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

Flektogon 35mm f/2.8

Carl Zeiss Jena · M42 + Exakta · 1950

our own finding

Also known as: Carl Zeiss Jena Flektogon 35mm f/2.8 · Carl Zeiss Jena Flektogon 2.8/35 · Carl Zeiss Jena Flektogon 2,8/35 · Carl Zeiss Jena DDR Flektogon 35mm f2.8 · Zeiss Jena Flektogon 35mm f2.8 · Zeiss Jena Flektogon 2.8/35 · Jena Flektogon 35mm f2.8 · CZJ Flektogon 35mm f2.8 · CZJ Flektogon 2.8/35 · Flektogon 35mm f/2.8 · Flektogon 35mm 2.8 · Flektogon 35mm 1:2.8 · Flektogon 35 f2.8 · Flektogon 35 2.8 · Flektogon 2.8/35 · Flektogon 2,8/35 · Flektogon 2.8 35mm · Flektogon f2.8 35mm · Flektogon 1:2,8 f=35mm · Flektogon35mm F2.8 · Flektogon/35ｍｍ/F2.8 · Flektogon 35mm f2.8 M42 · Flektogon 35mm f2.8 Exakta · Flektogon 35mm f2.8 Zebra · aus Jena Flektogon 35mm f2.8 · カールツァイス イエナ フレクトゴン 35mm F2.8 · フレクトゴン 35mm F2.8 · フレクトゴン 35/2.8

