An apparatus comprising a sensor capable of generating a signal pair used in focus detection. The apparatus obtains, based on a defocus amount obtained using the signal pair, a focus distance of a lens unit that is mounted to the apparatus and adjusts a focus distance of the lens unit based on the obtained focus distance. When the lens unit is a multi-scopic lens unit having a plurality of optical systems having different axes, the apparatus obtains the focus distance using an adjustment value obtained based on an axis position that is a position on the sensor through which an axis of the multi-scopic lens unit passes.