The ‘Film Out’ is the last step of the Digital intermediate work flow. DPX or Cineon files that have been stored on a SAN, or possibly from a portable storage device are recorded back to negative. A succession of frames, numbered and starting at the first frame of action (FFOA), to the last frame of action (LFOA) for each reel. A film is usually split into reels, which are edited to fit onto a 2000 foot reel of unexposed negative, a minimum of five would give you a movie of approx 90 minutes in length. A film recorder is the final output device for transferring data to film, they can record many different formats to film, however most DI houses will employ .DPX or .CIN.
DPX or CINEON?
One question when outputting digital film frames for film recording is the format to use. Although DPX tends to be the standard for DI post-production there is a major danger with this format when recording out to film. The DPX format can be Linear or Log, specified by a ‘flag’ within the header of the image file. However many film recorders do not read this flag and assume DPX to be linear! This can cause major issues with the film-out process. If working Log, as one should (or as I personally advocate), it is best to output Cineon .CIN files as these can only be Log, not Linear.
All film recorders typically work in the same manner. The image is fed from the computer by a raster file producing program. A film recorder will expose film with a beam of light output by a CRT - Cathode Ray Tube (Lasergraphics) or a focused laser (Arri). For colour image recording on a CRT film recorder, the red, green, and blue channels are separately displayed on the same grey scale CRT, and exposed to the same piece of film through a filter of the appropriate colour. This approach yields better resolution and colour quality than one could obtain with a colour CRT. The three filters are usually mounted on a motor-driven wheel. The filter wheel, as well as the camera's shutter, aperture, and film motion mechanism are usually controlled by the recorder's electronics and/or the driving software.
Higher-quality film recorders use focused lasers to write the image directly onto a film, one pixel at a time, usually employing three separate lasers, red, green and blue. The exposed film is developed and printed by regular chemical processing – back to the lab. This seems to be the accepted standard of film recording due to the exceedingly reliable and accurate Arrilaser breaking new ground. I have seen a companies overlooked because they do not offer Arri output, which seems can be paramount to seal the deal for the digital intermediate production company.
Arri produces the ever popular Arrilaser and the now obsolete, Kodak's Lightning II, both offer laser based film recorders. Celco, CCG (formerly AGFA) and Lasergraphics make use of CRT based film recorders. In 2003 CCG introduced the first motion picture film recorder utilizing LCD technology, the Definity, I personally have yet to see any outputs from this device.
Manufacturers seem to dip in the field and then disappear without trace, mainly due to the finance and cost prohibitive nature of this industry. One I have noted which has appeared and seem as though they need further investigation are PIQL who originally were known as Cinevation, a norwegian company.