{{Infobox lens design | name =Topogon | scheme =Richter-Zeiss Topogon (1933).svg | year =1933 | author =Robert Richter | elements =4 | groups =4 | aperture =6.3 }} '''''Topogon''''' is a wide field (originally 100 degrees field of view), symmetrical photographic lens patented by Robert Richter in 1933 for Carl Zeiss AG.<ref name=US2031792>{{cite patent |inventor=Robert Richter |fdate=July 25, 1934 |gdate=February 25, 1936 |number=2031792 |country=US |title=Anastigmatic objective for photography and projection |assign=Carl Zeiss |url=https://patents.google.com/patent/US2031792A/ |pridate=July 26, 1933 |status=Patent}}</ref> As there are four meniscus elements in four groups, deployed symmetrically around the central aperture, it is considered a double Gauss lens variant.
==Design== According to Richter, the ''Topogon'' was developed from the Goerz ''Hypergon'' (1900),<ref name=US706650A>{{cite patent |url=https://patents.google.com/patent/US706650A/ |title=Astigmatically-corrected wide-angle objective |inventor=Carl Paul Goerz |assign=Carl Paul Goerz |pridate=5 November 1900 |gdate=12 August 1902 |number=706650 |country=US |status=Patent}}</ref> one of the first super-wide-angle lenses.<ref name=Richter-Topogon/> Richter credits the mathematician Emil von Höegh, who had designed the ''Dagor'' anastigmat (1892), with designing the ''Hypergon'' for Goerz. Although the ''Hypergon'' covered a wide angle of view (140°) and had good flatness of field and distortion characteristics, the maximum aperture was limited to {{f/}}22 to control longitudinal spherical aberration and chromatic aberration.<ref>{{Kingslake-lens-history |chapter=4}}</ref>{{rp|54–55}} A new computation of a "fast" ''Hypergon'' was made by limiting the angle of view to 90°, which allowed an increased maximum aperture of {{f/}}6.3.<ref name=Richter-Topogon/>
The ''Topogon'' was derived from the "fast" ''Hypergon'' by adding a second, symmetric set of strongly curved meniscus elements inside the larger spherical elements to correct longitudinal spherical aberration.<ref name=Richter-Topogon>{{cite journal |url=https://www.asprs.org/wp-content/uploads/pers/1956journal/dec/1956_dec_868-874.pdf |title=Development and Perfection of the Topogon Lens |author=Richter, Robert |date=December 1956 |journal=Photogrammetric Engineering & Remote Sensing |volume=XXII |number=5 |pages=868–874 |accessdate=9 November 2018}}</ref> The initial design patented by Richter was for a f=66mm {{f/}}6.3 lens covering 100°, although the patent also contains two other refinements to the basic design, including one that used parallel elements to minimize vignetting.<ref name=US2031792 /> As the name suggests, the ''Topogon'' was intended to be used for topographical surveys and photogrammetry.<ref name=Cavina/>
The Topogon was later developed into the ''Pleon'' fisheye lens (1938)<ref name=US2247068>{{cite patent |title=Anastigmatic photographic objective |invent1=Robert Richter |assign=Carl Zeiss |pridate=July 18, 1938 |fdate=July 7, 1939 |pubdate=June 24, 1941 |number=2247068 |country=US |status=Patent}}</ref> and ''Pleogon'' lens by Richter and Friedrich Koch in 1956.<ref name=DE1097710>{{cite patent |url=https://patents.google.com/patent/DE1097710B/ |title=Anastigmatisches lens |invent1=Dr Robert Richter |invent2=Friedrich Koch |assign=Carl Zeiss SMT GmbH |pridate=4 May 1956 |fdate=19 January 1961 |number=1097710 |country=DE |status=Patent}}</ref> The ''Pleon'' was used for aerial surveillance during World War II, and was equipped with a large negative meniscus cemented group ahead of the ''Topogon'' core as an early example of an inverted telephoto design; a special projector was required to display an undistorted image.<ref>{{cite report |url=https://archive.org/details/jresv40n2p93/ |title=Lenses of Extremely Wide Angle for Airplane Mapping |number=RP1858 |author1=Gardner, Irvine C. |author2=Washer, Francis E. |date=February 1948 |publisher=National Bureau of Standards, U.S. Department of Commerce |access-date=24 March 2023}}</ref> The Pleogon, used for photogrammetry, used a cemented achromatic lens just ahead of the central stop and added two meniscus groups on either side to maintain lens symmetry.<ref name=Richter-Topogon />
