{{Short description|Optical device used in a viewfinder}} thumb|240px|A roof pentamirror contains 3 mirrors. A '''pentamirror''' is an optical device used in the viewfinder systems of various single-lens reflex cameras instead of a pentaprism. It is used to reverse again the laterally reversed image coming from the reflex mirror.<ref>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].</ref>
Instead of the solid block of glass of the prism in a 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.<ref>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].</ref>
This optical device is often (more precisely) referred to as ''roof pentamirror'' because of the roof-like ridge.<ref>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].</ref>
==Notes== <references/>
==External links== *[https://luminous-landscape.com/understanding-viewfinders/ Understanding Viewfinders] *[https://archive.today/20130104130831/http://picasaweb.google.com/duduzhong/InfoCanonEOS400DDigitalRebelXTi%235038444020269509538 Photo of a Canon 400d pentamirror]
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Category:Mirrors Category:Photography equipment