A focus detection apparatus having a first focus detection unit and a
second focus detection unit of a scheme differing from that of the first
focus detection unit, for detecting the shift amount of a focal position
by the first and second focus detection units, includes (a) an
instruction unit capable of instructing a detection mode for detecting
the shift amount, and (b) an image producing unit, when given the
instructions for the detection mode from the instruction unit, for
producing an object image.