SU756338A1 - Wide-angle pancratic objective lens - Google Patents

Description

The invention relates to lenses with variable focal length, used in photography, both amateur and professional.

Known pankraticheskie photographic-5 tiva, designed for SLR cameras. The lenses have impressive dimensions with a relatively low relative aperture or angular field of view. This 10 is explained by the use of positive optical power, as the first component of the fixed lens group. and as the second component of a strong negative moving 15

lens groups [1].

The closest to the invention according to the technical nature is a wide-angle pancratic lens containing three components, of which 20 are negative first made of two negative and one positive lenses, the second positive consists of two dual-glued lenses, and the third is made of single negative and two positive lenses and a negative lens behind the diffraction, a biconvex lens, and a negative meniscus;

The loop is stationary, and the first and second are mounted for movement in the direction along the axis [2].

The focal length of the lens changes when the first negative and second positive components move in the opposite direction at a distance of one order of magnitude.

However, in the specified lens, the design of the fixed last component does not allow focusing on it at ultrashort distances (macro focusing).

The purpose of the invention is to reduce the shooting distance.

This goal is achieved by the fact that in a wide-angle pancreatic lens containing three components, of which the first is negative from a single two negative and one positive lenses, the second positive consists of two two-glued lenses, and the third is made from single negative and two positive lenses and located behind the aperture negative lens, biconvex lens and negative meniscus, while the third component is fixed, and the first and second mouth 756338

movable in the direction along the axis, the biconvex lens and the negative meniscus of the third component form a two-glued component mounted for movement along the axis, as well as the fact that the negative lens of the third component located behind the diaphragm is displaceable along the axis.

The drawing shows the optical scheme of the lens.

The lens contains three components 1, 2 and '3.

Component 1 consists of a single negative 4 and 5 positive lenses, Component 2 consists of two lenses 6 and 7. Component 3 consists of two groups of 8 and 9 lenses separated by a diaphragm 10. The group of lenses 8 consists of negative lens 11 and two positive lenses 12 and 13. All lenses of group 8 are single. The group of lenses 9 consists of a single negative lens 14 and a two-glued negative 15 and a positive 16 lenses 17. The groups of lenses 8 and 9 are separated by an air gap of about 1/3 of the shortest focal length of the lens and form a reverse telephoto lens, which makes it possible to get an enlarged preset.

A negative lens 18 is installed in front of the negative lens 4 of component 1, which makes it possible to increase the relative aperture, field of view and improve the quality of the correction of aberrations. The negative component 1 and the positive component 2 with optical powers of the same order move to change the focal length along the axis in opposite directions. At the same time, in the position of the smallest 40 focal lengths, component 1 is pushed forward along the direction to the object, and component 2 moves closer to the stationary component 3. .The double-glued lens 17 is in position 45 1 _t ; _p has the ability to move along the optical axis towards the object (from position a to position b) at a distance of up to 10 mm to focus the lens on ultrashort distances to the object up to 10-15 cm.

 For this purpose, you can also use the movement of the lens 14 to 2-3 'mm in the direction of the image. This can be used as both of these movements simultaneously, so ^ 5

and any of them separately.

The focusing of the lens at a distance of up to 1 m is carried out,

as usual, the additional movable component 1.

The lens changes the set of three - conventional lenses: wide-angle ³ (6 "= 37-38 mm), normal (ί ¹ = 5 0-55 mm) and portrait

(? '= 75-80 mm). Besides he

It gives great operational advantages in comparison with existing lenses, allowing you to perform various kinds of work, including shooting from ultrashort distances (macro photography) with the composition of the frame in the process of shooting.

15 The use of the proposed lens makes it possible to equip domestic SLR cameras with a compact, high-aperture high-performance lens with a good image quality.

Claims (2)

Claim 25 1. Wide-angle pancratic a lens containing three components, of which the first negative is made of two single negative and one positive lenses, the second positive consists of two two-glued lenses, and the third is made of single negative and two positive lenses and located behind the diaphragm of the negative lens, biconcave lens and negative ³³ meniscus, while the third component is fixed, and the first and second are mounted for movement in the direction along the optical axis, characterized in that, in order to reduce the shooting distance, the biconvex lens and the negative meniscus of the third component form a two-glued component mounted for movement along axis. 2 ·. Lens pop.1, characterized in that the negative lens of the third component located behind the diaphragm is mounted for movement along the axis.