C-Mount

The C- Mount is a standardized threaded connection for camera lenses in the professional field. The outer diameter of the thread is 1 inch (2.54 cm), the thread pitch is 1/ 32 inches. The flange between the flange of the lens thread and the image plane has a value 17.526 mm (0.69 inches) (compared to CS -Mount: 12.5 mm). The C-mount is the SMPTE Standard SMPTE 76-1996 with the standardized and, after the standard ANSI B1.1 thread referred to as " 1-32 UN 2A ".

As a rule, C-mount lenses have manual focus and manual aperture setting (or " iris " in terms of film technology ): However, there are lenses with a motorized control of focus and aperture.

In the cine-film technology ( news cameras ) and later in video technology, the C -Mount a widely used standard. The lens mount was " 70 Filmo ", a 16 mm cine film camera introduced in the 20s of the 20th century by Bell & Howell with. In the cine-film and video technology, the C -mount standard is still used today. Since there is no active marketed movie camera system with a C-mount more, the use focused on monitoring and industrial cameras. Since the introduction of small digital system cameras such as Micro Four Thirds or Sony NEX -5 C- mount lenses are provided with suitable adapters used to diesern cameras. Kenko announced in February 2011 at a compact system camera for use with C-mount lenses.

In contrast to the film technique threaded connections have been replaced earlier in general photography with bayonet connectors, since the objective change was perceived by disconnecting and screwing as too time- consuming and tedious. To make a quick lens change is possible, several of the relatively small lenses with C -mount and fixed focal length lenses were first mounted in turrets or slide changers. Once zoom lenses were of sufficient quality available, these were used. For the small formats of film cameras were much earlier zoom lenses with sufficient quality is available than for the much larger formats. By retaining the C-mount connection one has the choice between small, light and inexpensive zoom lenses and big, heavy, strong light zoom lenses with large focal length range. It can be connected also special lenses with fixed focal length, extensions for close-ups, microscopes and telescopes. As the thread C -Mount can also be very much greater forces transmitted as an equal bayonet. Unlike other cameras, movie cameras, or they will always bearing mounting plate directly mounted on the tripod head to pivot can. Thus, the lens mount must be able to carry very heavy lenses. In the small-format photography, however, a heavy lens is mounted directly on the tripod, and the lens carries the relatively much lighter camera. Some professional film cameras like Bolex Eclair and who introduced vendor-specific bayonets, got a C-mount adapter to use existing special lenses can.

C- mount lenses are available with different image circles for different Sensor-/filmgrößen like 1/ 2 ", 2 /3", 1 ", 8 mm and 16 16mm/Super When connecting a lens with a small image circle to a camera with larger image window, it may accordingly come to vignetting, while conversely a crop factor must be taken into account for the determination of a picture angle.

In microscopy, the C-mount is used for connecting digital cameras. Often, here, a special port is provided on the microscope, which requires no additional magnification or reduction through eyepieces or projective. The image formed by the lens of the microscope is large enough to fully illuminate the sensors, which are much smaller than a conventional film formats. The additional magnification is done by drawing the small sensor image on the big screen.

Using an extension tube of 5 mm can convert a CS -mount lens to a C -mount lens or a CS- mount camera into a C - mount camera.

Weblink

• The C-Mount Lens Review, c- mountlens.com

• Lens Mount
• Standard
• Cine - Standard