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

RE GN Topcor 50mm f/1.8

Topcon · Exakta · 1973 · Gauss type, six elements (Paillard catalogue)

our own finding

Also known as: REGN Topcor 1:1.8 f=50mm · REGN Topcor 50mm f1.8 · RE GN Topcor 50mm f/1.8 · RE GN Topcor 50mm f1.8 · RE GN Topcor 50mm F1.8 · RE GN Topcor 50mm 1:1.8 · RE GN Topcor 1:1.8 f=50mm · RE GN Topcor 1:1.8 50mm · RE GN Topcor 1.8/50 · RE GN Topcor F1.8 · RE.GN Topcor 50mm f1.8 · REGN Topcor 50mm f1.8 · GN Topcor 50mm f/1.8 · GN Topcor 50mm f1.8 · GN Topcor 1:1.8 f=50mm · Topcon 50mm f1.8 RE GN · Topcon 50mm f/1.8 RE GN · Topcon RE GN 50mm f1.8 · Topcon GN Topcor 50mm f1.8 · Topcon GN 50mm f1.8 · Tokyo Kogaku RE GN Topcor 50mm f1.8 · REGNトプコール 50mm F1.8 · RE GN トプコール 50mm F1.8 · GNトプコール 50mm F1.8 · トプコール GN 50mm F1.8 · トプコン RE GN トプコール 50mm F1.8

Variants & identification

Variant Mount Years Serial ranges Production
RE GN Topcor 50mm f/1.8 (black) Topcon RE (Exakta-type bayonet) 1973 — —
  1. Specifications. The Maxifiche gives 6 elements, 47°, f/1.8–22, 0.4 m closest focus, bayonet hood, 62 mm filter and 280 g. Paillard's catalogue gives 6 elements, 45°, 62 mm, 1.3 ft and 10 oz (290 g), and calls it a Gauss type. Kamerastore's listing gives 6 elements in 5 groups, 6 aperture blades, 66 × 52 mm and 274 g. Tokyo Kogaku's RE300/RE200 instruction book gives 6 elements, 47°, f/1.8–22, 0.4 m, 62 mm and 280 g. The weight set is the 280 g of the instruction book and the Maxifiche; the group count and blade count rest on the one dealer listing and are not set either.
  2. Coating. Paillard calls only the f/1.4 GN Topcor M multi-coated, and Topcon Club says the f/1.4 is multi-coated on every group. Neither says so of the f/1.8. Topcon Club does mention, on its Macro Topcor page, a green coating 'like the RE GN Topcor 50mm' on late black lenses, without saying which aperture it means. No coating is set here.
  3. Super DM standard lens. The Maxifiche's model table gives the Super DM's standard lens as RE GN Topcor 1.4 or 1.8/50mm, but its own Super DM page reads 'f/1.4 ou 1.8 de 58mm'. Paillard, Modern Photography (March 1974) and Topcon Club all say 50mm.
  4. Bodies. The lens has the RE mount, which Topcon Club describes as the Exakta mount with mechanisms added from the RE Super on, and Paillard says every RE Topcor has 'a Topcon (Exakta) bayonet mount'. On the Super DM, RE Super and Super D it couples to the open-aperture TTL meter; the Super DM's CC finder also shows the set aperture in the viewfinder (Maxifiche, Paillard). The RE-2 meters at full aperture through a resistor coupling rather than the RE Super's chain (Topcon Club). The RE200 and RE300 of 1977–78 use the same RE mount (Topcon Club), and their instruction book lists the RE GN Topcor 50mm f/1.8 with automatic diaphragm and full-aperture metering. The RS has the RE Super's shape but no TTL meter, only a separate CdS meter of its own; Topcon Club notes that most RS bodies seen carry RE Auto-Topcors, though it is unclear how they were sold. No source describes the GN lens on the RS, and it stays linked on that basis. The R, RII and RIII have no TTL meter at all. Topcon Club says the original R has no automatic-diaphragm mechanism in the body, everything being in its own Auto-Topcors, and no source consulted describes how an RE lens's automatic diaphragm behaves on the R, RII or RIII. Those bodies stay linked because no source shows the lens failing to fit or work on them. The Maxifiche's warning runs the other way: it is the F Auto-Topcors of 1960–62 that must not be used on RE bodies.
  5. Exakta. The Maxifiche calls the Topcon R's mount a fully compatible Exakta bayonet, and says Exakta lenses mount on Topcon bodies without an adapter, but that the later evolution of the Topcon bayonet causes problems: some Exakta automatic-diaphragm lenses, notably the Carl Zeiss Jena series of 1961–70, do not mount because their diaphragm actuator fouls the body's outer bayonet ring, while preset and manual Exakta lenses and Angénieux automatic lenses mount without difficulty. It says nothing about Topcon lenses on Exakta bodies, and no source consulted documents this lens on an Ihagee Exakta body.
  6. Prices. Paillard's catalogue price is $139.45 for the lens with hood, and $470.95 for a Super DM with standard prism, this lens and hood (#80020). The catalogue is undated; its $727.45 for the Supreme I outfit (Super DM, CC finder, f/1.4 GN lens, auto winder) is the price Modern Photography gives for that outfit in March 1974. In France the Maxifiche reports a Super DM with the GN 1.8/50 at 2,920 Fr in June 1974, against 3,408 Fr with the GN 1.4/50. Paillard's is a US distributor's catalogue list price and the French figures are retail prices reported by the Maxifiche; neither is an auction result. No Japanese list price has been found.
  7. Dates. The lens came with the Super DM, which the Maxifiche dates 1973–1976 and Topcon Club dates from 1973. No end date for the lens is published. Topcon Club says Topcon left the general SLR market in 1981 with the Super DM, RE200/300 and RM300 as its last models, and that domestic 35mm sales ended with the RE300 (production ended 1980, sales 1981).
How to tell them apart (expand)
  • RE GN TOPCOR 1:1.8 f=50mm on the front ring. The f/1.4 GN lens reads RE GN TOPCOR M 1:1.4 f=50mm. The everyday RE Auto-Topcor standard lenses are 58mm, not 50mm
  • A guide-number scale beside a GN mark on the focusing ring, and a tab that couples the aperture to the focus for flash (Paillard; Modern Photography's description of the f/1.4)
  • Black barrel, 62 mm filter. The RE Auto-Topcor 58mm f/1.8 takes 49 mm filters
  • Not the leaf-shutter-system UV Topcor or Hi-Topcor lenses of the Wink Mirror, Unirex and IC-1, which have a different mount

