| 摘要 |
PURPOSE:To detect correctly a focus even in case when a contrast of an object is low by constituting a titled device so that focusing can be executed based on an average value of distance detecting information of plural times from a object distance detecting device. CONSTITUTION:A surface F corresponds to a focal plane of a photographic lens 1. That is to say, when a video camera is supposed, an image pickup sur face position of an image pickup tube becomes F. Accordingly, when the lens 1 changes a position by moving back and forth on an optical axis, a distance of an object for forming an image correctly on the surface F is different, and outputs an, bn of each picture element An, Bn, become an=bn and an-1=bn-1, respectively, but in case an image of an object which is not in a focused dis tance is caught said outputs become an=bm and anot equal to m. In order to calculate a shifting quantity and a direction of an an curve and a bn curve, a CPU executes a prescribed processing. The shifting quantity against the distance of the object is brought to a distance measuring operation repeatedly by pre scribed number of times, and its output is impressed to an averaging circuit 118. This circuit 118 operates an arithmetic average value of plural pieces of shifting quantity, and the lens is adjusted to a focused state. |
