An optical system is provided for a reproducing machine which scans an object to be reproduced, utilizing a pulsing light source to illuminate successive incremental portions of the object. The ray reflected from the scanned image is directed along an optical path onto the imaging plane. The scanned image is directed onto the imaging plane by a reflector element which has an active slit formed on its surface. The reflector element is positioned an optimum distance from the imaging plane such that the image is defocused at more than one magnification ratio.