Patent ID: 8203628

Claim:
A camera system comprising: a focus lens that advances and retreats in an optical axis direction to change a state of focus of an optical image of a captured object; a focus lens drive portion for driving the focus lens; a focus lens position detection portion for detecting a position of the focus lens, or a mechanism member that is linked to the focus lens; a zoom lens that advances and retreats in the optical axis direction to change a focal length of the optical image of the captured object; a zoom lens drive portion for driving the zoom lens; a zoom lens position detection portion for detecting the position of the zoom lens, or a mechanism member that is linked to the zoom lens; a zooming portion for effecting driving of the zoom lens; an imaging portion that receives the optical image and creates image data; an estimated value calculation portion for calculating an estimated value for auto focusing, based on the image data that are created by the imaging portion; a tracking table memory portion for storing a tracking table that tabulates a relationship between focal lengths that are determined every captured object distance and the position of the focus lens in the optical axis direction; and a control portion that determines whether to control the focus lens drive portion in a first control mode or a second control mode, based on information relating to the rate of change in the focal length, and controls the focus lens drive portion based on the control mode that is determined; wherein in a case where the control portion determines that control is to be performed in the first control mode, the focus lens drive portion drives the focus lens forward and backward in the optical axis direction, in accordance with a command from the drive portion, so as to change the captured object distance; the estimated value calculation portion calculates estimated values for auto focusing at a plurality of positions at which the focus lens is located when it is being driven forward and backward in the optical axis direction; and the control portion controls the focus lens drive portion so that it drives the focus lens in a direction that brings the captured object into focus, based on the estimated values for auto focusing at the plurality of positions that were calculated by the estimated value calculation portion; and wherein in a case where the control portion determines that control is to be performed in the second control mode, the control portion controls the focus lens drive portion based on the tracking table.