NIKKOREX 8 was sold as a beginner's model, quite unusual for Nippon Kogaku, but the fact is that an 8 mm cine camera with quite another concept was prototyped before.
It is known that the design of that prototype was started in 1956 and finished in 1959. Judging from the photograph of the prototype (see photo) that is kept even now by Nikon, it was quite a high-performance model.
Three taking lenses, CINE-NIKKOR 6.5 mm f/1.8, 13 mm f/1.8 and 38 mm f/1.8 can be interchangeably rotated by a turret. 6.5 mm lens has a fixed focus but other two lenses can make the distance adjustment with a helicoid.
Film is driven by a spring and its speed can be changed from 16 frames per second to 64 frames per second (fps.), and such special shooting as slow-motion (high-speed) shooting can be made.
Viewfinder is a direct optical view finder of which magnification changes in linkage with a switchover of the turret, and in addition it has a built-in selenium-cell, match-needle meter that controls the exposure in linkage with the stop value and the shooting speed.
A very interesting feature is a film loading method. 8 mm movie in those days was called "double 8" that used film of 16 mm wide and after first 25 feet (about 7.6m) was finished, film was taken out and the take-up reel and the supply reel were reversed and the shooting was made with rewinding the film. The right and left half of the 16 mm wide film were shot in both ways of going and coming.
This reversing operation is very troublesome and the reel was often dropped and the film was exposed.
As a countermeasure, this prototype adopts the method of loading an exclusive film magazine that is loaded with film in advance.
When the first 25 feet was finished to shoot, the entire magazine is taken out and turned upside down and loaded again. This magazine is very elaborately designed.
A light shielding shutter was provided at the location of shooting frame and was opened and closed in accordance with the key operation of opening and closing of the cover for film loading.
Anyway, the planned and prototyped 8 mm cine camera at first was a high-class model that was very like that of Nippon Kogaku.
I've heard that the object of this development project was "To provide high image quality of 16 mm professional cine camera with 8 mm cine camera".