A 1024 x 1024 pixel image digitizer has been developed that provides high speed electro-optical scanning of image transparencies. The system consists of a linear diode array mounted on a stepping motor assembly to produce a 1024 x 1024 pixel array. An optical system projects image transparencies onto the detector at variable scales. One design utilizes a 5:1 zoom lens with 1.0x and 2.4x channels for selection of image sample spacing from 1.3 to 16 pm. Another optical design utilizes projection optics to enable sample spacing above 16 pm. In this paper, we examine the design considerations applied to this type of instrument.