RU2431163C1 - Large-aperture lens - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: lens has two components separated by an aperture diaphragm. The first component has a negative meniscus whose convex side faces the object space, consisting of a negative and a positive meniscus glued to each other, a biconvex lens consisting a glued convergent 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, 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 × 18,6 mm) while simultaneously increasing the rear section and maintaining quality of the image.

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Description

The 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 installed sequentially:

a negative meniscus, a biconvex lens, a negative meniscus, a biconvex lens, a positive meniscus, two negative meniscuses and a biconvex lens, and a second component, including a biconvex lens, a biconcave lens, a positive biconcave meniscus, and two biconvex lenses.

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 positive lens glued together, consisting of a positive lens and a negative meniscus, and a negative meniscus facing the convex side into space object, and the second component contains a glued negative meniscus, facing concavity to the space of the object, and consists of a negative biconcave and positive two ypukloy lenses biconvex positive lens and a positive meniscus which is convex to the object space.

Unlike 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, glued from the negative and positive menisci, while the positive lens of the glued positive lens is biconvex, and the negative meniscus is turned concavity to the space of the object, except in addition, in the second component between the glued negative meniscus and the positive biconvex lens, a positive the nisk, facing concavity to the space of the object, and the positive meniscus, convex to the space of the object, is made in the form of a single lens.

In addition, in the first component, the negative meniscus convex to the space of the object, glued from the negative and positive menisci, a positive biconvex lens and a glued positive lens, consisting of a positive biconvex lens and a negative meniscus facing concavity to the space of the object, in the second component, the negative biconcave the lens of the glued negative meniscus, facing concavity to the space of the object, have a refractive index of n _d > 1,71, and negative the second meniscus of the first component, convex side facing the space of the object, and the other lenses of the second component have refractive indices n _d <1.62.

The optical forces φ of single and bonded positive lenses are 0.35 <φ <0.45, and with negative optical forces

,| φ | <0.9, where

,

φ _l - the optical power of the lens;

φ _eq is the optical power of the entire lens;

f ' _eq is the focal length of the entire lens.

The essence of the invention lies in the fact that this embodiment of the 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 surface of the lens to the film surface of ≥33 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 HELL.

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 of the first component, a negative meniscus is placed, which is convex to the space of the object, and is glued from a negative 9 and a positive 10 menisci.

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 the positive biconvex lens 6 and the positive biconvex lens 7, an additional positive meniscus 11 facing the concavity of the object space is placed, and the positive meniscus 8 facing the convex to the space of the object, made in the form of a single lens.

In addition, a negative meniscus convex to the space of the object, glued from a negative 9 and a positive 10 menisci, a positive biconvex lens 1 and a glued positive lens, consisting of a positive biconvex lens 2 and a negative meniscus 3, facing concavity to the space of the object in the first component, and a biconcave negative lens 5 in the second component have refractive indices of n _d> 1,71, and a negative meniscus 4 facing the convex side in the space of the object, the first to the exhibitors and other lenses 6, 7, 8 and 11 of the second component 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 0.35 <φ <0.45, and with negative optical forces | φ | <0.9,

,Where

,

φ _l - the optical power of the lens;

φ _eq is the optical power of the entire lens;

f ' _eq is the focal length of the entire lens.

The proposed fast lens works as follows.

The rays from the subject pass through the first component, limited to the aperture diaphragm.

An additionally introduced negative meniscus, convex to the space of the object and glued from the negative 9 and positive 10 menisci, allows you to increase the posterior segment, introducing negative spherical aberration, coma, slight astigmatism and curvature, distortion.

The positive biconvex lens 1 of the first component partially compensates for spherical aberration and distortion. A glued positive lens, consisting of a positive biconvex lens 2 and a negative meniscus 3, facing a concavity to the space of the object, corrects spherical aberration, coma, astigmatism, introducing significant distortion. Negative meniscus 4, facing the convex side into the space of the object, corrects for spherical aberration, coma, astigmatism, introducing curvature and distortion. A glued negative meniscus, facing concavity to the space of the object and consisting of negative biconcave 5 and positive biconvex 6 lenses, partially compensates for spherical aberration, coma, astigmatism and curvature.

Additionally placed positive meniscus 11, facing concavity to the space of the object, positive biconvex lens 7 and positive meniscus 8, facing convex to the space of the object, compensate for the residual spherical aberration, coma, astigmatism, curvature and distortion, creating a contrast image across the entire field of view on the format film S35, while the rear segment is large enough and allows you to use a fast lens not only in cameras, television cameras, but also in professional cinema filming equipment.

The introduction of additional single and bonded lenses, the choice of lens configuration, their optical forces and optical materials made it possible to provide correction of lens aberrations.

