Invented by photographer Robert Harris (RIT graduate). A guillotine-like shutter device that introduces color in moving objects, while keeping the stationary ones true-color.

The principle is that three color filters are placed in front of your lens in a sequence during one single exposure. The simple solution embodied in the Harris shutter uses gravity, but more complex solutions are imaginable.

 -----------
|           |
|           |
|  opaque   |
|           |
|           |                   
||---------||
||         ||
||  red    ||
||         ||
||---------||
||         ||
||  green  ||                   
||         ||                   
||_________||
||         ||                   
||  blue   ||                   
||         ||                   
||_________||
|           |
|           |
|           |         /----\
|           | \_ ____/     ||
|  opaque   |   |          |
|           |   |          |
|           |  _|____      |
|           | /      |_____|
|           |
-------------       (definitely not drawn to scale)

Operation: Place the camera on a tripod. Put the shutter in the position depicted above. Open the camera shutter on B. Let the shutter drop: the filters will pass in succession in front of the lens. At the end of the drop the opaque part of the shutter will be in front of the lens and it will keep light out.

Objects that have moved during exposure will have color fringes, while stationary objects will look reasonably normal. The real difficulty with the Harris shutter appears to be that it is difficult to find a triple of color filters that have similar density and yet cancel each other out - if they don't cancel out, at the end you will have an overall color cast.

A similar idea is painting with light and, in general, the idea of changing light condition during exposure. See also synthetic light. These effects are quite cool when first seen, but they become really boring after a while, like zooming during exposure, slow sync and solarization.

Diagram and ideas taken from: http://medfmt.8k.com/mf/tricolor.html and http://www.rit.edu/~andpph/pf-faq/faq-24.html.

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