Data sheet: Carl Zeiss Jena Flektogon 65 mm f/2.8 (Pentacon 6)

Pekka Buttler, 11/2025

Specifications

The table below summarizes the lens’ key specifications (measurements based on pictured lens):

Brand:	Carl Zeiss Jena	Lens name	Flektogon 2,8/65
Focal length(s)1	65 mm	Angle-of-view2	64 ° (on medium format)
Maximum Aperture	f/2.8	In Production	1956–≈1970 (for Pentacon Six)
Lens mounts	Pentacon 6	Subfamily (if applicable)	––
Length3	75,3 mm (from flange) 89,3 mm (max. length)	Diameter4	90,0 mm
Filter ring diameter	86 mm	Weight	457 grams
Lens element count	6	Lens group count	5
Aperture blades (S/R/C)5	8 S	Focus throw	300 °
Minimum focusing distance (measured)	74,8 cm	Maximum magnification (measured)	1:8.8
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Automatic	Aperture click stops 6	2.8•4•5.6•8•11•16•22

Further notes:
• The 65 mm f/2.8 Flektogon was originally designed as early as 1950. This made it Carl Zeiss Jena’s second retrofocus wideangle design (after the 35mm f/2.8 for 35 mm film) and the first⁷ retrofocus wide-angle for medium format.
• After its initial development and prototypes, the lens did not have an auspicious start as the systems that the lens was initially developed for went out of production. The design was therefore shelved until further notice.
• The 1956 launch of the Praktisix (later: Pentacon Six) system finally gave the 65/2.8 Flektogon a role to play and the availability of a bright wide-angle lens gave the Praktisix system a lot of early impetus.
• The design is – quite clearly – an early retrofocus design, built for a system that stresses such designs severely and the lens is known to suffer in the corner areas. There were several attempts to improve on the design, using more elaborate glass mixtures, but none of these were brought into production, likely in part due to challenges in sourcing sufficient amounts of elaborate glass.
• A partial reason for why the 65 mm Flektogon was never updated and was discontinued entirely, was the 1960/1966 (1^st/2^nd version) introduction of the even wider Carl Zeiss Jena 50 mm f/4 Flektogon [data sheet]. Not only was the 50 mm more wide, it was both cheaper to manufacture and offered at least equivalent image quality.
• All in all, only ≈ 8550 copies were made during the entire production life of the lens.

Versions

During the ≈14 years of serial production, there was only ever the one optical variant of the 65 mm Flektogon.

However those 14 years of production coincided with a period of cosmetic design changes leading to a number of cosmetic variants. Based on study of images of lenses, the following variants have been identified [change to previous always in bold]:
• V 1a – Serial# Range⁸: 4890430–6396428
– fluted front barrel: faux leather
– focusing ring: faux leather;
– distance scale: silver with black and red text;
– DOF scale: silver with black text;
– aperture ring: silver with red text.
• V 1b – Serial# Range: 6403016–7200405 [as pictured above]
– fluted front barrel: faux leather
– focusing ring: faux leather;
– distance scale: silver with black and red text;
– DOF scale: black with white text;
– aperture ring: silver with red text.
• V 2 – Serial# Range: 6797014–7280953
– fluted front barrel: faux leather
– focusing ring: rubber diamonds,
– distance scale: black with white and red text;
– DOF scale: black with white text;
– aperture ring: silver with red text.
• V 3 – Serial# Range: 7280883–8414608
– fluted front barrel: plain black
– focus ring: zebra
– distance scale: black with white and red text;
– DOF scale: black with white text;
– aperture ring: zebra

As can be noted from the above, there seems to be some minor overlap in the evidenced serial number ranges.

History of Carl Zeiss Jena

There are few names in camera optics more illustrious than that of Carl Zeiss. The company was founded in the German town of Jena in 1846 by Carl Zeiß (hence: ‘Carl Zeiss Jena‘). During 1846–1945 there are few major developments in lens optics that the company was not involved in. Names that are even today well-known in optics – such as Planar (1896), Tessar (1902), Sonnar (1929), and Biotar (1939) (as well as many names that only optics-buffs know) – were the product of Zeiss’ first century of technological innovation.

After the Second World War Germany was divided into a Soviet zone (subsequently: East Germany) and the west-allied zones (subsequently: West Germany). While the Zeiss works resided in Jena (optics and glasses) and Dresden (cameras), which were in the Soviet sector, a contingent of Zeiss managers decided to move west and ended up setiting up shop in the small town of Oberkochen in the American sector under the name of Opton Optische Werke Oberkochen GmbH. As the relations between the former allied deteriorated and the split into East and West Germany became all the more real, the Oberkochen works changed their name first to Zeiss-Opton and later to Carl Zeiss.

