| 摘要 |
PURPOSE:To form a focusing device which is capable of adjusting a start time of a focus detecting operationin accordance with a focus state by shortening a time interval for detecting a focus, as compared with the case when a focus state is far in case when a focus state of an image pickup optical system is close to the focusing state. CONSTITUTION:When a start signal STT of focusing control is inputted to a focusing control means 6, focusing is started, and first of all, a projecting signal d1 is sent to a light source 7. The light source is lighted by the signal d1, and a light spot is projected to an object 1. This light spot is projected onto a photodetecting part 10, and a position information Cd1 of a light spot 9 is obtained from an amplifying means 5. Because of Cd1>C5, the length td1 of the first TD becomes td1=TD3, and the time interval before the follwing d2 is outputted becomes long. Also, a signal ed1 for controlling a feed quantity of a photographic lens is sent to a driving means 8, and the feed quantity of the photographic lens is changed. When the time elapses by a length td1 after the signal d1 is outputted, the second projecting signal d2 is outputted, and focusing of the second time is started. Since Cd2 is C3<Cd2<C5, td2 is td2=TD2, and shortened. Also, ed2 becomes small, too. In this way, the focusing is repeated. |
