in a system for setting the aperture in a camera for flash photography , a minimum aperture is computed in response to parameters such as distance to an object , stroboscopic guide number and film sensitivity . in one embodiment , a predetermined aperture value is preestablished in the system and the computed minimum aperture is compared therewith . where the computed minimum aperture is below such predetermined aperture value , such computed minimum aperture is used in flash photography . on the other hand , when the computed minimum aperture is above such predetermined aperture value , an aperture larger than the predetermined minimum aperture value is used in flash photography . other embodiments for flash aperture setting are also set forth .