Editing Binoculars (section)

=====Roof=====
[[File:Schmidt-Pechan prism.svg|thumb|upright|Schmidt–Pechan "roof" prism design]]
[[File:Abbe-König prism.svg|thumb|Abbe–Koenig "roof" prism design|left]]

''[[Roof prism]] binoculars'' may have appeared as early as the 1870s in a design by Achille Victor Emile Daubresse.<ref name="google">{{cite web |url=http://groups.google.co.ke/group/sci.astro.amateur/tree/browse_frm/month/2002-08/5a0a50e6887feb69?rnum=71&_done=%2Fgroup%2Fsci.astro.amateur%2Fbrowse_frm%2Fmonth%2F2002-08%3F |title=groups.google.co.ke |access-date=2009-11-03 |archive-date=2010-07-30 |archive-url=https://web.archive.org/web/20100730175821/http://groups.google.co.ke/group/sci.astro.amateur/tree/browse_frm/month/2002-08/5a0a50e6887feb69?rnum=71&_done=%2Fgroup%2Fsci.astro.amateur%2Fbrowse_frm%2Fmonth%2F2002-08%3F |url-status=live }}</ref><ref name="PhotoDigital">{{Cite web |url=http://www.photodigital.net/lists/rec.photo.equipment.misc/4/0455.html |title=photodigital.net — rec.photo.equipment.misc Discussion: Achille Victor Emile Daubresse, forgotten prism inventor |access-date=2006-11-26 |archive-date=2010-07-31 |archive-url=https://web.archive.org/web/20100731095955/http://www.photodigital.net/lists/rec.photo.equipment.misc/4/0455.html |url-status=live }}</ref> In 1897 Moritz Hensoldt began marketing [[pentaprism]] based roof prism binoculars.<ref>{{cite conference |url=http://fp.optics.arizona.edu/antiques/History%20of%20Telescopes%20and%20Binoculars%20-%20SPIE.pdf |first1=John E. |last1=Greivenkamp |first2=David L. |last2=Steed |title=The History of Telescopes and Binoculars: An Engineering Perspective |book-title=Proc. SPIE 8129, Novel Optical Systems Design and Optimization XIV, 812902 |editor1=R. John Koshel |editor2=G. Groot Gregory |date=10 September 2011 |issn=0277-786X |doi=10.1117/12.904614 |s2cid=123495486 |archiveurl=https://web.archive.org/web/20141129083421/http://fp.optics.arizona.edu/antiques/History%20of%20Telescopes%20and%20Binoculars%20-%20SPIE.pdf |archivedate=2014-11-29 |url-status=live}}</ref>

Most roof prism binoculars use either the [[Schmidt–Pechan prism]] (invented in 1899) or the [[Abbe–Koenig prism]] (named after [[Ernst Karl Abbe]] and [[Albert König (optician)|Albert König]] and patented by Carl Zeiss in 1905) designs to erect the image and fold the optical path. They have objective lenses that are approximately in a line with the eyepieces.<ref name=sinnott />

Binoculars with roof prisms have been in use to a large extent since the second half of the 20th century. Roof prism designs result in objective lenses that are almost or totally in line with the eyepieces, creating an instrument that is narrower and more compact than Porro prisms and lighter. There is also a difference in image brightness. Porro prism and Abbe–Koenig roof-prism binoculars will inherently produce a brighter image than Schmidt–Pechan roof prism binoculars of the same magnification, objective size, and optical quality, because the Schmidt-Pechan roof-prism design employs mirror-coated surfaces that [[Schmidt–Pechan prism#Reflection losses|reduce light transmission]].

