Tokyo Kogaku

Tokyo Kogaku (Tokyo Optical Co., Ltd.), better known by its trademark Topcon, is the great "What If?" of the Japanese camera industry. Founded in 1932, they were the primary optical supplier to the Japanese Army during WWII (while Nikon supplied the Navy). This rivalry drove them to produce lenses of exceptional resolution and mechanical precision.

For the Leica M-mount and LTM user, Tokyo Kogaku is revered for one specific reason: the Topcor-S 50mm f/2. In the 1950s, while Canon and Nikon were busy copying the Zeiss Sonnar, Topcon produced a lens that many testing charts suggested was actually sharper than the Leica Summicron. They were the OEM lens supplier for Leotax cameras, making their glass the "premium" option for high-end Japanese Leica copies.

History

The company’s identity is defined by its military origins and its intense rivalry with Nikon.

The Army vs. Navy Rivalry (1932 to 1945)

Tokyo Kogaku was established in 1932 through a merger involving the surveying division of Hattori Seikosha (Seiko).

• The Mandate: The Japanese government designated Tokyo Kogaku as the optical supplier for the Imperial Japanese Army (sniper scopes, surveying tools), while Nippon Kogaku (Nikon) supplied the Navy. This rivalry meant Tokyo Kogaku’s glass was engineered for extreme durability and resolving power.
• The "Simlar" Era: Their pre-war and wartime lenses were branded Simlar. These are exceptionally rare and are considered the ancestors of the modern Topcor line.

The Leotax Partnership (1950s)

After the war, Tokyo Kogaku didn't build their own 35mm rangefinder body. Instead, they partnered with Showa Optical (Leotax).

• The "Premium" Kit: You could buy a Leotax camera with a cheaper commercially available lens, or you could pay extra for the "Topcor" kit. These lenses were marketed as the professional choice, often costing more than equivalent Nikon or Canon optics at the time [[1]].

Product Lines (LTM Native)

Topcon LTM lenses are famously consistent. Unlike other brands that had "good" and "bad" eras, almost every Topcor LTM lens is a high performer.

The Topcor-S 50mm f/2 (The Legend)

This is the lens that maintains the brand's cult status today.

• Design: It utilizes a standard Double-Gauss design, but with slight variations that corrected coma better than its competitors.
• Performance: It is famously sharp. Modern MTF tests of vintage copies often show it out-resolving the rigid Leica Summicron 50mm (Version 1) in the center. It produces a very modern, high-contrast look that is distinct from the "glowy" Sonnar look of the Nikkor 5cm f/1.4 [[2]].
• Aesthetics: It features a unique "panda" finish (black ring on chrome) or a satin all-chrome finish. The aperture ring has a distinctive "scalloped" feel.

The Topcor 50mm f/1.5

The rare, high-speed option.

• Rarity: While the f/2 is uncommon, the f/1.5 is rare.
• Rendering: Unlike the f/2, the f/1.5 leans into character. It produces the classic "swirly bokeh" associated with high-speed lenses of the 1950s but retains the trademark Topcon center sharpness. It is a direct competitor to the Canon 50mm f/1.5 but with significantly better build quality.

The Topcor 3.5cm (35mm) f/2.8

• Size: A very compact wide-angle lens.
• Ergonomics: It features a large, easy-to-grip focus lever (infinity lock) that is often smoother than the Leica Summaron.
• Optics: Extremely resistant to flare for its age, likely due to Tokyo Kogaku's experience with military coatings.

The Simlar Legacy

• Simlar 50mm f/1.5 & f/3.5: If you find a lens marked "Simlar" in LTM, you have found a museum piece. These are the immediate post-war predecessors to the Topcor. They are optically similar but use older, softer glass types and are much more fragile.

Technical Specifications

Feature	Specification Details
Native Mount	LTM (Leica Thread Mount)
Focus Coupling	Coupled. (Standard rangefinder coupling).
Build Materials	Heavy Brass with Satin Chrome finish. The "Panda" versions (black aperture rings) appear in the late 50s.
Glass Quality	Exceptional. Tokyo Kogaku had access to the best glass reserves in Japan due to their military status.
Markings	"Tokyo Kogaku" or "Topcor-S". Older lenses marked "Simlar".
Filter Thread	40.5mm (Common on the 50mm f/2).
Coatings	Hard Coated. Topcon coatings are generally durable and do not "wipe off" like early Zeiss coatings.

Why Photographers Choose Tokyo Kogaku

• The "Sharpness" Chaser: If you want the vintage 1950s aesthetic (metal construction, small size) but demand 2020s sharpness, the Topcor-S 50mm f/2 is the answer. It is widely considered the sharpest LTM standard lens of the 1950s.
• The "Navy vs. Army" Flex: Owning a Topcon lens alongside a Nikkor lens completes the historical set of the Japanese military industrial complex. It’s a distinct lineage from the consumer-focused Canon.
• Leotax Pairing: For owners of Leotax F or Leotax T cameras, a Topcor lens is the historically correct "high-end" pairing. A Leotax with a Topcor is worth significantly more than one with a generic lens.

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Sources

• [1] CameraQuest (Leotax & Topcor History): https://cameraquest.com/leotax.htm
• [2] 35mmc (Topcor 50mm f/2 Review): https://www.35mmc.com/16/10/2016/topcor-s-50mm-f2-ltm-review/
• [3] Topcon Club (Lens Compendium): http://www.topgabacho.jp/Topconclub/lens1.htm