Roof Prism Binocular Design

A roof prism also called a dach prism or dachkanten prism from the german.

Roof prism binocular design.

Dachkante lit roof edge is a reflective optical prism containing a section where two faces meet at a 90 angle. Porro prism binoculars are not obsolete however. Better porro prisms binoculars are made from a high density glass bak 4. These two 90 faces resemble the roof of a building giving this prism type its name.

Due to the path of light passage porro prism binoculars have bulkier wider design than roof prism binocular. Built to last in a harsh environment a roof prism binoculars central portion that connects the 2 tubes is either an open bridge or closed bridge design. The hinge between the two oculars is small presenting a structure like a letter h. The open bridge design has a focus mechanism close to the eyepiece with the stabilizing section towards the objectives while the closed bridge design has an enclosed focus mechanism.

Most roof prism binoculars use either the abbe koenig prism named after ernst karl abbe and albert koenig and patented by carl zeiss in 1905 or the schmidt pechan prism invented in 1899 designs to erect the image. Dollar for dollar a porro prism design will give better performance for the money especially in medium or low priced binoculars. According to wikipedia a monocular scope is a modified. Have a sleek and compact design.

Now there are a few variations of the roof prism design. Monocular scopes are unique small scale telescopes that have a variety of uses. The path of the light is straight thus giving it a more slim design. Today roof prisms dominate the top end birding binocular market.

Essentially they all maintain the same basic function to keep light waves entering and exiting the binocular in a straight line. This is why roof prism binoculars have an aligned eyepiece to objective lens construction. Binoculars using roof prisms may have appeared as early as the 1870s in a design by achille victor emile daubresse.