Photo finish

A photographic record of competitors crossing a finish line, used to establish their order when they finish close together. In racing, the result is judged by when each competitor’s torso reaches the finish line.

Finish line: A designated boundary that competitors must cross to complete a race. The image records competitors at the boundary whose crossing order decides the result.
Athletics: Track-and-field sports involving running, jumping, throwing, and walking events. Track races use photo finishes when athletes cross the line nearly together.
John C. H. B. Seed: A British inventor associated with early photographic timing equipment for horse racing. His work helped establish photographic evidence as a way to settle close race finishes.
1968 Summer Olympics men's 100 metres: The Olympic sprint final in Mexico City won by Jim Hines in 9.95 seconds. The race illustrates the use of electronic timing and finish photography in elite athletics.
Line-scan camera: A camera that builds an image one narrow line at a time as a scene moves past it. Its continuous scan turns movement across the finish into a time-ordered image.
Horse racing: A competitive sport in which horses race over a course. Judges use finish photographs to separate horses whose noses reach the line close together.
Horse racing in the United Kingdom: The organized sport of horse racing in Britain, including flat and jump racing. British racecourses were among the early settings for photographic finish adjudication.
1988 Kentucky Derby: The Kentucky Derby won by Winning Colors, with a close finish involving Forty Niner. Its tight finish is a prominent example of photographic review in horse racing.
Photoelectric cell: A device that detects light and converts it into an electrical signal. Some timing systems use a beam across the finish to register a crossing alongside the image.
Cycling: The sport of racing bicycles on roads, tracks, or off-road courses. Sprint finishes can bunch riders across the line, making photographic adjudication useful.

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