By the late 1800s, inventors introducing the Abbe-Koenig and Schmidt-Pechan prisms brought the roof prism to the binocular scene. These prisms made it possible to keep the objective lenses closely in line with the eyepieces. Since then, the roof prism has continued to grow in popularity for these reasons: Streamlined design is generally smaller than a comparable Porro prism. Straight barrel and compact design is able to tolerate rough treatment. Internal focus mechanism provides a high degree of structural integrity. Design is less susceptible to internal fogging and potential entry of dust or moisture. Top quality roof prism models do require precise tolerances during manufacturing because of their complex prism design --- one reason a roof prism may cost significantly more than a Porro prism of the same quality and configuration.
Safetyrich optical could fabricate the roof prism which roof angle tolerance within 3 second,if you have other request about the prism please send us your specification detail.