Patent ID: 7139472

Claim:
A camera system comprising: a camera having a photometering unit and a first light emission control unit; a first electronic flash unit having a first flash light emission unit, a light emission from which is controlled by the first light emission control unit, either built into or externally mounted at the camera; and a second electronic flash unit having a second flash light emission unit, a light receiving unit and a second light emission control unit, provided separately from the camera, wherein: the first light emission control unit transmits a light signal constituting a preliminary light emission command to the second electronic flash unit by causing the first flash light emission unit to emit light; the second light emission control unit engages the second flash light emission unit in a preliminary light emission upon receiving the light signal constituting the preliminary light emission command at the light receiving unit; and the first light emission control unit engages the photometering unit to photometer a subject when the second electronic flash unit executes the preliminary light emission, and if a photometered value thus obtained is equal to or greater than a predetermined threshold value, the first light emission control unit judges that optical communication between the camera and the second electronic flash unit is enabled and allows a photographing operation to be executed.