Pentamirror

Image:SLR Pentamirror.png

A pentamirror is an optical device used in the viewfinder systems of various single-lens reflex cameras instead of the pentaprism. It is used to reverse again the laterally reversed image coming from the reflex mirror.Mike Stensvold. The Complete Idiot's Guide to Photography Like a Pro, 2002, [https://books.google.com/books?id=cXy-yzb_nqgC&pg=PA26&dq=pentamirror&lr=&hl=it page 26].

Instead of the solid block of glass of the prism in pentaprism system, here 3 mirrors are used to perform the same task. This is cheaper and lighter, but generally produces a viewfinder image of lower quality and brightness.David D. Busch. Digital Photography All-in-One Desk Reference for Dummies, 2006, [https://books.google.com/books?id=-XENqZmgWm0C&pg=PA106&dq=pentamirror&lr=&hl=it page 106].

This optical device is often (more precisely) referred to as roof pentamirror because of the roof-like ridge.Paul R. Yoder. Opto-Mechanical Systems Design, 2005, [https://books.google.com/books?id=ukkZuvSSeUQC&pg=PA435&dq=%22roof+pentamirror%22&lr=&hl=it page 435].