Image pickup apparatus and control method thereof

An image pickup apparatus to which an optical apparatus including an image-pickup optical system is detachably attachable, the image pickup apparatus comprising:

• an image pickup device configured to electrically convert an object image formed by the image-pickup optical system to produce an image pickup signal;
• a first detector configured to detect a first in-focus position by a phase difference detection method;
• a second detector configured to detect a second in-focus position by a contrast detection method using the image pickup signal;
• a corrector configured to correct, based on a difference between the first and second in-focus positions, the first in-focus position for image pickup;
• and
• a controller configured to be capable of communicating with the optical apparatus and configured to control drive of a focus lens included in the image-pickup optical system,
• wherein the controller is configured to output, to the optical apparatus, an instruction to move the focus lens by a predetermined movement amount when detection of the second in-focus position is made, and configured to receive, from the optical apparatus, information on an actual movement amount of the focus lens in response to the instruction, and
• wherein the controller is configured to output again, when a difference between the predetermined movement amount and the actual movement amount exceeds a predetermined value, to the optical apparatus, the instruction to move the focus lens with change of the predetermined movement amount.