| 摘要 |
PURPOSE:To follow the action of a dynamic object even if focus detection becomes impossible temporarily and to drive a lens by obtaining the changing amount of defocus quantity from its changing speed caused by the movement of the object, and driving the focusing lens based on the changing amount. CONSTITUTION:A focus detecting means 1 detects the focusing state of a photographing lens, and outputs the defocus quantity (DFO). It is a variable and its mark indicates the direction of the defocus quantity and its absolute value indicates the magnitude of the defocus quantity. A changing speed detecting means 2 detects the changing speed VHO due to the movement of the object, and a changing amount detecting means 3 outputs the changing amount DELTADF of the defocus quantity, based on the speed VHO. A reliability deciding means 4 decides the reliability of the DFO from the focus detecting means 1, and when the DFO is unreliable, the focusing lens is driven by means of a lens driving means 5 based on the changing amount DELTADF, so that the lens can follow the movement of the object. |
