A lamphouse for a telecine allows the spectral composition of its output to be controlled electronically. A light beam (300) is bounced off mirrors to reduce its infrared content, then passes through three beam splitters (305, 310, 315) which split off the blue, red and green content. The blue, red and green beams pass through electronic shutters (320, 325, 330) and are then reflected off dichroic mirrors (335, 340, 345) to become a single beam (348) again. The spectral content of the single beam is controllable by turning the electronic shutters (335, 340, 345) corresponding to the blue, red and green beams on and off.