Automatic camera iris control - has photocells on prism side of periscopic optical system

摘要

Fully automatic control of the iris of cameras employing a prismatic periscope optical system. The photo - sensitive cell (8) or cells are placed on the vertical sides of the prism (7) or prisms (7, 2), used rather than the horizontal inward facing surfaces, and make use of the light scattered within the prism volume. The cell may be attached to the lower prism to supply directly the amplifier (9) or motor (10) controlling the iris (4) setting, between the objective lens elements (3, 6) or an additional cell may be attached to the upper prism, both cells feeding a differential system to provide more accurate control of the iris.