FOCUS DETECTION DEVICE AND METHOD

An optimum focus detection algorithm range is established in the focus detection area corresponding to the subject pattern. The method includes establishing a first region on the photoelectric conversion array; computing the contrast of the subject image in the first region based on the output signal strings of a plurality of photoelectric conversion elements contained in the first region; establishing a portion of the first region as a second region; and computing the contrast of the subject image in the second region based on the output signal strings of a plurality of photoelectric conversion elements contained in the second region. Subsequently, either the first region or the second region must be determined as the focus detection algorithm range based on the contrast of the first region and the contrast of second region. The focus adjustment condition of the shooting lens is computed based on the output signal strings of the first region or the second region, whichever is selected as the algorithm range.