To determine exposure so as to obtain an image output suitable for detecting a focus evaluation value.

An exposure calculation unit includes: an imaging means 103 that captures an image formed by optical systems 151, 152 and outputs an image signal; an extraction means 44 for extracting a part of the image captured by the imaging means 103 as a target image on the basis of the image signal output by the imaging means 103; a focus detecting means 44a for detecting a focusing state of the optical system 151, 152 on the basis of an image signal corresponding to a focus detection region corresponding to the target image among image signals from the imaging means 103; and a calculation means 44 for determining exposure of the imaging means 103 when obtaining the image signal corresponding to the focus detection region on the basis of a size of the target image.

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