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

Topcor 3.5cm f/2.8 (Leica screw mount)

Topcon · LTM · 1955 · Double Gauss, 6 elements in 4 groups

Also known as: Topcor 3.5cm f/2.8 · Topcor 3.5cm f2.8 · Topcor 3.5cm F2.8 L39 · Topcor 3.5cm 1:2.8 · Topcor 1:2.8 f=3.5cm · Topcor 2.8/3.5cm · Topcor 35/2.8 L39 · Topcor 35mm f2.8 L39 · Topcor 35mm f/2.8 L39 · Topcor 35mm f2.8 LTM · Topcor 35mm f/2.8 LTM · Topcor 35mm f2.8 M39 · Topcor 35mm f2.8 (L) · Topcor 35mm F2.8 L · Topcor 35mm f2.8 Leica · Topcor 35mm f2.8 Leica screw · Topcon Topcor 3.5cm f2.8 · Topcon 3.5cm f2.8 L39 · Topcon 35mm f2.8 L39 · Topcon 35mm f2.8 LTM · Topcon 35mm f2.8 Leica · Topcon Topcor 35mm f2.8 L39 · Topcon Topcor 35mm f2.8 LTM · Tokyo Kogaku Topcor 3.5cm f2.8 · Tokyo Kogaku Topcor 3.5cm 1:2.8 · Tokyo Kogaku Topcor 35mm f2.8 · Tokyo Kogaku Topcor 35mm f/2.8 · Tokyo Kogaku Topcor 1:2.8 f=3.5cm · Topcor Kogaku 3.5cm f/2.8 · Leotax Topcor 3.5cm f2.8 · Leotax Topcor 35mm f2.8 · トプコール 3.5cm F2.8 · トプコール 35mm F2.8 L · トプコール 3.5cm F2.8 L · 東京光学 トプコール 3.5cm F2.8 · 東京光学 Topcor 3.5cm F2.8 · トプコン トプコール 3.5cm F2.8 · Topcor 3.5cm F2.8 Lマウント · トプコール 35mm F2.8 Lマウント

