Roof Prism Binocular Design

Today roof prisms dominate the top end birding binocular market.

Roof prism binocular design.

This is why roof prism binoculars have an aligned eyepiece to objective lens construction. 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. 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. Due to the path of light passage porro prism binoculars have bulkier wider design than roof prism binocular.

Reflection from the two 90 faces returns an image that is flipped laterally across the axis where the faces meet. Dollar for dollar a porro prism design will give better performance for the money especially in medium or low priced binoculars. 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 path of the light is straight thus giving it a more slim design.

Essentially they all maintain the same basic function to keep light waves entering and exiting the binocular in a straight line. Now there are a few variations of the roof prism design. 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. Have a sleek and compact design.

Porro prism binoculars are not obsolete however. A roof prism also called a dach prism or dachkanten prism from the german. Monocular scopes are unique small scale telescopes that have a variety of uses. According to wikipedia a monocular scope is a modified.

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. Dachkante lit roof edge is a reflective optical prism containing a section where two faces meet at a 90 angle.