1. A focus detection apparatus having a first focus detection unit and a second focus detection unit of a type differing from said first focus detection unit, for detecting the shift amount of a focal position by said first and second focus detection units, said focus detection apparatus comprising: 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, wherein said image producing unit changes the position and size of the produced image on the basis of the distance information to a display device.