The slit-scan photography technique is a photographic and cinematographic process where a moveable slide, into which a slit has been cut, is inserted between the camera and the subject to be photographed.
Originally used in static photography to achieve blurriness or deformity, the slit-scan technique was perfected for the creation of spectacular animations. It enables the cinematographer to create a psychedelic flow of colors. Though this type of effect is now often created through computer animation, slit-scan is a mechanical technique. It was adapted for film by Douglas Trumbull during the production of Stanley Kubrick's 2001: A Space Odyssey and used extensively in the "stargate" sequence. It requires an imposing machine, capable of moving the camera and its support. This type of effect was revived in other productions, for films and television alike. For instance, slit-scan was used in Star Trek: The Next Generation to create the "stretching" of the starship Enterprise-D when it engaged warp drive. Due to the expense and difficulty of this technique, the same three warp-entry shots, all created by Industrial Light and Magic for the series pilot, were reused throughout the series virtually every time the ship went into warp. Slit-scan was also used by Bernard Lodge to create the Doctor Who title sequences from December 1973 to 1979.
Slit-scan is an animation created image by image. Its principle is based upon the camera’s relative movement in relation to a light source, combined with a long exposure time. The process is as follows:
Naturally, this effect is very time-consuming, and thus expensive, to create. A 10-second sequence requires a minimum of 240 adjustments.