Exposure control system with separate flash and ambient trigger levels

Abstract From the Canadian patent

An exposure control system is provided with means through which it is automatically actuated to change the exposure controlling characteristics thereof in response to the coupling of a source of artificial illumination therewith. The exposure control system is operable in both an ambient and flash mode of operation wherein the exposure control system anticipates a rather large shutter blade overshoot subsequent to the command signal to close the shutter blades during the ambient mode of operation which anticipation is automatically compensated for during the flash mode of operation to provide an optimum flash mode exposure interval prior to receipt of the command signal to close the shutter …