C-mount
The C-mount consists of a one inch diameter cylinder threaded to a pitch of 1/32-in, or 32 threads per inch. It was designed specifically for cine lenses used on 16mm cameras. Some of the better quality cameras had a turret with a capacity for two or more lenses for making rapid changes in focal length. Though zoom lenses were available in the 1940's, they were very expensive and involved some optical compromises, so were not widely used until they had achieved better and more consistent quality at lower prices, after which they eventually began to displaced the turret in the 1960's, particularly in cameras for the amateur film maker.
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| Schneider-Kreuznach 1:1.5 25mm Xenon on Micro 4/3 adapter image by mr. wood (Image rights) |
The "C" designation derives from the evolution of the mount from its original "A" and "B" predecesors. All shared the same thread and diameter, but had different mounting depths, and are not interchangeable. A-mount and B-mount lenses were used primarily on early Filmo and Victor cameras. Thread depths varied from maker to maker, but the proper A-B-C distinction lies not in the total thread depth but in the distance from the flange seat of the lens barrel to the innermost thread. The C-mount eventually became the standard mount for higher quality amateur 16mm equipment.
Cine cameras were often equipped with superb C-mount optics made by great lens makers like Taylor-Hobson-Cooke, Dallmeyer, Hugo Meyer, Meyer-Gorlitz, Angénieux, Elgeet, Berthiot, and Schneider-Kreuznach. Wollensak also made some fine cine lenses.
Consequently, a few users have begun to experiment with these lenses on their adaptable digital cameras, though they will find the older uncoated lenses more satisfactory for Bokeh experiments, and such zoom lenses as were made in C-mount, like the SOM-Berthiot, probably much too bulky and heavy to be suitable.
