Quote Originally Posted by David A. Goldfarb
MC should be for "multicoated," which would make these East German Zeiss lenses of relatively recent vintage. If you can post an image of the mount, I'm sure someone here can help you identify it. If the mount is something like M42, then you can easily adapt it for Nikon. If it's not, it might be easier to find a Praktika body to use them on (not sure offhand what mount they use--Exacta?).
Yes, Zeiss Jena (East Germany) made these lenses in mounts for several different cameras, including M42 screw mount ( the so-called Pentax screw mount).
M42 thread Adapters are available for most SLR cameras.

I believe that the f.2.8/ 28mm and the f2.8/135mm lenses were designs acquired from Meyer Optic when Zeiss Jena absorbed that company.

I have several Zeiss Jena lenses in the M42 screw mount including:
1. 20mm f4 Flektagon (single coated)
2. 20mm f2.8 Flektagon (Multi-Coated)
3. 35mm f2.4 Flektagon (Multi-Coated)
4. 135mm f4 Sonnar (single coated)
5. 50mm f1.8 Pancolar (Multi-Coated)

All of theses lenses are excellent performers, sharp and contrasty.

I use all of them with an adapter on My Contax RTS3 and my other Contax SLRs And, they screw right into my new Bessaflex.