摘要 |
PURPOSE:To raise the probability that focusing can be attained by correlation arithmetic operation of once, and to attain more efficient and high speed arithmetic operation, by subtracting the number of picture elements corresponding to the maximum shift amount peculiar to a lens from a photoelectric converting element string detecting a block being suitable for a focusing detection, from in the remaining photoelectric converting element string, thereafter, detecting a relative shift amount of this block and the other photoelectric converting element string. CONSTITUTION:A value N which represents a relative shift amount of two images corresponding to the maximum defocus amount peculiar to a lens by the number of picture elements is inputted, and subsequently, a picture element string of line sensors 17, 18 is divided into plural blocks, and the contrast of each block is derived. Next, a block with a contrast value larger than a prescribed value is detected from in the picture element string which is obtained by subtracting the number of continued picture elements N from the end part of the line sensors 17, 18. The maximum value of the number of picture elements N of the line sensors 17, 18 equivalent to an image phase difference goes to a value peculiar to a lens, which is determined by a focal distance of the lens, and the shortest photographic distance. After the normalization of the correlation arithmetic operation is executed, whether focusing can be executed or not is decided. |