An apparatus including a sensor for setting an exposure time or gain for each of pixel groups including at least one pixel includes an imaging unit including the sensor configured to capture a subject through an optical system to generate an image, an acquisition unit configured to acquire information about a specific image region in the generated image, a determination unit configured to determine a specific pixel region including at least one pixel group in the sensor and corresponding to the specific image region, based on the information about the specific image region, a change unit configured to change at least one of a number, a size, and a shape of pixel groups in the specific pixel region determined by the determination unit, and a control unit configured to control the exposure time or gain for each of the pixel groups.