What ensued was a lengthy international trademark dispute with both Zeiss’ (Jena and Oberkochen) laying claim to the name ‘Carl Zeiss’. The resulting stalemate – emblematic of the Cold War in its entirety – resulted in that Carl Zeiss Opton was allowed to use the name Carl Zeiss in the West, but had to use the Opton brand in the East bloc, whereas Carl Zeiss Jena was the only real Carl Zeiss as far as the east bloc was concerned, but could – mostly – not use the Carl Zeiss -name for exports to the West⁹. The fact remains however, that – starting in 1946 from a shared base – Jena and Oberkochen developed as two independent companies for more than 40 years. During the entire Cold War period, VEB Carl Zeiss Jena was seen by the country’s leadership both as a paragon of the East German technology industry and a showcase of the socialist/communist system as well as a major source of exports (and hence, western currencies). Within the centrally directed economy’s hierarchy, Carl Zeiss Jena therefore had a more prestigious role than other East German optics manufacturers (prominently Meyer-Optik Görlitz and, later, Pentacon), meaning that Carl Zeiss Jena received privileged access to tools and materiel (including the first computer in East Germany) and that its products were always considered the premium alternative.

After German reunification also Zeiss East and Zeiss West were united again, and have since again been at the undoubtable forefront of lens development. Even though it was manufactured after reunification, this lens sample harkens to the time of the cold-war and the East/West split.

History of the Flektogon designs

Carl Zeiss Jena was a central player in the development of a class of lenses today known as retro focus lenses (a.k.a. reversed tele focus) – a key approach to allowing the manufacture of wide-angle SLR lenses. While the jury is out on whether Angenieux (France) or Carl Zeiss Jena actually was the first company to bring the concept into production, it is evident that Carl Zeiss Jena was both genuinely innovative and prolific in this niche.

The ‘family name’ of Carl Zeiss Jena’s retro focus wide-angle lenses was ‘Flektogon’ (Carl Zeiss West called its corresponding family ‘Distagon’). The Flektogon family contained lenses with focal lengths of 20, 25 and 35 mm (for 135 film) and 50 and 65 mm (for 6×6 medium format).

Adapting

The Pentacon 6 mount offers a wide range of alternatives for adapting.

To use this lens natively, you will need a Pentacon 6 mount film body. In practical terms this means either a Praktisix or Pentacon Six medium format film camera or a Kiev 60/6C medium format film camera. While neither of these families of bodies were manufactured in their millions, they remain readily available, and even serviceable.

Thanks to the generous image circle Pentacon 6 lenses offer, and thanks to the copious flange focal distance (74,1 mm) of the Pentacon 6 system, this lens can be adapted to every full frame (and smaller) SLR, dSLR and mirrorless camera assuming a suitable adapter can be found or manufactured. Moreover, Pentacon 6 lenses are so uncomplicated that a simple ‘dumb adapter’ will do the job perfectly.

Thanks to the generous image circle, Pentacon 6 lenses have also long been a strong candidate to be used on smaller formats (full frame and smaller) in conjunction with tilt/shift adapters. Alternatively, one can choose to daisy-chain adapters (e.g. Pentacon 6->Canon EF; Canon EF –> mirrorless) which not only broadens the range of available adapters, but also allows using speed boosters for those photographers that use smaller than full-frame sensors.

Finally, regarding larger than full frame, there are also options. Digital medium format is perfectly usable (assuming adapter availability) and many 6×4,5 film formats are likewise theoretical possibilities, but gaining functional adapters may necessitate some DIY.

Footnotes

1. Focal length is (unless stated otherwise) given in absolute terms, and not in Full-frame equivalent. For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’. ↩︎
2. Picture angle is given in degrees (based on manufacturers’ specs) and concerns the diagonal picture angle. Rule of thumb:
   > 90 ° ==> Ultra-wide-angle
   70–90 ° ==> Wide-angle
   50–70 ° ==> Moderate wide-angle
   40–50 ° ==> ‘Standard’ or ‘normal’ lens
   20–40 ° ==> Short tele lens
   10-20 ° ==> Tele lens
   5-10 ° ==> Long tele lens
   < 5 ° ==> Ultra-tele lens ↩︎
3. Length is given from the mount flange to the front of lens at infinity. ↩︎
4. Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
5. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
6. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click.  ↩︎
7. Please note: While I am here expressing myself cautiously, saying the 65/2.8 Flektogon was Carl Zeiss Jena’s first retrofocus wide-angle for medium format, it is quite possible that it was the first (bar none) retrofocus wide-angle for medium format by any manufacturer. ↩︎
8. Serial number ranges reported are based on samples seen in the wild. Actual serial number ranges can be a bit wider. If you have lenses outside of these ranges to report, feel free to be in touch. ↩︎
9. Online one can find many lengthy and heated disputes stating that only Jena/Oberkochen is the true Carl Zeiss. While many of these discussions are riddled with misconceptions and a poor grasp of facts and timings, they largely also tend to be tainted by ideologies. Those discussions that focus on claims of one or the other Zeiss not really having rights to using designs developed at pre-war Zeiss are especially ludicrous because after the war practically the entire patent catalogue of pre-war German patents was given freely to everyone (the allied saw this as a form of reparations), hence also kickstarting the Japanese optics industry’s ascendancy (the Japanese optics companies were the most avid users of German optics patents). ↩︎