453 2.67 14.24
11 (Aperture) ∞ 1.05 14.94
12 58.529 4.41 1.81600 46.6 15.30
13 -23.507 2.34 15.33
14 -23.920 1.13 1.80518 25.4 13.77
15 14.266 2.23 1.80809 22.8 13.79
16 36.829 1.90 14.37
17 -37.219 2.83 1.69680 55.5 15.05
18 -20.144 0.15 16.87
19 681.181 3.25 1.59282 68.6 19.19
20 -28.427 39.30 20.05
Image plane ∞

Various data focal length 28.00
F number 2.86
Half angle of view (degrees) 37.69
Statue height 21.64
Total lens length 94.73
BF 39.30
Entrance pupil position 21.35
Exit pupil position -21.09
Front principal point position 36.36
Rear principal point position 11.30

Lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -60.86 33.48 2.53 -24.56
2 11 30.97 19.28 10.18 -5.92

Single lens Data lens Start surface Focal length
1 1 -53.68
2 3 56.23
3 5 -24.74
4 7 36.01
5 9 -140.94
6 12 21.06
7 14 -10.95
8 15 27.60
9 17 59.00
10 19 46.11

(Numerical example 5)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 42.046 1.50 1.59282 68.6 38.56
2 19.046 21.03 32.03
3 34.226 7.38 1.77250 49.6 26.02
4 -28.087 3.37 1.59270 35.3 24.92
5 -331.496 7.90 22.83
6 (Aperture) ∞ 2.23 18.82
7 -26.067 1.00 1.61340 44.3 18.57
8 16.000 3.32 1.59270 35.3 18.60
9 53.595 1.03 18.63
10 -484.125 0.97 1.80518 25.4 18.66
11 35.566 3.93 1.59282 68.6 19.03
12 -29.109 0.15 19.28
13 74.714 3.84 1.81600 46.6 20.35
14 -56.799 36.03 21.41
Image plane ∞

Various data focal length 35.00
F number 2.00
Half angle of view (degrees) 31.72
Statue height 21.64
Total lens length 93.66
BF 36.03
Entrance pupil position 26.81
Exit pupil position -16.84
Front principal point position 38.65
Rear principal point position 1.03

Lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 41.77 33.27 28.59 9.76
2 7 86.89 16.45 26.82 21.95

Single lens Data lens Start surface Focal length
1 1 -60.19
2 3 21.06
3 4 -51.99
4 7 -16.02
5 8 37.26
6 10 -41.11
7 11 27.63
8 13 40.07

(Numerical example 6)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 104.922 2.00 1.59270 35.3 49.85
2 37.065 5.72 44.01
3 127.780 5.10 1.83481 42.7 43.77
4 -171.330 9.39 42.81
5 * -118.668 1.50 1.58313 59.4 28.90
6 * 19.438 5.64 24.57
7 27.306 10.49 1.81600 46.6 23.68
8 -97.899 4.41 22.30
9 -62.080 1.00 1.59551 39.2 21.18
10 46.101 2.77 1.83481 42.7 21.07
11 141.972 2.72 20.89
12 (Aperture) ∞ 2.15 20.78
13 78.627 3.37 1.72916 54.7 20.64
14 -39.739 3.52 20.46
15 -20.073 0.90 1.80000 29.8 18.69
16 30.000 3.09 1.80518 25.4 19.33
17 90.704 1.39 19.60
18 -59.507 4.20 1.59282 68.6 19.62
19 -20.062 0.15 20.48
20 72.420 5.06 1.59282 68.6 25.06
21 -47.316 38.3 26.09
Image plane ∞

Aspheric data 5th surface
K = 0.00000e + 000 A 4 = 1.04381e-008 A 6 = 3.85467e-010 A 8 = 2.75687e-014 A10 = -1.31200e-015 A12 = -2.54756e-017
6th page
K = 1.97003e-002 A 4 = -2.14590e-006 A 6 = -5.64301e-008 A 8 = 4.71790e-010 A10 = -2.72648e-012 A12 = 4.80763e-015

Various data focal length 35.11
F number 2.05
Half angle of view (degrees) 31.64
Statue height 21.64
Total lens length 112.89
BF 38.30
Entrance pupil position 33.35
Exit pupil position -30.65
Front principal point position 50.59
Rear principal point position 3.20

Lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 1500.41 49.54 240.72 241.32
2 15 41.26 23.83 16.91 -1.99
Single lens Data lens Start surface Focal length
1 1 -97.77
2 3 88.36
3 5 -28.53
4 7 27.19
5 9 -44.27
6 10 80.72
7 13 36.64
8 15 -14.91
9 16 54.43
10 18 49.11
11 20 49.05

