As the name implies, it's a camera suspended over a rostrum, or platform. The camera is locked down at a certain distance, and objects like photographs and documents are then placed onto the rostrum. The rostrum moves in a variety of directions, enabling the operator to move the subject while exposing individual frames of film in the camera. The result of patient exposure of multiple frames of an object on a moving rostrum is stop motion animation. Additional effects can be registered on the film by multiple exposure, varied exposure times, and precision movement of the rostrum.