Quote Originally Posted by David A. Goldfarb View Post
Komura made teles with a "preset aperture" mechanism like that--one ring to set the shooting aperture and one without click stops to open the lens for focusing. I wouldn't be surprised if they were the manufacturer.
Back in the day preset aperature lenses were made by a variety of manufacturers. I had (still have actually) the 400/6.3 Spiratone lens, no way I can believe Komura made that, the 400's build quality just isn't all that good. Komura was a quality manufacturer.