RU1809411C - Zoom lens - Google Patents

Abstract

Usage: in optical instrumentation. The inventive lens contains a first negative component 1 made of two negative 3, 4 and positive menisci 5, convex to the object, the second component 2 is positive, made of a biconvex lens 6, positive meniscus 7, convex to the object, positive meniscus 9, convex to the object, a biconcave lens 10, and a positive meniscus 11, convex to the image. Field of view 2/3 73 - 34 °. 2 il ..

Description

The invention relates to the field of optical instrumentation, more specifically to variable focal length lenses, and is intended for use in amateur photography. One of the main trends in the development of this class of lenses is an increase in the field of view, a decrease in size and weight while maintaining high image quality.

The purpose of the invention is to increase the field of view and reduce the dimensions while maintaining high image quality.

In FIG. 1 shows an optical diagram of a lens with a variable focal length; in FIG. 2 shows the calculated modulation transmission coefficients for the three focal lengths.

The table shows the design parameters of one of the lens options with a variable focal length.

In FIG. 1 shows an optical diagram of the proposed variable focal length lens with the following characteristics: focal length varying from 28 mm to 70 mm, angle. Field of view 2/73 - 34 °, a relative aperture ranging from Ј 1: 3.2 to e 1: 4.8, consisting of 8 lenses combined into two components (1, 2), which are mounted with the possibility of movement along the optical axis. First component

(1) negative optical power is made of two negative (3, 4) and positive, (5) menisci, convex to the object. Second component

(2) positive optical power includes a biconvex lens (6), a positive meniscus (7) convex to an object, an aperture diaphragm (8), a positive meniscus (9), convex to an object, a biconcave lens (10) and positive meniscus (11), convex to the image. In the position of the components indicated in the drawing, when both components are as close as possible to each other, the lens has the largest focal length f max 70 mm and the smallest field of view 2/3 34 °. In the position when the components are maximally distant from each other, the lens has the smallest focal length f min 28 mm and the largest field of view 2/73 °. The ratio of the absolute values of the focal lengths of the second component to the first f 2 / Iff I 0.68 and the first component to the maximum focal length of the lens I f 11 / f max 0.87. The movement of the aperture diaphragm with the second component leads to a decrease in the relative aperture of open 1: 3.2 at Г 28 mm to Ј 1: 4.8

at f 70 mm. The length of the lens from the front to the last when folded is 46 mm, which is 0.66 of the maximum focal length, the light diameter of the front lens is

45mm.

In the proposed lens, the construction of the first component will increase the field of view angle to 2/73 ° and correct the aberrations of wide beams at f 70 mm and

distortion at f 28 mm. The construction of the second component corrects spherical aberration and astigmatism at f 28 mm. The specified ratio of the focal lengths of the components and the maximum

the focal length of the lens reduces the size of the lens.

The calculated values of the modulation transmission coefficients for the three focal lengths given in the table indicate that the resolution on the KN-1 photographic material with a resolution of 135 mm 1 at Kt 1 with a full relative aperture for the three focal lengths f 28 mm, f

50 mm and D 70 mm in the center of the floor (y1 0) will be at least 50, at the edge of the floor (at 19 mm) - at least 30 mm 1.

The proposed lens has a 1.2 times larger angle compared to the prototype

field of view, 1.3 times smaller light diameter of the front lens, 1.1 times less length from the front surface to the last when folded, and the same resolution on the same photographic material.

The positive technical and economic effect of the invention is that it allows you to create a lens with a variable focal length for SLR

cameras with a 24x36 mm frame format, field of view angle 2/73 - 34 °, reduced dimensions and high image quality, superior in performance to the well-known domestic

and foreign samples.

The formula is also an objective with a variable focal length, containing two components mounted with the possibility of movement along the optical axis, of which the first component is negative and made of three lenses, the second of which is negative, the third is a positive meniscus, o6pv

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convex to the space of objects, the second component is positive and contains a biconvex lens, a positive meniscus, convex to the space of objects, biconcave and positive lenses, characterized in that, in order to increase the field of view and reduce the dimensions while maintaining a high image quality, in the first component, the first and second lenses are made in the form of negative menisci, convex to the space of objects, in the second component

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in front of the biconcave lens, there is a second positive meniscus convex to the object, and the biconvex lens is single, and the positive lens is a meniscus convex to the image space, the ratio of the focal lengths of the second component to the first is in absolute value 0. 64-0.74, and the ratio of the focal length of the first component to the maximum focal length of the lens is 0.77-0.94,

Point on axis

Point off axis

Meridional section

Sagittal section

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