NIKKOR - The Thousand and One Nights No.27

Fastest 35mm lens

Ai Nikkor 35mm F1.4S

I have been telling the tale about digital camera lenses for two nights in a row, so let's get back to the NIKKOR lens for SLR cameras. The 35mm f/1.4 was my longing lens, which led me to meet the NIKKOR.

by Kouichi Ohshita

I. Encounter with Nikkor

Why this was once the lens of my dreams --- please keep me company for more stories from my past.

I took up photography in earnest to take photographs of the stars as mentioned before. It was the late 1960s to the early 1970s, when the space boom was set off in response to the landing of the manned spacecraft Apollo on the moon's surface and the following displaying of the moon rock in the Japan World Exposition in Osaka (Expo '70). I was a schoolchild at the time, wheedled my parents into buying a small astronomical telescope, never got tired of gazing at the craters on the moon, and used to get excited at the twinkling of the Pleiades star cluster visible from the balcony. My favorite books in my boyhood were the collections of photographs of stars written by Akira Fujii. The book carried many color photos of beautiful star clusters even though color photos were uncommon for us at that time. The technical information for the photos often contained a combination of Nikon F and Nikkor 35mm f/1.4 lens, the leading roles in the tonight tale, just like a standard combo.

Differently from recent years in which fast negative color films have come into general use, in those days, whenever we heard the term color film, we remembered reversal films; it was the age of Ektachrome ISO 64 (known as ASA at that time instead of ISO) and Fujichrome ISO 100. This means that a glimmer of starlight had to be captured at such low sensitivity as one-tenth or so of the present ISO 800 negative color films.

In addition, as those who are well acquainted with cameras may know, films involve a complication known as "reciprocity failure" effect; a long-time exposure period can cause the failure of the reciprocity law (the same density is maintained by doubling a shutter speed when stopping down one-stop aperture) and then an exposure longer than that based on the reciprocity law is required to obtain the same density with decreased shutter speeds. For this reason, color photographs of stars at the time were taken slowly and carefully in 30 minutes to one hour at an aperture of f/1.4. In actuality, however, due to the reciprocity failure, an f/2 lens cannot always provide the same good result in a one-hour exposure period in comparison with the combination of f/1.4 lens and 30-minute exposure period. The f/2 lens requires a longer exposure period and then, in those days, the small aperture lenses could not virtually take color photos of star clusters.

"No lenses other than Nikkor 35mm f/1.4 can take beautiful color photos of star clusters..." In this way, the names of Nikon F and Nikkor 35mm f/1.4 lens were deeply etched in my mind. Today, large-diameter lenses are often used to improve out-of-focus background (bokeh), but in those days, some scenes required the high speed of f/1.4, and there were shots that could not be taken without this lens.

II. World's first 35mm f/1.4 lens for SLR cameras

The tale originated in the time before and after the release of F. A plan was made to redesign the W-Nikkor 3.5cm f/1.8 discussed in Tale Three to decrease the f-number by one. The lens boasted of being the fastest in the world at the time of its release in 1956, but it became necessary to increase the brightness because the competitors offered faster lenses. In fact, there still is a report showing that a 35mm f/1.4 lens for Nikon S series was designed and prototyped around the mid-1960s. The lens was intended for the version subsequent to Nikon SP, but the development was discontinued in response to the aborted development of a successor to Nikon SP, and unfortunately the lens did not become a reality. However, the specifications of the 35mm f/1.4 were passed on to the lenses for Nikon F, and the development of 35mm f/1.4 lens for SLR was restarted.

As with the W-Nikkor 3.5cm f/1.8, even the large-diameter wide-angle lenses for rangefinder cameras are similar in size to standard lenses. The lens under development was intended to provide the same size as a standard lens and the same 52mm attachment size. The task of designing this lens was taken on by Yoshiyuki SHIMIZU. At that time lenses with similar specifications were available for rangefinder cameras, though the specifications for SLR cameras were the first. In addition, large-aperture lenses fail to deliver fully satisfactory performance even if minimal irregularities in lens aberration are present. Thus, it is not hard to imagine that our predecessors had difficulty both in designing and in manufacturing the lens. Almost five years had passed from the start of development to when the target performance was finally realized after two prototypes.