Variants & identification

Variant Mount Years Serial ranges Production
Topcor 1:2.8 f=3.5cm, 'Tokyo kogaku' name ring LTM — — —
Topcor 1:2.8 f=3.5cm, 'Tokyo kogaku Japan' name ring LTM — — —
  1. Date. Topcon Club, the Japanese collectors' site, says the lens came out around 1955, after Showa Optical Works had renamed itself Leotax Camera Co., and was already on sale in the Leotax F era. koiwide gives 1955 as its release year. Leica Copies Japan repeats Topcon Club's date and adds that the arrival of the accessory lenses is poorly documented: it has found no separate advertisements for them and wonders whether Tokyo Kogaku sold them only through Showa. No end date is published. Leica Copies Japan shows the 3.5cm in a 1957 Asahi Camera advertisement for the Leotax lens range.
  2. Filter threads. Topcon Club says the front carries two threads: an outer 40.5 mm one, shared with the Topcor 5cm f/2, and an inner 34 mm one, the size of the Topcor 5cm f/3.5. The outer thread turns with the aperture ring, and Topcon Club warns that the protruding inner thread can scratch a filter screwed into the outer one. koiwide also has 34 mm inside (around the name ring) and 40.5 mm outside (inside the aperture ring), and suggests a hood on the outer thread and a filter on the inner, or a 34 mm hood on the inner thread: it warns that a hood on the outer thread turns with the aperture ring and can shift the aperture unnoticed, while the inner thread stands slightly proud so that a hood there is not touched by the aperture ring. Single dealer and reviewer figures differ: Flashback Camera gives 34 mm, Manuell fokus 40.5 mm. The thread pitch is not published.
  3. Weight and focus. 154 g is Flashback Camera's measured weight; Manuell fokus gives 152 g. The closest distance is 3.5 ft (koiwide and Manuell fokus), shown here as 1.07 m; koiwide rounds it to about 1 m. koiwide describes a straight (non-rotating) helicoid, equally spaced click stops from f/2.8 to f/22 and nine blades; Manuell fokus also counts nine, straight-edged.
  4. Finder. The lens was sold with a 1:1 bright-frame finder of famously large size. Topcon Club says its box is labelled Topco Brilliant Finder; it uses the same name for the 5/9/13.5cm multi-frame finder sold with the Topcor 13.5cm, so the name on a box alone does not say which finder it held. Flashback Camera calls it the largest finder made for a 35mm camera, says it is nicknamed the obake (ghost) finder, and that its comic look has made it popular as an accessory in its own right. koiwide says the finder and the original Topcor hood are both rarer than the lens, the hood especially. Leica Copies Japan reports that the user manual of the Leotax TV2 (a 1958 model) offers a finder with 50mm and 35mm frames. None of the Leica or Canon screw-mount bodies linked here shows a 35mm field in its viewfinder, so an external 35mm finder is needed.
  5. Mamiya. Topcon Club says the lens was also supplied for the Mamiya 35 Wide. koiwide names the camera as the Mamiya-35 Wide-E of 1957 and the lens as Topcor-M 3.5cm f/2.8. That lens is fitted to a Mamiya camera, not cut to the Leica thread, so it is not listed here as a variant; neither source describes how it differs.
  6. Not an SLR lens. The Auto-Topcor and RE Auto-Topcor 3.5cm/35mm f/2.8 for the Topcon SLRs are seven-element retrofocus lenses with 49 mm filters, and the RE Topcor 35mm f/2.8 of 1977 is a different six-element design with a 52 mm filter. Both have their own pages; neither fits a screw-mount body.
How to tell them apart (expand)
  • Leica 39 mm screw mount, rangefinder-coupled; name ring engraved Topcor 1:2.8 f=3.5cm with Tokyo kogaku, never Auto-Topcor or RE (the Exakta-bayonet SLR lenses)
  • Compact silver barrel in two steps: the front of the focusing collar narrows, then the aperture ring flares out again; mixed finishes, with a chrome mount carrying the depth-of-field scale, a satin distance ring and a glossy focusing collar and aperture ring (koiwide)
  • Focusing lever; distance scale in feet, closest mark 3.5 ft
  • The only wide-angle among Tokyo Kogaku's screw-mount Topcors (Topcon Club; Leica Copies Japan)

Topcor 1:2.8 f=3.5cm, 'Tokyo kogaku' name ring:

  • Front name ring reads Topcor 1:2.8 f=3.5cm Tokyo kogaku, with no country of origin (koiwide)
  • Otherwise identical to the later lens: two-step silver barrel with the focusing collar pinched in behind a wider aperture ring, focusing lever, distance scale in feet only

Topcor 1:2.8 f=3.5cm, 'Tokyo kogaku Japan' name ring:

  • Front name ring adds Japan after Tokyo kogaku (koiwide)
  • A few copies of either name ring are engraved in a slightly different typeface, which koiwide says is unrelated to the change

Serial-range notes

28xxx–29xxx
koiwide finds serial numbers concentrated between about No. 28xxx and 29xxx and estimates from that a production of around 2,000 lenses. That is its own inference from the copies it has seen, not a factory figure; no maker's figure has been published.

Specifications

Formula
Double Gauss, 6 elements in 4 groups
Construction
6 elements / 4 groups
Aperture range
f/2.8–f/22
Diaphragm blades
9
Min. focus
1.07 m
Weight
154 g
Filter
40.5 mm, 40.5 mm outer thread (turns with the aperture ring); 34 mm inner thread
Years manufactured
1955
Country
Japan
Material
Brass (Topcon Club, Manuell fokus; Flashback Camera says aluminium and brass), with chrome-plated mount, satin-finished distance ring and a glossy (possibly anodised) focusing collar and aperture ring

