Porro vs Roof prism Binoculars

[sour01]

Is the quality of roof prism binos far superior to porro prism binos? For example: Bushnell Legend 10X42 run over $300 while Bushnell Legend 10X50's (porro) run half that. What is the major difference?

[sour01]

Is this too basic a question---or is it that no one has any thoughts on the subject?

[liquidorange]

for what its worth i dont know the technical reasons but from what ive read that unless the roof prism binos are phase corrected you are better off with the cheaper porro prisms.

[Stalker6]

Porro prizms transferr more light that roof prizms. The differance in price of the two binoculars that you state is more closely related to the differance in quality of glass and coatings. As the quality of coatings reduces Reflection and allows for greater light transmission.

Porro prisms are used in wide body binoculars. The light transmission for porro prism is about 90%. This is the prism only , not overall binocular performance. As the prism is only part of the system.

Roof prisms are used in the more compact straight barreled binoculars. Pechan roof prizms use a mirrored surface(reflection). This mirrored surface reduces the light transmisson to about 85%. The Pechan prizm is found in all roof prizm binoculars except Zeiss.

Zeiss uses an Abbe-Koening roof prizm which does not use a mirrored surface and provides a straighter optical path in the prizm. Abbe-Koening prizm give you the compactness of regular roof prisms and the 90% light transmission of porro prizms.