| 摘要 |
PURPOSE:To detect easily a focusing state, by using a focusing screen where a liquid crystal is interposed between a pair of transparent electrodes and making this liquid crystal transparent when the voltage of a focusing detection means is applied. CONSTITUTION:A transmission hole 8 is provided in the center of a mirror 2, and the reflection light is received through a small mirror 9 by a photodetector 10. The reflection light from the samll mirror 9 is received by the photodetector 10, and the input from the photodetector 10 is inputted to an operating circuit 12; and this input value reaches a set value, it is outputted to a voltage applying circuit 14, and thus, a prescribed voltage is applied across electrodes 17a and 17b of a focusing screen 3, and a liquid crystal 18 between electrodes 17a and 17b becomes transparent. Consequently, when the operating circuit 12 issues the output simultaneously with focusing of the image on a mat face 7 of the focusing screen 3, the photographer operates a photographic lens 1 while observing an eyepiece 6 of the finder to detect the focusing state when the focusing screen 3 becomes transparent. |
