Glass Bodies a variant-level encyclopedia of vintage lenses and cameras by iwillpat

Biogon 3.5cm f/2.8

Carl Zeiss · Contax RF · 1936 · Biogon — a symmetrical wide-angle, not a retrofocus

Also known as: Zeiss Biogon 35mm f/2.8 · Biogon 3.5cm f2.8

Variants & identification

Variant Mount Years Serial ranges Production
Carl Zeiss Jena (large rear element) Contax RF 1936–1945 — No figure published
Oberkochen / Zeiss Opton (shorter rear element) Contax RF 1951–1961 — No figure published
  1. Production totals from Pacific Rim Camera, which the variant table does not carry: about 2,500 of the 1946 Carl Zeiss Jena aluminium-barrel version, about 8,000 Zeiss-Opton lenses from 1950, and about 1,800 of the final version engraved Carl Zeiss from 1953.
  2. Pacific Rim Camera counts five versions where the variant table here counts two, and inserts a Carl Zeiss Jena version of 1946 — an aluminium body with the rear element slightly reduced in diameter and a ring around it to protect the glass — between the prewar lens and the Oberkochen one. That East German lens has no entry in the variant table above.
  3. The two published Jena tables agree closely across this lens's prewar life but differ at the edges: camera-wiki gives 1940 as 2,652,000–2,678,000 where Craig Camera leaves 1940 blank, and camera-wiki opens 1942 at 2,800,000 where Craig Camera opens it at 2,799,599.
  4. The compatibility warning above is now carried by three sources that do not depend on one another, and they describe the same mechanism from three directions. Camera-wiki states the consequence, that the rear element would touch the shutter. Pacific Rim Camera states the remedy, that the lens was reformulated to clear the thicker curtains of the IIa and IIIa. Mike Eckman, summarising the Zeiss Historica newsletters, states the cause from the camera's side: the Stuttgart Contax IIa and IIIa of 1950 and 1951 were built to Hubert Nerwin's wartime drawings "featuring improved shutter designs with aluminum rather than brass slats, a simpler rangefinder with shorter rangefinder base".
  5. Pacific Rim Camera's East German version of 1946, which the variant table above does not carry, is no longer a lone report. Ghisetti lists the 3,5cm Biogon among the prewar designs that Carl Zeiss Jena reissued after the war, beside the 8,5cm and 13,5cm Sonnars, and notes that postwar Jena barrels were not all aluminium as is usually said — several lots used brass because they were prewar warehouse stock reassembled.
  6. The element count changes between the versions, which is why the table above carries a group count and no element count. Pacific Rim Camera states both: the first version was six elements in four groups, and the reformulation seven elements in four groups. Camera-wiki gives no count at all. Four groups is common to both and is recorded; a single family-level element count would have to be wrong about one version or the other, so none is given.
  7. Two starting dates for the postwar lens. The variant table runs it from 1951; Pacific Rim Camera dates the Zeiss-Opton version to 1950, and Ghisetti has Opton-marked production running from 1948 at Coburg. The 1951 in the table should be read as approximate — no source consulted gives a month, and the three accounts differ by up to three years at the front end.
How to tell them apart (expand)
  • Symmetrical construction: the rear element sits close to the film, which is how it achieves its correction
  • The prewar and postwar lenses look similar from the front and differ entirely at the back

Carl Zeiss Jena (large rear element):

  • A large rear element that protrudes deep into the body
  • Six elements in four groups, on Pacific Rim Camera's count; the earliest are chrome-finished and uncoated, with no red T on the beauty ring

Oberkochen / Zeiss Opton (shorter rear element):

  • A shorter rear element; mounts on all Contax types
  • Pacific Rim Camera gives the reformulation as seven elements in four groups

