Simlar and Topcor 5cm f/1.5 (Leica screw mount)

Topcon · LTM · 1950

Also known as: Topcor 5cm f/1.5 · Topcor 5cm f1.5 · Topcor 5cm 1:1.5 · Topcor 1:1.5 f=5cm · Topcor 50mm f/1.5 · Topcor 50mm f1.5 · Topcor 50mm f1.5 LTM · Topcor 5cm F1.5 L39 · Topcor 1.5/5cm · Topcor 1.5/50 · Topcon Topcor 5cm f1.5 · Topcon Topcor 50mm f1.5 · Topcon 5cm f1.5 · Topcon 50mm f1.5 · Tokyo Kogaku Topcor 5cm f1.5 · Tokyo Optical Topcor 5cm f1.5 · Tokyo Optical Topcor 50mm f1.5 · Leotax Topcor 5cm f1.5 · Simlar 5cm f/1.5 · Simlar 5cm f1.5 · Simlar 50mm f1.5 · Simlar 1:1.5 f=5cm · Simlar 1.5/5cm · Tokyo Optical Simlar 5cm f1.5 · Tokyo Optical Simlar 50mm f1.5 · Tokyo Opt Simlar 5cm f1.5 · Leotax Simlar 5cm f1.5 · トプコール 5cm F1.5 · トプコール 50mm F1.5 · 東京光学トプコール 5cm F1.5 · トプコントプコール 5cm F1.5 · Topcor 5cm F1.5 Lマウント · シムラー 5cm F1.5 · 東京光学シムラー 5cm F1.5 · Simlar 5cm F1.5 Lマウント

Variants & identification

Variant	Mount	Years	Serial ranges	Production
Simlar 5cm f/1.5 (シムラー) · Sonnar-type front, Gauss-type rear; 7 elements in 4 groups and 12 blades according to Leica Copies Japan, which is not sure which of the two f/1.5 designs the figures describe	LTM	1950–1954	—	—
Topcor 5cm f/1.5 (トプコール) · Redesign of the Simlar: Sonnar-type front, Gauss-type rear, the rear group of a different design and the fourth element smaller (Topcon Club, citing Shashin Salon)	LTM	1955	153466 (Leitz Auction 47 lot 366, on Leotax F no.548045)	—

Two designs. Topcon Club says the Simlar and the Topcor 'share nothing at all in their design' (設計そのものは両者間で何ら同じところは見られない), though both put a Sonnar-type group in front of the diaphragm and a Gauss-type group behind it, and its cross-section page says the difference lies in the rear group. They are kept on one page as two variants because they share a name, a mount, a barrel style and a place in the Leotax line, and are often confused in listings. Topcon Club's Simlar entry has the halves the other way round ('前半がガウス型、後半がゾナー型であるのはトプコールと同様', Gauss front and Sonnar rear, 'as on the Topcor'); its Topcor entry, its cross-section page and its lens test all put the Sonnar half in front, and the entry follows them.
Formula name. Perry Ge, quoted by 35mmc, calls it 'half Sonnar half Gauss'. A reader's comment under the 35mmc review argues that the Simlar is a modified Biotar (Gauss) design. Leica Copies Japan gives 7 elements in 4 groups and 12 blades for the 'Simlar f/1.5', and is not sure whether the figures describe the first lens, the revised one or both. No element count or blade count is given for the Topcor in any source read, so the family fields are left empty.
Simlar on the Leotax F. Topcon Club says the early Leotax F of 1954 came with the Simlar 5cm f/1.5 or f/3.5, that the Simlar on the F has a differently designed barrel from the one on the D IV, and that the lenses were renamed Topcor in 1955. Leica Copies Japan, reading Topcon Club, calls the F's lens 'the redesigned Simlar f/1.5'. So it is not settled whether the optical redesign arrived with the F in 1954 under the Simlar name or with the Topcor name in 1955. No photograph of an F-type Simlar f/1.5 has been found, so it is not listed as a variant.
Filter. Leica Copies Japan gives the Simlar f/1.5 a 40 mm filter ring and the Topcor 40.5 mm, and writes that the change came at some point: perhaps with the revised lens, perhaps with the name change. Check the thread before buying filters for a Simlar.
Price. No price for the lens alone has been found. An Asahi Camera advertisement of 1955, reproduced by Leica Copies Japan, lists the Leotax F with the Topcor f/1.5 at ¥65,000 and with the Topcor f/3.5 at ¥38,500; Leica Copies Japan's table gives the same ¥65,000 under a 1956 Leotax advertisement. These are list prices for camera and lens together.
Topcon Club also says, in English only, that Tokyo Kogaku made a Topcor 5cm f/1.4 that was never sold. Nothing more is known of it.

