RE Auto-Topcor 20mm f/4

Topcon · Exakta · 1969 · Retrofocus

via machine translation — corrections welcome

Also known as: RE Auto-Topcor 20mm f/4 · RE Auto-Topcor 20mm f4 · RE Auto Topcor 20mm f4 · RE Auto Topcor 20mm f/4 · RE.Auto-Topcor 20mm f4 · RE. Auto-Topcor 20mm f4 · RE.Auto-Topcor 1:4 f=20mm · RE Auto-Topcor 1:4 f=20mm · Auto-Topcor 1:4 f=20mm · Topcor 1:4 f=20mm · RE Auto-Topcor 4/20 · RE, Auto-Topcor 4/20 · Auto-Topcor 4/20 · Auto Topcor 20mm f4 · Auto-Topcor 20mm f4 · Topcon 20mm f4 RE.Auto-Topcor · Topcon 20mm f4 RE Auto-Topcor · Topcon 20mm f4 RE Auto Topcor · Topcon RE Auto-Topcor 20mm f4 · Topcon RE Auto-Topcor 20mm f/4 · Topcon RE Auto Topcor 20mm f/4 · Tokyo Kogaku RE Auto-Topcor 20mm f4 · Tokyo Kogaku Topcor 20mm f4 · Topcon 20mm f4 · Topcon 20mm f/4 · Topcon 20mm 1:4 · Topcor 20mm f4 · Topcor 20mm f/4 · Topcor 20mm 1:4 · Topcor 4/20 · Topcor 4/20mm · Topcor 20 f4 · Beseler Topcon 20mm f4 · トプコール 20mm F4 · REオートトプコール 20mm F4 · RE オートトプコール 20mm F4 · オートトプコール 20mm F4 · トプコン 20mm F4 · トプコン RE Auto-Topcor 20mm F4 · トプコン REオートトプコール 20mm F4

Variants & identification

Variant	Mount	Years	Serial ranges	Production
RE.Auto-Topcor 1:4 f=20mm, chrome	Exakta	1969	—	—

Specifications: 8 elements, 94°, f/4 to f/22, closest focus 0.3 m and 215 g per Maxifiche; the Paillard catalogue agrees on 8 elements, 94°, 7½ oz (215 g) and 1 ft. Neither gives groups or blade count. An MFlenses owner says his copy focuses closer than 30 cm, and in a later post puts its nearest point at 'somewhere around 15cm'; that is one owner's estimate, not a specification.
Filter: 62 mm per the Paillard catalogue, Kamerastore and English Wikipedia; an MFlenses owner confirms the lens has filter threads, unlike the 25mm f/3.5 with its rear bayonet filters. Maxifiche's table gives 'Baïonnette' in the filter column for both the 20mm and the 25mm, which for the 20mm looks like a column error. The hood itself is engraved USE SERIES 9 FILTER, so a Series IX filter can be fitted in it, as Topcon Club describes for the 25mm.
Date: 1969 is English Wikipedia's introduction year, given without a citation. It fits the other evidence: Beseler's Topcon catalogue, © 1966, starts its lens list at the 25mm f/3.5, as does an undated Beseler Super D sheet, and the 20mm appears in the Paillard catalogue that lists the Super DM of 1973. Maxifiche's RE Auto-Topcor series runs 1963–1976 from 20 to 500 mm without dating each lens. No end date is recorded.
A black 20mm: Maxifiche says RE Auto-Topcors were generally chrome and more rarely black, and Topcon Club reports a small black batch of the 25mm, but neither names a black 20mm, and Topcon Club says the 20mm kept its chrome finish to the end. No variant is listed.
The R (1957): Topcon Club says the R body has no automatic-diaphragm mechanism of its own; its semi-automatic Auto-Topcors carried it in the lens. The RE Auto-Topcor fits the R's bayonet, but its diaphragm is closed by a lever in the body, which the R lacks, so nothing on the R stops it down. No source describes this lens on an R; the link is kept with that limit.
The Automatic R (RII), RIII and RS (1960–63): Topcon Club says the RII added a fully automatic diaphragm and a stop-down lever in the body, and that many RS bodies are found with RE Auto-Topcors. Maxifiche notes that the meter-coupling finger of the F Auto-Topcors made for the RII, RIII and RS turns the opposite way to the RE Auto-Topcors' and that the F series must not be used on the RE bodies; it says nothing against RE lenses on the earlier bodies. None of these bodies meters through the lens: the RIII and RS take clip-on meters coupled to the shutter speed only (Topcon Club), so the lens's meter coupling does nothing on them. No source describes the 20mm on these bodies specifically, so the automatic diaphragm on the RII and RIII is expected rather than confirmed.
RE Super, RE-2, Super D and Super DM: full-aperture metering and focusing, per Paillard ('Exposure measurement and focusing are done at full aperture'). Paillard also says the lens 'can be used without mirror lock-up'. RE200 and RE300 (1977–78): Topcon Club says they keep the RE mount of the RE Super line, with open-aperture TTL metering; they were sold with the new RE Topcor N lenses, but the cameras' own instruction book lists the RE Auto-Topcor 20mm f/4 in its table of Topcor lenses, with automatic diaphragm and full-aperture metering.
Exakta bodies: Maxifiche says Exakta lenses mount on Topcon bodies without an adapter, and Topcon Club notes that Topcon put its release on the opposite side to Exakta's, so lenses worked by an external arm lose that function when moved between the two. Maxifiche adds that some automatic Exakta lenses, notably the Carl Zeiss Jena series of 1961–70, do not mount because their rear diaphragm mechanism fouls the Topcon bayonet's outer ring. Neither source describes an RE Auto-Topcor on an Exakta body.

