| 摘要 |
PURPOSE:To extend a focus detecting area and to execute the precise focusing by providing a leader system optical path for enlarging and projecting the image of a microfilm and a dedicated optical path for detecting the focus and forming an image on a focus detection element by reducing an enlarged image. CONSTITUTION:A lens and mirror position control circuit 31 sets an optical path folding mirror 11 in the position of the optical path 3 for detecting the focus. When a film detection circuit 34 confirms the loading of the film F, a lamp 4 irradiates the film F and the light is incident on a photodetector 13 and a focus detection circuit 30 judges a focusing state and sends a signal to the circuit 31. The circuit 31 moves a projecting lens 10 to the position where image-formation can be expected on an image formation scheduled surface 15 through a lens moving mechanism 36. By switching the mirror 11 to the leader system optical path 2, the image focused on a screen 15 can be obtained. Thus, the focus detecting area is extended and the precise focusing can be executed.
|