Serial-range notes

the whole number
How to date one. Carl Zeiss drew every photographic lens number from a single running sequence covering all models at once, so a Zeiss lens is dated by reading its number off a serial/year table rather than by counting within its own type — there is no per-model list of the Leitz kind. camera-wiki's table, taken from Wilkinson and Glanfield's A Lens Collector's Vade Mecum, runs the Jena sequence from 137,418 in 1912 to about 2,900,000 in 1942; Craig Camera publishes a near-identical list.
1674882–2900000
The Jena year boundaries that bracket this lens's prewar production, from camera-wiki: 1936 = 1,674,882–1,942,806; 1937 = 1,930,150–2,219,775; 1938 = 2,267,991–2,527,984; 1939 = 2,527,999–2,651,211; 1940 = 2,652,000–2,678,000; 1941 = 2,678,326–2,790,346; 1942 = 2,800,000–2,900,000. The table stops there, so a wartime Biogon of 1943–45 cannot be dated from the running number alone.
above 3000000 (Jena) against 10000–3000000 (Oberkochen)
After 1945 the sequence forks, and the same figure means two different decades. Carl Zeiss Jena in the East carried the old numbers on from 3,000,000 — 3,000,000–3,200,000 = 1945–49, 3,200,000–3,470,000 = 1949–52, 3,470,000–4,000,000 = 1952–55, 4,000,000–5,000,000 = 1955–58, 5,000,000–6,000,000 = 1958–61. Carl Zeiss Oberkochen in the West began a fresh sequence at 10,000 in 1946 — 10,000–500,000 = 1946–51, 500,000–1,100,000 = 1951–53, 1,100,000–2,600,000 = 1953–59, 2,600,000–3,000,000 = 1959–61. A six-figure number on a Zeiss-Opton or Oberkochen barrel is therefore early 1950s, not 1920s.
1100000–2600000, on an Oberkochen barrel
Where a postwar Biogon marked Zeiss-Opton or Carl Zeiss should fall. The Oberkochen band of 1,100,000–2,600,000 is dated 1953–1959 and the band below it, 500,000–1,100,000, 1951–1953, which brackets a lens the variant table runs from 1951 to 1961; numbers over 2,600,000 fall in the 1959–1961 band.
any number near a year boundary
Blocks were allotted to production in sequence, but batches were not always finished in block order, so the published year ranges overlap — 1935 runs to 1,752,303 while 1936 opens at 1,674,882 — and a serial places a lens within a year or two rather than to a month. Pentacon Six sets out the mechanism and points to Hartmut Thiele's Fabrikationsbuch Photooptik, a transcription of the factory books, for batch-level dates.
a letter followed by five digits
Not a lens number at all. That is the Zeiss Ikon CAMERA sequence, inherited from ICA in 1909, which rolls to the next letter at 99,999, reached Z in 1936 and restarted at A. A Contax body number and a Zeiss lens number belong to separate schemes and must never be read against the same table.
a red T on a prewar barrel
Not by itself proof that a Biogon is postwar. Coating was normally reserved for military optics, usually in Leica screw mount, but Ghisetti records that some ordinary Contax-bayonet lenses built in the years right up against the war were given the red T as well, and names the 3,5cm Biogon among them alongside the 5cm f/1,5 and f/2 and the 8,5cm and 13,5cm Sonnars. A coated Jena Biogon still has to be identified by its rear element, not by the T.
no serial list has been published for this lens
No source consulted publishes serial ranges or batch blocks for the 3.5cm Biogon in any of its forms. Pacific Rim Camera, which prints batch numbers for the 50mm, 85mm and 135mm Contax lenses, gives production totals for the Biogon but no numbers. A copy is dated from the general Zeiss tables above and identified by version from the barrel and the rear element, not from a list.

Specifications

Formula
Biogon — a symmetrical wide-angle, not a retrofocus
Designed by
Ludwig Bertele — optical design
Construction
4 groups
Aperture range
f/2.8
Min. focus
0.9 m
Filter
40.5 mm
Years manufactured
1936–1961
Country
Germany

What reviewers say

History

The Biogon is Bertele’s wide-angle, and it is built the way wide-angles were built before retrofocus designs existed: symmetrically, with the rear element sitting very close to the film. That geometry is what gives it its correction, and it is also what makes it a hazard.

The prewar Jena Biogon must not be mounted on a Contax IIa or IIIa. When Zeiss Ikon redesigned the camera in Stuttgart after the war it used thicker aluminium shutter slats in place of the prewar brass, and the lens’s rear element reaches far enough back to touch them. The lens is damaged, not the camera. Zeiss’s answer in 1951 was a new Biogon with a shorter rear element that fits everything — and the two look much the same from the front.

This is the same story that runs through the Leica system with the Super-Angulons and the early 28mm Elmarits, arriving fifteen years earlier and with sharper consequences. A symmetrical wide-angle wants the space behind it, and every camera improvement that puts something in that space breaks it.

The design went to the Soviet Union with the rest and became the Jupiter-12, which inherited both the optics and the protruding rear element.

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This history is AI-written, from the sources listed at the foot of the page. Where the record is silent it says so rather than filling the gap — but no human wrote these sentences.

Example photos

Sample photo wanted — shot with a Biogon 3.5cm f/2.8? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $350 across 8 fixed-price listings on 2026-09-11 (middle half $310–$420). Tracked since 2026-09-06, 2 days: unchanged from $350.

By day
DateMedianMiddle halfListings
2026-09-11$350$310–$4208
2026-09-06$350$310–$4208

Asking prices from the listings scanned, not sales; junk-flagged rows and auction lots excluded; other currencies are not converted.

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Listings updated 2026-09-11. Links go to the shop or marketplace that carries the item.

Related: Biogon 21mm f/4.5 · Jupiter-12 35mm f/2.8 · Tessar 2.8cm f/8

Sources (10)

Every page here is assembled from public sources, and the gaps are real ones. If you own this lens, know a serial number I'm missing, or can see where I have it wrong, tell me — corrections, serials and sample photos are all worth having.