Topcor-S 5cm f/1.8 (Leica screw mount)

Topcon · LTM · 1961

our own finding

Also known as: Topcor-S 5cm f/1.8 · Topcor-S 5cm f1.8 · Topcor-S 5cm 1:1.8 · Topcor-S 1:1.8 f=5cm · Topcor-S 50mm f/1.8 · Topcor-S 50mm f1.8 · Topcor-S 1.8/5cm · Topcor-S 1.8/50 · Topcor S 5cm f1.8 · Topcor S 5cm f/1.8 · Topcor S 50mm f1.8 · Topcor S 1:1.8 f=5cm · TopcorS 5cm f1.8 · Topcor 5cm f1.8 · Topcor 5cm f/1.8 · Topcor 1:1.8 f=5cm · Topcor 50mm f1.8 LTM · Topcor 50mm f1.8 L39 · Topcor S 50mm f1.8 LTM · Tokyo Kogaku Topcor S 5cm F/1.8 · Tokyo Kogaku Topcor-S 5cm f1.8 · Tokyo Kogaku Topcor 5cm f1.8 · Tokyo Kogaku Topcor S 5cm F/1.8 Leica LTM39 · Topcon Topcor-S 5cm f1.8 · Leotax Topcor-S 5cm f1.8 · トプコールS 5cm F1.8 · トプコール S 5cm F1.8 · トプコール-S 5cm F1.8 · トプコール 5cm F1.8 · 東京光学トプコールS 5cm F1.8 · 東京光学トプコール 5cm F1.8 · トプコールS 5cm F1.8 Lマウント

Variants & identification

Variant	Mount	Years	Serial ranges	Production
Topcor-S 5cm f/1.8, black	LTM	1961	—	No figure published for the lens. Topcon Club calls it extremely scarce; the Leotax G it was made for is put at about 500 (Japanese Wikipedia via Leica Copies Japan; camera-wiki) or is said to be about 1,000 (Topcon Club), and not every G carries it

One design or two. Leica Copies Japan, followed by Leicaphilia, describes the f/1.8 as looking very similar to the black aluminium f/2 'including the 6 elements in 4 groups optical design, 10 aperture blades and 40.5 mm filter thread', with noticeably different front elements. Topcon Club, which handled both, says it had assumed the f/2 lenses and the f/1.8 shared a basic design and found they do not: the f/1.8 is a redesign with a larger, differently curved front element, and it seems to use a different glass. Neither source contradicts the element count; the page gives LCJ's figures and keeps Topcon Club's account of the redesign.
The metre scale is read from two photographs (Topcon Club's and Leica Copies Japan's), not stated by any source.
Production. Leica Copies Japan reports, after Japanese Wikipedia, that a subcontractor assembled 500 Leotax G from parts, but notes that its own G serials (90105x–90207x and one 90587x) span about 1,020 numbers and doubts the 500 is the whole story; it guesses, calling it 'not even a theory', that the 500 may refer to camera-and-lens sets. Camera-wiki says 500 were sold. Topcon Club says about 1,000 G were made. No source gives a production figure for the lens itself.
Price. No source quotes a period price for the lens or for the Leotax G outfit. Rokuwa's flyer advertised the G with the f/1.8 lens (Leica Copies Japan), but no figure from it is given.
Leonon on the G. Topcon Club says some Leotax G came with a Leonon instead of the Topcor. Leica Copies Japan reads Topcon Club as suggesting a cheaper Leonon f/1.8, doubts that one existed, finds no reference to it, and suspects the Leonon f/2 is meant; its own records show the plain Leonon f/2 on three G and the Leonon-S on two.

How to tell them apart (expand)

Leica 39 mm screw mount, rangefinder-coupled, rigid; 40.5 mm filter; 10 blades (Leica Copies Japan)
Not the black aluminium Topcor-S 5cm f/2, which looks almost the same: read the aperture on the name ring and look at the front element, which is larger and bulges further forward on the f/1.8 (Topcon Club). Not the RE GN Topcor 50mm f/1.8 or any Auto-Topcor 58mm f/1.8, which are Topcon SLR lenses in the Exakta-type bayonet

Topcor-S 5cm f/1.8, black:

Name ring reads Topcor-S 1:1.8 f=5cm, Tokyo Kogaku, with the S in red (Leica Copies Japan's photograph)
Black aluminium barrel with a broad ribbed focusing ring and a chrome band at the mount (Leica Copies Japan's photograph), the same barrel diameter as the black aluminium Topcor-S 5cm f/2 (Topcon Club)
Front element clearly larger than on any f/2 Topcor and bulging further forward; the name ring is made thicker to hide its edge, so at a glance it passes for the f/2 (Topcon Club). Leica Copies Japan: 'the front elements are noticeably different'
Some of the diaphragm stays visible wide open, as on the black f/2 (Topcon Club)
Distance scale in metres on the examples photographed by Topcon Club and Leica Copies Japan ²

Topcor-S 5cm f/1.8, black: The standard lens of the Leotax G, the last Leotax, which a subcontractor assembled after Leotax went bankrupt and which Rokuwa released in October 1961 (Photo Art, December 1961, via Leica Copies Japan). Topcon Club notes that the lens is in the 1961 new-product report for the G but in no Leotax advertisement of mid-1959, before the bankruptcy, and reasons that Tokyo Kogaku developed it for the G's planned launch in October 1959, so it was probably finished soon after the bankruptcy. It thinks Tokyo Kogaku may have sold finished lenses on its own in the two years before the G appeared, but that they were almost certainly not sold on the Merite or Elite. Of the 19 Leotax G that Leica Copies Japan has recorded, 7 carry this lens, 3 an f/2 Topcor-S, 3 the plain Leonon and 2 the Leonon-S, though it does not know whether the Leonon lenses at least are original to their cameras.