How to tell them apart (expand)

Leica 39 mm screw mount, rangefinder-coupled, rigid (not collapsible) chrome barrel; f/1.5 on the front ring
Not the Topcor 5cm f/2, Topcor-S 5cm f/2 or Topcor-S 5cm f/1.8, which share the Leotax and the Topcor name; and not the RE Auto-Topcor 5.8cm f/1.4 or any Auto-Topcor, which are Exakta-bayonet SLR lenses

Simlar 5cm f/1.5 (シムラー):

Engraved Simlar, not Topcor; the copy Topcon Club photographs reads Tokyo Optical Co. on the front ring
Aperture ring at the very front of the barrel, round the name ring. Topcon Club has seen it with a knurled grip in two steps, in one step, and set back as on the Topcor
Rigid chrome barrel with a 40 mm filter thread, an awkward size that 40.5 mm filters do not fit (Leica Copies Japan)

Topcor 5cm f/1.5 (トプコール):

Front ring engraved Topcor 1:1.5 f=5cm, Tokyo Optical Co. and No. (Leitz Auction 47 photographs; Topcon Club's photograph)
Aperture ring set back behind the name ring, not at the very front as on most Simlars (Topcon Club)
Heavy brass barrel, chrome finish; click-stopped aperture (35mmc)
40.5 mm filter thread (Leica Copies Japan)

Simlar 5cm f/1.5 (シムラー): The fast standard lens of the Leotax D IV and Leotax S (1952): Leica Copies Japan finds it offered on the D IV by 1950 and shown mounted on the camera in a 1951 Leotax advertisement, and the only lens listed in an advertisement for the S. Topcon Club says it was made until the early Leotax F of 1954 and that the Simlar fitted to the F has a differently designed barrel from the D IV's (see the table notes). Topcon Club names the Simlar after Shimura, the district around Tokyo Kogaku's works in Itabashi. Perry Ge, as reported by 35mmc, says the Simlar has an even more unusual character than the Topcor, and that he has seen fewer of the Topcor. No serial range has been published.
Topcor 5cm f/1.5 (トプコール): The standard lens of the Leotax F in its most expensive form. Topcon Club says the magazine Shashin Salon (写真サロン) announced it as a redesign of the Simlar 5cm f/1.5 and dates its sale to 1955, when Tokyo Kogaku's screw-mount lenses took the Topcor name; Leica Copies Japan also dates the renaming 1955. Leica Copies Japan says it no longer seemed to be offered by the time of the Leotax TV in 1957, and reports Topcon Club's view that, like rival lenses of its speed, it priced itself out of the market. The Leitz Auction copy has a distance scale in feet.

Specifications

Formula: Sonnar-type front group and Gauss-type rear group behind the diaphragm (Topcon Club)
Aperture range: f/1.5
Filter: 40 mm (Simlar 5cm f/1.5 (シムラー)) · 40.5 mm (Topcor 5cm f/1.5 (トプコール))
Years manufactured: 1950
Country: Japan
Material: Chrome-plated brass barrel (35mmc; Leitz Auction photographs)

What reviewers say

Hamish Gill, 35mmc (blog) — Built like the Canon 50mm f/1.5 and a pleasure to use; very sharp and contrasty in the centre but falling away towards the corners even at f/8, lower in contrast with a glow wide open; a collector's lens at around £1,500.
Topcon Club (blog) — Shot at f/8 on a Leotax FV against the other screw-mount Topcors: solid resolution from wide open, faultless at f/8, strong colour contrast; ranked a close second among the screw-mount Topcor standard lenses, behind the middle Topcor-S 5cm f/2, and called an all-rounder.

