DE1779206U - PHOTOGRAPHICAL LENS WITH CONTINUOUSLY CHANGING FOCAL LENGTH. - Google Patents

Description

Pho'bographic lens with continuously changing Licher focal length The present invention relates to photographic lenses with continuously variable focal length for recording and / or projection, which consist of four lens groups, of which the first and the third are samuelnd, the second and the fourth are dispersive, the change in focal length, essentially by shifting the second divergent lens group along the optical axis it "follows (cf., inter alia, the manual" The scientific and turned photography ", first volume" The photographic object tiv "'by J. Flügge, Vienna:, 1955, page 207 as well as the French- schch patents 1 112 979 and 1 120 271).

Since with such a displacement of the second lens group i. a. the image position changes depending on the movement of this lens group another lens group shifted so that the image position fluctuation compensates will.

According to the invention, the constancy of the image position is now brought about by this that not just one but the two converging lens groups along the optical Axis be moved? while the fourth negative lens group is relative to the Image plane is fixedly arranged.

By having the two converging lens groups of the objective for keeping the image position constant, one gains the advantage that the required adjustment ranges of the two converging lens groups kept relatively small can be.

A particularly useful and simple embodiment of this inventive concept is obtained by moving the two collecting lens groups together in this way 9 that their mutual distance remains constant, because in this case one is with a single control curve for these two lens groups and the displacement range less than, for example, 3.5% of the displacement range of the negative lens group can be held.

In order to be able to focus the objective on different object distances, the first lens group, or in the case of a multi-part construction, a part of this group, is additionally arranged to be displaceable independently of the above-mentioned displacement. In the following figures, an example of an objective according to the invention is in three different positions according to FIGS. 1 to 3 for three adjustable focal lengths f = 70? 9 rom; 50 p 7 mm and 25? 5 mm shown. In the next-- I. The following table shows the progression of the displacement of the individual lens groups and the assignment of the distances between the individual lens groups to the change in focal length achieved thereby.

Herein I mean; II; III; IV the lens groups and a; b; c the variable vertex distances.

As can be seen from the table, in the example chosen, the sum of the distances (a + b) remains constant over the entire adjustment range between the focal lengths f = 78.9 nm and f 2 5 9 5 mm. Table 1 fabc 78.9 82.00 5.014 4.600 68.3 72.00 15.014 4.912 58.8 62.00 25.014 5.058 50.7 52.00 35.014 5.091 43.7 42.00 45.014 5.048 37.9 32.00 55.014 4.959 33,022.00 65,014 4,843 28.9 12, 00 75, 014 4, 713 25.5 2.00 85.014 4.578

Claims (1)

Protection claims 1. A photographic lens with continuously variable focal length, consisting essentially of four groups of ones, of which the first and third are collecting, the second and fourth dispersing in the sense of the direction of light, the change in the focal length being essentially by shifting the second dispersing The lens group takes place along the optical axis, characterized in that the constancy of the image position is achieved by shifting the two converging lens groups along the optical axis, while the fourth dispersing lens group is arranged stationary relative to the image plane. c 2. Photographic lens according to protection claim 1, characterized in that; that the displacement of the two converging lens groups takes place jointly in such a way that their mutual distance remains constant, the adjustment range of these two converging lens groups being less than 3, 5/1 of the adjustment range of the displaceable diverging lens group ..