To provide an image synthesizer for properly acquiring a signal of an image focused on a specific photographic object in a photographic image.

The image synthesizer includes: an input means 101 to be user for inputting a plurality of light reception signals obtained by receiving light flux; and an image generation means 104 generating a first image signal obtained by selecting a part of the plurality of light reception signals by a first selection form, and a second image signal obtained by selecting a part of the plurality of light reception signals by a second selection form different from the first selection form, and generating the image signal having a maximum evaluation value based on an evaluation value related to contrast of the first image signal and an evaluation value related to contrast of the second image signal.