Film core

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Film cores , also known as bobbies , are wound bodies for motion picture film that are handled in lengths of a few centimeters up to several kilometers. In contexts that are all about film, one often speaks of nuclei instead of nuclei.

Film cores should be solid, light, chemically stable, environmentally friendly and yet available in different colors. Initially turned out of wood, over time they became mass-produced articles made of injection-molded plastic, for example polypropylene , acrylonitrile-butadiene-styrene or polycarbonate .

Dimensions and sizes are described with the international standard ISO 1039. In general, the film cores have a hole with a groove for single-inch mandrels with a driver, in particular smaller inner diameters for the reel mandrel of European projectors, the 8 mm camera square or even more delicate mandrels, especially for older devices.

Film is rolled from core to core: in the film factory, in the film camera , in the sound camera, during preparation for development, in the projection (core diameter at least 5 inches or 125 mm), on the cutting table, in film cleaning devices and other film processing systems. Safe transport of film is possible with the film core if the material is wrapped tightly on it, secured with adhesive tape to prevent loosening and packed in a bag and can. To ensure a secure grip on a roll, film cores are often shaped to allow finger engagement, and sometimes they have grooves on the inside of the waistband. Most of the cores have a slot at an angle to the radius in which the film can be attached. The film core should always be a little narrower than the film.

3er normal film core.jpg
Left and right a bobby for 35 mm film, in the middle one for 16 mm film (the two yellow bobbies are for use in editing tables, the black bobby is used when sending film copies to cinemas)

Colours

Colored cores are useful when editing films. The following assignments are (have been) common in Europe:

  • White → general use for raw film and developed material
  • Gray → auxiliary materials, e.g. B. Blank film with image line
  • Black → Used for raw film and the auxiliary material black film
  • Red → number 1, image originals
  • Blue → Number 2, sound originals (from the light sound camera)
  • Green → number 3, duplicate images
  • Orange → number 4
  • Purple → number 5
  • Yellow → number 6
  • Colorless transparent → blank film
  • Brown → magnetic film

Various important types

  • Core 'A' with an outer diameter of 1 inch and alternating bore, used in camera magazines for 35 mm film
  • Universal core, 2 inch outer diameter, 1 inch bore, driving groove over the entire width, for 35 mm film
  • Core 'R', same as U, but driving groove only over half the width
  • Core 'T', like U, for 16 mm film

The cores are usually used with outside diameters of 50 mm, 75 mm and 100 mm. With shorter film lengths, larger cores will be used, as this is more gentle on the film (larger winding diameter, less film tension when winding up).

Manufacturer

  • Agfa-Gevaert, Mortsel
  • BASF, Ludwigshafen
  • Bochemie, Moscow
  • Du Pont, Wilmington
  • Eastman-Kodak, Rochester
  • Foma Bohemia, Hradec Králové
  • Fuji Photo Films, Tokyo
  • Ilford, Knutsbridge
  • Winkel, Hamburg