Strip photography
 "Grand Prix de Circuit de la Seine" (June 26th, 1912) |
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"The Spirit and Frenzy of Olympic Efforts" |
Strip photography (or slit photography) is a photographic technique of capturing a 2-dimensional image as a sequence of 1-dimensional images over time, rather than a single 2-dimensional at one point in time (the full field). As one moves across (in the direction of scanning), one moves in time, rather than, or in addition to, moving in space. The image can be loosely interpreted as a collection of thin vertical or horizontal strips patched together, hence the name. This is correct if the strips are discrete, as in a digital sensor that captures one line at a time, but in film photography, the image is produced continuously, and thus the "strips" are infinitesimal – a smooth gradation.
Many photographic devices use a form of strip photography due to the use of a rolling shutter for engineering reasons, and exhibit similar effects. This is common both on cheaper cameras with an electronic shutter (more sophisticated electronic shutters are global, not rolling), as well as cameras with mechanical focal-plane shutters.
This technique can be implemented in multiple ways. In film photography, a camera with a vertical slit aperture can either have fixed film and a moving slit, or a fixed slit and moving film. In digital photography, one can use a line sensor, generally one that is moving, as in a rotating line camera, but also an image scanner (flatbed or hand).
The fundamental property of strip photography is that it is a 2-dimensional slice across space-time. In some cases this is a slice perpendicular to the frame, in 1 spatial dimension (the slit) and 1 temporal dimension (the exposure time), if the slit is stationary (as in a photo finish), showing one strip over time (e.g., the finish line), where the scanning direction (e.g., horizontal) represents time, not space. In other cases this is a slice diagonal (in space-time) to the frame, with 1 spatial dimension (the slit) and 1 spatial-temporal dimension (the exposure time and moving slit) if the slit moves, as in a panoramic camera, which shows a single frame, but different strips are at different times, in which case the scanning direction represents both space and time. Thus, even though the image is viewed as a 2-dimensional spatial image, it does not depict a single instant.
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