Variants & identification

Variant Mount Years Serial ranges Production
First version, seven elements (1950) · Seven elements: the Biometar 2,8/35 base with its rearmost lens split into a cemented pair, behind the negative front meniscus M42 or Exakta (the mount of the 1950 lots is not recorded) 1950 3,419,976 and 3,419,983, from the same lot About 250: 50 in July 1950, listed by Thiele as 'Flektogon 3,5 cm', and 200 in November 1950 (Kröger)
M42 preset, silver (1950s, six elements) M42 — 5,889,787 (M42, preset, 49 mm filter) —
M42 automatic, 1960 calculation: studded black, then zebra M42 — 9,122,152 (zebra, on a Praktica LTL2) —
Exakta, semi-automatic, and preset (1950s to 1960) Exakta — — —
Exakta automatic (ASB, from September 1960) Exakta 1960 — —
Exakta, black cross-knurled, single-coated (to December 1985) Exakta — 10,245,242
2054 (four-digit number) 		—
Praktina, semi-automatic (from February 1954) Praktina (bayonet) 1954 — —
Praktina automatic (ASB, from June 1956) Praktina (bayonet) 1956 5,892,065 —
  1. Specifications differ by version, so this entry gives no family-wide closest focus, blade count, smallest aperture, size or weight. The 1950s preset scales in Kröger's photographs end at f/16; the Praktina ASB and the 1960s lenses go to f/22. The 1960s lenses focus to 0.18 m from the film plane, the earlier ones less close. JAPB's zebra M42 has 5 straight blades and measures 49.3 × 65.8 mm and 230 g. The Wolfen museum gives 61 × 72 mm and 245 g for its lens no. 3603 (note ⁹). The diagonal angle is 62° in the 1951 Zeiss brochure and 63° in JAPB. Richard Haw says early lenses differ in blade count, without giving numbers.
  2. The real focal length is close to 37 mm, not 35. Jena's function test of 9 September 1953 measured almost 37 mm, and Kröger's own ray trace of the 1955 data gives about 36.7 mm with a back focus of just over 37 mm. Without the front meniscus the Biometar base would have a back focus of only 21.5 mm.
  3. One page covers every calculation, on Kröger's account that they are reworkings of one design. He counts fifteen surviving data sheets, and his table of calculations runs from experiment V39 (25 May and 16 July 1948) through the series calculation 550602 of 13 August 1949 (seven elements, about 250 made), V113 of 13 December 1951 (the first six-element form, one sample only), V118/550602A of 8 February 1952 (lanthanum crown SK22 in two lenses, FK5 front meniscus; over 11,000 from September 1953 to February 1957), V187 and the series sheet 550602B (BK3, later BK7, in the front lens to save cost; about 44,000 from October 1956 to early 1963) and V269A of 23 September 1960 (one version for the SLRs and the Werra, from January 1963 to December 1985), with a last data sheet of 1 June 1966. The 1955 dates differ within Kröger's page: his text gives V187 a completion date of 6 September 1955, while his table dates the V187 sheets 17 January and 1 February 1955 and gives 6 September 1955 to 550602B. JAPB's summary, recalculations in 1953, 1955 and 1960, is an approximation of this.
  4. The date of the first calculation is given two ways: 13 August 1949 by Kröger, from the surviving data sheet, and 19 August 1949 on Pancolar's diagram on Wikimedia Commons. Both give about 250 lenses of that version.
  5. Kröger contradicts himself on the semi-automatic M42 lens. He writes that Jena supplied the Flektogon with the semi-automatic spring diaphragm apparently only for the Praktina FX and the Exakta, 'nie jedoch für M42'. On the same page he gives 348 Mark for the semi-automatic lens 'für M42 oder Exakta', almost the price of a Contax F body, 'mit der diese Springblende ausgenutzt werden konnte'. No semi-automatic M42 Flektogon is entered as a variant here.
  6. DDR prices from Kröger's compilation of price lists: preset 280 Mark to May 1960 and 216 Mark from June 1960; semi-automatic 348 and 245 Mark; Praktina IIA automatic 396 Mark (1959); Werra version 223 and 183 Mark; M42 automatic pressure diaphragm 280 Mark (1970); a Pentacon Super version 289 Mark (1970). For comparison the same lists give the Contax F body at 462 Mark in 1957, 445 in 1959 and 337 in 1960. None of the sources cited gives a 1950 launch price or a US price.
  7. Not entered as variants: the Werra lens and the Pentacon Super lens. Jena calculated a separate Werra version on 12 March 1956 (V214, drawing 550602C) with the same optics but a rear lens about 2 mm smaller and a front lens about 2 mm larger, to fit the Werra's leaf shutter; 11,000 were made in two lots in summer and autumn 1958, for the Werra III and IV. From 1963 one version served both (Kröger). The 1970 price list names a Pentacon Super version, for which no example is cited here.
  8. Kröger says the shortened names Jena used in the trademark dispute with Oberkochen ('Jena T', 'Jena S', 'Jena B') were not needed for postwar names such as Flektogon. The maker's name could still change: the photograph of a zebra Exakta lens sold on Yahoo! Auctions in 2026 shows 'aus JENA' on the front ring in place of 'Carl Zeiss Jena'.
  9. The Industrie- und Filmmuseum Wolfen records a Flektogon 2,8/35 numbered 3603, in a black leather case, with a guarantee card dated 29 August 1984 and a price tag of 301.10 Mark, as a preset lens for the Praktina with a bayonet mount, 6 elements in 5 groups, E49, 0.18 m (0.36 m in the catalogue), 61 × 72 mm and 245 g. A lens sold in 1984 would on Kröger's account be the late Exakta version, and a late black Exakta lens offered in 2026 also has a four-digit number (2054), so the record's Praktina mount and preset diaphragm are doubtful and it is not used as a marker.
  10. ⁰ The Soviet Mir-1 is a copy of the Flektogon from an earlier stage of its development, without the lanthanum crowns, and is honestly engraved 37 mm (Kröger). It is a different lens and is kept off this page.
How to tell them apart (expand)
  • Six elements in five groups on every series version from 1953; only the roughly 250 lenses of 1950 have seven
  • One design across four mounts (M42, Exakta, Praktina and the Werra) and four decades: the barrel, mount and diaphragm say which version a lens is, the number only roughly when it was made
  • Not the Flektogon 2,4/35, made from August 1975 as probably Jena's first multicoated series lens and usually marked MC (Kröger); even the last 2,8/35 lenses are single-coated

First version, seven elements (1950):

