This zoom lens was a revolutionary product insofar as it was the first ever lens of the concave-convex 2-group zoom type which is now the benchmark configuration for today's standard and wide angle zoom lenses. HIGUCHI, Takashi was at the time tackling the development of this new genre, the standard zoom, from two completely different approaches, the 43-86mm f/3.5 3-group zoom type, and the 35-85mm f/2.8 2-group type.The lens has a unique arrangement of scews in the mount, instead of three screws in the mount as with other early Zoom-Nikkors, there are six arranged in three pairs. The aperture scale and focal length index are also offset about 45° to the left side. Presumably this is to make them visible to the operator, in the normal position the view would be blocked by the bulk of the lens and metering head on the camera.
However the 35-85mm f/2.8 zoom was never mass-produced or sold, despite the announcement of its creation. According to the May 1961 issue of Japanese "Shashin Kogyo" ("Photography Industry", pub. Shashin Kogyo Shuppansha) magazine in which the announcement appeared, the lens had an 8-group, 13-element configuration, length of 95mm, maximum diameter of 90mm, weight of 1.1 kg, and a filter attachment size of 82mm diameter, making it a behemoth of a lens.
Two prototypes are known which differ in some details:
Second prototype with black barrel: