| 摘要 |
PURPOSE:To attain high speed focusing and highly accurate focusing at the same time by using a focus detection sensor arranged before and after an image pickup element in the optical axis direction so as to detect the out of focus in the forward and reverse directions and driving a stage stepwise within the stage moving range by means of the binary search thereby detecting the focus. CONSTITUTION:The deviation from out of focus detection sensors 103, 104 is calculated to obtain the deviation from the focal position in the image pickup element 102. The stage 107 is driven stepwise by using the out of focus deviation and the location where the out of focus deviation is zero is a focusing point. In this case, the stage is driven stepwise to obtain the focusing point by the binary search method. In adding a numeral N newly to a series arranged in the ascending order, in the binary search method, comparison is executed at, the midpoint in the search range and whether the object resides in the upper or the lower half of the entire range is judged at first. Moreover, the middle point being a half point of the judged range is checked and which range the object resides (i.e., 1/4) is judged further. The processing above is repeated and the final object point is converged. |