RE GN Topcor 50mm f/1.8 (black):

  • Front ring engraved RE GN TOPCOR 1:1.8 f=50mm, with no M after TOPCOR (the M marks the multi-coated f/1.4) (Paillard catalogue photograph)
  • Aperture ring 1.8 2.8 4 5.6 8 11 16 22; distance scale in feet and metres; a guide-number scale on the focusing ring (Paillard catalogue photograph and text)
  • Black barrel only: the Maxifiche says the RE GN lenses are always black, where most RE Auto-Topcors are chrome
  • 62 mm filter thread and bayonet hood mount, the same as the f/1.4 GN lens; Paillard lists one hood (#82000) for both

Specifications

Formula
Gauss type, six elements (Paillard catalogue)
Construction
6 elements
Aperture range
f/1.8–f/22
Min. focus
0.4 m
Weight
280 g
Filter
62 mm
Years manufactured
1973
Country
Japan
Original price
$139.45 with hood (Paillard Inc. US catalogue, c.1974) (today $887)

What reviewers say

No reviews aggregated yet — this family is still in the research queue. Written one? We'd love to index it.

History

The RE GN Topcor 50mm f/1.8 was the cheaper of the two standard lenses Tokyo Kogaku made for the Topcon Super DM of 1973, the last of the RE Super line. The other was the multi-coated RE GN Topcor M 50mm f/1.4. Both replaced the 58mm RE Auto-Topcors that had come with the RE Super and Super D. In the United States, Paillard’s Topcon catalogue lists it as the “optional standard lens for Topcon Super DM” at $139.45 with hood, against $234.45 for the f/1.4, and Paillard sold a Super DM with standard prism, this lens and hood for $470.95. That catalogue is undated, but its price for the f/1.4 outfit with auto winder matches the $727.45 Modern Photography quoted in March 1974. In France the Maxifiche of the Club Niépce Lumière reports a Super DM with the GN 1.8/50 at 2,920 francs in June 1974. Both figures are retail prices of the day. No Japanese list price has been found.

