Originally posted by Cuthbert Actually the P meant the lens was multicoated and supposedly at the same standard of better than the Zeiss T lenses
I have read that as well, though with Zeiss T (no star), the distinction was coated vs. non-coated.* That is where things get sticky. The coatings on FSU lenses post WWII evolved over time with the earliest lenses being non-coated. The Zeiss coating technology was specifically negotiated as part of war reparations at the Yalta Conference and the Soviets were quick to apply the tech to their optical industry. For the earliest Zeiss-derived lenses the red P obviously followed the Zeiss convention...the lens elements were German-sourced. Whether the red P had any particular significance later is hard to tell.
Conventional wisdom is that all Soviet glass from the mid-50s on is coated. The red P may signify better coatings or a more elaborate process. There is one thing that is sure, none of those red P lenses are multi-coated in the modern sense of the term. The technology did not exist prior to the Pentax SMC and Zeiss T* products. Those Soviet lenses that are multi-coated are prominently labeled as such and date from fairly recently.
Steve
* Zeiss invented anti-reflective lens coatings in 1935 and the process was widely copied after WWII. SMC and T* MC coatings were developed by a joint Asahi/Zeiss venture in the early 1970s.