PURPOSE: To obtain a device which permits the movement of an eyepiece relatively to the home position for the purpose of photographing simply by mounting a photographing device to the body of the eyepiece part and returns the eyepiece part again to the original diopter adjusting state when the photographing device is removed from the eyepiece part.

CONSTITUTION: When a photographing device 3 is mounted to the body 2 of an eyepiece part, the overhanging part 19 of the device 3 pushes in a push pin 13, forcing the end part 13a of the pin 13 to contact with the end part 7a on the eyepiece side of a moving member 7. When the part 19 advances further and contacts the end part 2e of the body 2, the member 7 is pushed in by the pin 13 to the position where the spacing between an eyepiece 8 and the end face of the bundle 5 attains the distance necessary for photographing. This movement corresponds to the movement of the position of the eyepiece 8 relatively to the position where the light emitted from the end face of the optical fiber bundle forms its image on the image plane position of the device 3.