Camera using calibrated aperture settings for exposure control

摘要

A camera includes a mechanically-controlled aperture mechanism providing two or more aperture sizes for regulation of the intensity of image light gathered by the camera, a storage device for storing aperture calibration data corresponding to the measured transmissivity of each aperture size, and means for controlling camera exposure according to the value of one or more exposure parameters other than the aperture. The exposure errors caused by the aperture mechanism are thereupon compensated for with an exposure circuit that utilizes the stored aperture calibration data in order to establish the value of at least one of the exposure parameters other than the aperture. Such other exposure parameters include the shutter time and quench time for a flash, and in the case of an electronic camera the gain applied to the captured image signal.