A flying-spot telecine detects film alignment by a light interrupter disc (28) (or drum) which is directly mounted on the axle of a sprocket wheel (22) of the film transport mechanism. The film is moved approximately to an expected position, and a light source (34) and detector (36) on opposite sides of the disc provide pulses representative of the determined film positions. Differences between determined and expected film positions are calculated to provide a correction signal used to adjust the vertical position of the scanning raster of the telecine CRT(2).