Abstract: A first carriage carries a lamp for illuminating the original and a first mirror. A second carriage carries two mirrors and moves at half the speed of the carriage so that a constant optical path length is maintained from the original, via the three mirrors and a focusing lens to a rotating image receptor drum. The carriages are driven by individual motors via pulleys and belts and, during scanning, the speeds of the two motors are controlled in sympathy to move the carriage at a speed corresponding to the selected reduction/enlargement factor and to move the carriage at half this speed. Before scanning, only the second motor is energized to position the second carriage in accordance with the said factor. In a modified embodiment, a clutch couples the two carriages for movement at the correct relative speeds during scanning which is effected solely by means of the first motor. The initial positioning of the carriage by the second motor is effected with the clutch disengaged.