GN stands for guide number. Topcon called the system Flash Matic: with the flash’s guide number set on the lens, the aperture follows the focusing distance, so a manual flash gives correct exposure wherever the subject is. Paillard describes this for both GN lenses: the guide number is engraved on the barrel, the distance scale is locked to it, and the lens then sets the right f-stop as the photographer focuses. Modern Photography, testing the f/1.4, describes how: set the focus to infinity, set the lens wide open, turn the focusing ring until the guide number sits against the red dot on a black tab, then slide the tab forward to engage the ring. Nikon’s GN Nikkor 45mm f/2.8 came first. Topcon Club explains the difference: Topcon put a specially shaped cam in the focusing ring so that focus and aperture turn in equal steps, while Nikon managed without one by keeping its lens slow and short. Topcon Club adds that once the guide number is coupled the aperture clicks release, so intermediate apertures can be set freely. It also reports that Nikon later traded the licence to its GN-lens patent for the use of Topcon’s open-aperture metering patent when it moved to Ai. The lens otherwise behaves as an RE lens, with a fully automatic diaphragm and metering at full aperture. Paillard credits it with “exaggerated cam action focusing” for speed.

Optically it is a six-element Gauss type, and the sources agree on little beyond that. The Maxifiche gives 47°, f/1.8 to f/22, 0.4 m closest focus, a 62 mm filter and 280 g. Paillard gives 45° and 290 g. Kamerastore gives six elements in five groups, six blades and 274 g. Paillard calls only the f/1.4 multi-coated, and Topcon Club, which says the f/1.4 is multi-coated on every group, says nothing of the f/1.8’s coating. The f/1.8 shares the f/1.4’s 62 mm filter and its hood, and the Maxifiche says the RE GN lenses were made only in black. No other version is recorded in the sources consulted: no chrome lens, no Beseler, Hanimex or Exakta-badged copy, and no US Navy marking. The RE GN Topcor 35mm f/1.8 that Topcon announced in the mid-1970s was never sold.

The lens has Topcon’s RE bayonet, the Exakta mount with the RE Super’s meter coupling added. It meters at full aperture on the RE Super, Super D, Super DM and RE-2, and with the Super DM’s CC finder the set aperture is also shown in the viewfinder. The later RE200 and RE300 keep the same mount, and their instruction book lists the lens with full-aperture metering. The RS, an RE Super-shaped body without TTL metering, is mostly found with RE Auto-Topcors, though no source describes the GN lens on it. The earlier R, RII and RIII have no meter to couple to. The original R also has no diaphragm mechanism in the body, and no source describes how an RE lens’s automatic diaphragm behaves on those three bodies. It is not a lens for the IC-1 or the leaf-shutter Topcons, which use the different UV mount. No source consulted documents it on an Ihagee Exakta body.

When buying, check that the front ring reads RE GN TOPCOR 1:1.8 f=50mm, with no M: the RE GN Topcor M is the f/1.4, and the RE Auto-Topcor standard lenses of the same aperture are 58mm. On Yahoo! Auctions Japan the lens turns up both alone and on Super DM bodies, the outfit it was sold in. Check that the diaphragm snaps closed and reopens cleanly, and that the GN tab slides and couples to the focusing ring. With the guide number engaged, the aperture should move smoothly with the focus. On the MFlenses forum, an owner remarked on the 40 cm closest focus and a switch for clickless aperture. Paillard sold the lens with its bayonet hood and also listed the hood on its own as #82000, the same part as for the f/1.4.

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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 RE GN Topcor 50mm f/1.8? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $300 across 3 fixed-price listings on 2026-11-10 (middle half $200–$300). First day tracked.

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

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

Sources (15)

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.