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

Flektogon 50mm f/4

Carl Zeiss Jena · Pentacon Six · 1960

single source, unconfirmed our own finding

Also known as: Flektogon 4/50 · Flektogon 4/50mm · Flektogon 4/50 mm · Flektogon 1:4/50 · Flektogon 1:4/50mm · Flektogon 4,0/50 · Flektogon 50mm f/4 · Flektogon 50mm f4 · Flektogon 50mm 1:4 · Flektogon 50 mm f/4 · Flektogon 50/4 · Flektogon 4 50mm · Flektogon 50 · Flektogon 50mm · Carl Zeiss Jena Flektogon 4/50 · Carl Zeiss Jena Flektogon 50mm f/4 · CZJ Flektogon 50 · CZJ Flektogon 4/50 · Flektogon 50 Pentacon Six · Flektogon 50 P6 · Flektagon 50mm f4 · Флектогон 4/50 · Флектогон 50 · フレクトゴン 50mm F4

Variants & identification

Variant Mount Years Serial ranges Production
First calculation (V271 of 1958), thoriated front lens Praktisix / Pentacon Six breech-lock, automatic diaphragm 1960–1965 below 7,281,500 just under 4,000 to the end of 1965 (Kröger)
Recalculation of 27 May 1966, single-coated (zebra and other pre-MC finishes) Praktisix / Pentacon Six breech-lock, automatic diaphragm 1966 above 7,281,500 (seven-digit) —
MC Flektogon (multicoated, all black) Pentacon Six breech-lock, automatic diaphragm 1976–1990 — —
  1. Launch: Kröger dates the launch to the Leipzig spring fair of 1960, with the Flektogon 4/25, after the Tessar 80 and Flektogon 65 that came with the Praktisix. Zach Horton lists the Flektogon 50 in the 'complete original line' of the system without a date.
  2. Angle of view: 78° in pentaconsix.com's table; Kröger computes about 75° on the real 56 × 56 mm frame, from a true focal length of about 52.3 mm and a back focus of 64.5–64.6 mm, enough for the Praktisix mirror to swing up.
  3. Construction: no source gives an element and group count. Dietzsch (2002) described an afocal reversed-telescope attachment in front of a triplet base lens; Kröger, working from the original design data, finds the front pair and the lens behind it have about +100 mm focal length together, so they are not afocal, and reads the lens as an ordinary retrofocus: a base lens of about 48 mm focal length and 29 mm back focus with a −71 mm negative group set almost 40 mm in front of it.
  4. Weight: 480 g in pentaconsix.com's table and 620 g for 'an earlier version', which pentaconsix.com does not tie to a calculation. Length 87 mm, close focus 0.5 m and an M86 × 1 filter thread from the same table; close focus 0.5 m, 86 mm filter and f/22 as the smallest stop from mflenses.com's fact sheet.
  5. Production: just under 4,000 of the 1958 design to the end of 1965, over 75,000 of the 1966 design to the summer of 1990, at least about 80,000 in all (Kröger). These figures rest on Kröger alone; the single-source flag on this page is for them.
  6. Prices are DDR retail prices (EVP) from Kröger's compilation of price lists: 364 Mark for the Praktisix ASB lens in 1974 and 378 Mark for the MC version in 1989. Kröger's Flektogon 65 page says the 65 still cost 412 Mark after the price cut of spring 1960, 48 Mark more than the new Flektogon 4/50, which puts the 50 at 364 Mark from its launch. No US dollar or West German price was found.
  7. Names on export lenses: pentaconsix.com shows a 1964 Praktisix II brochure for the United States in which the Biometar and Sonnar appear only as Bm and S, from Jena, because of West German Zeiss's lawsuits, while the Flektogon kept its name because West German Zeiss had never used it. pentaconsix.com adds that name-ring lettering varied with the intended market.
  8. Not listed as versions: a commenter on mflenses.com (May 2010) reports a rare Bronica S-mount version seen twice on eBay, with no maker, date or example given. Kröger describes a second 6×6 retrofocus 4/50 calculated as trial V280 of 3 January 1959, a medium-format variant of the Flektogon 4/25, more than 20 mm shorter, which Jena's test found inferior to V271 except in the extreme corners; it was not produced. pentaconsix.com says a Pentacon Six TL slightly modified by Zeiss, the 'Pentacon-Six m', went on a joint USSR–GDR manned space mission in 1968 with its standard lens, the Flektogon 50 and the Sonnar 180, citing 'Fifty Years'.
  9. The Mir-26 45mm f/3.5 that Arsenal made for the Kiev-88 and the Pentacon Six mount is described by allphotolenses as based on this Flektogon, redesigned for more speed; no other source consulted makes that claim, and it is a different lens.
How to tell them apart (expand)
  • Made for the Praktisix / Pentacon Six breech-lock (a single unconfirmed report of a Bronica S version is in the table notes), with a fully automatic spring diaphragm worked by a pin in the bayonet; it fits the Praktisix, Pentacon Six, Exakta 66 and Arsenal's Kiev-6S, Kiev-60 and Kiev-88CM, not the screw-and-bayonet Salyut and Kiev-88
  • Large 86 mm front filter thread; Zach Horton names the 86 mm filters and the hood they need among its drawbacks
  • White specks seen from the front are not cement separation: Kröger says the black paint on the ground bevel of the cemented group has come away, a cosmetic fault that can be repainted; sellers describe it as missing blackening ('fehlt die Schwärzung') between the elements
  • Two calculations, split at serial 7,281,500; finishes in the Jena sequence as pentaconsix.com gives it: black rings with a bumpy plastic grip, mostly black with a leather band (from 1965), zebra (about 1967–74), then all black, multicoated from about 1976. Zach Horton gives a different order for the range, with the plastic band replacing the leather band rather than preceding it, and says the all-black lenses of the mid-1970s are mostly but not all multicoated
  • Not the Distagon 50mm f/4 of Carl Zeiss Oberkochen for Hasselblad and Rollei, which shares the specification

