A focus range is determined on the basis of an object distance, focal distance, and aperture value, after an autofocus operation. When SW2 is operated, an exposure is performed only during a period that a displacement of a blur in an optical-axis direction is within the focus range. If an exposure time for one exposure does not reach an exposure time to obtain an optimum exposure, a plurality of exposures are performed until a total exposure time reaches the exposure time to obtain the optimum exposure. When the plurality of exposures are performed, a plurality of images obtained are combined to generate an image with the optimum exposure.