The lens went on sale successfully in 1971 with the features of Close-Range Correction (CRC) System introduced first in the 24mm f/2.8 and the Nikkor's first multi-layer-coating treatment. It utilized all available technical know-how that the then Nippon Kogaku could offer, suitable for the world's first 35mm f/1.4 lens for SLR cameras.

III. Lens construction

Fig. 1

This is a retrofocus lens composed of nine elements in seven groups as shown in Fig. 1. The lens is characterized by two similar concave elements in the front end and three separate convex elements in the rear end groups. Fast lenses entail larger lens diameters. The larger lens diameters can, in turn, cause larger aberrations in the lenses. In this lens, the front groups were composed of two concave elements and the rear end groups were composed of three converging elements, unlike the conventional composition of two elements, to decrease the radius of curvature of the lens and to minimize possible aberrations in individual lenses. Any aberrations left uncompensated were corrected through the two groups of two cemented lenses arranged across the diaphragm, thereby imparting a very effective configuration to the lens. The lens was rated as excellent in that the increased thickness of the cemented lenses on front of the diaphragm contributed to the elimination of the front-end convex elements in the 28mm f/3.5 lens, and limited the front-end groups in this lens to only two concave elements. Without this lens construction, the 35mm f/1.4 lens that accepts a 52mm attachment size would not have been possible. This lens construction demonstrates how Nikon has put a great deal of effort into standardization of attachment size.

IV. Lens performance and imaging characteristics

Sample 1 (JPEG:3.20MB)Open in a new window
Nikon F5 Ai Nikkor 35mm f/1.4S f/1.4 Auto. RVP F
©2005 Kouichi Ohshita
Sample 2 (JPEG:4.56MB)Open in a new window
Nikon F5 Ai Nikkor 35mm f/1.4S f/5.6 Auto. RVP F
©2005 Kouichi Ohshita

Now, let's check what this lens can do.
I have been using a variety of cameras and lenses to take shots for my work, but I have not found lenses similar to this one very often, which can provide all kinds of effects depending on the film used and/or scenes targeted.
In our company, lenses have been tested and evaluated with various sensitized materials including monochrome film, color reversal film and color negative film, and recently further evaluation by digital cameras has also been added. Using such a diverse range of photosensitive materials for evaluating the lenses is based on the fact that the imaging characteristics of the lens depend on the film used, and in fact, this lens clearly shows this.

When used with a monochrome or color negative film with an full aperture, the lens provides a unique, sensitive image including a somewhat veiled but detailed reproduction. This comes from a considerably large sagittal coma flare. The soft gradation results due to the overall decreased contrast is caused by a slight coma flare in the highlights. In contrast to this, unexpectedly clear and crisp results with an full aperture surprise us when photographing night scenes on color reversal film through this lens. Looking at Sample Photo 1, a sagittal coma flare is visible also in the color reversal photographs, though it is not so prominent, which may be explained in terms of the fact that the reversal films differ in tone reproduction characteristics from the negative films intended for photo prints, and reversal lens can better capture the core of the light source.

In addition, flat scenes, when shot at a near-open aperture, result in a slightly moist texture and a vivid image of the person?fs skin possibly due to the effect of the coma flare.

This lens also provides greatly varying results according to the lens aperture setting. The sagittal coma flare may be almost eliminated by slightly stopping down the lens and thus, each one-stop down increases the contrast, and when stopping down to f/4 to 5.6, the lens provides high-contrast, sharp images worthy of Nikkor as demonstrated by Sample Photo 2. For myself, I am attracted by faithful reproduction available at a wide to a half-stop aperture.

V. Continual improvements

This lens has been used to date since its first introduction in 1971 through changes in the lens barrels and the adoption of what was then the latest super-integrated coating technologies; changes were also made to the optical system at the time when the lens barrel design was changed to the NEW-Nikkor. Though the basic lens construction remained unchanged, the glass material and the lens curvature were changed by Teruyoshi TSUNASHIMA, to improve the performance at open aperture.

The lens has been consistently in use for over 30 years, thanks to the efforts for continual improvement of our predecessors even after the lens was brought to perfection.
Today, this lens can no longer boast of having unique specifications, although the 35mm f/1.4 offering the attachment size of 52mm is still unparalleled. The lens will keep holding the title of the smallest 35mm f/1.4 for SLR cameras, at least for the time being.

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.