Had to check my more common 223xxxx 8.5cm F2- goes to F22, and uncoated. The original Nikkor 8.5cm F2 only went to F16.
Shortly after "Tokyo" changed to "Japan" the Nikkor added click stops and went to F32. The brass is also thicker on the older ones. I have one in S-Mount that goes to F16, my later 'C'ontax lens goes to F32.
Who was suing who? Jena suing Oberköchen in West German courts? Soviets couldn’t care less about borders, patents, lawsuits or intellectual property. Unlike nowaday…😎
Put yourself back into the 1950s. East Germany has very few avenues to generate hard, foreign currency. One of those avenues is Carl Zeiss Jena. CZJ produces their Sonnars, Tessars, Biotars, etc. and marks them Zeiss, with a red T (after all it was Jena that developed the coating). These are shipped to England, France, Italy, the Netherlands, Belgium, etc. in competition with Zeiss Oberkochen. Zeiss, Oberkochen then sues Jena in England, France, Italy, the Netherlands, Belgium, etc. for copyright infringement. Remember, this s before EU. Every country has its own copyright laws and court systems to enforce them. Every jurisdiction determines its own solution to the problem. As these are all western European courts, Jena loses a string of lawsuits. Each country imposes its own rules controlling how Jena can market its products. This is why, during that period, lenses sold by Jena in the west have a wide variety of different trademarks and logos.
The 'F' coating mark also appears on Opton-Biogon lenses in that early period. It's when the 'T' as well as the "Carl Zeiss" mark were under dispute.
Why 'F'? Well it clearly had been a 'T' before being made into an 'F'-- there aren't many letters in the alphabet that you can turn a 'T' into without having to erase lines, which obviously isn't possible with milled/engraved lettering.
Also I'd strongly debate that the Soviets "just" seized the factory. They got the workers and a lot of the personnel and know-how with it. In fact the production of lenses hardly skipped a beat and a lot of the lenses that are now sold as "war-time" were actually made from war-time parts but under Soviet supervision by Zeiss workers using Zeiss parts before the whole works (including the workers!) got shipped to Krasnogorsk.
There are in fact interviews with surviving ex-Zeiss then-KMZ workers out there on the internet.
It's quite interesting reading.
The thread definately got diverted. That said, I have several KMZ J-3s that are stellar perfromers, and really well made.