Schmidt–Pechan prism
A Schmidt–Pechan prism is a type of optical prism used to rotate an image by 180°. These prisms are commonly used in binoculars as an image erecting system. The Schmidt–Pechan prism makes use of a roof prism section (from the German: Dachkante, lit. 'roof edge'). Binoculars designs using Schmidt–Pechan prisms can be constructed more compactly than ones using Porro or Uppendahl roof and Abbe–Koenig roof prisms.
A Schmidt–Pechan prism is sometimes called a Pechan prism pair.