The data of each pixel of a CCD, acquired from double pre-emissions performed in accordance with a shutter operation, is estimated to determine appropriate luminous energy for actual photography. Specifically, in each frame between the shutter operation and emission for actual photography, a CCD is driven so that only the data of the pixels corresponding to an estimation area is transferred, and the data of the other pixels is destroyed. The estimation area is included in the image pickup area of the CCD and used to determine the appropriate luminous energy. As a result, the time required to transfer pixel data unnecessary for estimation is omitted, thereby reducing the total processing time ranging from the pre-emissions to the emission for actual photography, and realizing prompt actual photography with appropriate luminous energy.