The Carl Zeiss Jena 50mm f/2.8 M42 thread lens coupled via an adapter to a Canon digital SLR is perhaps not the ideal landscape lens. It gives a field of view of 80mm: more suited to portraits, really. I gave up the pursuit of M42 thread lenses and sold the Canon - an EOS 20D, and a remarkably well made instrument - but the only M42 lens I truly miss is the humble CZJ 50mm f/2.8 Tessar.