  • Engraved 'Carl Zeiss Jena Nr. 3419983 Flektogon 1:2,8 f=35mm' with a red T on the lens Kröger shows; the lens in the February 1951 Zeiss brochure reads 'Flektogon 1:2,8 f=35mm' the same way, while his 1953 lens reads 'Flektogon 2,8/35'
  • Preset diaphragm already on the 1950 lots: a knurled preset ring at the front, silver barrel, black front ring, depth-of-field scale to 16
  • Numbers around 3,419,9xx, inside Carl Zeiss Jena's 1949–52 block of 3,200,000–3,470,000 on camera-wiki's table

M42 preset, silver (1950s, six elements):

  • Two rings at the front: a knurled preset ring and the aperture ring behind it; silver aluminium barrel with scalloped focusing grips and a black rear
  • Front ring engraved 'Flektogon 2,8/35' after a small logo, with 'Carl Zeiss Jena' and the number (Kröger's photographs of 1953 and later lenses)
  • Kröger's 1953 lens, from the first lot of the 1952 calculation (he does not give its mount), has its preset scale to f/16 and a distance scale in feet and metres
  • No filter thread on the first lot of September 1953, mount not stated, which Jena meant for slip-on filters because a test of 5 September 1953 found that a screw-in filter darkened the corners beyond a 30 mm image circle; later Jena supplied screw-in 'W' filters that did not cut the angle of view (Kröger). The thread is 49 mm on the lens below and on JAPB's zebra
  • Kleinanzeigen, September 2026: M42 no. 5,889,787 with working preset ('Vorwahlblende'), aluminium, 49 mm filter, offered as made about 1959
  • No external marker is published that separates the 1952 optics (V118) from the cheaper 1955 optics (V187) that replaced them in October 1956

M42 automatic, 1960 calculation: studded black, then zebra:

  • Pin-operated automatic diaphragm with a small stop-down lever for depth-of-field preview; JAPB calls its zebra lens automatic-only, so on an adapter the pin must be held in for the iris to close
  • Extra-steep helicoid to 0.18 m from the film plane, the last mark on the distance scale in Kröger's photographs; at full extension f/4 is the widest aperture that can be set, a built-in correction for the extension (Kröger)
  • Kröger dates a black barrel with a studded plastic focusing grip to the early and mid 1960s; the plastic often came loose so that the ring spun freely, and turned brittle and cracked. The zebra barrel followed and was made for about ten years
  • JAPB's zebra M42: 6 elements in 5 groups, 5 straight blades, f/2.8–22 with half-stop clicks, 49 mm filter, 49.3 mm long, 65.8 mm across, 230 g, 320° focus throw, 1:2.8 at closest focus

Exakta, semi-automatic, and preset (1950s to 1960):

  • Exakta bayonet. Exakta and Praktina lenses can look much like M42 lenses from the front, so check the rear
  • Semi-automatic (SB) version: cocking the lever on the barrel opens the iris fully, and on release it springs to the preset stop (Kröger). Kröger's Exakta SB lens, silver with a single knurled ring at the front, also carries a release arm with its own plunger on the side, while the Praktina SB lens, which the camera controls from inside the body, has none
  • Preset form: Kröger says the 1950 lots, offered above all for the Exakta Varex, already had the preset diaphragm, and the price lists give a preset lens without naming its mount, but no photographed preset Exakta lens is cited here

Exakta automatic (ASB, from September 1960):

  • Release arm with a plunger on the side of the lens, as on the semi-automatic lens, but no cocking lever: the iris reopens by itself after the exposure
  • Kröger's example has a black and chrome barrel with a vulcanite-covered focusing ring, aperture scale to f/22 and a distance scale in feet and metres

Exakta, black cross-knurled, single-coated (to December 1985):

  • All-black barrel with a cross-knurled focusing ring, distance scale to 0.18 m and an Exakta release arm
  • Single-coated, although the multicoated Flektogon 2,4/35 was already in production (Kröger)
  • Exakta mount only. Kröger's example is numbered 10,245,242 and engraved 'Carl Zeiss Jena'; a lens offered on Kleinanzeigen in October 2026 has the same barrel and release arm but reads 'Carl Zeiss Jena DDR' with the four-digit number 2054

Praktina, semi-automatic (from February 1954):

