Nikon’s Roots Vol. 08 – Nikkomat/Nikomat FT

Re-challenge to make a popular model

After the Nikon F was released in 1959, many new Nikon F mount interchangeable lenses have been released over the years, including unique products such as the fisheye lens Fisheye Nikkor, the close-up Micro Nikkor, and the compact super telephoto Reflex Nikkor. The addition has enriched the lineup. However, even if users want to use these lenses, they cannot afford the expensive Nikon F. Manufacturers also need to supply cheaper bodies to expand sales of interchangeable lenses. Therefore, in 1962, the Nikkorex F was released, but it ended in failure. However, Nikon did not give up, and in 1965, hoping to make a comeback, it tried again in the field of popular models with the Nikkormat FT and FS. The Nikkormat FT is marketed as Nikomat FT in Japan.

Copal Square S

One of the triggers for the birth of the Nikkormat series was the appearance of Copal Square S. The biggest problem with the first generation Copal Square used in the Nikkorex F was its height. Perhaps for this reason, there are only a few cameras that use it, other than Nikkorex F, there is Konica FS and its successor. It is likely that other manufacturers had considered it, but they were hesitant due to its height.

Therefore, Copal focused on reducing the height of this unit focal plane shutter. The result is Copal Square S. The front and rear curtains are folded and stored in the space above and below the screen frame, so the height can be lowered by increasing the number of divisions of the curtain. The first curtain and second curtain were each divided into two parts, but in Copal Square S, this was increased to three parts. Additionally, in the first generation, the shutter curtain was driven and speed controlled using a large camshaft that ran through the top and bottom of the body. This was probably done in consideration of the usability of the previous drum-type focal plane shutter. With a drum shutter, the shutter dial is placed on the top of the camera body. In order to make it easier to use, Nikon decided to use a rotating shaft that runs vertically through the camera body to drive the curtain and control its speed.

The Shutter Dial

However, with a square shutter, the arms and drive springs that drive the front and rear curtains are all installed around a rotation axis that runs in the front and back direction of the camera body. Therefore, it is reasonable to make the axis of the speed control mechanism the longitudinal axis as well. In the Copal Square S, the shaft of the shutter dial also rotates in the front-rear direction, which was successful and made it possible to achieve a significant reduction in size.

With that setup, the shutter dial will pop out to the front of the camera body. Many cameras that use this shutter, such as the Topcon RE2 and Konica Autorex, still have a shutter dial on the front of the body. Nikkormat FT added one more twist to this by adding a shutter dial around the lens mount. This made it possible to achieve operability similar to that of a lens-shutter camera that has a shutter dial on the lens barrel. Also, since the shutter dial is coaxial with the aperture linking ring, it is also convenient for linking the exposure meter.

Nikkormat FT Built-in TTL Exposure Meter

When the Nikkormat FT was introduced, the world of single-lens reflex cameras was undergoing a major transformation, with the introduction of built-in exposure meters, interlocking, and TTL. Of course, the Nikkormat FT was also developed with a built-in linked exposure meter using CdS, but initially it was an external light type rather than a TTL. However, with the release of the Topcon RE Super in 1963 and the Pentax SP in 1964, the world was moving towards cameras with built-in TTL exposure meters. So, just as mass production was approaching in 1965, the company suddenly changed its policy and decided to incorporate a TTL exposure meter into the Nikkormat FT. However, the body die-cast mold could not be corrected in time, so the early batches of this camera had a hole in the die-cast front plate for the external light exposure meter sensor, and they were assembled by blocking this hole with a metal plate.

The Photometric Optical System

There are various types of photometric optical systems for TTL, but we chose a type that has light receiving elements on both sides of the eyepiece to receive the subject light diffused by the finder screen. This is the same method as the Pentax SP, but the Nikkormat FT uses a Fresnel lens for focusing light in front of the light receiving section. The purpose is to reduce the influence of back-incidence light to the eyepiece, which is one of the problems with TTL photometry. This condensing lens will lead to center-weighted photometry later.

Problems with aperture metering and lens aperture F-number

When TTL metering first appeared, there was a lot of discussion about whether it was wide-open metering or aperture metering. I’m sure it was a hot topic at the time. Up until then, most single-lens reflex cameras did not have a means to transmit the set aperture value of the interchangeable lens to the body, so either the lens mount could be modified and an aperture value transmission mechanism could be added to enable wide-open metering, or the lens mount There was a debate as to whether to use aperture metering as is, but since Nikon was equipped with a crab-claw transmission method from the beginning, it was natural to choose aperture metering. In that sense, Nikon made sure they were one step ahead of other companies.

However, the problem was the aperture f-number. Since it is equipped with an automatic aperture mechanism, the light from the subject when the lens is wide open enters the photodetector, but even if the brightness of the subject is the same, the amount of light that reaches the photodetector depends on the aperture of the lens attached. The amount will be different. I have to correct that amount. To do this, when transmitting the set aperture value from the lens to the body, instead of telling the absolute value of the aperture, it is necessary to tell how many stops from the aperture aperture of the lens to stop. Manufacturers that provided an aperture interlocking mechanism did so. However, Nikon’s crab claws are designed to transmit the absolute value of the set aperture for external light cameras, so it is necessary to separately import the lens’s aperture aperture and correct the photometric value accordingly. .

The Solution?

Therefore, the Nikkormat FT adopted a method of shifting the film sensitivity setting according to the aperture of the lens. This makes sense, but every time you change lenses, you have to reset the film sensitivity to match the aperture. If you forget to adjust the settings, you won’t be able to get the proper exposure, and this problem would continue to plague Nikon and Nikon users for 12 years, until the “gacha-gacha” method was replaced by the “AI method.” This means that the company’s innovative ability to quickly make the light meter work in both directions with a crab claw actually backfired.

Nikkormat FT : In-house development, in-house production

The Nikkormat FT, which was introduced to the world as a popular model for the Nikon F, was a success. This, in turn, spurred sales of the Nikon F, which had been on the decline. One of the reasons for its success may be that it was developed and produced in-house, unlike the development of the Nikkorex F, where everything was left to others. An assembly workplace for the Nikkormat series was created within the Ohi Plant, and assembly and adjustments were carried out there. Thanks to this, Nikon was able to ensure the quality and performance typical of Nikon even though it was a popular model.