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NIKKOR-N 5cm F1.1

The following information is extracted from Nikkor - The Thousand and One Nights No. 7 written by Haruo Sato, The Complete Nikon Rangefinder System by Robert J. Rotoloni, and of course, OLJ's Kenneth Min Zee,  as owner and users of this magnificent lenses.  We own two external mount versions and one internal mount version modified to Leica M mount. 

The lens was introduced in 1956-02, being the second lens in history from ZUNOW 5cm f/1.1, released in 1953 by Teikoku Optical Industries, later known as ZUNOW Optical Industries).

Starting around this time, the competition to develop super-fast lenses grew more intense and eventually led to lenses with performance ratings beyond even f/1.0.  It was during this period of energetic research and development that the idea of "lenses faster (brighter) than the human eye" first entered the collective consciousness of photographers around the world.


The optics of the NIKKOR-N 5cm F1.1 were designed by MURAKAMI, Saburo, who at that time was manager of Nikon's 3rd Mathematics Section, Design Department. MURAKAMI was the right-hand man of AZUMA, Hideo, designer of the W-NIKKOR 3.5cm F1.8, which was unveiled in September 1956, mentioned in the 3rd Tale.

Though just a handful of Japanese optics designers have attained worldwide renown, the paper trail they left behind -- patents, reports and such -- are available to shed more light on their accomplishments.

For example, MURAKAMI filed a patent application for the NIKKOR-N 5cm f/1.1 in 1957; he received a U.S. Patent the following year.
His design was regarded as a new invention, a totally new type of super-fast lens. MURAKAMI devoted two years of painstaking design work and prototyping to develop the lens.

The designers back then used only an abacus and a sheet of logarithms to conduct ray tracing calculations.
The mind reels at the thought of the incredible volume of calculations and the hours it must have required to arrive at the final design.
Indeed, to succeed during that era, designers needed determination, resilience and, above all, an overriding desire to make better lenses.

Lens structure and features

Taking a look at the cross-section of the 5cm f/1.1 lens in Fig. 1., it is rather obvious that this is fundamentally a Gaussian (Gauss-type) design.  Like other NIKKOR lenses, the ZUNOW 5cm f/1.1 was an extension of the Sonnar type lens. The NIKKOR 5cm F1.1, therefore, differed from its predecessors.

A key design feature of the 5cm F1.1 lens was the use of a newly developed type of optical glass made with the rare-earth element lanthanum (La) in three (3) convex (positive) lenses. This provided significant improvements in spherical aberration, curvature of field, sharpness, and image flatness. The addition of convex (positive) lens on front side and cemented convex (positive) lenses on rear sides made it possible to lower the power of individual lens elements to the conventional Gaussian (Gauss-type) design (Aberration can be reduced by using lenses with lower power, an especially attractive proposition for super-fast lenses).  It also made it more practical than the Sonnar type lens, which in effect corrects aberration with more aberration created by extremely high-powered lenses, a design that makes it more difficult to manufacture and assemble.

If you look closely at the cross-section, you'll notice it resembles AZUMA's 3.5cm F1.8 lens design (Fig. 2.). It appears these lenses, which were developed at about the same time, could have been designed by two like-thinking minds who shared technical knowledge and stimulated each other's creativity. The design executions, however, are markedly different; this is the difficulty and joy of designing photographic lenses.

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II. Rendition characteristics and lens performance

What about the characteristics of the 5cm F1.1 lens ?

Because of symmetric design, the lens achieves low distortion, small lateral chromatic aberration and high resolving power. The shape of spherical aberration curve is almost straight. This is very unusual for a high speed lens.   But a minimal amount of curvature of field appears. The lens also has very small astigmatism. Considerable coma remains on the periphery, however, and the flare causes a drop in both contrast and resolving power.

Therefore, when image quality is judged on the basis of residual aberration, the central portion has decent resolving power due to very small spherical aberration, but the large coma at the periphery does significantly degrade performance. The drop in brightness at the periphery so common in symmetric lenses is also present; the "rugby-ball" vignetting and coma aberration when the aperture is almost fully open can cause an art-shaped vortex of blur to form.