First calculation (V271 of 1958), thoriated front lens:

  • Serial below 7,281,500, the number Kröger gives for the start of the 1966 recalculation
  • Front element of SSK10, a lanthanum- and thorium-bearing dense crown, 73 mm across and 12 mm thick in the blank; Kröger calls this version a notorious warm renderer today, which shows mainly on colour slide film
  • A 1964 Praktisix II brochure shows the 50 with black distance and aperture-index rings, the bumpy black plastic focusing grip and a light-alloy aperture ring (pentaconsix.com); the grip cracks or works loose with rough handling
  • pentaconsix.com gives 620 g for 'an earlier version of the 50mm Flektogon' against 480 g for the lens in its table, without saying which calculation the earlier weight belongs to

Recalculation of 27 May 1966, single-coated (zebra and other pre-MC finishes):

  • Serial above 7,281,500 (Kröger)
  • Front element of the cheaper SK22 (= LaK2) in place of SSK10; the thoriated SSK10 survives only in the rearmost positive element, 18 mm across and 4 mm thick, so the later lens is not thorium-free, but Kröger says its glasses are largely free of yellowing and recommends it for colour work
  • Most often in the zebra finish, black with bright metal stripes on the focusing and aperture rings, which pentaconsix.com dates to about 1967–74 across the Jena range; Kleinanzeigen sellers offered zebra 4/50s in September and November 2026
  • pentaconsix.com's table gives 480 g and calls a 620 g lens 'an earlier version'; it does not say which calculation either weight belongs to
  • No. 9126089, offered on Kleinanzeigen in September 2026 with hood and case, falls in the 1970–75 serial block

MC Flektogon (multicoated, all black):

