DE1086062B - Photographic lens with continuously variable focal length - Google Patents

Description

The 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 the third being convergent, the second and the fourth being dispersive, the change in focal length being substantial takes place by shifting the divergent second lens group along the optical axis (cf. Among other things, the manual “The scientific and applied photographic”, first volume “The photographic Lens «by J. Flügge, Vienna, 1955, p. 207, as well as the French patents 1 112 979 and 1 120 271).

Since with such a shift of the second lens group the image position generally changes, If, depending on the movement of this lens group, another lens group has been shifted in such a way, that the image position fluctuation is compensated.

According to the invention, the constancy of the image position is brought about by the fact that not only one, but the both converging lens groups are shifted along the optical axis, while the diffusing one fourth lens group is fixed relative to the image plane.

By having the two converging lens groups of the lens to keep the Using the image position, one gains the advantage that the required adjustment ranges of the two collecting Lens groups can be kept relatively small.

A particularly useful and simple embodiment of this inventive concept is obtained if you move the two converging lens groups together, in such a way that their mutual distance remains constant because in this case you have a single control curve for these two lens groups comes from, and the displacement range is less than, for example, 3.5% of the displacement range diffusing lens group can be held.

In order to be able to focus the lens at different object distances, the first Lens group, or if the same is constructed in several parts, a part of this group, regardless of the above-mentioned group Displacement also arranged to be displaceable.

In the drawing, an example of an objective according to the invention is shown in three different positions according to FIGS. 1 to 3 for three adjustable focal lengths / ₀ '= 78.9 mm, 50.7 mm and 25.5 mm. The table below shows the course 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 with them .

Photographic lens

with continuously
variable focal length

Applicant:
Carl Zeiss, Heidenheim / Brenz

Here I, II, III, IV denote the lens groups and α, 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 _o '= 78.9 mm and f _o = 25.5 mm.

/ 0 ' α b C. 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 33.0 22.00 65.014 4,843 28.9 12.00 75.014 4,713 25.5 2.00 85.014 4,578

Claims (2)

Patent claims: 1. Photographic lens with continuously variable focal length, consisting of four Lens groups, of which the first and third collectively in the sense of the direction of light, the second and the fourth are dispersive, the change in focal length being essentially by displacement the divergent second lens group takes place along the optical axis, characterized in that that the constancy of the image position by shifting the two converging lens groups along the optical axis is achieved while 009 568/162 the divergent fourth lens group is fixed relative to the image plane. 2. Photographic lens according to claim 1, characterized in that the displacement of the both collecting lens groups together follows, in such a way that their mutual distance remains constant, the adjustment range of this two converging lens groups is less than 3.5% of the adjustment range of the displaceable diffusing lens group. 1 sheet of drawings