Optisches System zur Focussierung,bei dem Glasfaser verwendet wird

摘要

In an optical focusing system as in a finder optical system of a reflex camera or in an optical focusing system wherein an image on the focusing screen disposed on the focal plane is observed from the back of said screen whereby the focusing condition of the image forming optical system can be detected, the present invention relates to a device for optical focusing, utilizing a glass fiber focusing plate as a focusing screen, which is characterized in that said focusing screen is provided with an incident end face of an optical fiber plate composed of many optical fibers secured with one another in a parallel array. In order to observe through the light ray passing through the circumferential portion of the lens of the image-forming optical system, which comes into said incident end face, it is possible to observe at a position away from the optical axis of said image-forming optical system, on the back of said optical fiber plate.