Patent ID: 7616252

Claim:
A control apparatus for controlling a driver driving an optical element of an image pickup device to adjust a focus position of the image pickup device in the capturing of an image of a subject, the control apparatus comprising: relative angle variation calculating means for calculating a relative angle variation, the relative angle variation being a change per unit time of a relative angle of the image pickup device with respect to the subject, the relative angle variation calculating means including in-field integrated luminance value calculating means for calculating an in-field integrated luminance value through integrating a luminance value of each pixel of the captured image of the subject within a field, mean value calculating means for calculating the mean value of the in-field integrated luminance values, calculated by the in-field integrated luminance value calculating means, within a time range having a predetermined time length, difference calculating means for calculating a difference value between the mean value of a first time range, equal to the time range having the predetermined time length, containing the current field and the mean value of a second time range immediately prior to the first time range, each mean value calculated by the mean value calculating means, and normalizing means for normalizing the difference value, calculated by the difference calculating means, with the in-field integrated luminance value of the current field and the length of the time range, and handling the normalized difference value as the relative angle variation; mode change detecting means for detecting of a change of a mode of the relative angle variation through determining whether the mode of the relative angle variation, calculated by the relative angle variation calculation means, is a stable mode involving a small amount of change or an unstable mode involving a large amount of change; and focus position control process startup means for managing a startup of a focus position control process, the focus position control process for controlling the focus position through controlling the driver in response to a pattern of the change of the mode detected by the mode change detecting means.