Patent ID: 7319487

Claim:
A camera comprising: a shooting optical unit; and a focusing system for moving a focal position of the shooting optical unit by a predetermined positional interval, for obtaining an image pickup signal at each focal position, and for detecting a focus position based on contrast values of the obtained image pickup signals, wherein the focusing system comprises: a control unit for, when an instruction is given to detect a position at infinity, controlling the focusing system to perform a plurality of times a process comprising: performing said moving and said obtaining to position the focal position of the shooting optical unit at a plurality of positions at the predetermined positional interval in a range where the position at infinity is expected to be included, and to obtain an image pickup signal at each of the positions at which the focal position of the shooting optical unit is positioned; a filter unit comprising a first filter for normal position detection and a second filter for infinity position detection having a frequency characteristic different from a frequency characteristic of the first filter, wherein when the instruction is given to detect the position at infinity, the filter unit performs frequency filtering processing on the obtained image signals using the second filter; and a focus position detecting unit for detecting the focus position based on the contrast values of the obtained image pickup signals; wherein, when the instruction is given to detect the position at infinity, the focus position detecting unit detects, for each time that said process is performed, a provisional focus value based on the contrast values of the obtained image pickup signals which have undergone the frequency filtering processing using the second filter, so as to obtain a plurality of provisional focus values, and the focus position detecting unit detects a final focus position based on the plurality provisional focus values.