Roof Prism Design

These two 90 faces resemble the roof of a building giving this prism type its name.

Roof prism design.

While light loss and transmission rates are huge factors in optical quality there are many other factors that allows a roof prism bino for possible. A roof prism also called a dach prism or dachkanten prism from the german. The porro prism design was simpler and more light efficient and its images showed better contrast. Nevertheless the roof prism design s appeal was so great that manufacturers went all out to perfect it.

Differences in binoculars build and design. 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. There are two prisms and these meet at a 90 angle with the shape looking similar to the roof of a house. Roof prisms enable slim binoculars.

Roof prisms are the newer option. The design of the prisms means they work together to correct blurred images and let you see your target clearly. 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. Today roof prisms dominate the top end birding binocular market.

Reflection from the two 90 faces returns an image that is flipped laterally across the axis where the faces meet. While the roof prism design is inferior to the porro prism in its basic form roof prisms often have higher quality glass and stricter engineering controls versus cheap porro prism binos. Dachkante lit roof edge is a reflective optical prism containing a section where two faces meet at a 90 angle.