Abstract: The lamphouse is used for the production of prints on variable control paper and comprises a first tungsten filament lamp from which light passes through a color selective filter which passes light in one of two mutually exclusive wavebands. A second filament lamp and filter passes light in the other of the two mutually exclusive wavebands. A diffusing screen is placed to pass the filtered light out of the lamphouse and through a transparency which is to be printed.Between each lamp and an alternating voltage source is connected a bidirectional thyristor, whose phase angle of conduction is determined by a microprocessor according to data stored in a read-only memory and by single manual controls for the selecting alternative addresses in the memory according to the contrast of print to be made.

Abstract: The meter senses flashes of illumination, it converts the illumination to an electrical current whose magnitude is proportional to the intensity of the illumination; it integrates the current over a period of time corresponding to a selected shutter speed by charging a capacitor; it discharges the capacitor and measures the time required to do so; it converts the time required to discharge the capacitor into a corresponding signal representative of an appropriate camera aperture setting for a preselected film sensitivity and shutter speed via a microprocessor and a stored data program; and then displays the camera aperture setting on a multi-segment display. This process is repeated with each new flash of illumination automatically. The meter also measures multiple flashes and displays an accumulated camera aperture setting as well as the number of flashes needed to accumulate that setting.