A camera system is provided, which performs exposure amount control operation in combination with gradation conversion processing for an image signal acquired from a CCD. With such a camera system, a control unit performs control operation so as to perform pre-shooting multiple times with different exposure amounts prior to real shooting. A conversion property calculation unit calculates conversion properties with respect to the image signals acquired in the pre-shooting, which are to be used in the gradation conversion processing. An exposure control unit determines an exposure amount used in the real shooting based upon the image signals acquired in the pre-shooting, the exposure amounts used in the pre-shooting, and the conversion properties. The control unit performs control operation so as to perform the real shooting based upon the determined exposure amount. A gradation conversion unit performs gradation conversion processing on the image signals obtained in the real shooting.