  • Praktina bayonet with a small cocking lever on the barrel and no external release arm: the camera trips the iris from inside the body (Kröger)
  • Kröger calls the semi-automatic and the automatic Praktina versions incompatible with each other, so check which one a Praktina outfit needs

Praktina automatic (ASB, from June 1956):

  • Praktina bayonet, no cocking lever: the fully automatic spring diaphragm (ASB) for the Praktina IIA
  • Kröger's example, no. 5,892,065: chrome and black barrel with a vulcanite-covered focusing ring, aperture scale to f/22, distance scale in feet and metres

Serial-range notes

3,419,976 to 10,245,242 (examples, 1950–1985)
THE RULE. Carl Zeiss Jena numbered every lens it made in one running sequence, so a Flektogon is dated from the company's block table, not from a list for this lens. Camera-wiki's postwar Jena table: 3,200,000–3,470,000 for 1949–52, 3,470,000–4,000,000 for 1952–55, 4,000,000–5,000,000 for 1955–58, 5,000,000–6,000,000 for 1958–61, then a million every three years to 9,000,000 in 1970 and 10,000,000 in 1975. The number does not tell the optics apart: Kröger dates the change from the 1952 to the 1955 calculation to October 1956, in the middle of a production order.
3,419,976 and 3,419,983
The first lot of 1950. Kröger takes 3,419,976 to be the fair sample, though he cannot say whether it was shown at the spring or the autumn fair of 1950; 3,419,983, photographed by Alun Thomas, has the preset diaphragm.
3,743,853; 3,746,195 and 3,746,196
Jena's own test lenses. Kröger reproduces a test report comparing sample 3,743,853 of September 1952, built to the 1952 calculation, with samples 3,746,195 and 3,746,196 built to the cheaper 1955 calculation; the older lens resolved clearly more.
5,889,787; 5,892,065; 7,110,542; 9,122,152; 10,245,242
Numbers on lenses in the sources cited: 5,889,787, an M42 preset offered on Kleinanzeigen in September 2026 as made about 1959; 5,892,065, Kröger's Praktina ASB; 7,110,542, an M42 lens offered on Kleinanzeigen in April 2025 at 143 €, in the 1964–67 block; 9,122,152, Kröger's zebra on a Praktica LTL2, in the 1970–75 block; 10,245,242, his late black Exakta lens.
2054; 3603
Four-digit numbers, outside the running sequence: 2054 on a black cross-knurled Exakta lens engraved 'Carl Zeiss Jena DDR', offered on Kleinanzeigen in October 2026, and 3603 on the Wolfen museum's lens with a guarantee card of August 1984 (note ⁹). Both fit the late lenses; no source cited here explains when or why the short numbers were used.

Specifications

Formula
Retrofocus: a Biometar-type base lens behind a large negative front meniscus
Construction
6 elements / 5 groups
Aperture range
f/2.8
Filter
49 mm
Years manufactured
1950–1985
Country
East Germany (Carl Zeiss Jena)
Coating
Single-coated. A red T is engraved on the 1950 lens, the lens in the 1951 brochure and the silver preset lens on Kröger's Pentacon FB, though not on every 1950s lens he shows. The surviving data sheet of the 1955 version records a colour-corrected coating that pulls the warm cast of the lanthanum glasses towards neutral (Kröger). Never multicoated: Kröger notes that even the last lenses of 1985 are single-coated
Material
Aluminium barrel: bright silver in the 1950s, then a vulcanite-covered focusing ring, black with a studded grip in the early to mid 1960s, zebra for about ten years, black cross-knurled at the end (Kröger)
Original price
280 Mark (DDR) with preset diaphragm and 348 Mark with semi-automatic spring diaphragm, both as listed to May 1960; 216 and 245 Mark from June 1960; 396 Mark for the Praktina IIA automatic version (1959); 280 Mark for the M42 automatic version (1970) (Kröger's compilation of DDR price lists). None of the sources cited gives a 1950 launch price or a US price

What reviewers say

Optical Ratings

Aggregated from the reviews above — follow the links for the full picture.

