Yes Stephen I have heard that too about the Komura. And it doesn't have RF coupling like this. The more I look into this the more I realise what a rare bird it is. Production figures are said to number just a few thousand. Mine is serial no 006007 and I have identified no's 002505, 002717, 003606, 005758, 005782 and 006299. So perhaps 6500 max?? How rare is that in the grand scheme of things?
They were made in the 80's for FED, presumably at Tochpribor or Techpribor (depending who you read) presumably because they were a specialist optical factory.
The general consensus of opinion as I read it is that it is extremely good compared to other TC's.
This lens was offered to me as I was looking at an Orion 15. Way cheaper but infinitely rarer. I can get another Orion. I'll be waiting a long time before I get another rarity like this so cheap.
One on ebay was fully coupled and there was an uncoupled version as well, both the same poorer Komura optics. By the look of the extended front the Russian one is a five element type some simpler ones can be as low as three. The only other make that works well is the dedicated Tamron 135 converter, which only works on that lens.
The Russians seem to have been good builders of teleconvertors, there was an oddity shown to me at the TOE shop in Holborn, London, a 5x exclusively for the Photosniper outfit, never marketed as the light drop would put off most users. They did do a 2x at one point for the sniper. Stephen
They also made decent front element convertors for the Quartz Cine cameras, wide and tele, and they work fine, unlike most Far Eastern products, maybe because they were made by the same lens makers. Stephen
I've used the converter a few times since I started this thread. I bent the coupling lugs out half a millimetre or so and now it couples with the Canon. There is a little colour fringing if you pixel peep, but you scarcely notice it off film.