Patent ID: 8254773

Claim:
An image apparatus comprising: a screen configured to display an image formed by an optical system and a plurality of detection position marks superimposed onto the image; a detecting unit configured to detect information regarding focus of the optical system at a detection position corresponding to at least one of the plurality of detection position marks; a determining unit connected to the detecting unit and configured to determine whether the information regarding the focus is within a predetermined range; an acquiring unit connected to the determining unit and configured to acquire reference image information of a tracking target at the detection position when the determining unit determines that the information regarding the focus is within the predetermined range after the detecting unit starts detecting the information regarding the focus, the acquiring unit being configured not to acquire the reference image information at the detection position when the determining unit determines that the information regarding the focus is not within the predetermined range after the detecting unit starts detecting the information regarding the focus; and a control unit connected to the acquiring unit and configured to evaluate subsequent image information using the reference image information to track the tracking target using the subsequent image information.