  • 'MC' on the name ring and an all-black barrel; pentaconsix.com says the letters were in red at first and usually white from about 1980, and that some lenses of about 1976 were multicoated before the marking appeared, which shows as reflections of several colours
  • Lenses made after mid-1980 have four- or five-digit serials, after Jena restarted its numbering at 10,982,372 (pentaconsix.com): MC no. 12269 was offered on Kleinanzeigen in October 2026 with its leather case and guarantee card
  • Sellers title the early ones 'red MC'; the last Jena lenses of about 1990 show distances in metres only, without the red feet scale, and a black front edge to the focusing ring (pentaconsix.com, from Biometars of 1978 and 1989–90)

Serial-range notes

the whole number
Carl Zeiss Jena numbered all its lenses in one running sequence, so a Flektogon is dated from the postwar table camera-wiki publishes: 5,000,000–6,000,000 for 1958–61, 6,000,000–7,000,000 for 1961–64, 7,000,000–8,000,000 for 1964–67, 8,000,000–9,000,000 for 1967–70 and 9,000,000–10,000,000 for 1970–75. pentaconsix.com adds that Jena did not always make batches in the order their number blocks were issued, so a serial dates a lens only approximately (it still calls serials a good guide), and that numbering restarted at four and five digits after reaching 10,982,372 in mid-1980.
7,281,500
Kröger's dividing line: lenses above it are the recalculation of 27 May 1966 with the SK22 front element.
9126089
Offered on Kleinanzeigen in September 2026 as a Pentacon Six lens with hood and case; the 1970–75 block, so the 1966 calculation.
12269
MC lens offered on Kleinanzeigen in October 2026 with case and guarantee card; a post-1980 number after the restart.

Specifications

Formula
Retrofocus wide-angle: a strongly negative cemented front pair, set almost 40 mm ahead of a positive base group made of a single positive lens and a triplet-type group whose rear part is a three-element cemented group; the cemented surface in the front pair corrects distortion, and the whole lens has only eight glass-air surfaces (Kröger, from the original design data and Dietzsch's 2002 account)
Designed by
Dannberg Wolf — led the design, as he had the Flektogon 4/25 · Dietzsch Eberhard — did most of the calculation work (trial V271 of 25 March 1958), which he later called his first development task; recalculation of 27 May 1966
Aperture range
f/4–f/22
Min. focus
0.5 m
Dimensions
87 mm long
Filter
86 mm
Years manufactured
1960–1990
Country
East Germany (Jena)
Coating
Single coating at first; three-layer multicoating (MC) in the second half of production (Kröger). pentaconsix.com dates multicoating across Jena's lenses from 1976, the MC marking in red paint at first and white from about 1980
Original price
364 Mark (DDR retail price, EVP) in 1974, and by Kröger's arithmetic from the 1960 launch; 378 Mark for the MC version in 1989 (Kröger's compilation of DDR price lists). No US or West German price found.

What reviewers say

Optical formula — Retrofocus wide-angle: a strongly negative cemented front pair, set almost 40 mm ahead of a positive base group made of a single positive lens and a triplet-type group whose rear part is a three-element cemented group; the cemented surface in the front pair corrects distortion, and the whole lens has only eight glass-air surfaces (Kröger, from the original design data and Dietzsch's 2002 account)

History

The Flektogon 50mm f/4 is the wide-angle lens Carl Zeiss Jena made for the Praktisix and its successor the Pentacon Six. The Praktisix arrived in 1956 with the Flektogon 2.8/65 as its only wide lens, a design of 1950 that gave barely more than 60 degrees on 6×6. Jena wanted about 75 degrees. The new lens was designed in 1957–58, and Kröger finds it closely related to the Flektogon 4/25 that Jena had just designed for 35mm. Wolf Dannberg led the work and Eberhard Dietzsch did most of it: trial V271 was completed on 25 March 1958, and Dietzsch later called it his first development task. The patent, DDR 23.869, was filed on 8 March 1960, and the lens was launched at the same time, at the Leipzig spring fair of 1960, together with the Flektogon 4/25. It is a retrofocus design. A strongly negative cemented pair sits almost 40 mm in front of a positive base group: a single positive lens and, behind it, a group that is a triplet in principle, with its rear part cemented into three elements. The cemented surface in the front pair corrects the distortion that such an asymmetric design would otherwise have. Marco Kröger, working from the original design data, notes that the lens has only eight glass-air surfaces, so it flares little even single-coated, though it should not take light from the side.

