MOS (camera technology)

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In the film industry, the abbreviation MOS describes recording without sound. The abbreviation serves both as a reference to the process itself and to categorize film cameras.

Origin of the term

The meaning of the acronym MOS has not been clarified beyond doubt. It is often said that the name goes back to a director who immigrated to Hollywood from Germany in the 1930s, who, because of his rudimentary knowledge of English, liked to announce “with no sound” during silent takes (i.e. those without recording an original sound). MOS may also be unpretentiously composed of Motor Only Sync or Motor Only Shot .

use

Film recording

The designation indicates that a movie scene is being recorded without sound. This is on the in a corresponding field clapperboard (ie which therefore correct "synchronous flap" and traditionally falls within the remit of the Tondepartments) noted, so that the film editor in the section know that there is no to the scene original sound are -Track. With MOS recordings, the flap does not have to be opened; it is then enough to hold them in the picture.

To clarify: With film cameras, unlike video cameras, no sound is recorded. This must be recorded using an external sound recording device, which makes it necessary to use a clapperboard to identify the sound recordings in order to assign the appropriate settings. For a short time there were systems that were complicated to use (such as the Commag system or the Arriflex BL16Q), which recorded the sound directly in the film camera, but which proved to be impractical in detail.

MOS cameras

Due to their design, MOS cameras are too loud for simultaneous sound recordings. The latter is made possible by SyncSound cameras, which, thanks to a quieter film transport, a sound-absorbing housing construction and, in newer models, also soundproof lens mounts (PL mount), achieve an extremely low sound level, so that sound recordings are possible even in the immediate vicinity of the camera without recording operating noises.

In the first decades of cinematography , there were practically only MOS cameras. With the introduction of the sound film, they were built into large and heavy soundproof housings (so-called blimps ) in order to reduce the camera's own noise. Working with blimps was not uncommon until the 1970s. Often films were shot entirely in MOS and then dubbed afterwards .

Nevertheless, MOS cameras are still manufactured today and used in areas where the original sound is irrelevant or even annoying, or where the sound is produced separately anyway. These include in particular:

  • Music videos
  • advertising
  • Special effects, such as time lapse or slow motion
  • Underwater photography
  • Landscape shots
  • Close-ups in danger areas that can mean the loss of the expensive camera ( victim camera )

In addition to the lower purchase price, MOS cameras are characterized by their lower weight and size than comparable SyncSound cameras, which makes them more attractive for steadicam recordings.

Current MOS cameras are in the 35 mm segment, e.g. B. the Arriflex 435 and 235. The latter is characterized by its very small size and light weight. In 16-mm segment, there are virtually no new MOS cameras more. It was there that the Éclair NPR began developing the self- blurred film cameras, which Arri continued with the BL16, and later with the SR series. Previously, this format was used almost exclusively with the Arriflex 16ST MOS camera, which is still partially used today due to its robustness and variety of accessories. Currently available 16 mm MOS cameras are the H16 cameras from Bolex , which are still manufactured and sold today according to the old construction and are still interesting today because of their modifiability to Super 16 . A really newly developed MOS camera is the Ikonoskop A-Cam.