от: Tigra Girl
Visionar - хорошие стекла! На среднем формате - особенно.
The Visionar lenses are high-speed lenses for the projection of 35mm cinema film designed in the late 50s at Carl Zeiss Jena (patent application was filed on 29th October 1958 ).
Most likely the calculation of these lenses was done on the first east german computer "OPREMA" (stands for "Optik-Rechen-Maschine", i.e. Computer for Optics), a relay computer consisting of 16626 relays, 500 kilometres of cable and using up 55 square metres of space, which was developed at Carl Zeiss Jena and put into operation in 1955.
They are of a modified Double-Gauss design of 6 elements in 6 groups (i.e. no cemented doublets), which was also featured in their yearly scientific publication "Jenaer Jahrbuch" in 1960.
Available focal lengths were 50mm, 55mm, 60mm, 65mm, 71mm, 77mm, 84mm, 92mm, 100mm, 109mm (all f1.6), and 119mm, 130mm, 141mm, 154mm, 168mm, 183mm, 200mm (all f1.9), roughly in increments of the focal length multiplied with the 8th root of 2.
They were sold under the brands of "Carl Zeiss Jena" and "Rathenower Optische Werke".
Like basically all projection lenses I am aware of they are optimised for wide open use, they don't have a aperture mechanism neither a focussing helicoid. Even though they are calculated for 35mm cinema film (roughly equivalent to APS-C), they cover 35mm full frame quite well. Typically for projection lenses they show a quite even illumination across the frame combined with very good contrast wide open.
