PHOTOGRAPHIC EXPOSURE CONTROL DEVICE FOR FLASH EXPOSURE

摘要

An image recording apparatus and method employing a diaphragm shutter having a time variable exposure aperture with flash firing, following actuation of the shutter, after a time interval dependent on subject range. The functional relationship between the time interval and subject range establishes a parametric relationship between the brightness of the subject due to its flash illumination and the scan time of the diaphragm shutter. The inverse of this parametric relationship constitutes the timewise variation in the exposure aperture area of the shutter. Consequently, whenever the subject is within a predetermined maximum distance from the camera, dependent upon the maximum aperture area attainable by the shutter, the instantaneous product of subject brightness and aperture area will be a constant with the result that proper exposure of the photographic film is achieved independent of the subject range.