AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED Lens
Lenses Quietly Continue to Change:
A Designer Looks Back at a Decade of Evolution
Mr. YAMAZAKI, you've been involved in lens design for over a decade.
To what degree do you think lens design has evolved over that time ?
I don't think there has been much of a change in the way the lens is perceived as a product, but there has been considerable change in terms of design.
First of all, there has been an enormous improvement in optical design, which is largely due to the improved capabilities of the computers used in the design process. It has become possible to simulate virtually any conditions, which has allowed us to pursue higher precision in our designs.
Secondly, production technology for aspherical (ASP) lenses has advanced significantly. The AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED Lens doesn't employ aspherical lenses, but these lenses have enabled the creation of a range of wideangle and standard products offering specs and performance not possible with conventional lens designs.
Those developments certainly would contribute to improved optics, wouldn't they ?
No doubt about it. Now, the third remarkable development in lens design is the evolution of coating technology.
The glass used in lenses is not merely polished, you know. It also has to be coated as needed. When light is reflected off a lens element, it generates green and purple flashes, right ? This is a result of the coating on the lens element. Coatings can change the reflectivity of the surface or suppress specific colors, and the technology behind these coatings has improved enormously in the last ten years.
This lens employs a newly developed multi-layer coating (Nikon Super Integrated Coating, or SIC) for even better color balance and clear image.
From a mechanical standpoint, we've seen some vital improvements in the quality of materials. The lens barrel of the AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED Lens, for example, uses a magnesium (Mg) alloy. Magnesium burns pretty easily, however, which made it quite difficult to work with. Now, with the considerable advances in fabrication technology, we are able to use magnesium in lens barrels -- a fantastic development for us lens designers.
Yes, you can finally use the material you've always wanted to use.
Computer Aided Design Simulation Employed in Repeated Strength Testing "Photographic Lenses Are Constantly Evolving"
What sort of simulations do you use in the design stage ?
Well, in strength testing we would usually make a prototype and completely destroy it in the process, which was pretty wasteful. We had to make educated guesses about what areas needed reinforcement, and by how much.
Our design process and procedures used to be based largely on experience, but now we can combine that considerable experience with computerized simulation capability in, say, strength testing. It has greatly increased our efficiency, while giving us the freedom to be more creative earlier in the design process.
And that's why we conducted so many simulations on the new lens. Naturally, once a physical prototype was available, we performed countless tests on it as well.
How do you feel about the progress made in microcontrollers ?
LSI chip capacity and performance have both increased, which provides us with greater design freedom. We are able to employ increasingly intricate units for lens control, for example, which enhances the precision of control functions.
Lenses are precision instruments, aren't they ?
And today there are a whole slew of technologies available that couldn't even have been imagined a few decades ago.
That's right. Autofocus lenses are wonderful. Manual-focus lenses are great, too, of course, but there are a lot of situations where you don't know you've made a focusing error until you look at the prints. That's where having an autofocus lens really pays off. Once the proper focus is achieved, all you have to do is check the shutter speed and f-stop, which makes composition easier and more fun. You can concentrate on capturing scenes, while leaving focusing and camera shake entirely up to the lens in these new designs.
The Quest of the Lens Designer:
"We Want to Perfect Predictive AF Drive"
When do you feel that your work is enjoyable ?
It's always enjoyable !
One aspect of my work that interests me no matter how many times I do it is during the initial lens production stage, when the engineers and designers sit down together and talk.
You'd be surprised at the number of people involved in the design of a lens. And though the lens designer has a difficult job, I'd have to say the people who really have it rough are those who assemble the lenses at the factory.
Lenses like the AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED Lens are comprised of a lot of parts. We made it a priority to keep the lens as compact as possible, which made packing all of the necessary electrical components and microcontrollers and whatnot into the lens quite a task. Of course, testing is performed a unit at a time, and there are many steps in the adjustment process -- this makes life difficult for the assembly team.
We have to take actual component assembly into account when designing products, too. The manufacturing people look at our design drawings and point out places where functionality could be improved, or reinforcement is necessary. This interaction helps us to improve our designs, devising better lenses that are easier to put together. The overall lens improves and matures, and this is something that you can't do by yourself.
It's a team effort - working as a unit, putting designs together and taking them apart again many times, to get a clear picture of the lens' strengths and weaknesses. And that's a fascinating process.
What kind of lenses do you want to design in the future ?
I want to improve the autofocus predictive drive.
OK, let's say you're shooting a racing car in action. With the AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED Lens, you focus on the car and the lens itself will automatically measure the range, and estimate where the car will be after so many seconds. The term "predictive drive focus" refers to the holding of the focus on the subject in this situation, but this type of tracking requires more than just range data -- information on the motion of the subject is also necessary.
Or suppose you wanted to photograph a soccer player during a match. You can predict where a car is likely to be in a few seconds, but you certainly can't guess where a soccer player might be. You might guess he'll go right, only to have him break left... or just stop entirely!
Even after you capture the athlete with the AF lens, it isn't possible to accurately predict in which direction he'll run. The human eye, though, is capable of following such unpredictable motion. Compared to our eyes, lenses are still too slow.
My goal is to speed up the feedback of range data, and develop a lens capable of following even unpredictable motion. And I'm working toward that goal every day.