In the first component:

- positive biconvex lens 1 partially compensates for spherical aberration, distortion, as well as chromatic aberration of position and magnification;

- the negative meniscus placed in front of it, convex to the object’s space and glued from the negative 9 and positive 10 menisci, allowed to increase the posterior segment and, with the minimum values of higher order aberrations, introduce significant III-order aberrations negative to spherical coma, as well as negative astigmatism and distortion;

- a glued positive lens, consisting of a positive biconvex lens 2 and a negative meniscus 3, facing concavity to the space of the object, introduces a significant positive spherical aberration, coma, third-order astigmatism and distortion, as well as negative position chromatism;

- negative meniscus 4, facing the convex side into the space of the object, corrects for spherical aberration, coma, astigmatism, introducing significant negative distortion of the third order.

In the second component:

- glued negative meniscus, facing concavity to the space of the object and consisting of negative biconcave 5 and positive biconvex 6 lenses, introduces significant negative spherical aberration of the third order, as well as negative coma, astigmatism, positive chromaticity of position and magnification.

Application in the first component in the first five lenses:

a negative meniscus convex to the space of the object glued from a negative 9 and a positive 10 menisci, a positive biconvex lens 1 and a glued positive lens consisting of a positive biconvex lens 2 and a negative meniscus 3 facing concavity to the space of the object, and a negative biconcave lens 5 the second component of materials with large refractive indices n _d > 1.71, and in the remaining six lenses: a negative meniscus 4, convex to the space The properties of the object of the first component and lenses 6, 11, 7, and 8 of the second component of materials with values of n _d <1.62 allowed minimizing higher-order aberrations.

The difference in dispersions Δν of more than 10 in the bonded lenses 9, 10, 2, 3 of the first component and 5, 6 of the second component made it possible to minimize the increase in chromatism.

The choice of optical forces φ of single 1, 7, 8, 11 and glued 2, 3 lenses is positive with a value of forces that satisfy the condition

0.35 <φ <0.45,

and single 4 and glued 5, 6 and 9, 10 are negative with a value of forces satisfying the condition | φ | <0.9, it allowed to solve two problems:

- correct the curvature of the image, the condition for the correction of which is to ensure

- corrected the chromaticity of the position and sufficiently the chromaticity of the increase, the correction condition of which are

Thanks to the use of the proposed technical solution, an ultra-fast lens with a focal length f '= 35 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.

In the lens, the lenses have optical powers and are made of

optical materials.

Lens φ / φ _equiv 9 N-LAK 8 n _d = 1,713 φ _9.10 = -0.59 V _d = 53.83 10 N-LASF 45 n _d = 1,80107 V _d = 34.97 one N-LAF36 n _d = 1.779952 φ ₁ = 0.36 V _d = 42.37 2 N-LAK 8 n _d = 1,713 φ _1.2 = -0.40 V _d = 53.83 3 N-SF 1 n _d = 1,71736 V _d = 29.62 four N- SSK 8 n _d = 1,61773 φ ₄ = -0.89 V _d = 49.83 5 N-SF 1 n _d = 1,71736 φ _5.6 = -0.69 V _d = 29.62 6 N- PSK 53A n _d = 1,618 V _d = 63.39 eleven N-SK 5 n _d = 1,58913 φ ₁₁ = 0.45 V _d = 61.27 7 N- PSK 53A n _d = 1,618 φ ₇ = 0.40 V _d = 63.39 8 N- PSK 53A n _d = 1,618 φ ₈ = 0.41 V _d = 63.39

The dispersion difference Δν in the bonded lenses is:

Δν _9.10 = 19; Δν _2,3 = 24; Δν _5.6 = 24.

The main characteristics of image quality.

Television distortion for y '= 12.25 (normalized coordinate) = 1.5%;

the image contrast at a frequency of 30 l / mm over the entire field is more than 40%, while the prototype ≈ 20% with a relative aperture of 1: 1.2 and with a relative aperture of 1: 2.8 - more than 65% (in prototype ≈ 20%).

The rear segment is S '= 33.73 mm, with the light diameter of the last lens D = 37.2 mm. This allows the lens to be used both in digital motion picture cameras and in cameras operating on film strip.

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 positive lens glued together, consisting of a positive lens and a negative meniscus, and a negative meniscus with the convex side facing the space of the object, and the second component contains a glued negative meniscus facing concavity to the space of the object, consisting of a negative biconcave and positive biconvex lenses, a positive biconvex lens and a positive a meniscus convex to the space of the object, characterized in that the positive lens of the first component is biconvex and a negative meniscus is placed in front of it, facing the space of the object, glued from the negative and positive menisci, while the positive lens of the glued positive lens is biconvex, and the negative meniscus faces the object space in a concavity, in addition, in the second component, between the glued negative meniscus and the positive two ovypukloy lens is further arranged a positive meniscus facing concavity to the object space, and a positive meniscus facing convex toward the object space, it is formed as a single lens. 2. The fast lens according to claim 1, characterized in that in the first component the negative meniscus is convex to the space of the object, glued from the negative and positive menisci, a positive biconvex lens and a glued positive lens, consisting of a positive lens and a negative meniscus, the negative biconcave lens of the glued negative meniscus has a refractive index n _d > 1.71, and the negative meniscus of the first component, convex side in spaces about the object, and the other 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 powers φ of single and bonded positive lenses have values of 0.35 <φ <0.45, and with negative optical powers | φ | <0.9,
Where

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

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