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The Nano Crystal Coat

Overcoming the barriers to commercial development and winning the Optics Design Grand Prix

What was the impetus for applying the nano particle coating used in steppers to the camera lens?

Tanaka:

Soon after moving over to the field of design of interchangeable lenses, having reached a hiatus in the development of lens coats for steppers, I was having a drink with some coating engineers and innocently suggested that I'd like to try using a nano particle coating in a camera lens. “That's absurd-it can't be done!” came the snap reply. The reason given was that it would be impossible to apply the technology from an ultra precision stepper to a mass production consumer device-which sounds reasonable enough. In addition, the material would have to be strengthened to cope with the rigors of consumer product manufacturing. To extend the analogy of the nano particle coating as a highly permeable paved road, compared to the strength of the Nano Crystal Coat of today, the nano particle coating of that time was like a gravel road that would become rutted as cars traveled over it. Thus, my response was that if we could make the road strong enough not to become rutted when cars passed over it, we would be able to apply the technology to the camera lens as well.

Is that to say then that if the granular structure is a major advantage, then all you need to do is increase its strength?

Murata:

That's right. In fact, one of the people with whom Mr Tanaka had a drink was my boss. Since I am also a keen photographer, I thought that this sounded great. When I heard about Mr Tanaka's idea from my boss, I felt a certain empathy with him. However, as an expert in coating, although I could foresee increased lens capability, at the same time I could also foresee how hard it would be to turn this into a commercialized industrial product. However, I believed that if we could just deal with a certain number of issues, we would probably be able to bring the idea to fruition.

Tanaka:

I had long been a keen photographer and owned a lens whose tendency to yield red ghosts bothered me. I thus asked Mr Murata to do me a big favor and apply a coat to the lens. He applied a coating to the two surfaces that were particularly prone to producing ghosts, and when I came to take a photograph, the formerly prominent red ghosts had been transformed into a weak blue color that was barely noticeable. After I told my boss how fantastic this was, he spread the word to the manufacturing department and other interested parties.

That was the real breakthrough, wasn't it? Did trial production require much time?

Murata:

The basic experiments using a small test piece took longer than the trial production. Once this preparation had enabled us to establish the basic technology, it took surprisingly little time to put it into practice. Having verified the theory in the basic experimentation stage, we took the most direct route possible, which I believe is what enabled us to apply this technology exceptionally quickly in comparison with other forms of high technology.

Tanaka:

One major reason why we were able to enter trial production immediately was that, as an optical manufacturer, Nikon already possessed a rich array of assets in the form of expertise in materials, basic development, and manufacturing. I think that this represents an overwhelming advantage for the firm over other companies, which have proved incapable of emulating Nikon.

Murata:

We exhibited a sample product at the 2004 Photokina, a general trade fair for imaging industries that is staged in Germany, and although it was our first time exhibiting a thin film coating, we drew the rapt attention of our competitors. The same year we were awarded the grand prix at the Optics Design Grand Prix Awards, sponsored by the Optical Society of Japan's Optics Design Research Group. This was in fact the first time that an optical thin film had been awarded the grand prix. The significant advances compared to existing technology in terms of capability and the fact that we had actually been able to apply the technology in a product seemed to be factors that weighed heavily in our favor when the decision to award the grand prix was taken.

An obsessive pursuit of the highest levels of performance and a never say die spirit

When did this technology first capture the world's attention as a component of a commercial product?

Tanaka:

In the AF-S VR Nikkor 300mm f/2.8G IF-ED, which was released in 2005. This was when the technology first appeared under the Nano Crystal Coat brand name. The effectiveness of the Nano Crystal Coat is most readily apparent in a wide angle lens, and the way that the timing worked out meant that its first appearance coincided with the release of the “328” (300mm, f/2.8) class of lenses. With the debut of the AF-S NIKKOR 14–24mm f/2.8G ED, the first ever ultra wideangle zoom lens to be released, we applied a Nano Crystal Coat to the concave surface of this top class lens. You really have to see it for yourself.

Murata:

If you compare the samples, you can see that an ordinary coating yields a reddish reflection the closer one gets to the peripheral section of the large curvature lens. This is what causes red ghosts. The lens used in the AF-S NIKKOR 14–24mm f/2.8G ED, to which a Nano Crystal Coat has been applied, does not exhibit a high degree of color polarization, and the reflected color is just a weak blue. I’d like to add that the Nano Crystal Coat is also effective on non wide angle lenses. It’s just that it is more effective on wide angle lenses where light can enter the lens diagonally. Since this technology can reduce reflectivity compared to conventional coat technology, it is perfectly effective in both telephoto and standard lenses.

On the 14–24mm lens, the “N” mark shines even brighter, doesn’t it.

It must be rare for a coating technology to become a brand.

Murata:

The T* coating technology by Germany's Carl Zeiss company is well known. However, we pride ourselves on the fact that there is no other thin film technology in the world that is as highly innovative and effective as the Nano Crystal Coat, and we're delighted to be the developers of a technology that has proven powerful enough to become a brand.

What is it, do you think, that lies behind the passion for craftsmanship that you have both shown in the course of this development work?

The two developers talk about the benefits of Nano Crystal Coat by comparing a photograph taken with a lens featuring the technology to one that does not.

Murata:

As developers, we are obsessed with the pursuit of the highest levels of performance. In the development of the Nano Crystal Coat too, we had a strong desire to achieve a level of performance that others would be unable to emulate. I believe that having an interest in a subject and thus being able to sustain a high level of motivation is crucial. Additionally, both the work and the workplace must be enjoyable. Unlikely and unnecessary as that may sound, this does give rise to the generation of development ideas.

Tanaka:

As an example of the work being enjoyable, it was really good fun to go to the Shinjuku Imperial Gardens and take photographs with the working prototype. When we took test photographs of the ghosts, we shouted “Ah! There they are! There they are!” and applauded. Then, after we had switched to a lens with the coating, we shouted “Ah! The ghosts have gone!”, and clapped again. Three grownup men!

Murata:

That's right. As well as being lucky in terms of our workplace environment, our respective characters are probably well suited to this work. Since it's my nature to obsess about detail, if a problem is bothering me, I have to solve it, I think.

Thank you very much for talking with us today.

Affected by the sun within the frame, bluish ghosts appear in the lower left of the picture (left) taken with an ordinary multi-coat lens; whereas ghosts are hardly noticeable in the picture (right) taken with a Nano Crystal Coat lens.