NIKKOR - The Thousand and One Nights No.76
An E-series lens that was never sold in Japan
Nikon Series E 135mm f/2.8
This tale covers a lens from Nikon's E series, which we haven't talked about since Tale 42. The Nikon Series E 135mm f/2.8 was never released in Japan. I'll use this lens as the subject for a discussion about the origins of the Nikon EM and Nikon Series E lenses.
by Kouichi Ohshita
The Engineering Plastic (EP) Technology Department
The 1970s were a decade in which SLR manufacturers were concentrating on reducing size, weight, and price, and were releasing one new product after another. Nikon had established a solid position in the professional SLR market, first by releasing the Nikon F in 1959, and then the Nikon F2, which was a significantly improved version of the F, in 1971. In the popular SLR market, however, despite the release of the Nikomat (Nikkormat) FT for general users in 1965 and continued and steady improvements after that, Nikon struggled against the offensives of rival companies. Even Nikon was preparing the Nikon FM and FE to counter these offensives, but the U.S. market was demanding an even smaller and more affordable model.
Plastic is the key technology for achieving a small size, light weight, and low price. In the mid-1970s, a project team was established to develop injection molding technologies for engineering plastics. The team began researching the switch to plastics for lens barrels. They began by making a prototype for a plastic lens barrel, and developed technologies for lens holding mechanisms and mold correction. Based on their results, the EP Technology Department was established with the goal of promoting and achieving wide use of plastic technologies. The EP Technology Department developed the elemental technologies needed for the Nikon EM and Nikon Series E lenses, namely the high-precision injection molding technologies required for cameras and lenses, as well as the finishing and plating technologies that are indispensable when plastics are used for the exterior parts of cameras and lenses.
By the time I started at Nikon in 1985, EP Technology Department had been merged into Machine, Tool and Material Engineering Department with an organizational change, but the fact that I was able to interact with the members of the former EP Technology Department through the development of viewfinder lenses and other optical components was a tremendous asset to me as an engineer.
The Nikon EM and the Nikon Series E lenses
As I mentioned earlier, development of the Nikon EM began in response to strong demands from the American market. To achieve its compact size, light weight, and low price, internal mechanisms had to be redesigned from scratch to reduce the number of components, and plastic was used for parts like the camera's top and bottom covers and the film winding lever. In addition, all unnecessary features were eliminated, leaving only the bulb and flash sync shutter speed needed for a dedicated aperture-priority AE camera. Further, the shutter speed dial normally available on conventional SLR cameras was eliminated. While there was certainly a lot of internal debate about doing so, the fact that other companies had already released dedicated aperture-priority AE cameras is likely what tipped the scales in Nikon's decision to do so. Further, the restructuring of internal mechanisms made it possible to incorporate a winding mechanism that allows the "fractional winding" as with a high-end model equipped with a focal-plane shutter that runs horizontally.
In tune with this small Nikon EM, lighter weights were achieved through the use of plastic for the exterior parts of the Nikon Series E lenses, as well as their aperture rings and lens chambers that hold lens elements. Even the helicoid was plastic on some of the lenses. The price of the lenses was reduced by minimizing the number of lens elements required for optical components and using less expensive glass materials. This is how the Nikon EM and Nikon Series E lenses were developed. They made their debut in the U.S. in March 1979. However, there was a great deal of cautious debate about releasing the Nikon EM in Japan. Ultimately, it was announced with the launch of the flagship Nikon F3 and released in March 1980, one year after its U.S. release. Any concerns about releasing the Nikon EM in Japan were quickly dispelled. It was a hit with a total production volume that exceeded 1.5 million, and it led to the creation of successors like the Nikon FG and FG-20.
The Nikon Series E 135mm f/2.8
Now let's talk about the Nikon Series E 135mm f/2.8. This lens was one of the second round of Series E lenses released in 1981, primarily for the American market. It was not released in Japan. The second generation of Series E lenses looked different than the first. Knurling on the focus ring was changed, and a silver ring was positioned near the aperture ring as it was on AI NIKKOR lenses to achieve a more elegant appearance and a design more consistent with the rest of the NIKKOR lineup.
This lens was designed by Sei Matsui, whose name can also be seen in some of the past tales of The Thousand and One Nights. In designing this lens, he probably compared it with the AI Nikkor 135mm f/2.8, which had already been on the market for some time. Nikon does not compromise on optical performance, even with its inexpensive lenses. The lens shown in Figure 1 was the result of trial and error as to how to make an inexpensive lens without sacrificing conventional NIKKOR quality.
A lens like that shown in Figure 1 comprised of two convex elements followed by a concave element and finally another convex element is known as an Ernostar-type lens. By adding a meniscus-shaped convex element between the lead convex element and the concave element that make up the convex-concave-convex triplet, spherical aberration and coma generated by the faster (brighter) aperture value can be well corrected with this type of lens. Another characteristic of the Ernostar type is that it exhibits good performance even if inexpensive glass with a low refractive index is used for the front two convex elements. I imagine this is why Matsui chose this type of lens.
