I have the same lens, in PK mount.
It has a beautiful slide-in rectangular hood, has very good build, and has a complex 9E/7G optical layout with a very convex front glass.
It is part of the late lineup of Komura lenses, marked Komura Mfg. Ltd KMC Komuranon.
The name of the company was changed in the late seventies, as far as I remember.
Older objectives were marked either:
Sankio Koki Komura
Sankio Kohki Komura
Sankyo Kohki
My interest for Komura lenses was sparked by the unplanned acquisition, back in the eighties, of a great objective I knew nothing about. It was the Komura f/2.8 152mm for 4x5".
I bought it on a whim, from a famous photografica/pro shop in Milano, Italy.
I was there to buy a like-new Pentax-A Star 2.8/300 mm with A 2x-L and huge Helioplan circular polarizer, and sell them a Leica M wide angle. When I saw the Komura I couldn't resist
It was so visually attractive, on its large Copal No. 3 shutter, that I got derailed... and also bought a completely unnecessary Rodenstock Rotelar tele, complete with a matching rangefinder cam for my old Technika.
Later on I realized it was the only "normal" on leaf shutter for the 4x5" format with such large aperture, together with the crazy expensive Schneider Xenotar 2.8/150mm. Even the Zeiss Planar was left behind...
I also learned that Komura didn't make knock-off's like most Japanese lens makers of the time, and that Sigma and Tamron lenses of the same vintage were far worse (but cheaper!).
In the sixties Komura made a line of super fast primes for the SLR cameras of the time, small and medium format, and used three different generations of "UNI" mounts that allowed to adapt the same lens to another camera.
Komura LTM lenses were adopted by Leica users along with Canon ones, and Sankyo Kohki released the only rangefinder-coupled 200mm in M39 mount, plus their own take on the Visoflex (like Kilfitt).
They also made Tele designs for large format of very good quality, and converters for small and medium format way above average.
All this to say that Komura is part of the Japanese lens makers aristocracy, but at that time people wanted either cheap or OEM... so eventually Komura went out of business.
Those interested can find a nice early Komura catalogue on CameraEccentric.com.
BTW, I still have the A* 300mm, but I sold the Komura 152mm cause I knew I would never use it again, and it was too good a lens to become a collector's item.
Compliments to the OP,
finding a late Komura Mfg. Ltd lens in good working order without paying good money is not so common.
I have a KMC Komuranon 2.5/135mm missing the two rubber grips.
I'd like to restore it using a cheap 3D printer of a friend of mine. If anyone out there has printed focusing/diaphragm rings with mid-sized diamond patterns, I'd be very interested in getting the project file. I'm no good at 3D design!
EDIT:
Here is a magazine advertising with the 2.5/28mm specs, plus details about a Komuranon-S enlarging lens which I also happen to own...
Cheers
Paolo
Last edited by cyberjunkie; 01-11-2018 at 09:39 AM.