US Patent 7536094 Focus detection apparatus and image taking apparatus

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.