Abstract: An optical system for use within a copying machine of the type in which sequential line portions of the original document are illuminated and the light therefrom is reflected by a primary mirror onto an objective element which, in turn, forms a focussed image on a copying drum which rotates in synchronism with the motion of the illumination. In order to provide copying capability at another ratio of reproduction, the primary mirror is made pivotable. In its second position, it reflects the light from the illuminated line portion onto a first supplemental mirror which reflects it onto a second supplemental mirror that directs it to a second objective element. The second objective element forms a focussed image on the copying drum, that image being of different size but located at the same edge of the copying drum as the image from the first objective element.