Specifications

Formula: Gauss type. Leica Copies Japan gives 6 elements in 4 groups, as on the black f/2 Topcor-S; Topcon Club calls it a redesign of the f/2 with a differently shaped front element and, it seems, different glass (see note ¹)
Construction: 6 elements / 4 groups
Aperture range: f/1.8
Diaphragm blades: 10
Filter: 40.5 mm
Years manufactured: 1961
Country: Japan
Material: Black aluminium barrel, like the last Topcor-S 5cm f/2 (Topcon Club; Leica Copies Japan)

What reviewers say

Topcon Club (blog) — Shot at f/8 on a Leotax FV beside the other screw-mount Topcors. Often taken for the black f/2 but an entirely different lens, with more neutral colour; a little behind the f/1.5, no worse than the early chrome Topcor-S, plainer in drawing than the forceful black f/2. A tentative third among the screw-mount Topcor standards, level with the late collapsible f/3.5.

History

The Topcor-S 5cm f/1.8 is the last screw-mount lens Tokyo Kogaku (Tokyo Optical, later Topcon) made for Leotax cameras, and, by Topcon Club’s account, one of the scarcest. It is in Leica 39 mm thread, couples to the rangefinder of any Leica-thread body, and was the standard lens of the Leotax G, the camera Leotax was developing when it went bankrupt in 1959 (in October, according to Mikio Awano, as cited by Leica Copies Japan). A subcontractor assembled the G from parts and the distributor Rokuwa released it in October 1961, according to the December 1961 issue of Photo Art, which gives the camera with this lens as 810 g. Topcon Club notes that the lens appears in the 1961 report on the G but in no Leotax advertisement from mid-1959. Its reading is that Tokyo Kogaku designed it for the G’s planned launch in October 1959 and had it ready soon after the bankruptcy.

The lens looks almost exactly like the black aluminium Topcor-S 5cm f/2 that came before it, with a black barrel of the same diameter and a broad ribbed focusing ring. Leica Copies Japan gives it the f/2’s six elements in four groups, ten blades and 40.5 mm filter thread, with noticeably different front elements. Topcon Club, which put the two side by side, goes further and calls the f/1.8 a redesign and “an entirely different lens”. Its front element is larger and bulges further forward, and the name ring is made thicker to hide its edge. Topcon Club thinks the glass differs too. It tested the lens at f/8 beside the other screw-mount Topcors and found the colour more neutral than the black f/2’s and the drawing plainer. It found the f/1.8 a little behind the Topcor 5cm f/1.5 and placed it, tentatively and level with the late collapsible f/3.5, third among the screw-mount standard lenses.

How many were made is not known. The Leotax G is put at about 500 (Japanese Wikipedia, as reported by Leica Copies Japan, and camera-wiki) or is said to be about 1,000 (Topcon Club); Leica Copies Japan notes that its own G serials span about 1,020 numbers, and not every G came with this lens. Of the 19 G that Leica Copies Japan has recorded, seven carry the f/1.8, three an f/2 Topcor-S and five a Leonon or Leonon-S. Topcon Club calls the f/1.8 extremely scarce. No source quotes a period price for the lens or for the G outfit.

When buying, read the name ring first. Topcor-S 1:1.8 f=5cm is this lens. The black f/2 is far commoner, and in small photographs the two are easily confused. A Leotax G with this lens is the expected combination, but camera and lens sold together prove nothing either way. Topcon Club warns that the f/1.8’s glass seems more prone to haze than the f/2’s and that few survive in perfect condition, so ask for a photograph through the lens against a light. Check the diaphragm for oil and the focusing for smoothness, as on any lens of this age. Do not confuse it with Topcon’s own 50mm f/1.8 SLR lenses, such as the RE GN Topcor, which have the Exakta-type bayonet and do not fit a screw-mount camera.

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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

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Live listings

Asking price, USD: a median of $830 across 3 fixed-price listings on 2026-11-10 (middle half $390–$830). First day tracked.

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

Rare!! CLA'd [NEAR MINT] Tokyo Kogaku Topcor S 50mm f/1.8 Lens L39 LTM Leica L — $389.99 · eBay NEW
TOPCON Tokyo Kogaku Topcor-s 5cm F1.8 [L39] — ¥60,500 · Tokyo CAMERA (東京CAMERA)
:[RARE 1/500] Tokyo Kogaku Topcor-S 50mm 5cm f1.8 L39 LTM Leica Screw Mount Lens — $825.00 · eBay
CLA’ｄRare Vintage [N.MINT] LEOTAX-G Film Camera Topcor S 5cm/1.8 Lens From JAPAN — $2,999.99 · eBay NEW

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