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Theslit-scan photography technique is aphotographic andcinematographic process where a moveable slide, into which a slit has been cut, is inserted between thecamera and the subject to be photographed.

More generally, "slit-scan photography" refers to cameras that use a slit, which is particularly used inscanning cameras inpanoramic photography. This hasnumerous applications. This article discusses the manual artistic technique.^[1]

Originally used in static photography to achieve blurriness or deformity, the slit-scan technique was perfected for the creation of spectacularanimations. It enables the cinematographer to create apsychedelic flow of colors. Though this type of effect is now often created through computer animation, slit-scan is a mechanical technique.

John Whitney developed it for the opening credits of theHitchcock filmVertigo. After he sent some test sequences on film toStanley Kubrick, the technique was adapted byDouglas Trumbull for2001: A Space Odyssey in 1968 for the "star gate" sequence, which required a custom-built machine.^[2]

This type of effect was used in other films and television productions. Slit-scan was used byBernard Lodge to create theDoctor Who title sequences forJon Pertwee andTom Baker used between December 1973 and January 1980. Slit-scan was also used inStar Trek: The Next Generation (1987–1994) to create the "stretching" of the starshipEnterprise-D when it engagedwarp drive. Due to the expense and difficulty of this technique, the same three warp-entry shots, all created byIndustrial Light and Magic for the series pilot, were reused throughout the series virtually every time the ship went into warp. Slit-scan photography was also used onInterstellar for scenes in thetesseract at the end of the movie.

Slit-scan is ananimation created image by image. Its principle is based upon the camera’s relative movement in relation to alight source, combined with a longexposure time. The process is as follows:

1. An abstract colored design is painted on a transparent support
2. This support is set down on the glass of a backlighting table and covered with an opaque masking into which one or more slits have been carved.
3. The camera (placed high on top of a vertical ramp and decentered in relation to the light slits) takes a single photograph while moving down the ramp. The result: at the top of the ramp, when it is far away, the camera takes a rather precise picture of the light slit. This image gets progressively bigger and eventually shifts itself out of the frame. This produces a light trail, which meets up with the edge of the screen.
4. These steps are repeated for each image, lightly peeling back the masking, which at the same time produces variation in colors as well as variation of the position of the light stream, thus creating the animation.

Naturally, this effect is very time-consuming, and thus expensive, to create. A 10-second sequence at 24 frames per second requires a minimum of 240 adjustments.

• Example code to create slit-scans
• Slit-Scan Photography
• Unwrapping the 2001 Slit Scan sequences
• ABC Movie of the Week opening sequence, created in 1969
• Total Recall (1990) main title sequence

• Special effects
• Photographic techniques

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