An electric storage apparatus in which a first projecting portion projecting on one side and a second projecting portion projecting on the opposite side of the one side are formed at different positions in a direction orthogonal to a direction in which the first and second projecting portions project. A group of objects is identified in an image. A circular area is illuminated if a light source is placed into registration with each aperture. A plurality of corresponding level equalization calibrations for each anticipated dynamic range are made at every power-up initialization.