Telerecording

Telerecording (known as kinescoping in the US) is the British name for a process pioneered during the 1940s for the storing of electronically shot television programmes on film. It was used for the preservation, re-broadcasting and sale of television programmes before the use of commercial broadcast-quality videotape became prevalent for these purposes.

Technique

The telerecording process works by aiming a film camera at a specially adapted flat television screen, with the camera shooting at a frame rate in synchronisation with the television frame rate. In the UK and the rest of Europe, television runs at 25 frames – or more correctly, 50 fields – per second, so the film camera would be run at 25 frames per second rather than the cinematic film standard of 24 frames.

Because television is a field-based rather than frame-based system, however, not all the information in the picture can be retained on film in the same way as it can on videotape. The time taken physically to move the film on by one frame and stop it so that the gate can be opened to expose a new frame of film to the two fields of television picture is much longer than the vertical blanking interval between these fields - so the film is still moving when the start of the next field is being displayed on the television screen. It is not possible to accelerate the film fast enough to get it there in time without destroying the perforations in the film stock - and the larger the film gauge used, the worse the problem becomes.