History

The Topcor 5cm f/1.5 and the Simlar 5cm f/1.5 before it were the fast standard lenses that Tokyo Kogaku (Tokyo Optical, later Topcon) made in Leica 39 mm screw mount for Showa Optical’s Leotax cameras. The Simlar came first. Leica Copies Japan finds it offered on the Leotax D IV by 1950, and it was the lens shown on the camera in a Leotax advertisement of 1951 and the only lens listed in an advertisement for the Leotax S. The name Simlar comes from Shimura, the district round Tokyo Kogaku’s works in Itabashi, according to Topcon Club, the Japanese collectors’ site. In 1955 Tokyo Kogaku’s screw-mount lenses took the Topcor name. The Topcor f/1.5 was then the fast lens of the Leotax F, and Topcon Club calls it the most expensive Topcor of all. An Asahi Camera advertisement of 1955 lists the Leotax F with it at ¥65,000, against ¥38,500 with the Topcor 5cm f/3.5; both are prices for camera and lens together. By the Leotax TV of 1957 it no longer seems to have been offered. Leica Copies Japan reports Topcon Club’s view that, like the other f/1.5 lenses of the time, it had priced itself out of the market.

The two lenses look alike but are not the same design. Both put a Sonnar-type group in front of the diaphragm and a Gauss-type group behind it, which is why the lens is often called a semi-Sonnar. Topcon Club says the magazine Shashin Salon announced the Topcor as a redesign of the Simlar. The main change was in the rear group, where the fourth element is smaller, and Topcon Club says the two have nothing in common in their actual design. It is not settled when the change came. Topcon Club says the early Leotax F of 1954 still had a Simlar, with a barrel unlike the D IV’s. Leica Copies Japan calls that lens the redesigned Simlar, but Topcon Club’s own lens page presents the redesign as the Topcor, on sale in 1955. Leica Copies Japan gives 7 elements in 4 groups and a 12-blade diaphragm for the Simlar, but is not sure which version those figures describe.

The two are easy to tell apart on the barrel. The name ring reads Simlar or Topcor, both followed on the copies pictured by Tokyo Optical Co. and the serial number. Most Simlars have the aperture ring at the very front of the barrel, round the name ring, with a knurled grip in two steps or in one. The Topcor’s aperture ring sits further back, though Topcon Club has seen Simlars made the same way. The Simlar takes 40 mm filters and the Topcor 40.5 mm, according to Leica Copies Japan, so a Simlar needs filters of an awkward size. Both are rigid, chrome-plated and heavy. 35mmc found the Topcor’s build as solid as the Canon 50mm f/1.5’s, with a brass barrel and a clicked aperture.

Both reviewers read rate the Topcor highly. Topcon Club finds it sharp from full aperture with little flare, and with contrast it doubts even the later RE Auto-Topcor 5.8cm f/1.4 for the SLRs could match; it notes a slight focus shift as it is stopped down. In its test of the screw-mount Topcors it ranked the f/1.5 second, just behind the middle Topcor-S 5cm f/2. Hamish Gill of 35mmc found it very sharp in the centre, but soft towards the corners even at f/8 and with a glow wide open. Gill called it a collector’s lens and put the near-mint copy he borrowed at around £1,500, his estimate of its value rather than a sale. At Leitz Auction 47 a Leotax F with a Topcor f/1.5, no.153466, sold for €780 including premium, under its €1,000–1,200 estimate.

When buying, read the name ring first. A lens engraved Simlar is the earlier design and takes 40 mm filters. Do not confuse either lens with the Topcor 5cm f/2, the Topcor-S 5cm f/2 or the Topcor-S 5cm f/1.8, which were sold on the same cameras. Both lenses fit any Leica-thread body and couple to its rangefinder. A lens offered on a Leotax F may be original to the camera, but a camera and lens sold together are no proof that they left the factory together. As with other fast lenses of the 1950s, check the front element for cleaning marks, look for haze and separation inside, and check that the focusing is smooth over the full travel.

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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.

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