FOCUSING DEVICE, CONTROL METHOD THEREOF, AND ELECTRONIC DEVICE

原文（中文）

Disclosed is a focusing device that performs focus adjustment of an imaging optical system so that a subject area detected from a captured image is in focus. the focusing device sets a plurality of areas for calculating a defocus amount as areas in an image and selects an area to be used for focus adjustment from the plurality of areas. The focusing device then performs focus adjustment of the imaging optical system based on the defocus amount calculated for the area to be used for focus adjustment. The focusing device sets the plurality of areas in a range encompassing the subject area. In a case where the subject area is smaller than a predetermined size, the focusing device sets the range that is narrower than in a case where the subject area is not smaller than the predetermined size.