RU2431164C1 - Large-aperture lens - Google Patents

Abstract

FIELD: physics. ^ SUBSTANCE: lens has two components separated by an aperture diaphragm. The first component contains a negative meniscus whose convex side faces the object space, a glued negative meniscus whose convex side faces the object space, consisting of a biconvex and a biconcave lens, a biconvex lens, a glued biconvex lens consisting of a biconvex lens and a negative meniscus whose concave side faces the object space, and a negative meniscus whose convex side faces the object space. The second component contains a glued negative meniscus whose concave side faces the object space and consisting of a biconcave and a biconvex lens, a positive meniscus whose concave side faces the object space, a biconvex lens and a single positive meniscus whose convex side faces the object space. ^ EFFECT: increasing the linear field of vision to a S35 film format (25,5 ù 18,6 mm) while simultaneously increasing the rear section and maintaining quality of the image. ^ 3 cl, 1 dwg, 1 app

Description

The present invention relates to film technology, namely to film-making and photo equipment.

Known fast wide-angle lens [1], consisting of two components separated by an aperture diaphragm. The first component includes those installed sequentially: a negative meniscus, a biconvex lens, a negative meniscus, a biconvex lens, a positive meniscus, two negative menisci and a biconvex lens, and a second component that includes a biconvex lens, a biconcave lens, a positive biconvex meniscus and

The lens has the following characteristics: relative aperture 1: 1.2, field of view 84 °. But this lens can be used to shoot movies in the S16 format (12.3 × 7.5 mm).

The closest technical solution to the proposed invention is a fast aperture lens with a large relative aperture [2].

The lens consists of two components sequentially located along the optical axis, separated by an aperture diaphragm. The first component includes a meniscus-shaped positive lens convex to the space of the object, a double-glued positive lens consisting of positive and negative menisci, a negative meniscus facing the convex side into the space of the object.

The second component consists of a negative meniscus facing concavity to the space of the object glued from a biconcave lens and a positive biconvex lens, a positive biconvex lens and a positive meniscus convex to the space of an object glued from a negative and positive meniscus.

The lens has a high relative aperture of 1: 0.95, satisfactory image quality, but its linear field of view is 12.3 × 7.5 mm (film format S16), the rear segment from the last surface of the lens to the plane of the film is too small, which does not allow use it when shooting professional filming equipment containing a mirror shutter, with which the operator has the opportunity to simultaneously monitor the composition of the frame and the sharpness of the subject.

The main task to which the invention is directed is to increase the linear field of view to the S35 film format (25.5 × 18.6 mm) while increasing the back section while maintaining image quality.

To solve this problem, a fast lens was proposed, which, like the prototype, contains two components separated by an aperture diaphragm, the first of which contains a positive lens, a glued lens, a negative meniscus facing the convex side into the space of the object, and a second component consisting of a glued negative meniscus facing concavity to the space of an object consisting of a negative biconcave and positive biconvex lenses, a positive biconvex lens and positively a meniscus which is convex to the object space.

In contrast to the prototype, the positive lens of the first component is biconvex and in front of it there is a negative meniscus convex to the space of the object, and a negative glued meniscus convex to the space of the object, consisting of positive biconvex and negative biconcave lenses, while the glued positive biconvex lens from a biconvex lens and a negative meniscus facing concavity to the space of the object, and in the second component between the glue This negative meniscus and the positive biconvex lens additionally contain a positive meniscus facing concavity to the space of the object, while the positive meniscus convex to the space of the object is made in the form of a single lens.

In addition, a negative meniscus convex to the space of objects, a negative glued meniscus convex to the space of objects, containing a positive biconvex and negative biconcave lens, and a positive biconvex glued lens, containing a biconvex lens and a negative meniscus that faces the first object concave and a negative biconcave meniscus lens in the glued second component have refractive indices of n _d> 1,71, and negative ny meniscus convexity to the space of the first component of the object, and the last four positive lens of the second component have refractive indices n _d <1,62.

The optical forces φ of single and bonded positive lenses are 0.23 <φ <0.5, and with negative optical forces | φ | <0.5,

,Where

,

φ _l - the optical power of the lens;

φ _eq is the equivalent optical power of the lens;

f ′ _equiv - equivalent focal length of the lens;

f ′ _l - the focal length of the lens.

The essence of the invention lies in the fact that this embodiment of the proposed fast lens allowed to increase the linear field of view to the film format S35 (25.5 × 18.6 mm), approximately two times, while maintaining a high relative aperture of 1: 1.2, and the rear the segment from the last lens surface to the film surface ≥32 mm, which allows the use of this lens not only in cameras, but also in professional filming equipment. The image is contrasted across the entire field of view.

Thus, the technical result is achieved, consisting in increasing the linear field of view and the rear segment, as well as the contrast of the image over the entire field of view.

