Carl Zeiss Opton Sonnar 50mm f/2

Carl Zeiss Opton Sonnar 50mm f/2

The Opton Sonnar 50mm f/2 marks the postwar, West German chapter of one of the most influential rangefinder designs of the twentieth century. After the division of Germany split the Zeiss organization, the Oberkochen works relaunched the f/2 Sonnar around 1950 under the Zeiss-Opton name, supplying a coated normal lens for the Contax rangefinder system [1][2]. The optical concept traces back to Ludwig Bertele, whose six-element, three-group Sonnar derived from the fast Ernostar and deliberately limited the number of internal air-glass surfaces to preserve contrast, a major advantage in the era before anti-reflection coatings [1][2].

Mechanically the Opton version is a rigid lens with a chrome-over-brass barrel, distinct from the earlier prewar and collapsible Jena Sonnars [2]. It keeps the classic six-element, three-group Sonnar arrangement of a single element paired with two cemented groups, focuses down to about 0.91 m, and weighs roughly 140 g in its compact silver mount [1]. The lens uses the Contax rangefinder bayonet rather than a Leica mount, so on a Contax body the camera's helical drives focus; as a bare lens it is not independently rangefinder coupled in the Leica sense.

The postwar Oberkochen lenses were among the first in the line to be fully coated, and early examples carry the famous red "T" marking to indicate the coating; the "T" was later dropped once coating had become standard across the range [1][2]. These lenses also adopted a double-diaphragm iris, and the blade count is variously described, with some sources citing the 22-blade double diaphragm and others an 11-blade arrangement [2][3]. Identification rests on the Zeiss-Opton name on the front ring: as West German Zeiss prevailed in the trademark disputes, later lenses dropped "Opton" and were engraved simply "Carl Zeiss," while the East German factory lost the right to use the Zeiss name on exports [1][2].

Optical qualities

Rendering Documented rendering character for the f/2 Sonnar centers on its coated, contrast-favoring layout. The three-group design with few air-glass surfaces was specifically intended to hold contrast, and the postwar T coating further reduced internal reflections and light loss compared with the uncoated prewar lenses [1][2]. Detailed, standardized test data for the Opton variant specifically is limited, so claims about fine sharpness, bokeh, distortion, or vignetting beyond this general behavior are not well established in the consulted sources.

History

Development and Launch The Sonnar name comes from the German word for sun, and the 50mm Sonnar was introduced by Carl Zeiss Jena from 1932 as a lens for the Contax rangefinder, a complete redesign away from an earlier Tessar-type lens of the same name [1]. Bertele's f/2 version used six elements in three groups; an even faster f/1.5 sibling shared the family [1][2]. After the Second World War the Zeiss organization was split between East and West Germany, and the western branch at Oberkochen relaunched the lens as Zeiss-Opton around 1950 with a coated optical design and a chrome-over-brass body [1][2].

Production Evolution The f/2 Sonnar was reformulated repeatedly across its long life to exploit new optical glasses, passing through black-and-nickel, black-nickel-and-chrome, collapsible, and rigid chrome forms before the war [1][2]. T coating began to appear on Jena lenses in the late 1930s and became widespread by the early 1940s [2]. The Oberkochen Zeiss-Opton lenses were rigid, chrome-over-brass, initially carrying the red T and using a double-diaphragm iris; later the T marking was discontinued and, following the trademark rulings, the engraving changed from Zeiss-Opton to Carl Zeiss [1][2].

Special editions No major factory special editions specific to the Opton f/2 are widely documented in the consulted sources. Adjacent rarities belong to the wider Sonnar family rather than the Opton variant, including wartime alloy lenses with military markings and a very small ivory-finished batch made for an experimental Contax that never reached series production [2].

Collector Notes The clearest identification point is the front-ring engraving: "Zeiss-Opton" denotes the early West German Oberkochen lenses, while a plain "Carl Zeiss" engraving indicates the later post-trademark production [1][2]. Buyers should confirm the Contax rangefinder mount and check the coating, as the red T denotes the early coated examples [1][2]. Reported blade counts differ between sources, with the double-diaphragm iris variously described as 22 blades or 11 blades, so it is worth inspecting the actual lens rather than relying on a single published figure [2][3]. As with any lens of this age, examine the glass for haze, cleaning marks, and coating wear before purchase.

Sources

• [1] Camera-wiki.org. Sonnar 50mm. https://camera-wiki.org/wiki/Sonnar_50mm
• [2] Pacific Rim Camera. 50/2 Zeiss Sonnar for Contax. https://www.pacificrimcamera.com/pp/zicontax50f2.htm
• [3] Kamerastore. Carl Zeiss 50mm f2 Sonnar T Opton - Lens*. https://kamerastore.com/en-us/products/carl-zeiss-50mm-f2-sonnar-t-opton-contax-kiev