In a circumstance in which light is emitted from many electronic flashes, e.g., a press conference hall or a wedding hall, light emission from other electronic flashes overlaps preliminary light emission performed before main light emission. This decreases the photometry accuracy with respect to preliminary light emission and makes it difficult to perform proper flash exposure. In a camera system designed to perform preliminary light emission before main light emission, photometry is performed a plurality of number of times upon preliminary light emission, and flash exposure is performed by suppressing photometric values which may have been influenced by light emission as disturbance other than the preliminary light emission.