ABSTRACT
Graphic communication media such as book or newspaper illustrations and traditional kinds of typesetting and printing plate production processes involved forming images on sensitized materials at various stage of production. A lens for a process camera, commonly referred to as a process lens, needs to be of very long focus to cover the formats involved and to be optimized for unit magnification, as many of the copying applications are done at this scale. Process photography, and colour separation work using red, green and blue tricolour filters require a high degree of chromatic correction in the process lens, to give identical image sizes and focus for the various spectral bands used. Process cameras use very high contrast sensitized materials such as line film and lith film for most of their applications. Process lenses have extra-large front and rear elements to reduce mechanical vignetting to zero at the working aperture. The assembly of process lenses and optical alignment must be very accurate.
