Abstract: Projection apparatus for photodrafting equipment in which an exposure control disc is rotated to vary the intensity of the projected light during exposure of a line is provided with a region which on rotation of the disc effects progressive decrease in the intensity, that region being followed by an aperture or clear region and that in turn being followed by an opaque region. Thus the disc can be rotated in one direction to progressively reduce the intensity, then produce a brief flash at maximum intensity, and then shut off the projected light completely. The preferred form of the exposure control disc, believed novel in itself, comprises a tapered slot movable lengthwise through the optical path of the apparatus to selectively restrict the exit pupil thereof.

Abstract: Photodrafting equipment which can be operated alternatively in first and second modes. In the first mode, the equipment can expose continuous lines in conventional manner. In the second mode, the equipment can expose a plurality of discrete areas or "pads" without interruption of carriage movement. To this end the projection apparatus of the equipment comprises a relatively low intensity light source for exposing the lines, a relatively high intensity flash light source for exposing the pads, and a rotatable reflecting prism to select one or the other of the light sources in accordance with the mode of operation.