This is really unfortunate, because the lens has sufficient elements needed for good blurring performance, such as spherical aberration, and a thoughtful aperture design. The NIKKOR-N 5cm F1.1 was designed more than 40 years ago, the first of a totally new type of super-fast lens, so evaluation based on modern-day criteria will render skewed results.

Mr. Sato was compelled to point out that the genesis of the Ai Noct-Nikkor 58mm F1.2 lens (1977) can be traced to the NIKKOR-N 5cm F1.1, which is more than two decades its senior.  He personally tested and evaluated several high-speed lenses (F1.2 to F0.95) from this period, including the ZUNOW 5cm F1.1. His conclusion ? The NIKKOR-N 5cm F1.1 is a standout in its class.  He called it to be unique.


Mr. Sato explains what you can expect from Nikkor-N 5cm F1.1 at various apetures as shown below:

1) From F1.1 to F1.4, there is a slight contrast drop in the exact center, but relatively good resolving power. From the intermediate to peripheral regions, however, coma flare gradually degrades contrast and creates a soft photographic veil.

Curvature of field is strong in faraway backgrounds, so resolving power drops off in intermediate regions but improves again in the periphery. 

2) From F2 to F2.8, there is a marked improvement in both contrast and resolving power from the center to the intermediate region.

3) At F2.8, the entire image, with the exception of portions of the periphery, is sharp, with excellent blur characteristics.

4) From F4 to F5.6, the entire image is sharp, with excellent blur characteristics.
For portraits, F2.8 to F4 would be best.

5) From F8 to F16, the entire image is sufficiently sharp, but contrast will be moderately high.

Three Versions of Nikkor 5cm F1.1

Nikon originally announced three versions of Nikkor 5cm F1.1, and they are:

1. Internal S mount : 835 units 

Nikon originally announced this internal S mount version in February 1956 and shown in Tokyo in May at a price tag of US$299.50, Much cheaper than Zunow's US$450. The lens hood was priced at US$12.50 including its leather case.


In April 29, 2016, I acquired the internal S mount version from Meteor HK for my Leica M-P Type 24o.  In order to mount on my Leica, I needed a S-M adapter. However, my experience with the S-M coupling which I obtained in Japan from   Katsumido Camera Store on January 29, 2015 for ¥42,000, which I originally purchased for Nikkor P.C 8.5cm F2 left me extremely dissatisfied.  Although the coupling was Contax-Leica screw mount adapter, it was obvious that the lens was too heavy regardless of its imperfect fit. Throughout its use, I constantly grappled with a sense of unease, fearing that my lens might unexpectedly detach. Unfortunately, my fears became a reality one day when my lens fell off right on my doorstep upon returning home. Fortunately, it landed on the carpet, protected by its lens filter and  cover, and the fall was a mere 30 cm. Despite the minor impact, this incident prompted me to take action.  The 5cm F1.1 lens proved to be too heavy for the camera's existing setup, making it difficult to securely attach.  The original Nikon coupling design on lens was evidently flawed, prompting me to seek a more reliable solution. One of the three coupling section on the lens end broke off and could not be repaired.  Despite the fact that my lens will definitely devalue if modified and can not go back to original appearance, I simply had no choice but to modify to a M-mount with helix.  I remember I had paid approximately US$400 to have it retrofitted.  

2. External S mount : 1,547 units​

The exact moment Nikon's designers recognized the potential focusing mount distortion stemming from the large Internal F1.1 Nikkor remains uncertain. However, we can confirm that by July 1958, they had initiated the development of a replacement solution, which ultimately reached the market no later than June 1959. The most logical approach involved reimagining the lens barrel design to capitalize on the notably sturdier external bayonet mechanism utilized by wide-angle and telephoto lenses. This strategic decision marked a significant leap forward in lens engineering. It's worth noting that this transition occurred merely two years after the introduction of the Internal F1.1 Nikkor.

The adoption of the external bayonet had far-reaching benefits, primarily in the even distribution of the lens's weight across a broader surface area, effectively countering any distortion issues. Furthermore, the use of the external bayonet substantially minimized any potential play, ensuring enhanced stability during lens mounting. Notably, even lenses as compact as the F2 and F1.4 Nikkors sometimes exhibited slight movement when attached.

