Difference between revisions of "C-mount"

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Originally the '''C-mount''' was no affair concerning still cameras. The one inch screw-mount was one for cine lenses, used on 8mm and 16mm cine cameras, surveillance cameras and TV-cameras. Old sophisticated cine cameras had a revolver with several one inch threads to hold a whole set of C-mount lenses. After the invention of the [[zoom lens]] the most cine cameras lost this revolver feature.
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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.
 
 
Cine cameras need fast lenses because of shooting 18 or more images per second. That's the reason for a completely different culture behind the large variety of cine lenses. Thus f1.2, f1.4, f1.5, f1.8 and so on are typical standard lens speeds of these items, whilst f1.7, f1.8 and f2.8 are the most common standard lens speeds of still cameras. Even cine [[zoom lens]]es have speeds beginning with f1.2, f2, f2.4, while most still camera zoom lenses start with lens speed f3.5 .
 
  
 
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Since [[Olympus]] and [[Panasonic]] had introduced the first cameras for the [[Micro Four Thirds]] autofocus lenses there are still cameras in the market with a flange focus distance almost like that of the C-mount lenses. That was the first chance for photo amateurs to think about using C-mount cine and CCTV lenses on still cameras. Soon the appropriate [[adapter]]s were available, even cheap ones made in [[China]]. When [[Sony]] introduced the concurrent Sony NEX camera system the adapter makers offered C-mount adapters for the NEX too.
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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.  
  
The original reason for that c-mount lens hype of still camera users is that especially sophisticated cine cameras were often equipped with superb optics made by great old lens makers like [[Taylor-Hobson]], [[Angénieux]], [[Cooke]], [[Elgeet]], [[Berthiot]], [[Kowa]], [[Canon]] and [[Schneider-Kreuznach]]. [[Pentax]] Cosmicar lenses are partially even available as new items, as well as simpler so-called "CCTV" lenses for survey cameras. Customers must care not to buy the cheaper CS-mount lenses instead. These are only usable for a newer generation of survey cameras, and definitely not on the C-mount adapters for still cameras.
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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.
  
The quality of C-mount lenses differs much. There are sophisticated lenses, once used on luxurious Beaulieu cine cameras, and there are simple lenses without aperture selector. Thus the lenses with limited settings are good for experimental [[photography]] while well-preserved cine lenses of higher quality will be full-scale photography lenses but with cine characteristics when used on a still camera. Nowadays there are much more C-mount adapters available than good old C-mount cine lenses. That's because of the CCTV lens having been discovered as new kind of camera toy. Many people like to experiment with these simple lenses on their digital cameras like others do with [[pinhole camera|pinhole]] "lenses" even on sophisticated [[SLR]]s.
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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.  
  
 
==Links==
 
==Links==

Revision as of 19:18, 29 March 2011

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.

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.

Links