What reviewers say

History

The Topcor 3.5cm f/2.8 is the only wide-angle lens Tokyo Kogaku made in Leica 39 mm screw mount. Like the company’s other screw-mount Topcors, it was made for the Leotax rangefinders of Showa Optical Works, renamed Leotax Camera Co. in the mid-1950s. Topcon Club, the Japanese collectors’ site, dates it to about 1955 and says it was already on sale in the Leotax F era, and koiwide and the dealer Flashback Camera both give 1955. Tokyo Kogaku had supplied the Leotax with standard lenses since just after the war, but its range of accessory lenses never grew beyond this 3.5cm, the 9cm and 13.5cm telephotos and an earlier, low-volume telephoto (Leica Copies Japan). Leica Copies Japan has found no separate advertisements for them and wonders whether they were sold only through Showa. The lens appears in a 1957 Asahi Camera advertisement for the Leotax range. No end date is published.

Optically it is a six-element, four-group double Gauss. koiwide notes that the rear element is larger than the front, a common way of reducing corner darkening at the time. The barrel is brass and compact, about 150 g (Flashback Camera weighed one at 154 g, Manuell fokus 152 g). It has a straight helicoid with a focusing lever, a distance scale in feet down to 3.5 ft, and nine blades with equally spaced clicks from f/2.8 to f/22. Its finishes are unusually mixed: a chrome mount, a satin distance ring, and a glossy focusing collar and aperture ring. The front has two filter threads. The outer one, 40.5 mm as on the Topcor 5cm f/2, turns with the aperture ring. The inner one, 34 mm as on the 5cm f/3.5, does not turn with it (koiwide). Topcon Club warns that the inner thread stands proud and can scratch a filter screwed into the outer one, and koiwide suggests a filter on the inner thread and a hood on the outer. Dealers and reviewers quote one or the other figure (Flashback Camera 34 mm, Manuell fokus 40.5 mm), so a listing may give either.

The lens was sold with a 1:1 bright-frame finder so big that it has become a collectible in its own right. Topcon Club says its box was labelled Topco Brilliant Finder, though the same name appears on the 13.5cm’s multi-frame finder, and Flashback Camera says it is nicknamed the obake, or ghost, finder. The finder and the original Topcor hood are both rarer than the lens. Topcon Club and koiwide both say the lens was also supplied for a Mamiya camera, which koiwide names as the Mamiya-35 Wide-E of 1957, engraved Topcor-M. That version is not in screw mount and is not covered here.

The only version difference recorded is on the name ring. koiwide describes an earlier type reading simply Tokyo kogaku and a later one reading Tokyo kogaku Japan, with a few copies of either in a slightly different typeface. It has seen only feet scales. From serial numbers clustered between about 28xxx and 29xxx it estimates that around 2,000 were made. That is a collector’s inference, not a factory figure, but Topcon Club, koiwide, Leica Copies Japan and Manuell fokus all describe the lens as scarce, and Topcon Club says it is usually expensive when it does turn up.

Reviewers describe a gentle rather than a crisp lens. koiwide finds corner darkening and softness wide open, low contrast but rich colour, and an even, soft-toned picture by f/8. Manuell fokus found the centre sharp at full aperture, needed f/11 for the best corners on a Nikon Zf, saw contrast drop quickly against the light, and thought the price owed more to rarity than to performance. When buying, check the name ring reads Topcor 1:2.8 f=3.5cm and not Auto-Topcor or RE: those are the seven-element SLR lenses for the Topcon bayonet and do not fit a screw-mount body. Look for haze and cleaning marks, check the inner filter thread for damage, and make sure the helicoid and clicks are smooth. Flashback Camera advises holding the base of the barrel, not the head, when screwing the lens on or off. Allow for a finder: no Leica or Canon screw-mount body linked here shows a 35mm field, so you need the original 1:1 finder or any 35mm accessory finder.

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

More sample photos elsewhere

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

Sample photo wanted — shot with a Topcor 3.5cm f/2.8 (Leica screw mount)? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $940 across 5 fixed-price listings on 2026-11-10 (middle half $940–$990). First day tracked.

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

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.

Sources (6)

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.