Embracing the external bayonet approach necessitated a unique approach for each lens: crafting an individual focusing helicoid for every unit. In contrast, the internal version relied on the camera body's built-in helicoid for coupling with the rangefinder cam. By incorporating the external bayonet, Nikon achieved superior focusing precision, particularly evident when handling weightier lenses like the F1.1 Nikkor and telephotos.

3. Leica thread mount : 211 units 

​We never owned the Leica thread version.  After all there were only 211 units sold in the world.  Estimated price range if you find on eBay at US$50,000, similar price range of Noctilux 5cm F1.2 double aspherical.​ Nikon use the very same optical formula for all versions of Nikkor 5cm F1.1 and the difference on the barrel.

Nikkor 5cm F1.1 Lens Original Hood and The Origin of OLJ's Patent Pending Hood  

In May 1956, with the debut of the Nikkor 5cm F1.1 Lens, the plastic lens hood came at a price of $12.50, and it included a leather case. The lens itself carried a price of US$299.50, making the lens hood account for 4.2% of the total cost.

Nikon's decision to primarily employ plastic for these hoods remains shrouded in mystery, as only a limited number were crafted from in metal.

Distinguishing between the two variations, the metal version, crafted from aluminum, carries a slightly greater weight. On the other hand, the plastic iteration boasts the N-K triangular logo and exhibits a notably delicate composition.

Insights from our Master Yoshiaki Kubota suggest that the choice of plastic was driven by its ease of production by Nikon through casting molds, making it readily replaceable at a low cost to the users. The value of $12.50 from that time equates to approximately $143 in today's currency.   

Regrettably, as a consequence of this chosen material, only a small number of plastic hoods have managed to endure over the years, resulting in their scarcity. In the modern market, these plastic hoods are highly sought after and are priced between $2,000 and $3,300, frequently spotted on platforms such as eBay. Conversely, the metal version could potentially fetch twice the price of its plastic counterpart, albeit with only a limited number still in existence today.

Through simple  straightforward calculations, it becomes evident that the lens hood's value has surged by an impressive 160 to 260-fold. Yet, the prospect of purchasing and possessing one often dissuades users from employing these delicate, valuable hoods as protective measures for their lenses.

This situation has sadly resulted in the unfortunate practice of storing away valuable high-quality lenses in dry boxes or cabinets, effectively consigning them to a life of obscurity and denying them the chance to revel in the warm embrace of sunlight—a fate that deeply diminishes the inherent worth of these optical treasures.

In direct response to these challenges, we've embarked on a dedicated mission to create custom-designed lens hoods. These hoods possess a magnetic aesthetic appeal while also addressing the historical issues that have plagued lens enthusiasts. Our goal is to engineer hoods that not only showcase a striking appearance but also conquer the obstacles of the past.  By doing so, we enable lenses to break the shackles of confinement and at last, realize their untapped potential.

Expertly designed, meticulously crafted, and adorned with an elegant black paint finish on brass, our lens hood stands as a bespoke companion for the Nikkor 5cm F1.1 lens. This exceptional accessory is painstakingly painted in Japan, reflecting the precision and artistry embedded in its creation. Despite its substantial weight of 198.73 grams, this lens hood is a testament to enduring quality, poised to accompany you throughout a lifetime of photographic journeys. As time unfolds, you'll witness the gradual emergence of a unique patina, adding an intimate touch to the black finish and seamlessly echoing the history of your Nikkor 5cm F1.1 lens. This metamorphosis imparts an unmistakable character to both the hood and your photographic experiences.

Comparison between Original Nikkor 5cm F1.1 Hood with OLJ Type 2 Lens Hood by photos

OLJ's Patent Pending (for Approval in Japan) Lens Hood 


Distinguished by its type 2 configuration, this lens hood offers versatility that transcends convention. Capable of being flipped over and securely screwing in, it provides comprehensive safeguarding for your cherished Nikkor 5cm F1.1 lens. In addition to its multifunctional design, we're thrilled to share that this innovation is currently undergoing patent approval in Japan—a testament to its pioneering features and remarkable ingenuity.

We're excited to announce that these exceptional lens hoods are now obtainable for purchase directly from our website.  We are selling total of 88 units, 38 for Japan market, and 50 for the rest of the world.  

Our aspiration is to ensure that these purpose-built hoods inspire lens owners to break the cycle of storage and instead unleash their lenses to capture the world with the excellence they were designed for.