| 摘要 |
PURPOSE:To prevent malfunction of an AF mechanism based on decreased light amount, by making a lens driving system in an AF mechanism with diaphragming operation inoperative, in a TTL automatic focus (AF) mechanism for a single-lens camera. CONSTITUTION:Light flux transmitted to a lens 1 having a diaphragm 2 is made incident to a photodetector 3, the output is operated at an operation circuit 4, and a control circuit 5 controls a focusing drive motor 8 and a focusing state display circuit 7 accordingly. On such an AF mechanism, if diaphragming is made through the operation of a diaphragm button 6', the distance measurement can be disable depending on the F value, a signal circuit 6 is provided, the drive motor is stopped immediately before diaphragming to keep the lens at the state prior to diaphragming and a diaphragming state is displayed in a display circuit, allowing to prevent misoperation and mistake of photographing. |