How to tell them apart (expand)

Engraved RE.Auto-Topcor and 1:4 f=20mm; the widest lens in the RE Auto-Topcor line (Maxifiche: 'du grand angulaire de 20 mm au téléobjectif de 500 mm')
Fully automatic diaphragm with no A/M switch, closed by the body's lever at the moment of exposure; focusing and metering at full aperture on the RE bodies (Maxifiche, Paillard)
Not the RE Auto-Topcor 25mm f/3.5 (2.5cm), which is larger and takes small rear bayonet filters; not the leaf-shutter UV Topcors; not the R-Topcor 200mm f/4, which some dealers mis-title '20cm'

RE.Auto-Topcor 1:4 f=20mm, chrome:

Satin-chrome barrel with a black ribbed focusing band; black front ring engraved in white 1:4 f=20mm TOKYO KOGAKU, RE.Auto-Topcor and the serial number (the Wikimedia Commons example)
Short and compact for its angle: Topcon Club contrasts it with the bulkier 25mm f/3.5, and an MFlenses owner calls it smaller than the 25mm
Black push-on hood with a masked, roughly rectangular opening and a clamping screw on its side, engraved RE.AUTO-TOPCOR 4/20mm and USE SERIES 9 FILTER MADE IN JAPAN (the Commons photograph; Paillard describes it as an adjustable metal masked shade that clamps onto the lens)
Stayed chrome after 1972, when Topcon turned every other lens black (Topcon Club)

RE.Auto-Topcor 1:4 f=20mm, chrome: The only version recorded. Topcon Club says the 20mm was made in small numbers, and that when Topcon changed its barrels to black from the Super D of 1972 the 20mm and 25mm alone were left in chrome, and ended that way. No black 20mm is recorded; the 25mm, by contrast, had a small black batch exported to the United States in about 1963–64 (see the table notes).

Specifications

Formula: Retrofocus
Construction: 8 elements
Aperture range: f/4–f/22
Min. focus: 0.3 m
Weight: 215 g
Filter: 62 mm, 62 mm thread (Paillard, Kamerastore); the masked hood takes a Series IX filter
Years manufactured: 1969
Country: Japan
Original price: US$272.10 with hood and leather case (Paillard Incorporated catalogue no. 80530, list price; the catalogue is undated but lists the Super DM of 1973)

What reviewers say

Topcon Club (topgabacho.jp) (blog) — Opinion on the 20mm was divided, the collector writes, but the breakdown at the edges once reported in a 'Lens White Paper' (レンズ白書) test does not show in his own pictures, and its centre sharpness is beyond complaint. It lacks the strong three-dimensional rendering of the 25mm f/3.5. via machine translation — corrections welcome
Mir, on the MFlenses forum (blog) — First outing for a cleaned and relubricated copy on a crop-sensor digital body: lovely colours, neutral bokeh, the usual barrel distortion, sharp and slow to flare, with a short focus throw and very close focusing. Expensive, he says, but worth it. single source, unconfirmed

History

The RE Auto-Topcor 20mm f/4 was the widest lens Tokyo Kogaku made for its Topcon focal-plane reflexes. Maxifiche, the French collectors’ sheet, opens its table of RE Auto-Topcors with it, “from the 20 mm wide-angle to the 500 mm telephoto”, and gives eight elements, an angle of view of 94°, f/4 to f/22, a closest focus of 0.3 m and 215 g. The American distributor Paillard printed the same figures, describing a “radical retro-focus design” with “a minimum of distortion”. Like the other RE Auto-Topcors it has a fully automatic diaphragm, closed by the body at the moment of exposure, and a coupling that gives full-aperture metering on the RE Super and later bodies. Paillard notes that it can be used without locking the mirror up. The mount is Topcon’s development of the Exakta bayonet.

