Abstract: A camera accommodating film cartridges having structural signals differently configured according to the corresponding film speeds and selectively accepting a photoflash unit with a predetermined high guide number and a photoflash unit with a predetermined low guide number is provided with an automatic diaphragm mechanism which, in flashbulb photography, adjusts the aperture according to the object to camera distance. The camera includes a luminosity attenuator for guide number compensation and a luminosity attenuator for film speed compensation, each attenuator being displaceable between a nonattenuating position displaced from the camera objective light path and an attenuating position in said light path. Internal of the camera is a first sensor for differential detection of the guide number classification of a photoflash unit to be mounted on the camera for flashbulb photography.

Abstract: A photoflash photography system includes a camera separably housing individual film cartridges carrying indicia, physical or electrical, representing the sensitivity of the film contained in the respective cartridge. A photoflash unit is coupled to the camera and has a light output which automatically varies inversely with the film sensitivity in response to the sensitivity indicia. The light output is varied by varying the charge voltage on the flash tube storage capacitor or the capacitor capacitance value. The electrical indicia may be resistors of different values and the physical indicia may be recesses of different depths or differently disposed shoulders or fingers which are detected by movable sensing members.