Topogon lenses have been produced with maximum apertures ranging from f/3.5 to f/15 in various focal lengths.<ref name=Cavina>{{cite web |url=http://www.marcocavina.com/articoli_fotografici/Hypergon_Topogon_Biogon_Hologon/00_pag.htm |title=Hypergon - Topogon - Russar - Biogon - Aviogon - Hologon: La storia definitiva dei super-grandangolari simmetrici |trans-title=Hypergon - Topogon - Russar - Biogon - Aviogon - Hologon: The definitive history of the super-wide angle symmetric lenses |lang=it |author=Cavina, Marco |archive-url=https://web.archive.org/web/20101231080900/http://www.marcocavina.com/articoli_fotografici/Hypergon_Topogon_Biogon_Hologon/00_pag.htm |archive-date=December 31, 2010 |url-status= |accessdate=8 November 2018}}</ref>
<gallery heights=150px widths=200px caption="''Hypergon'', ''Topogon'', and Zeiss development"> File:Goerz Hypergon (1900).svg|Goerz ''Hypergon'' by von Höegh (1900), from US 706,650<ref name=US706650A/> File:Richter-Zeiss Topogon (1933).svg|Zeiss ''Topogon'' by Richter (1933), from US 2,031,792<ref name=US2031792/> File:Richter-Zeiss Pleon (1938).svg|Zeiss ''Pleon'' by Richter (1938), from US 2,247,068<ref name=US2247068/> File:Richter & Koch - Zeiss Pleogon (1956).svg|Zeiss ''Pleogon'' by Richter & Koch (1956), from DE 1,097,710<ref name=DE1097710/> </gallery>
==Influence== [[File:0563 Mamiya Universal 65mm f6.3 lens with finder (9124210190).jpg|thumb|right|upright=1.2|''Topogon''-design lens and auxiliary viewfinder for the Mamiya Press line of cameras]] Goerz was merged into the Zeiss Ikon company in 1926.<ref>{{cite web |url=https://www.pacificrimcamera.com/pp/zeissikon.htm |title=Zeiss Ikon |website=Pacific Rim Camera, Photographica Pages |access-date=24 March 2023}}</ref> An independent branch of Goerz in America, which had been established in 1895, licensed the ''Topogon'' design to Bausch & Lomb, who produced it as the ''Metrogon'' for the United States, citing the same US patent as the ''Topogon''. The ''Metrogon'' was introduced in the early 1940s at the same cost "as a light automobile", limiting its market to aerial surveillance cameras for the United States Army Air Corps.<ref>{{cite magazine |url=https://books.google.com/books?id=9iYDAAAAMBAJ&pg=PA104 |title=Lens Doubles Area Covered by Aerial Camera, Saving Time in Air Corps Mapping |page=104 |date=September 1941 |magazine=Popular Science |volume=139 |number=3 |publisher=Popular Science Publishing Co., Inc.}}</ref> A later patent by Wilbur B. Rayton, assigned to Bausch & Lomb in 1943, separated one of the outer positive meniscus lenses into two air-spaced positive menisci,<ref name=US2325275A/> similar to an earlier patent issued in 1938 to Hasselkus & Richmond.<ref name=US2116264A/>
Although the main market for the ''Topogon'' similarly was aerial photography and mapping for military and government applications, a consumer version was produced for the pre-war Zeiss Ikon Contax 35mm rangefinder cameras and produced in small numbers as the ''Topogon'' 2.5 cm {{f/|4}}. Lenses using similar designs also were produced by Canon (25mm {{f/|3.5}}, 1956),<ref name=CanonMuseum-25>{{cite web |url=https://global.canon/en/c-museum/product/s35.html |title=CANON 25mm f/3.5 |date=December 1956 |website=Canon Camera Museum: S Lenses (19–35mm) |publisher=Canon Inc. |access-date=26 March 2023 |quote=A super wide angle lens with a diagonal angle of view 82°, developed based on Topogon (manufactured by Carl Zeiss, Germany. Angle of view: 100°. f/6.3). This lens has a unique optical system: a spherical lens element with a very high refraction index is used as the first lens element and a special optical glass lens element with the infinite radius of curvature is used as the rearmost lens element.