Abstract: In a light-tight photoplotter, a system handles sheets of photosensitive media from an initial supply location through the photoplotter and advances them to final a location. The system includes a loading device interposed between the supply location and a workpiece support surface on which surface a work operation is conducted on the involved media sheet. It further includes an off-loading device positioned at the opposite end of the workpiece support surface and the collecting location. The loading device includes a locating mechanism which allows the involved media to be precisely oriented on the workpiece support surface in registry with two orthogonally oriented coordinated axis. The system further permits loading and unloading of covered cassettes in daylight without exposing the media supply to light which might otherwise be cast onto it. The system further provides for the safety locking of stacked media within the photoplotter to prevent inadvertent removal.