1. An imaging device comprising: a pixel region that includes a plurality of pixel elements for imaging an object based on an incident light; and a reading unit configured to control the plurality of pixel elements to output signals such that in a first frame, signals are output from a first set of pixel elements of the plurality of pixel elements, and in a second frame, signals are output from a second set of pixel elements of the plurality of pixel elements, the second set of pixel elements being exclusive of the first set of pixel elements, wherein the reading unit is configured to control such that the first set of pixel elements are selected from a wider area of the pixel region than the second set of pixel elements.