}}</ref><ref>{{cite web |url=https://www.canonrangefinder.org/Canon_25mm.htm |title=Canon Rangefinder 25mm lenses |website=Canon Rangefinder |access-date=24 March 2023}}</ref> KMZ (''Oриoн-15''/''Orion-15'' 28mm {{f/|6}}, 1964),<ref>{{cite web |url=http://www.sovietcams.com/index71c4.html |title=Orion-15 |website=Soviet Cams |access-date=24 March 2023}}</ref> and Nikon (''W-NIKKOR·C'' 2.5cm {{f/|4}}, 1954)<ref>{{cite web |url=https://imaging.nikon.com/imaging/information/story/0029/index.html |title=W-NIKKOR·C 2.5cm F4 (No.29) |author=Sato, Haruo |website=NIKKOR - The Thousand and One Nights |publisher=Nikon Imaging |access-date=24 March 2023 |quote=The entire world gradually became caught in the vortex of World War II. Under the circumstances, the Topogon lens was highly valued for its low distortion and curvature of field, and was then saddled with heavy responsibility as an optical system for aerial photography and cartography. Optical designers in many countries began to devote all their energies to develop a distortion-free, wide-angle lens of the Topogon type. In those days, the lack of an accurate map of enemy territories meant certain defeat. At that time, Nippon Kogaku was also reportedly studying vigorously the Topogon-type lenses. After peace returned to the world, the efforts of the pioneers bore fruit in the world of the artistic culture of photography. Their efforts were incorporated also in the Nikkor 2.5cm f/4.}}</ref> for their rangefinder systems after World War II.<ref name=Cavina/> In addition, Mamiya released a lens with a similar design for the Mamiya Press camera system, the ''Mamiya–Sekor'' 65mm {{f/|6.3}}.<ref name=Cavina/><ref>{{cite web |url=https://photothinking.com/2021-07-03-mamiya-press-super-23-frustratingly-good/ |title=Mamiya Press Super 23 — Frustratingly Superb |date=July 4, 2021 |author=Panagopoulos, Theo |website=PhotoThinking |access-date=24 March 2023}}</ref><ref>{{cite web |url=https://www.pacificrimcamera.com/rl/02625/02625.pdf |title=Mamiya Press Super 23 / Universal Press: Compact multi-format cameras, lenses, and accessories |website=Pacific Rim Camera, Reference Library |date=February 1976 |publisher=Bell & Howell / Mamiya Company |access-date=26 March 2023}}</ref>
===Hybrid designs=== The front meniscus elements of the ''Topogon'' were paired with the rear half of a double Gauss by Albrecht Tronnier and released as the Voigtlander ''Ultragon'', a wide angle lens for large format cameras.<ref name=Croell>{{cite web |url=https://www.arnecroell.com/voigtlaender.pdf |title=Voigtländer Large Format Lenses from 1949-1972 |author=Cröll, Arne |date=August 10, 2020 |access-date=16 May 2023}}</ref>{{rp|16–17}}
As the opposite hybrid asymmetric design, the rear meniscus elements of the ''Topogon'', forming a Gauss lens, have been paired with the front elements from a ''Planar''-type double Gauss lens, resulting in the designs shared by the Schneider Kreuznach ''Xenotar'' (1952)<ref name=US2683398>{{cite patent |country=US |number=2683398 |inventor=Günther Klemt |invent2=Karl Heinrich Macher |title=Optical system with four air-spaced members |pridate=March 20, 1952 |fdate=March 20, 1953 |gdate=July 13, 1954 |status=Patent}}</ref><ref>{{cite web |url=https://www.nocsensei.com/camera/tecnica/marco-cavina/marcocavina/carl-zeiss-planar-80mm-128-per-rolleiflex-tlr/ |title=Carl Zeiss Planar 80mm 1:2,8 per Rolleiflex TLR |author=Cavina, Marco |lang=it |trans-title=Carl Zeiss Planar 80mm 1:2,8 for Rolleiflex TLR |website=NOC Sensei |access-date=24 March 2023}}</ref> and Zeiss ''Planar'' (1953)<ref name=US2724994>{{cite patent |country=US |number=2724994 |inventor=Günther Lange |title=Photographic objective comprising four meniscus shaped air spaced components |pridate=March 17, 1953 |fdate=March 10, 1954 |gdate=November 29, 1955 |status=Patent}}</ref> & ''Biometar'' (1959).