Biotar

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Carl Zeiss Jena Biotar 5.8 cm 1: 2 and Biotar 7.5 cm 1: 1.5 with M42 thread
Carl Zeiss Jena Biotar 7.5 cm 1: 1.5 on a Contax D modified with an accessory shoe
Biotar 1: 2/58 mm for 35mm cameras
Biotar 1: 2 / 12.5 mm on a Pentaka 8 mm camera

The Biotar is a six-lens lens for film and photo cameras. Its basic construction follows the Gaussian double lens . Biotar constructions achieved a high light intensity as early as the 1920s .

The first Biotar was calculated by the Zeiss designer Willi Merté in 1927, intended for the cinema. As with the Planar , the Biotar has four lenses on each side of the Gaussian double lens extended by a further outer lens. The inner two pairs of lenses are cemented like the planar. Merté followed the xenon lens developed by Albrecht Wilhelm Tronnier for Schneider-Kreuznach in 1925 by introducing an important asymmetry: the field-side (front) three-part lens group was made larger than the group behind the diaphragm. Furthermore, the two outer converging lenses each have a larger diameter than the two inner lens pairs. Horace Williams Lee of the Taylor-Hobson Company had taken the first steps in this direction .

In the 1930s, Merté calculated further Biotar optics, including the 1: 2/40 mm for small images, the popular 1: 2/58 mm and the 1: 1.5 / 75 mm as well as the 1: 2/80 mm for medium format and the 1: 2/100. The extremely bright 1.4 / 140 mm and a 1: 2/250 mm were developed presumably for military purposes.

The Biotar was offered by Zeiss for decades, often with a remarkable initial light intensity of 1: 2 with a focal length of 58 mm. The calculation for 35mm SLR cameras came from 1936 and was later reproduced in millions of copies as "Helios 44 2.0 / 58" in the Soviet Union. For even higher light intensities, as required for filming (1: 1.5 or 1: 1.4), these lenses could only be used in exceptional cases (e.g. for portraits: Biotar 1: 1.5 / 75 mm) (1938), after the war as a Russian version with 85 mm and recently issued again by KMZ / Moscow with modern remuneration for western amateurs). Zeiss released a revised 25mm f / 1.4 Biotar for 16mm films and around 1930 a 50mm f / 1.4 Biotar for 35mm film cameras.

However, Biotar lenses do not have to follow the basic structure described here. Willi Merté also designed an extremely bright R-Biotar 1: 0.85 for X-ray cameras . Such special lenses were used for the photographic fixation of the weakly fluorescent screen image of the X-ray machines of that time. The structure of the R-Biotar follows a Petzval lens .

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  1. a b artaphot.ch: Zeiss Planar and Biotar - FS143_History_ZeissPlanarBiotar_150dpi.pdf , accessed on February 11, 2015