The photofinish camera, a level of precision at 1/20.000th of a second
This system is essential for some disciplines especially for high-speed racing, motor racing, motorcycle, where an arrival can be played to the millionth of a second.
For example :
In a final sprint, it is impossible to decide between two cars with the naked eye, as shown in this picture, the two cars are so close that no other timing system can separate the cars. Due to the high precision of our camera photofinish both cars could be separated with 0.0006 seconds of difference.
How it works?
The photofinish is not a snapshot of the arrival, but a temporal representation of what happens in the axis of the camera, perfectly aligned with the finish line.
The image provided by this camera is cut to keep only the central band (the finish line), this image is 1 pixel wide by 1024 pixels high. Every thousandth of a second, the chronograph timer adds the central band of the image (1 pixel) after the previous image, creating a non-instantaneous image but a sort of “drop-down” of time. This explains the “distorted” aspect of the images produced by the photofinish camera.