Optical printer

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Inexpensive J-K 16 mm optical printer using a Bolex camera.




The first, simple optical printers were constructed early in the 1920s. Linwood G. Dunn expanded the concept in the 1930s, and during World War II he was commissioned by the United States armed forces' photographic units to design an optical printer that could be ordered as a stock item like a camera.[2] Development continued well into the 1980s, when the printers were controlled with minicomputers.[3] Prime examples of optical printing work include the matte work in Star Wars (1977).[4]

In the late 1980s, digital compositing began to supplant optical effects. By the mid-nineties, computer graphics had evolved to rival and surpass what was possible with optical printers, and many now consider optical printing all but obsolete.[5] Improvements in film scanners and recorders allow for a complete feature film to be processed by computers, have special effects applied, and then be processed back to film.



As in any analog process, every re-printing degrades the picture, just like a photocopy of a photocopy. Properly performed contact printing generally creates less degradation provided that the contact between the negative and the print film is perfect. Optical printing can emphasize the grain structure and any imperfections in the negative.[7] Also, since a new, different piece of film was exposed and printed, matching the exact colors of the original was a problem. Usually the printer work was limited to only the parts of a dissolve needing the effect. The original footage was spliced mid-shot with the optically-printed portion, often resulting in an obvious change in image quality when the transition occurs.


Restoration printing[edit]

Scratches, abrasions, cinch marks caused by rewinding a film too tightly, and other blemishes are a common problem with films that are candidates for restoration. Most of these scratches are in the back side of the film in the transparent substrate that forms the film base, rather than in the photographic emulsion on the front that holds the film's actual image.[8] In the normal process of duplicating a film in an optical printer, collimated light passes through the film base on its way to illuminate the emulsion. Any scratches, abrasions, etc., in the film base cause the light to bend such that the duplicated film ends up with bright or dark (depending on whether copying from a negative or positive original) copies of the scratches. This bending of the light is being caused by the difference in the refraction index of the substrate and the air.[9]


The second method is wet-gate printing. The "gate" in a projector is the apparatus that holds the film in place as each frame is shown. A wet gate is filled with a fluid that coats the film as it is fed through, constantly replenishing the fluid as needed.[9]



See also[edit]


  2. ^ "Company News; DEVELOPERS OF OPTICAL PRINTER WIN OSCAR FOR SPECIAL EFFECTS". New York Times. 3 April 1981. Retrieved 17 August 2015. 
  3. ^ Gustafson, Darryl E. "Dedicated Minicomputers In Optical Design". SPIE. Retrieved 17 August 2015. 
  4. ^ Marine, Joe. "Watch How the Masters Used to Create VFX for Movies in These ILM Videos". nofilmschool.com. NONETWORK, LLC. Retrieved 17 August 2015. 
  5. ^ Betancourt, Michael. "Optical Printing and Digital Computers". Cinegraphic.net. Retrieved 17 August 2015. 
  6. ^ Richardson, John, Claudia Gorbman and Carol Vernallis (2013). The Oxford Handbook of New Audiovisual Aesthetics. Oxford: Oxford University Press. pp. 241–43. ISBN 9780199733866. Retrieved 17 August 2015. 
  8. ^ a b c http://www.google.st/patents/US4023903
  9. ^ a b http://www.nfsa.gov.au/preservation/glossary/wet-gate-printing
  10. ^ http://www.folkstreams.net/vafp/clip.php?id=46