BNCR mount

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BNCR is a lens mount developed by Mitchell for use with their 35 mm movie cameras. The mount may also be referred to as BNC, NC, or Mitchell. The full abbreviation stands for "Blimped News Camera Reflex", which meant that it was a 35 mm camera intended for news reporting, and included a blimped housing to reduce noise and a reflex shutter to allow the camera operator to view the action through the lens while filming. The reflex option was only added in 1967, while the blimp was available since the camera's introduction in 1934. The lens mount is identical across all variants - thus there is no difference between a BNC and BNCR mount, for instance. BNCR is only the current convention as it was the last version of the camera and in relatively current use through until the 1990s. The mount contains four pronged flanges only one of which contains a notch towards the center. This notch is used to align the mount to a locating pin located approximately 45 degrees clockwise from the top of the camera's lens mount. The mount is locked into place using a friction locking ring which, in conjunction with the four prongs of the flange, creates a very strong lens seating. The quality of this design has been a key influence in the design of the Arri PL and Panavision mount, both of which are the main film camera mounts in use today, and both of which have four-pronged flanges oriented based on locating pin-notch combinations. The Arri PL mount in particular is very similar in appearance to the BNCR mount, the only immediately apparent difference being the ability to seat any of the four notched prongs against the locating pin. (The flange focal distance and diameter also differ.)

With the slow obsolescence of the Mitchell cameras, which likely took so long precisely because they were so well-regarded in mechanical design aspects such as their steady movement registration and strong mounts, the mounts have gradually become less common in the past two decades, but remained an option for third party cameras produced as recently as the 1980s. Many of the cameras are still in usage in fields such as animation. Though the mount is not quite as common today, it is still very well regarded in the field.

[edit] Technical specifications

• Flange focal distance: 61.468 mm
• Diameter: 68.00 mm
• Cameras:
  • 35 mm Mitchell NC, Mitchell NCR, Mitchell FC, Mitchell FCR, Mitchell BNC, Mitchell BNCR, Mitchell S35R, Arri 35BL3, Cinema Products XR35, Cinema Products CP35, Fries 435, IMAGE 300, Moviecam SuperAmerica, Moviecam Compact, PhotoSonics 4ER, PhotoSonics 4ML, Ultracam