Chiyoda Kogaku

Chiyoda Kogaku Seiko K.K. (later known as Minolta) was a Japanese optical manufacturer that played a pivotal role in the post-war rangefinder boom. While the company is globally famous for its later innovations in SLR autofocus technology (the Maxxum/Dynax series), its relevance to the Leica M-mount community lies in its production of 35mm rangefinder cameras and lenses between 1947 and 1958. During this specific era, the company manufactured optics using the LTM (Leica Thread Mount) standard, making them natively compatible with Leica screw-mount cameras and fully adaptable to modern Leica M bodies.

For collectors and shooters today, Chiyoda Kogaku is synonymous with the "Super Rokkor" lens series. These lenses are distinct from their Canon and Nikon counterparts due to their unique aesthetic character, often featuring complex optical formulas (like the 50mm f/2) that rivaled German glass, packaged in compact, high density brass housings. The brand is also remembered for the Minolta-35, a camera that successfully combined the modularity of the Leica system with the ease of use of a self timer and combined viewfinder/rangefinder window.

History

The company's history is deeply rooted in the "Japanese-German" collaboration that defined the early Japanese camera industry.

Foundations (1928 to 1946)

The company was founded on November 11, 1928, by Kazuo Tashima in Osaka under the name Nichidoku Shashinki Shoten (Japanese-German Camera Store). Tashima enlisted German engineers to help establish the production of high quality shutters and lenses. The company name was changed to Chiyoda Kogaku Seiko K.K. in 1937. While they produced various folding and TLR cameras pre-war, it was not until after World War II that they entered the 35mm interchangeable lens market.

The Minolta-35 Era (1947 to 1958)

In 1947, Chiyoda Kogaku released the Minolta-35, the first Japanese focal plane shutter camera to successfully enter mass production after the war. Unlike Canon or Nikon which started with 50mm standards, Chiyoda Kogaku initially adopted the 24x32mm "Nihon format" to save film, eventually moving to the standard 24x36mm format in later models. The camera utilized the standard M39 / LTM mount, ensuring that their lenses could be used on the vast ecosystem of Leica copies flooding the market.

The Rise of "Rokkor" (1950s)

The brand name "Rokkor" comes from Mount Rokko, a mountain visible from the company's factory near Osaka. Throughout the 1950s, Chiyoda Kogaku refined its optical coatings, developing the signature "Achromatic" coating (often appearing green or purple) which became a hallmark of the Super Rokkor line. By 1958, seeing the industry shift toward Single Lens Reflex (SLR) cameras, the company released the Minolta SR-2 and effectively ended its LTM rangefinder production, leaving behind a compact but highly regarded catalog of screw mount lenses.

Product Lines (LTM Compatible)

Chiyoda Kogaku lenses are typically engraved with "Chiyoda Kogaku" or "Chiyoko" on the beauty ring. They are exclusively LTM (Leica Thread Mount).

The "Plum Blossom" (45mm f/2.8)

This is the brand's most recognizable optic in the rangefinder community.

• Design: The Super Rokkor 45mm f/2.8 is a tiny, pancake style lens comprising 5 elements. It is famously nicknamed the "Plum Blossom" (Umebachi) due to the unique shape of its focus tab, which resembles the petals of a plum flower.
• Rendering: It is valued for its incredible compactness and distinct vintage sharpness. It is often cited as one of the most aesthetic lenses to mount on a Barnack Leica (e.g., Leica IIIf) due to its period correct styling and small footprint.

The Standard Primes (50mm)

• Super Rokkor 50mm f/2: A serious competitor to the Leica Summicron and Nikkor-H. It features a 7-element design, which was complex for the time, delivering high resolution and a "crunchy" contrast that differed from the softer Sonnar designs of the era. It is often referred to as the "Japanese Summicron" in forum discussions due to its build and performance.
• Super Rokkor 50mm f/1.8: The high speed flagship of the line. It is significantly larger and heavier, built with dense brass and high quality glass to correct spherical aberrations wide open.
• Super Rokkor 50mm f/2.8: A more budget friendly triplet derivative, known for unique "soap bubble" bokeh effects when shot wide open against complex backgrounds.

The Telephotos

• Super Rokkor 8.5cm (85mm) f/2.8: A classic portrait focal length. Like the 50mm lenses, it is built from heavy brass and chrome, offering a very different tactile experience from the lighter aluminum telephotos produced by Canon in the late 1950s.

Technical Specifications

Feature	Specification Details
Focus Type	Manual Focus (Rangefinder Coupled)
Native Mount	Leica Thread Mount (LTM / M39)
M-Mount Compatibility	100% Compatible via LTM to M adapter ring
Markings	Engraved "Chiyoko" (early) or "Chiyoda Kogaku"
Build Materials	Heavy Chrome Plated Brass or Aluminum (late versions)
Aperture	Clickless (early versions) or Clicked (later versions)
Filter Thread	34mm (45mm f/2.8), 40.5mm, 46mm (50mm f/1.8)
Coatings	Single Coated (Blue/Purple/Green tint)

Why Photographers Choose Chiyoda Kogaku

• The "Chiyoko" Aesthetic: The 45mm f/2.8 "Plum Blossom" is a cult classic not just for its images, but for its physical beauty. It is widely considered one of the most stylish lenses to pair with a screw mount body.
• High Density Build: Collectors often note that Super Rokkor lenses feel denser and more "solid" than contemporary Canon Serenar lenses, featuring smooth, heavy focus throws that feel luxurious to operate.
• Optical Distinctiveness: Unlike many Japanese manufacturers that strictly copied Zeiss Sonnar formulas, Chiyoda Kogaku often utilized modified Gauss or Tessar designs, giving their lenses a rendering signature that stands apart from the ubiquitous "Sonnar look" of the 1950s.

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Sources

• Minolta Global History: https://www.konicaminolta.com/about/corporate/history.html
• Pacific Rim Camera (Minolta Rangefinder Reference): https://www.pacificrimcamera.com/pp/minolta.htm
• Earth, Sun, Film (Super Rokkor 50mm f/2 Review): https://earthsunfilm.com/minolta-chiyoko-super-rokkor-50mm-f2-no-longer-neglected/
• Couv Camera (45mm "Plum Blossom" Review): https://couvcamera.wordpress.com/2020/04/14/little-vintage-rokkor-delivers/
• Antique Cameras (Minolta 35 System): https://antiquecameras.net/minolta35rf.html