Rotating Drum cameras have a film track which lines the inside cylinder of the rotating drum. A special film cassette is used to load a specified length of film into the inside perimeter of the drum. This cassette also recovers the film after exposure for processing. The drum is powered by an electric motor, controlled by an electronic control unit or variable power source.

Streak drum cameras produce a record by reflecting a line image to the film with a stationary mirror. Film movement beneath this point creates the time dimension of the streak record. Framing drum cameras employ a rotating mirror mechanically coupled to the drum. During exposure, successive faces of the mirror reflect light through relay lenses at regular intervals. The relay lenses focus the light into images on the moving film, creating the regularly spaced discrete frames.

Rotating Drum cameras produce frame records at up to 200,000 frames per second and streak records at up to 0.31 mm/µs. In faster models, the drum rotates in a housing which is evacuated to reduce air friction. This allows the drum to reach higher speeds with less power, and reduces temperature rise and the slight image resolution loss due to air turbulence.

ROTATING DRUM CAMERA