| 摘要 |
PURPOSE:To perform quick and accurate focusing, by setting the distance between a lens and an image pickup surface within an allowable range which is decided by the incident light and the depth of field, and reducing the working range for focusing as less as possible. CONSTITUTION:An incident light volume detector 10 produces a signal which shows the incident light volume through a lens 1. An aperture value detector 11 and a focal distance detector 12 produce digital signals which show the aperture value and the focal distance respectively. These signals are supplied to an arithmetic circuit 13 to produce a signal which shows a shift extent of the lens corresponding to the depth of field. These signals are supplied to a lens shift range setting circuit 14 to produce a signal which shows a boundary of the allowable range for the lens shift. This signal is supplied to a comparator 16 to be compared with a lens position signal. If the position of the lens 1 is outside the allowance range, an output signal is produced at the circuit 16 to control a motor driving signal processing circuit 17. |
