Automatic focusing binocular

Abstract

An automatic focusing binocular is herein disclosed in which a light, signifying the inability of the automatic focusing system to operate due to the lack of available light contrast, is provided within the user's field of vision as he looks through the binocular. This is accomplished by the use of a focus detection module. When the reflected images from apertures proximate to the objective lens coincide in the module, a focusing signal is produced which terminates the motion of the eyepieces at a point corresponding to the distance of the object from the objective lens. When these coinciding images do not have sufficient light contrast for the module to produce the focus signal, a detection signal is produced which illuminates a warning light. A rod-shaped prism is disposed such that light from the light source condenses at the forward focal point of the eyepiece. In the case where the eyepiece assembly is moved in its entirety, as opposed to the movement of only one of its eyepiece lenses, a diopter adjusting ring is provided and appropriate apertures cut, such that the adjusting ring may be turned while maintaining the prism position at the focal point of the eyepiece assembly.