| 摘要 |
PURPOSE:To improve focusing precision by composing a movable mirror of a main body that has a transmissive part, allowing part of incident light to transmit it, away from an optical axis and a reflective surface for transmission prevention on the front surface of the main body. CONSTITUTION:Light having passed through taking lens 2 is reflected on reflective surface 4b by movable mirror 4 and, at the same time, divided into light viewed through finder 9 and light led to detector 8 via focusing mirror 5 after transmitting part of the transmissive part of main body 4a by way of slit 4c of reflective surface 4b. Part of the light passing through slit 4c of reflective surface 4b is reflected on the back surface of movable mirror 4, but it is almost reflected by reflective surface 4b on the front surface of mirror 4, so that light transmitted from the front surface will nearly be eliminated. Slit 4c and the optical axis are positioned away from each other and light when the aperture is fully opened or close to it can be photodetected. The quantity of photodetected light of photodetector 8 can be increased, so that the focusing precision can be improved. |
