support plate 17 while a pair of reflecting mirrors 26 27 are fixedly mounted on a movable member 25 at right angles with each other these mirrors being effective to direct the reflected light from the color original to a lens unit 29 which is fixedly mounted on a stationary member after passing through the lens unit 29 the light is reflected by a reflector mirror 31 which is fixedly mounted on a stationary member 28 and is projected onto a belt shaped photosensitive member 32 having a photoconductive response before passing through the lens unit 29 the light is directed through an interchangeable filter 30 whereby a color separation image corresponding to the filter 30 used is projected onto the photosensitive member 32 a pair of shield plates 33 34 form a light path for the reflected light and a diaphragm 35 is mounted internally of the shield plates for pivotal motion about a pin 36 for adjusting the amount of reflected light let therethrough the movable member 25 is movable to a position 25a shown in phantom lines in a direction parallel to the original receptacle 13 the rate of its movement being one half that of the lamp units 15 16 so that the length of the light path between the color original and the lens unit 29 can be maintained constant the photosensitive member 32 extends around a pair of guide rollers 37 38 and a.