One drawback of the Ernostar type is the pincushion distortion caused by a lack of symmetry due to the addition of an extra convex element to the triplet construction. However, the degree of distortion for this lens with its narrow angle of view was kept to around 1%. While another drawback is that aberration varies greatly depending upon the shooting distance, this lens was balanced to achieve the best performance at medium distances of four to five meters. Furthermore, spherical aberration, which changes to a negative value (indicating insufficient correction) as the distance decreases, also serves to soften background bokeh. That characteristic was used to achieve soft and gentle bokeh.
Being equipped with a built-in hood and with much of its exterior made of metal, as with other AI NIKKOR telephoto lenses of the time, this lens showed a great presence among the Series E lenses, most of which were lightweight.
As always, let's take a look at this lens rendering characteristics with actual images. The sample images for this tale were captured using the Z 6 full-frame mirrorless camera and FTZ mount adapter.
Sample 1 is a distant view captured at maximum aperture. It's not common to use maximum aperture to capture distant views like this, but I wanted to emphasize the characteristics of this lens. The first you may notice is the drop in peripheral illumination. The blue sky is a little dark in the upper left corner. If you enlarge the image and look closely, you can see some flare along the contours of the handrails and window frames, and that their edges have a purplish red tint. This isn't as noticeable at the center of the frame, but becomes more prominent toward the frame periphery. This is a characteristic of this lens. While the amount of peripheral illumination is not as large as with other telephoto prime lenses, it is quite noticeable with this type of scenes for which clear and crisp rendering is demanded all the way to the edges of the frame. However, effective use of this characteristic could also help to emphasize the subject at the center of the frame. In addition, the flare-like bleed around the frame periphery is the result of priority having been placed on performance at the medium distances often used for portraits and the like, and improves as the aperture is stopped down.
Sample 2 is a distant landscape for which the aperture was stopped down to f/5.6. This image is clearly rendered with none of the flare or lack of consistency noticeable in Sample 1. Peripheral illumination is greatly improved at f/4, with illumination becoming consistent throughout the frame at f/5.6. On the other hand, while flare through to the intermediate portions of the frame is improved at f/4, some does remain at peripheral areas of the frame. This flare is nearly completely eliminated throughout the entire frame at f/5.6.
Sample 3 is a photo of a lotus flower captured at maximum aperture. You can see that the background bokeh that occupies the upper half of the frame is soft with edges that do not stand out. Further, although it is not noticeable in this image, with scenes exhibiting high bokeh contrast captured at maximum aperture, the background may appear as if swirling concentrically due to bokeh at frame peripheries being shaped like a rugby ball. Should this occur, try stopping down the aperture to f/3.5 or f/4.5.
Sample 4 is a photo of a daylily (a Hemerocallis cultivar) captured near the minimum focus distance. One drawback of this lens is that the minimum focus distance is quite long at 1.5 m. That is an unfortunate characteristic of this lens when compared with the Micro lens that was the topic of my previous tale. As in Sample 3, the background of this image is beautifully blurred. If you enlarge the image for a closer look, you will notice a small amount of flare and some color fringing on background and foreground bokeh, but neither is very noticeable in photos of front-lit scenes like this, even with shooting at maximum aperture.
Sample 5 is a photo of a sulfur cosmos captured at the minimum focus distance and maximum aperture. This is a backlit photo captured with the sun just above the frame. The built-in hood served me well here. In backlit photos like this, flare surrounding the subject and color fringing around bokeh are clearly noticeable. If we enlarge the image, we can see that foreground bokeh is ring-shaped with a purplish red fringe around the edges. Background bokeh is surrounded by slightly yellowish-green flare while leaving a bright core at the center.
What's more, as only a single coating was used on all lens elements in an effort to reduce costs, the entire frame may be enveloped in a pale flare with backlit shooting like this. To prevent this flare, try using the built-in hood or other means of blocking halation.
Why the lens was not sold in Japan
A total of eight Series E lenses–50mm f/1.8, 28mm f/2.8, 35mm f/2.5, 100mm f/2.8, 135mm f/2.8, 36-72mm f/3.5, 75-150mm f/3.5, and 70-210mm f/4–were sold in the U.S. In Japan, the appearance and lens coating were changed for the 50mm f/1.8 and it was released as a NIKKOR lens, but the 28mm f/2.8 and 135mm f/2.8 were not released at all. Why? What were the differences? It seems that there was a rule that E-series lenses with the same specs as existing NIKKOR lenses would not be released in Japan. In fact, there was a 35mm f/2.8 lens but no 35mm f/2.5 lens, and there was a 105mm lens but no 100mm lens in the NIKKOR lens lineup at the time. Both the 36-72mm and 75-150mm lenses had specifications not found in any existing NIKKOR lenses, so they were released in Japan.
The Nikon Series E was born with the Nikon EM and died when the successor FG-20 was discontinued. One reason for the Nikon Series E discontinuation might have been the inability to promote superior product quality. Looking at the history of NIKKOR, however, it seems that the ideas behind the E series were incorporated into NIKKOR lenses for further advancement. In fact, optical designs for some E-series lenses have been applied as-is to NIKKOR lenses, and the use of plastics for lens chambers and exteriors introduced with E-series lenses continued with later AF NIKKOR lenses. While this series was popular for its reasonable prices, they are in fact Nikon's legendary lenses.
NIKKOR - The Thousand and One Nights
The history of Nikon cameras is also that of NIKKOR lenses. This serial story features fascinating tales of lens design and manufacture.