Yes, Zeiss Jena (East Germany) made these lenses in mounts for several different cameras, including M42 screw mount ( the so-called Pentax screw mount).Originally Posted by David A. Goldfarb
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.