(Numerical example 7)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 134.144 3.88 1.51633 64.1 41.98
2 -976.721 0.10 39.64
3 78.860 1.30 1.59522 67.7 34.29
4 17.628 4.61 26.56
5 51.964 3.19 1.51633 64.1 26.29
6 -359.345 4.70 25.22
7 43.585 0.90 1.59522 67.7 16.50
8 10.512 2.44 13.76
9 37.499 3.79 1.74950 35.3 13.44
10 -85.674 0.50 11.84
11 -87.022 8.57 1.76182 26.5 11.71
12 -106.727 1.00 13.66
13 (Aperture) ∞ 1.00 14.03
14 109.830 5.25 1.81600 46.6 14.40
15 -18.392 1.29 14.77
16 -24.621 2.25 1.80809 22.8 13.69
17 -12.000 3.16 1.80518 25.4 13.65
18 34.666 1.34 14.10
19 -56.320 2.03 1.69680 55.5 14.37
20 -24.467 0.15 15.57
21 -18183.106 3.14 1.59282 68.6 17.32
22 -24.128 38.03 18.26
Image plane ∞
Various data

Focal length 24.50
F number 2.86
Half angle of view (degrees) 41.45
Statue height 21.64
Total lens length 92.61
BF 38.03
Entrance pupil position 19.82
Exit pupil position -20.06
Front principal point position 33.99
Rear principal point position 13.53

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -46.46 33.97 3.56 -24.02
2 13 28.08 19.61 9.86 -4.87

Single lens Data lens Start surface Focal length
1 1 228.70
2 3 -38.45
3 5 88.16
4 7 -23.51
5 9 35.27
6 11 -762.00
7 14 19.67
8 16 26.83
9 17 -10.75
10 19 60.50
11 21 40.75

L1 First lens group L2 Second lens group SP Aperture stop

Claims (13)

In an optical system including a first lens unit having a positive or negative refractive power, an aperture stop, and a second lens group having a positive refractive power in order from the object side to the image side,
The second lens group is a negative lens unit including a cemented lens in which a negative lens and a positive lens are cemented in order from the object side to the image side, or a cemented lens in which the positive lens and the negative lens are cemented in sequence from the object side to the image side. Have
Assuming that the partial dispersion ratio for g-line and F-line is θg.F, the abnormal partial dispersion Δθg.F is
Δθg.F ＝ θg.F- (0.6438-0.001682 × νd)
And
The Abbe number of the positive lens material constituting the negative lens unit is νp, the anomalous partial dispersion is Δθg.F_p, the Abbe number of the material of the negative lens constituting the negative lens unit is νn, and the anomalous partial dispersion is Δθg. .F_n, where f is the focal length of the entire optical system, and fsg is the focal length of the negative lens unit.
0.72 ≦ νp / νn ≦ 1.00
0.005 ≦ Δθg.F_p- Δθg.F_n ≦ 0.050
-0.8 ≦ fsg / f ≦ -0.5
An optical system that satisfies the following conditional expression:   2. The optical system according to claim 1, further comprising a first positive lens unit made of a single lens or a cemented lens and a second positive lens unit made of a single lens or a cemented lens on the image side of the negative lens unit. . The negative lens unit and the first positive lens unit are marginally contacted, the radius of curvature of the lens surface on the image side of the negative lens unit is R1a, and the radius of curvature of the lens surface on the object side of the first positive lens unit is When R2a
| R1a / R2a | ≦ 1.7
The optical system according to claim 2, wherein the following conditional expression is satisfied.   4. The optical system according to claim 1, wherein a part of the lens portion on the image side of the first lens group and the second lens group move integrally during focusing. 5.   4. The optical system according to claim 1, wherein a part of the lens portion on the image side of the first lens group moves during focusing.   The second lens group includes, in order from the object side to the image side, a positive lens, a cemented lens obtained by cementing a negative lens and a positive lens, a meniscus positive lens having a concave object side, and a positive lens. Item 6. The optical system according to any one of Items 1 to 5.   2. The second lens group includes, in order from the object side to the image side, a cemented lens in which a negative lens and a positive lens are cemented, a cemented lens in which a negative lens and a positive lens are cemented, and a positive lens. 6. The optical system according to any one of items 1 to 5.   The second lens group includes, in order from the object side to the image side, a positive lens, a cemented lens in which a positive lens and a negative lens are cemented, a meniscus positive lens having a concave object side, and a positive lens. Item 6. The optical system according to any one of Items 1 to 5.   9. The first lens group according to claim 1, wherein the first lens group includes a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a negative lens in order from the object side to the image side. Optical system.   The optical system according to claim 1, wherein the first lens group includes a negative lens, a positive lens, a negative lens, a positive lens, and a negative lens in order from the object side to the image side. .   9. The optical system according to claim 1, wherein the first lens group includes a negative lens and a cemented lens in which a positive lens and a negative lens are cemented in order from the object side to the image side.   9. The first lens group includes a negative lens, a positive lens, a negative lens, a positive lens, and a cemented lens obtained by cementing a negative lens and a positive lens in order from the object side to the image side. The optical system according to any one of the above. An optical apparatus comprising the optical system according to claim 1.