In roof prism designs, optically relevant prism angles must be correct within 2 [[arcsecond]]s ({{sfrac|1|1,800}} of 1 degree) to avoid seeing an obstructive double image. Maintaining such tight production tolerances for the alignment of their optical elements by laser or interference (collimation) at an affordable price point is challenging. To avoid the need for later re-collimation, the prisms are generally aligned at the factory and then permanently fixed to a metal plate.<ref name=hacks>{{cite book |url=https://books.google.com/books?id=piwP9HXtpvUC&q=%22porro+prism%22+binoculars+produce+brighter+image+than+%22roof+prism%22&pg=PA34 |title=Astronomy Hacks |pages=34 |date=2005-06-24 |access-date=2009-11-03 |isbn=9780596100605 |last1=Thompson |first1=Robert Bruce |last2=Thompson |first2=Barbara Fritchman |publisher="O'Reilly Media, Inc." |archive-date=2022-04-19 |archive-url=https://web.archive.org/web/20220419130538/https://books.google.com/books?id=piwP9HXtpvUC&q=%22porro+prism%22+binoculars+produce+brighter+image+than+%22roof+prism%22&pg=PA34 |url-status=live }}</ref> These complicating production requirements make high-quality roof prism binoculars more costly to produce than Porro prism binoculars of equivalent optical quality and until [[phase correction coating]]s were invented in 1988 Porro prism binoculars optically offered superior resolution and contrast to [[Roof prism#Phase correction|non-phase corrected roof prism]] binoculars.<ref name=sinnott>{{cite web |url=https://skyandtelescope.org/astronomy-resources/astronomy-questions-answers/why-do-the-best-roof-prism-binoculars-need-a-phase-correction-coating/ |title=Why do the best roof-prism binoculars need a phase-correction coating? |author=Roger W. Sinnott |date=July 24, 2006 |work=Sky and Telescope |access-date=2022-07-20 |archive-date=2022-06-04 |archive-url=https://web.archive.org/web/20220604133953/https://skyandtelescope.org/astronomy-resources/astronomy-questions-answers/why-do-the-best-roof-prism-binoculars-need-a-phase-correction-coating/ |url-status=live }}</ref><ref name=hacks /><ref>{{cite book |url=https://nimax-img.de/Produktdownloads/44543_3_Leseprobe.pdf |chapter=Binocular Optics and Mechanics |title=Binocular Astronomy |author=Stephen Tonkin |isbn=978-1-4614-7466-1 |date=2014 |publisher=Springer |access-date=2022-07-20 |archive-date=2022-08-18 |archive-url=https://web.archive.org/web/20220818165600/https://nimax-img.de/Produktdownloads/44543_3_Leseprobe.pdf |url-status=live }}</ref><ref>{{cite web |url=https://www.ronspomeroutdoors.com/blog/porro-prism-binocular-best-buy |title=Porro Prism Binocular a Best Buy |author=Ron Spomer |access-date=2022-07-20 |archive-date=2020-11-12 |archive-url=https://web.archive.org/web/20201112011914/https://www.ronspomeroutdoors.com/blog/porro-prism-binocular-best-buy/ |url-status=live }}</ref>

In the early 2020s, the commercial offering of Schmidt-Pechan designs exceeds the Abbe-Koenig design offerings and had become the dominant optical design compared to other prism-type designs.<ref>{{Cite web |url=https://www.optics-trade.eu/en/binoculars.html |title=Binoculars dealer offerings, showing Schmidt-Pechan designs exceed the Abbe-Koenig designs by more than 13 times in May 2022 |access-date=2022-05-24 |archive-date=2015-11-01 |archive-url=https://web.archive.org/web/20151101110203/http://www.optics-trade.eu/en/binoculars.html |url-status=live }}</ref><!--Binoculars dealer offerings, showing Schmidt-Pechan designs exceed the Abbe-Koenig designs by more than 13 times in May 2022-->

Alternative roof prism-based designs like the [[Uppendahl prism]] system composed of three prisms cemented together were and are commercially offered on a small scale.<ref>{{Cite web |url=https://www.flickr.com/photos/binocwpg/8103359604/in/album-72157632281149716/ |title=Image of a Uppendahl prism system used in Leitz Wetzlar, Trinovid 7×42B binoculars. The first Trinovid series featuring a Uppendahl prism system was made until 1990. |date=18 October 2012 |access-date=2022-07-21 |archive-date=2022-07-21 |archive-url=https://web.archive.org/web/20220721181629/https://www.flickr.com/photos/binocwpg/8103359604/in/album-72157632281149716/ |url-status=live }}</ref><!--Image of a Uppendahl prism system used in Leitz Wetzlar, Trinovid 7×42B binoculars. The first Trinovid series featuring a Uppendahl prism system was discontinued in 1990.--><ref name="auto">{{Cite web |url=https://www.houseofoutdoor.com/wp-content/uploads/2020/02/Leica-kijker-test-dd-29-febr-2020.pdf |title=PROPERTIES AND PERFORMANCE OF THE NEW LEICA TRINOVID 7X35B (=HERE NAMED RETROVID) COMPARED WITH OLDER LEITZ-LEICA TRINOVIDS AND WITH BINOCULARS FROM BECK, FOTON AND THE NEW KOWA 6,5X32. February 2020 by Dr. Gijs van Ginkel |access-date=2022-09-10 |archive-date=2022-11-15 |archive-url=https://web.archive.org/web/20221115202450/https://www.houseofoutdoor.com/wp-content/uploads/2020/02/Leica-kijker-test-dd-29-febr-2020.pdf |url-status=live }}</ref>