1. An image processing apparatus comprising: an image acquisition unit configured to acquire an image from an imaging unit for acquiring an image signal from an object; a first image combining unit configured to align and synthesize a plurality of image frames acquired by the acquisition unit at a predetermined accuracy, wherein a synthesized image acquired by the first image combining unit is used for focus detection; and a second image combining unit configured to align and synthesize a plurality of image frames acquired by the imaging unit at an accuracy lower than the accuracy of the first image combining unit, or synthesize the plurality of image frames without performing alignment processing, wherein a synthesized image acquired by the second image combining unit is recorded or displayed as a captured image.