The present invention is illustrated in the drawing, which shows the optical scheme of the fast lens, as well as the Appendix, which gives the design parameters and graphs of the frequency-contrast characteristics.

The fast lens contains two components separated by an aperture diaphragm AD.

The first component contains a positive biconvex lens 1, a glued positive lens consisting of a positive biconvex lens 2 and a negative meniscus 3 facing concavity to the space of the object, a negative meniscus 4 facing the convex side into the space of the object, and a second component consisting of a glued negative meniscus, facing concavity to the space of the object, consisting of a negative biconcave 5 and a positive biconvex 6 lenses, a positive biconvex lens 7 and 8 ozhitelnogo meniscus which is convex to the object space.

In front of the positive biconvex lens 1, there is a negative meniscus 9, convex to the space of the object, and a negative meniscus, convex to the space of the object, and consisting of a positive biconvex 10 and a negative biconcave 11 lenses.

In the second component, between the glued negative meniscus facing the concavity to the space of the object, and consisting of the negative biconcave 5 and positive biconvex 6 lenses and the positive biconvex lens 7, an additional positive meniscus 12, facing the concavity to the space of the object, and a positive meniscus 8, facing the bulge to object space, made in the form of a single lens.

In addition, a negative meniscus 9 convex to the space of the object, a negative meniscus convex to the space of the object, consisting of a positive biconvex 10 and a negative biconcave 11 lenses, a positive biconvex lens 1 and a bonded positive lens, consisting of a positive biconvex lens 2 and meniscus 3, facing concavity to the space of the object, in the first component, as well as in the second component, negative biconcave lens 5 glued negative the meniscus facing concavity to the space of the object, and consisting of negative biconcave 5 and positive biconvex 6 lenses, have refractive indices n _d > 1.71, and the negative meniscus 4, convex side facing the space of the object, the first component located in front of the aperture diaphragm , and the remaining lenses 6, 7, 8, and 12 have refractive indices n _d <1.62.

The difference in dispersions Δν in the bonded lenses of the first and second components has values Δν> 10.

The optical forces φ of single and bonded positive lenses are 0.23 <φ <0.5, and with negative optical forces | φ | <0.5,

,Where

,

φ _l - the optical power of the lens;

φ _eq is the equivalent optical power of the lens;

f ′ _equiv - equivalent focal length of the lens;

f ′ _l - the focal length of the lens.

The proposed fast lens works as follows.

Rays from the subject pass through the first component, limited to the aperture diaphragm AD.

The introduction of additional single and bonded lenses, the choice of the configuration of bonded and single lenses, their optical forces and parameters of optical materials (n _d , ν) made it possible to correct the lens aberrations.

In particular, a bonded positive biconvex lens, consisting of a biconvex 2 lens and a negative meniscus 3, facing concavity to the space of the object, introduces significant positive spherical aberration, coma, astigmatism and distortion.

Positive biconvex lens 1 introduces positive spherical aberration and slight coma, astigmatism and distortion, negative meniscus 4, convex side facing the space of the object and glued negative meniscus facing concavity to the space of the object, and consisting of negative biconcave 5 and positive biconvex 6 lenses the sum contribute significant negative spherical aberration and astigmatism, and small in size coma and distortion.

A positive biconvex lens 7 and a positive meniscus 8, convex to the space of the object, introduce positive spherical aberration, negative astigmatism and distortion.

The positive meniscus 12, facing concavity to the space of the object, corrects for distortion and introduces significant spherical aberration.

Negative meniscus 9, convex to the space of the object and negative meniscus, convex to the space of the object, and glued from the positive biconvex 10 and negative biconcave 11 lenses, correct the residual spherical aberration, coma, astigmatism and distortion.

Thus, the spherical aberration of the first component is negative and equal in magnitude to the spherical aberration of the second component.

Coma and astigmatism of the first component are positive and compensate for coma and astigmatism of the second component.

The distortion of the first component is positive and compensates for the distortion of the second component.

The choice of the location of the negative meniscus 9, convex to the space of the object and the negative meniscus, convex to the space of the object, and glued from the positive biconvex 10 and negative biconcave 11 lenses in the first component and the positive meniscus 12, facing the concavity to the space of the object in the second component, and also the choice of optical materials in the first component for the first six lenses 9, 10, 11, 1, 2, and 3 in the first component and the 5th lens in the second component with a refractive index n _d > 1.71, and for the negative meniscus 4, the convex side facing the space of the object, the first component, and the last four lenses of the second component 6, 12, 7, and 8 with a refractive index n _d <1.62, it was possible to minimize higher-order aberrations and ensure their mutual compensation.

The dispersion difference Δν> 10 in the bonded lenses 10, 11; 2, 3; 5, 6 allowed to minimize the increase in chromatism.

