Where have all of the wires gone?

[Echo Farm]

In order to avoid possible wrong decisions over the order in which racehorses, athletes, racing cars, etc. pass the finishing post when the result is very close, the finish of a race can be recorded by a special camera called a photo-finish camera. Until recently this has been a specially constructed or modified film camera, taking 70 mm or larger roll-film. Instead of a normal focal-plane shutter this camera has only a capping shutter, and in the focal plane a fixed vertical slit centred on the optic axis of the lens. The camera is set up so that the image of the finishing post falls on the slit, with a high viewpoint so that the competitors do not mask one another. To record the finish of the race the lens is uncapped and the film is set in motion at a speed matched to the movement of the image of the participants. This is calculated according to the formula v = f/D × V, where v is the required film movement speed, f the focal length of the lens used, D the average distance of the competitors from the camera, and V the average speed of the participants, all measurements being made in the same units.

more http://www.answers.com/topic/photo-finish-camera

I believe that the camera is mounted in a precice position directly across from the mirror.........but not sure