1. An imaging system comprising: an imaging device configured to capture an image formed by an imaging optics; a recognition device configured to recognize a target object candidate in the image captured by the imaging device; a focus detector configured to detect a focus adjustment state of the imaging optics; a correcting device configured to obtain a magnification of an image of the target object candidate and configured to correct the magnification based on the focus adjustment state with respect to the target object candidate detected by the focus detector; and a selecting device configured to select a target object from the target object candidate based on the corrected magnification corrected by the correcting device.