The choice of optical forces φ single 1, 12; 7, 8, and glued from 2, 3 lenses with positive optical power satisfying the condition

0.235 <φ <0.5,

and single 9, 4 and glued 10, 11; and 5, 6 with negative optical forces satisfying the condition | φ | <0.5, it was possible to correct two aberrations:

- the curvature of the image, the correction condition of which is the fulfillment of the condition

- chromatism of position and increase, the condition for correction of which is

The introduction of additional negative lenses in the first component, menisci 9 and glued out of 10, 11, introduced significant negative position chromatism and positive magnification chromaticity, compensating for the chromatic aberration of the entire lens.

Thanks to the use of the proposed technical solution, a fast lens with a focal length f ′ = 25 mm, a relative aperture of 1: 1.2 and a linear field of view of 25.5 × 18.6 mm was calculated.

The calculation results are given in the Appendix.

The optical materials of the lenses and their optical powers are shown in the table.

Lens number Material n _d Optical power φ / φ _equiv ν _d 9 N-LAK 8 1,713 -0.28 53.83 10 N-LASF 45 1,801 -0.33 34.97 eleven N-LAK 8 1,713 53.83 one N-LAF 36 1.8 0.26 42.37 2 N-LAK 8 1,713 0.5 53.83 3 N-SF 1 1,717 29.62 four N-SSK 8 1,617 -0.28 49.83 5 N-SF 1 1,717 -0.45 29.62 6 N-PSK 53A 1,62 63.39 12 N-SK 5 1,59 0.39 61.27 7 N-PSK 53A 1,62 0.23 63.39 8 N-PSK 53A 1,62 0.26 63.39

The difference of the dispersions Δν in the bonded lenses 10 and 11 are:

Δν _{10, 11} = 18.9; Δν _{2, 3} = 24; Δν _{5, 6} = 34.

The main characteristics of image quality:

Television distortion for y ′ = 12.25 mm (normalized to coordinate) = 2.45%;

- image contrast at a frequency of 30 l / mm with a relative aperture of 1: 1.2 more than 25% over the entire field of view, while the prototype ≈20%, with a relative aperture of 1: 2.8 - more than 40%, the prototype ≈20% , with a relative aperture of 1:11 - more than 28%, the prototype ≈20%.

The rear segment is S′≥32 mm, while the light diameter of the last lens is D = 34.2 mm. This allows the lens to be used both in digital film cameras and in cameras working on film, in which, due to the presence of an optical shutter, it is necessary to provide a large rear segment.

Thus, the proposed fast lens allowed to increase the linear field of view to the film format S35 (25.5 × 18.6 mm) while increasing the rear segment and to improve image quality.

INFORMATION SOURCES

1. Russian Federation, patent No. 2133713, IPC: G02B 9/62, G02B 11/34, publ. 12/20/1998

2. Germany, patent No. 269693, IPC: G02B 9/62, G02B 11/34, publ. 07/05/1989 - a prototype.

Claims (3)

1. A fast lens containing two components separated by an aperture diaphragm, the first of which contains a positive lens, a glued lens, a negative meniscus with the convex side facing the space of the object, and a second component consisting of a glued negative meniscus facing the concavity of the space of the object, consisting of negative biconcave and positive biconvex lenses, positive biconvex lens and positive meniscus convex to the space of the object, exl which means that the positive lens of the first component is biconvex and a negative meniscus convex to the space of the object and a negative glued meniscus convex to the space of the object, consisting of a positive biconvex and negative biconcave lens, are glued in front of it, while the bonded positive biconvex lens from a biconvex lens and a negative meniscus facing concavity to the space of the object, and in the second component between glued a negative meniscus and a positive biconvex lens additionally placed a positive meniscus facing concavity to the space of the object, while the positive meniscus convex to the space of the object is made in the form of a single lens. 2. A fast lens according to claim 1, characterized in that the negative meniscus convex to the space of the object, the negative glued meniscus convex to the space of the object, containing a positive biconvex and negative biconcave lens, and a positive biconvex glued lens containing a biconvex lens and the negative meniscus facing concavity to the space of the object, the first component and the negative biconcave lens in the glued meniscus of the second component have refractive indices n _d > 1.71, and the negative meniscus convex to the space of the object, the first component, and the last four positive lenses of the second component have refractive indices n _d <1.62. 3. The fast lens according to claim 1, characterized in that the optical forces φ of single and bonded positive lenses are 0.23 <φ <0.5, and with negative optical forces | φ | <0.5,
Where

,
φ _l - the optical power of the lens;
φ _eq is the equivalent optical power of the lens;
f ' _eq is the equivalent focal length of the lens;
f ' _l - the focal length of the lens.

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