Roof Prism Types

The common roof prism binos use either the s p or a k configurations.

Roof prism types.

Roof prism binoculars vs porro prism binoculars a comparison roof prism binoculars. Porro prism vs roof prism. The prisms are usually coated to increase reflectivity and to keep the light waves in the right direction. The simplest roof prism is the amici roof prism with other common roof prism designs being the abbe koenig prism the schmidt pechan prism and probably the best known being the roof pentaprism pictured here.

If you see a pair of straight tube binoculars there s a good chance you re looking at a set equipped with roof prisms. Both types of prism have advantages and disadvantages. Essentially they all maintain the same basic function to keep light waves entering and exiting the binocular in a straight line. They re more compact and streamlined lighter weight and much easier to carry around than the bulky porro style binos.

It uses an amici roof followed by a rhomb. These are the more modern of the two types of binoculars. Zeiss has famously made a number of a k binos over the years though most roof binos use s p. This is why roof prism binoculars have an aligned eyepiece to objective lens construction.

The only current bino use of the amici roof prism i can think of is the apm apo 90 bt. Binoculars with roof prisms are straighter and more compact.