Roof Prism Binocular Design

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

Roof prism binocular design.

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. Better porro prisms binoculars are made from a high density glass bak 4. The hinge between the two oculars is small presenting a structure like a letter h. Binoculars using roof prisms may have appeared as early as the 1870s in a design by achille victor emile daubresse.

Reflection from the two 90 faces returns an image that is flipped laterally across the axis where the faces meet. Due to the path of light passage porro prism binoculars have bulkier wider design than roof prism binocular. Dollar for dollar a porro prism design will give better performance for the money especially in medium or low priced binoculars. Today roof prisms dominate the top end birding binocular market.

According to wikipedia a monocular scope is a modified. Essentially they all maintain the same basic function to keep light waves entering and exiting the binocular in a straight line. Porro prism binoculars are not obsolete however. 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.

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. Like binoculars the roof prism design in the spotting scopes results in a more streamlined shape but the porro prism design offers greater depth perception and generally offers a wider field of view. These two 90 faces resemble the roof of a building giving this prism type its name. Monocular scopes are unique small scale telescopes that have a variety of uses.

This is why roof prism binoculars have an aligned eyepiece to objective lens construction. Now there are a few variations of the roof prism design. Have a sleek and compact design.