Vignetting
heavy wide open
Optical formula — Retrofocus: a Biometar-type base lens behind a large negative front meniscus
Six elements in five groups, drawn from Figure 1 of US patent 2,793,565 (Harry Zöllner and Rudolf Solisch, filed 26 April 1955, granted 28 May 1957). Kröger notes that the patents name different glasses from those used in production
Six elements in five groups, drawn from Figure 1 of US patent 2,793,565 (Harry Zöllner and Rudolf Solisch, filed 26 April 1955, granted 28 May 1957). Kröger notes that the patents name different glasses from those used in production — Mliu92, via Wikimedia Commons, CC BY-SA 4.0

History

The Flektogon 35mm f/2.8 is Carl Zeiss Jena’s answer to the problem every 35mm reflex had with short lenses: the swinging mirror needs room behind the lens, and a conventional 35mm wide-angle sits far closer to the film. Before the war Jena’s shortest lens for the 35mm reflex was a Tessar 4,5/4 cm of January 1938, and Bertele’s Biogon 2,8/3,5 cm for the Contax rangefinder had a back focus of only about 7.5 mm, which Marco Kröger, who works from original Jena data sheets and memos preserved by Günther Benedix, reckons would have had to grow almost fivefold for a reflex. He describes the solution: the Biometar 2,8/35 calculated for the Contax rangefinder on 12 November 1947 was used as a base lens and a large negative meniscus was set far in front of it, at an air gap that Kröger, citing the patent, puts at almost 73 percent of the focal length. The focal length barely changes and the back focus grows to just over 37 mm. Harry Zöllner, head of the photographic department, started the project; Rudolf Solisch did most of the computing, by hand with mechanical calculators and seven-figure tables. The first data sheet for an “Objektiv mit langer Schnittweite 1:2,8 f = 3,5 cm” is dated 25 May 1948 and the series calculation was completed on 13 August 1949, which on Kröger’s reading makes it probably the first retrofocus wide-angle for the 35mm SLR. Angénieux was working on the same idea in France, and camera-wiki says the Retrofocus reached the market first. The lens was shown at the Leipzig spring fair in March 1950, where the trade report named it a lens above all for the Contax S, the Exakta Varex and the Praktica.

Few lenses were reworked as often. Kröger counts fifteen surviving data sheets. The seven-element original reached only about 250 lenses, in lots of July and November 1950, apparently all with a preset diaphragm. A Jena memo of May 1953 compares the next calculation with “dem Retrofocus”, Angénieux’s R1, and Kröger concludes that the French lens had overtaken the first Flektogon and that Jena stopped production until it had a better one. A calculation of December 1951 used the new lanthanum crown glass to drop one element, leaving six in five groups, and the calculation of 8 February 1952 refined it with lanthanum crown in two lenses and a fluor crown front meniscus. In the 1953 test it matched the Angénieux in the centre and beat it at the edges. It went into assembly in September 1953, and over 11,000 were made by February 1957. The first lot had no filter thread at all, because a screw-in filter darkened the corners of a lens that already vignetted heavily. A calculation of 1955 replaced the fluor crown front lens with ordinary borosilicate crown, which Kröger takes for a cost saving: Jena’s own test found the older sample sharper, but the new version took over in October 1956 and about 44,000 followed by early 1963. A separate Werra version of 1956 differed only in the diameters of its front and rear lenses. The calculation of 23 September 1960 merged the two and was built from January 1963 to December 1985. Over 196,000 were made in all. Patents followed late, in the DDR and West Germany in 1953 and in the US and Britain in 1955, which Kröger suggests is why the lens is seldom counted as a contemporary of the Angénieux. Some time after the patents Solisch left for the West: on 10 November 1956 he filed a patent for ISCO in Göttingen for what became the Westrogon 4/24, another retrofocus built on a Biometar. The Soviet Mir-1 copies an earlier stage of the design and is engraved, more honestly, 37 mm; Jena’s own measurements put the Flektogon close to that figure.

