Zunow 5cm F1.1: History, Variations and Four Lenses in
My Collection
By Kenneth Min Zee · Updated September 23, 2026
The story of the Zunow 5cm F1.1
The Zunow 5cm F1.1 is one of the most intriguing Japanese rangefinder lenses of the 1950s. Its origins are commonly traced to work begun during the Second World War, with the lens eventually reaching the market in 1953. The name “Zunow” is often associated with the Japanese word zunō, meaning intellect or brain.
Early accounts connect the design with Michisaburo Hamano, who had a naval background, worked at Nippon Kogaku and later joined Teikoku Kogaku. The development reportedly took about a decade. When the lens appeared in 1953, its reported price was US$450—an extraordinary amount for a photographic lens at the time.
The Zunow was offered in versions for Leica thread mount, Nikon S mount and Contax rangefinder cameras. Its very fast F1.1 aperture, compact size and unusual construction have made it a favourite among collectors. I find it remarkable that a lens with such an ambitious aperture remains relatively easy to carry and handle.
The earliest version, usually called Type 1, had a rounded rear element housing that gave it the nickname “Ping-Pong Ball.” It is generally described as a nine-element, five-group design based in part on Sonnar principles. This distinctive rear also made the lens less convenient to use. Accounts of the early design mention flare and disappointing performance at full aperture. Its extraordinary collectability should not be confused with being the best version for taking photographs.
Kenji Kunitomo of Nippon Kogaku and Yoshitatsu Fujioka of Yashima Kogaku are named in accounts of the redesign. The improved lens, usually called Type 2, appeared around 1955. It has a flatter rear and is generally described as having eight elements in five groups. The redesign was intended to address the early lens's flare and performance at F1.1, and Type 2 received a more favourable response. Some early lenses were reportedly modified to the later configuration, which makes it difficult to identify every example by its serial number alone.
The company changed names during this period too. Teikoku Kogaku Kenkyujo became Teikoku Kogaku Kogyo in 1954, and the company later adopted the Zunow Optics name. The engraving on the front ring changed from “Teikoku Kougaku” to “Zunow Opt.” on later lenses, adding another historical clue for collectors.
A 1955 photography-industry article attributed to Genta Fujitani describes the front of the optical design in relation to the Sonnar and the rear as a Zunow solution developed over years of research. It discusses residual spherical aberration from full aperture to about F2.8, giving images a gentle softness, while also describing good control of other aberrations. The article connects the lens's many elements and large diameter with a tendency toward a yellowish tint and discusses a change from blue-violet to amber coating. I enjoy reading this kind of period explanation alongside photographs made with the lens: its character is more interesting to me than a modern sharpness score.
Why collectors still seek it
The Zunow combines rarity, speed and a distinctive look in a surprisingly manageable lens. Its rendering can be gentle at wider apertures, with attractive highlights and a character quite different from a modern high-contrast lens. I particularly like its scalloped focusing ring and elegant aperture control. In size, it reminds me of the MS Optical 50mm F1.1 Sonnetar. Some photographs have a sparkle in the out-of-focus highlights that gives the lens a personality of its own.
Details vary between examples. Lenses can have distance scales in metres or feet, and coatings and operating directions are not necessarily the same. I have seen different helicoid rotation directions across mounts. Leica thread mount examples have an infinity lock. These differences are one reason I prefer to examine a particular lens before making general claims about the entire production run.
Serial numbers offer clues, but I would not treat them as absolute proof of a lens’s optical construction. Accounts mention numbers in the 1500 range around the announcement period, examples in the 2500 range described as prototypes, and commercial production beginning around the 3500 range. The eight-element, five-group configuration is generally associated with the 5400 series and later. Around the 5500 series, the name ring changed to “Zunow Opt.” Production appears to have continued into the 6400 range; I have not confirmed an example in the 6500 range. Serial numbers may have been allocated by mount rather than following a single uninterrupted sequence.
Estimates of total production vary: I have seen figures of about 800 and 1,000. The number of surviving, unmodified Ping-Pong lenses is harder still to establish. I have heard estimates of fewer than 50, but I regard that as an estimate, not a documented count. Owners of early lenses were reportedly offered modifications, so an example originally made with the rounded rear may look quite different today.
Four Zunow lenses in my collection
I currently own four Zunow 5cm F1.1 lenses:
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A Leica thread mount lens that accepts my 54.5 mm Bell & Howell filter.
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A black-paint Nikon S-mount lens that accepts the same 54.5 mm filter.
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A Nikon S-mount lens with a 55 mm filter thread. I understand that this lens began as a Ping-Pong Type 1 and was later modified to a Type 2-style rear configuration, although I cannot independently establish every detail of its earlier state.
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A second Leica thread mount lens that accepts the 54.5 mm filter. Kanto Camera serviced it in July 2023.
It may sound excessive to own four examples of the same rare lens, but that is why I call myself an Old Lens Junkie. Each of the four has its own feel and character. Two experienced Japanese old-lens specialists have told me that spacing between the five optical groups can differ from lens to lens. This makes work involving fogged elements especially delicate. I have been told that Hayata Camera does not undertake this particular restoration. If your Zunow needs internal work, I would consult a repairer with direct experience of the model.
I am curious about the original Ping-Pong design, yet I am not eager to pay a substantial premium for an example that may be less satisfying to shoot. Reports of strong flare, the high prices compared with Type 2, and the difficulty of finding an untouched example all matter to me. I would love to examine and photograph with one before forming a firmer opinion of its optical performance.
I have not owned or personally examined an unmodified Ping-Pong Type 1. My converted lens is an interesting clue to how some early examples were built, but it cannot establish the filter size, aperture direction or optical performance of every original Type 1. That is why I treat broad Type 1 and Type 2 rules with caution. On my lenses, the direction of focusing toward infinity also differs by mount: the Nikon S-mount examples turn one way, while the Leica thread mount examples turn the other and have an infinity lock. These mechanical details are as enjoyable to compare as the images.
Filter threads: what I found across four lenses
I do not own an original Zunow filter. However, my Bell & Howell S L39 54.5mm C filters fit three of my four lenses well. These filters have a 54.5 mm × 0.75 mm mounting thread, so the fit strongly suggests that those three lenses use the same thread size and pitch. This is an observation from my own examples, rather than a specification I can confirm for every Zunow.
An unwanted Bell & Howell filter can also provide a useful adapter. If its glass is damaged, or it has a colour you will never use, you can remove the glass and keep the metal frame. The front thread of my filter frame is 55 mm, allowing me to attach a 55-to-62 mm step-up ring and then use my OLJ Type 2 hood. A 55 mm filter can also be mounted on the empty frame.
My fourth Zunow has a 55 mm front thread, so the 55-to-62 mm ring attaches directly, without the Bell & Howell frame. On this lens, the aperture opens when I turn the ring to the right; on the other three, it opens when turned to the left. I cannot confirm the thread size or aperture direction of an unmodified Ping-Pong Type 1 from these observations.
Take care when fitting any filter or ring to an old lens. Start gently and stop if the threads resist; a good fit should never need force.
