1. A focus detection apparatus having a first focus detection unit and a second focus detection unit of a differing from said first focus detection unit, and for detecting the shift amount of a focal position by said first and second focus detection units, said focus detection apparatus having: an instruction unit capable of instructing a detection mode for detecting the shift amount; and an image producing unit, when given the instructions for the detection mode from said instruction unit, for producing an image for detecting the shift amount of a focal position.