What are the prisms in binoculars?
The prism system of a binocular consists of a set of special glass prisms which reduce the physical size needed to accomodate the focal length of the object lenses. The prism system also turns what would be an upside-down image right-side-up. There are two types of prism systems, roof and porro. 1. Roof Prism System: In roof prism binoculars the prisms overlap closely, allowing the objective lenses to line up directly with the eyepiece. This results in a slim, stream-lined shape in which the lenses and prisms are aligned in a straight line. 2. Porro Prism System: In porro prism binoculars the objective lens is offset from the eyepiece. This prism system provides greater depth perception and generally a wider field of view. Many standard design binoculars use this type of prism system.