<ref name=US2968221>{{cite patent |country=US |number=2968221A |inventor=Harry Zollner |assign=VEB Carl Zeiss Jena |title=Photographic five-element lenses of the modified Gauss type |fdate=March 17, 1959 |gdate=January 17, 1961 |status=Patent}}</ref> The ''Xenotar'' and ''Planar'' were fitted to Rolleiflex TLR cameras as an upgrade over ''Tessar''/''Xenar'' types,<ref>{{cite web |url=https://www.filmshooterscollective.com/analog-film-photography-blog/rolleiflex-buying-guide-1-11 |title=Rolleiflex buying guide |author=Allen, Colton |date=January 25, 2018 |website=Film Shooter Collective |access-date=26 March 2023 |quote=In general though, a Planar or Xenotar should perform better than a Tessar or Xenar, especially wide open. My experience with my 2.8C Planar and 3.5F Xenotar is that the 3.5 Xenotar is a sharper lens while the 2.8 Planar has better character. I strongly suspect that has more to do with the difference of the 3.5 vs 2.8 than Planar vs Xenotar.}}</ref> and the ''Biometar'' was the standard lens for the Pentacon Six (aka Praktisix / Exakta 66) SLRs, with a ''Xenotar'' available for the same camera.<ref>{{cite web |url=http://www.zachhorton.com/academia/the-pentacon-6-lens-hit-list/ |title=The Pentacon 6 Lens Hit List |author=Horton, Zach |website=Convergence |access-date=26 March 2023 |quote=This [Xenotar 80mm f/2.8 MF] was Schneider's entry as the best 6×6 lens in the world. It measures up. It blows away the Zeiss 80mm Planar f/2.8 made for the Hasselblad system, and that is considered the best of the best. It is sharp wide open, has mechanics to dream of (like all of the Exakta 66 lenses), and has a special character to its rendering that makes it more pleasing than any other medium format 80mm lens I’ve ever seen.}}</ref>
<gallery heights=150px widths=200px caption="''Topogon'' derivatives"> File:Hasselkus & Richmond US2116264A (Topogon-5, 1936).svg|''Topogon'' derivative by Hasselkus & Richmond (1936), from US 2,116,264<ref name=US2116264A>{{cite patent |country=US |number=2116264A |inventor=John William Hasselkus |invent2=George Arthur Richmond |title=Objective suitable for photographic purposes |pridate=June 9, 1936 |fdate=June 8, 1937 |gdate=May 3, 1938 |status=Patent}}</ref> File:Rayton US2325275A (Metrogon, 1942).svg|Bausch & Lomb ''Metrogon'' by Rayton (1942), from US 2,325,275<ref name=US2325275A>{{cite patent |country=US |number=2325275A |inventor=Wilbur B. Rayton |assign=Bausch & Lomb Optical Company |title=Photographic objective |pridate=February 12, 1942 |fdate=February 12, 1942 |gdate=July 27, 1943 |status=Patent}}</ref> File:Tronnier US2670659A (Ultragon, 1951).svg|Voigtländer ''Ultragon'' by Tronnier (1951), from US 2,670,659<ref>{{cite patent |country=US |status=Patent |number=2670659A |title=Modified gauss-type photographic objective formed of four components arranged in two groups |inventor=Albrecht W. Tronnier |assign=Voigtländer & Sohn AG |pridate=August 30, 1951 |fdate=July 29, 1952 |pubdate=March 3, 1954}}</ref> File:Klemt & Macher US2683398A (Xenotar, 1952).svg|Schneider ''Xenotar'' by Klemt & Macher (1952), from US 2,683,398<ref name=US2683398/> File:Lange US2724994A (Planar, 1953).svg|Zeiss ''Planar'' by Lange (1953), from US 2,724,994<ref name=US2724994/> File:Zöllner US2968221A (Biometar, 1959).svg|Zeiss ''Biometar'' by Zöllner (1959), from US 2,968,221<ref name=US2968221/> </gallery>
==References== {{reflist}}
== External links == *[http://www.marcocavina.com/articoli_fotografici/Hypergon_Topogon_Biogon_Hologon/00_pag.htm HYPERGON - TOPOGON - RUSSAR - BIOGON - AVIOGON - HOLOGON: LA STORIA DEFINITIVA DEI SUPER-GRANDANGOLARI SIMMETRICI]
Category:Photographic lenses Category:Zeiss lenses