TELEVISION CAMERA IRIS APERTURE CONTROL

Apparatus is provided for automatically controlling or locking the iris aperture of a camera. The brightness level of a signal produced by the camera is detected and an automatic control circuit responds to this detected brightness level to energize an iris drive, thereby establishing the iris aperture. The actual size of that aperture is represented by an aperture signal. This aperture signal is used by a control signal generator to generate a control signal corresponding thereto. A selecting circuit is operable to select either an automatic control mode wherein the iris drive is energized by the detected brightness level of the signal produced by the camera, or an iris lock mode wherein the iris drive is energized to maintain the iris aperture at a fixed size irrespective of changes in that brightness level. An iris lock circuit responds to the selection of the iris lock mode for storing the control signal which is generated just prior to the selection of the iris lock mode, and compares the stored control signal to the aperture signal that is produced during the iris lock mode to energize the iris drive as a function of the difference therebetween. In the iris lock mode the automatic control circuitry is disabled. The iris aperture thus is fixed at a size determined by the stored control signal.