A scanning apparatus providing separate fixed object focal planes for transmissive and reflective original documents to be scanned, wherein a scan carriage containing illumination, sensor, and optical elements is moved together to scan an original document and to obtain a digitized representation thereof. The movable scan carriage has an illumination source disposed between the reflective and transmissive object focal planes, with the object focal plane to be used selected by changing the position of a single optical element within the scan carriage. The illumination source comprises a single lamp disposed for correct illumination of the selected object focal plane. Automatic resolution selection and focusing of the original image can occur using a converging device comprising a first and second focusing lens.