There are two optical versions, and the serial number tells them apart. The first had a front element of SSK10, a dense crown containing lanthanum and thorium, in a blank 73 mm across and 12 mm thick. That glass was hard to make in quantity, and Kröger counts just under 4,000 lenses of this version by the end of 1965. On 27 May 1966 the lens was recalculated with the cheaper SK22 in front and the layout unchanged. Kröger says lenses numbered above 7,281,500 are the new version. Thoriated SSK10 remains only in the small rear element, so the later lens is not thorium-free either. Mass production began after the change and ran to the summer of 1990: over 75,000 of the 1966 version and at least about 80,000 in all, a figure Kröger says is otherwise found only in 35mm. The first version has since turned into what he calls a notorious warm renderer, which matters mainly on colour slide film. For colour work he recommends the later lens, and with so many more made it is the easier one to find.

The finishes follow Jena’s sequence for the whole Pentacon Six range. A 1964 Praktisix II brochure shows the 50 with black rings and the bumpy black plastic focusing grip, which cracks and works loose. A mostly black style with a leather band followed in 1965, then the zebra barrel of about 1967–74, then all black. Multicoating came in the second half of the run. pentaconsix.com dates it from 1976 across the range, with the MC lettering in red at first and in white from about 1980, which is why sellers write “red MC”. Jena restarted its serial numbers in mid-1980, so the last lenses have four or five digits, like the MC no. 12269 offered in Germany in 2026. Because Jena used up old parts as styles changed, the barrel only roughly dates a lens, and the serial is the better guide. The DDR retail price was 364 Mark in the 1974 list, the same figure Kröger’s arithmetic gives for 1960, and 378 Mark for the MC lens in 1989. Kröger thinks this was affordable for an amateur compared with what similar lenses from other makers later cost.

The lens fits every body with the Pentacon Six breech-lock: the Praktisix, Pentacon Six and Exakta 66, and Arsenal’s Kiev-6S, Kiev-60 and Kiev-88CM. It does not fit the Salyut or the ordinary Kiev-88. Kievaholic calls the Flektogon 50 and the Sonnar 180 the two jewels of the Jena line. Zach Horton describes it as very sharp in the centre and only average in the corners, a bargain that he nevertheless finds outclassed by Schneider’s far dearer Curtagon 60mm for the Exakta 66. Its 86 mm filter thread and large hood are part of the price of a wide-angle with a mirror-clearing back focus on 6×6. Do not confuse it with the Distagon 50mm f/4 that Carl Zeiss Oberkochen made for Hasselblad and Rollei, or with Arsenal’s Mir-26 45mm, which allphotolenses alone describes as derived from it.

When buying, look into the front of the lens. Many Flektogon 50s show white specks or patches there. Kröger is emphatic that this is not separating cement but black paint flaking off the ground edge of the cemented group, a cosmetic fault that costs nothing in sharpness and can be scraped and repainted once the front group is out. Sellers often describe it as missing blackening. Check that the spring diaphragm snaps shut and reopens when the pin in the bayonet is pressed, and that the plastic grip of a pre-zebra lens is still fixed. Read the serial against 7,281,500 if colour rendering matters.

Left open by the sources consulted here: an element and group count stated by any source, which of the two calculations the 620 g weight belongs to, the date of the first MC lens, whether any lens of the 1966 calculation left the factory in the pre-zebra finishes, and any US dollar or West German price.

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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

These photographers keep all rights to their work — enjoy it at the source.

Sample photo wanted — shot with a Flektogon 50mm f/4? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $270 across 36 fixed-price listings on 2026-11-09 (middle half $190–$300). First day tracked.

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

Show 72 more listings

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

Related: Flektogon 35mm f/2.8

Sources (9)

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.