In a copying device for selectively copying sheet originals and thicker originals, the thicker originals being copied while positioned on a reciprocating original carriage. In one mode of copying thick originals, the original carriage is reciprocated one time for each rotation of the photosensitive drum while in another mode each reciprocation corresponds to two rotations of the drum. In one mode of copying sheet originals the photosensitive drum rotates once for each copy while in another mode a plurality of copies are formed for each rotation. The copying device has a control system for detecting the position of the reciprocating carriage and for controlling the forward and reverse movement of the carriage as a function of the size of the original being copied as well as the position of the carriage.