Image Number 4 for United States Patent #4474450.
A system and method for adapting a multi-purpose electronic flash for use with an automatic exposure control camera is disclosed. The system responds to a ready signal from the multi-purpose flash and a reference signal from the automatic exposure control camera by providing a signal representative of the correct aperture for a given film speed (ASA) and range of flash to subject distances. Film speed is provided to the system by setting one portion of a variable resistance, while range is provided to the system by setting another portion of the variable resistance which is associated with a graded density optical filter located in front of the photosensor. A bipolar range about the reference signal is established to permit positive or negative signal excursions about the reference signal for indication of correct aperture. A scaling amplifier may also be provided for signal conditioning to ensure compatibility with the camera. The scaling amplifier may be arranged to provide less than unity amplification, thereby reducing system error. A special housing connects between the foot of the flash and the camera to provide access to the camera accessory shoe terminals and also to permit the flash to be operated on or off the camera. Various alternatives are disclosed.