Patent ID: 7548269

Claim:
An autofocus system for controlling the focus of a taking lens by specifying a subject to be autofocused within an AF area, which is part of the field of view of a camera, and automatically focusing on the subject, comprising: a target subject specifying device which specifies a target subject to be focused; a target subject movement detection device which detects the movement of the target subject specified by the target subject specifying device utilizing a plurality of movement detection methods, within the field of view, wherein the target subject movement detection device switches between the movement detection methods based on a parameter; and an AF-area altering device which alters the extent of the AF area to track the movement of the target subject detected by the target subject movement detection device, wherein the target subject movement detection device captures a subject image in the field of view of the camera through an imaging device and detects the movement of the target subject based on the captured image, wherein the target subject movement detection device comprises a storing device which captures a target subject image specified by the target subject specifying device through the imaging device and stores the target subject image, wherein a first movement detection method includes detecting a pattern of the image stored in the storing device from among the images of the field of view of the camera captured through the imaging device.