The optics changed less than the barrels. The 1950s lens is bright silver aluminium with a preset ring in front of the aperture ring. Jena supplied a semi-automatic spring diaphragm, cocked by a lever on the lens, for the Exakta and, from February 1954, for the Praktina, where the camera trips it from inside. The Praktina lens became fully automatic in June 1956 for the Praktina IIA, the Exakta lens only in September 1960. Kröger’s Praktina and Exakta automatic lenses have a vulcanite-covered focusing ring. In the early 1960s came a black barrel with a studded plastic grip and an extra-steep helicoid that focuses to 0.18 m from the film and limits the aperture to f/4 at full extension. The zebra barrel followed and ran for about ten years. In M42 the automatic lens has a pin that the camera presses, plus a stop-down lever. The last lenses, black with a cross-knurled ring, were made only in Exakta mount and never multicoated, although its successor, the Flektogon 2,4/35, had been in production since 1975. Kröger notes that a postwar name like Flektogon did not need the shortened forms, such as ‘Jena T’ and ‘Jena B’, that Jena used for its older names in the dispute with Oberkochen; the maker’s name could still change, and a zebra Exakta lens sold in Japan in 2026 reads ‘aus JENA’ in place of ‘Carl Zeiss Jena’.

The 1950 fair report names the Contax S first among the cameras the Flektogon was meant for, though Kröger writes that it was offered above all for the Exakta Varex. On the Dresden line it was the fast and expensive wide-angle; Kröger’s price lists give Jena’s Tessar 4,5/40 at 184 Mark in 1956 and Meyer’s Primagon 4,5/35 at 165 Mark in 1957. The Contax D, E and Pentacon take the preset M42 lens, since they have no diaphragm release of their own. The Contax F of 1956 and its FB, FM and FBM successors have a release in the mirror box. Whether Jena ever sold the semi-automatic Flektogon in M42 is unclear: Kröger writes on one page that it went only to the Praktina and the Exakta, “nie jedoch für M42”, and on the same page prices the semi-automatic lens “für M42 oder Exakta” at 348 Mark, almost the cost of a Contax F body. The preset lens cost 280 Mark until the price cut of June 1960 brought it down to 216.

When buying, check the mount first: Exakta and Praktina Flektogons can look like M42 lenses from the front, and the Exakta semi-automatic and automatic lenses carry an external release arm. Early M42 lenses have a conical rim behind the thread that jams the Praktica L bodies of 1969 and later, and Kröger says it has to come off for the Praktica B’s M42 adapter and some digital adapters too; many have been filed down or notched. The studded grip of the early 1960s often spins loose or cracks. An automatic M42 lens needs its pin held in on an adapter for the iris to close. Richard Haw lists the common faults as oily or corroded aperture blades, heavy helicoids, fog-like marks on the rear element, rear glass scratched by cameras with large mirrors, and bent front rings; he warns that the coatings are delicate and come off easily when fungus is cleaned. He gives prices from just over $100 to just under $300 for an excellent copy and advises against paying even $50 for one with scratched rear glass or a bent front ring. In 2025–2026 German private sellers asked about 99–110 € for zebra M42 lenses and 100–165 € for silver ones. Haw, and Jena’s own filter tests of 1953, both describe heavy vignetting wide open, and Haw gets his best results at f/5.6. On flare they differ: Haw found his lens surprisingly resistant, while Kröger cites a Jena addendum of September 1953 on the reflections of this type of lens and blames the big front element. A hood is worth having either way.

Left open by the sources consulted here: the mount of the 1950 lots; whether a preset Exakta Flektogon was made and what it looks like; whether a semi-automatic M42 Flektogon existed; how to tell the 1952 optics from the 1955 optics by number or marking; when the M42 lens first had the automatic diaphragm and when M42 production ended; the blade counts of the early versions; how the four-digit numbers on late lenses were assigned; and any launch price outside the DDR.

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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

More sample photos elsewhere

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Sample photo wanted — shot with a Flektogon 35mm f/2.8? We'd love to feature it (with credit).

Live listings

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Listings updated 2026-10-30. Links go to the shop or marketplace that carries the item.

Related: Tessar 40mm f/4.5 (Jena, 1938 design)

Sources (16)

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.