AUTOMATIC FOCUSING DEVICE

PURPOSE:To quicken a focusing action by directly performing passive range- finding in an image phase difference detection system in accordance with the result of active range-finding in a trigonometrical survey system or performing the passive range-finding after a focusing action based on the active range- finding. CONSTITUTION:This device is provided with an active range-finding system 11 in the trigonometrical survey system and a passive range-finding system 12 in the image phase difference detection system, and a focusing mechanism 30 performs the focusing action by either of them. First, a difference between the active range-finding data and the present position of a focusing lens is obtained by a microcomputer 21 and the relation of magnitude between the obtained difference and the previously set deviation is obtained. When the difference is larger than set deviation, the focusing mechanism 30 is made to perform the focusing action based on the active range-finding data. When the difference is smaller than the set deviation or after the focusing action based on the active range-finding is completed, the focusing mechanism 30 is made to perform the focusing action based on the passive range-finding data.