It came late. English Wikipedia dates it to 1969 without citing a source. Beseler’s Topcon catalogue of 1966 starts its lens list at the 25mm f/3.5, and so does an undated Beseler Super D sheet. The 20mm is listed in the Paillard catalogue of the Super DM era at US$272.10 with hood and leather case, a list price, against $200.00 for the 25mm. Topcon Club, the Japanese collectors’ site, says few were made. Flashback Camera in Tokyo rates it a lens that turns up about once a year. A recent marketplace listing is no list price either: a copy in excellent condition was offered on GearFocus at $469.69 in 2025 and marked sold.

There is one version. The barrel is satin chrome with a black ribbed focusing band, and the black front ring reads 1:4 f=20mm TOKYO KOGAKU and RE.Auto-Topcor. When Topcon turned its lenses black with the Super D of 1972, Topcon Club says the 20mm and 25mm alone stayed chrome, and they ended that way. No black 20mm is recorded. The lens is compact for its angle, smaller than the 25mm. Its hood is distinctive and worth having: a black push-on shade with a masked opening, held by a side screw and engraved RE.AUTO-TOPCOR 4/20mm and USE SERIES 9 FILTER. The front takes 62 mm filters by Paillard’s and Kamerastore’s account, and an owner on the MFlenses forum confirms the threads. Maxifiche’s table puts “Baïonnette” in the filter column for both ultra-wides, which is right for the 25mm, with its small rear bayonet filters, and probably a slip for the 20mm.

The lens fits every Topcon focal-plane body but does not work fully on all of them. On the RE Super, RE-2 (Beseler D-1), Super D and Super DM it focuses and meters at full aperture. The RE200 and RE300 of 1977–78 keep the RE mount, and their instruction book lists this lens with full-aperture metering. The Automatic R (RII), RIII and RS have a stop-down lever in the body for automatic diaphragms but no through-the-lens meter; many RS bodies turn up with RE Auto-Topcors, though no source describes this lens on the RII or RIII. The original R of 1957, Topcon Club says, has no diaphragm mechanism in the body, so it has nothing to stop this lens down. Topcon Club notes that the Topcon release sits on the opposite side to the Exakta’s, so lenses worked by an external arm do not cross between the two; no source describes an RE Auto-Topcor on an Exakta body. The leaf-shutter Topcons (Wink Mirror, Uni, Unirex, IC-1) take the separate UV-mount lenses, and none of those is a 20mm.

Opinions on the optics differ. Topcon Club writes that a “Lens White Paper” (レンズ白書) test of the day reported the edges breaking down. The writer does not see that in his own pictures, and calls the centre sharpness beyond complaint, though without the three-dimensional rendering of the 25mm. An MFlenses owner who shot a cleaned copy on a crop-sensor body in 2013 found it sharp, slow to flare and pleasant in colour, with ordinary barrel distortion. When buying, check that the diaphragm snaps shut and reopens when the stop-down pin at the rear is pressed, look at the front element for cleaning marks, and make sure the masked hood comes with it.

Expand Collapse

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 taken with the RE Auto-Topcor 20mm f/4 — RE Super bodies and RE Auto-Topcors; the chrome 20mm f/4 (front ring 1:4 f=20mm TOKYO KOGAKU) stands in the middle of the lens group, its masked hood engraved RE.AUTO-TOPCOR 4/20mm beside it — Stevemark, via Wikimedia Commons (CC BY-SA 4.0)

More sample photos elsewhere

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

Sample photo wanted — shot with a RE Auto-Topcor 20mm f/4? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $700 across 3 fixed-price listings on 2026-11-10 (middle half $600–$700). First day tracked.

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

[Near MINT] Tokyo Kogaku RE-Auto-Topcor 20mm f/4 Exakta Mount MF Lens Japan — $595.79 · eBay
Topcon Tokyo Kogaku Re. Auto-Topcor 20mm F/4 Exakta Mount MF Lens from Japan — $699.99 · eBay
Topcor 20mm f4 — $799.00 · eBay
【訳あり品】トプコン Topcon RE,Auto-Topcor 20mm F4 Series 9 フィルターセット e3404 — from ¥46,560 · Yahoo! Auctions Japan · auction 2026-11-12
美品東京光学 RE AUTO-TOPCOR 20mm F/4 MFレンズ Exaktaマウント動作確認済 — from ¥100,000 · Yahoo! Auctions Japan · auction 2026-11-12

Buying from Yahoo! Auctions outside Japan. It is a domestic marketplace: sellers ship within Japan, and most will not register an overseas buyer. A proxy service bids on your behalf, receives the item and forwards it, for a fee and a wait. Buyee, Jauce and ZenMarket each accept a Yahoo auction number directly. Listed alphabetically for information — none is recommended over another, and none of these is an affiliate link.

Listings updated 2026-11-10. Links go to the shop or marketplace that carries the item.