I love this lens! By far the best fast prime lens for Leica screw mount or M mount cameras under $500. The main competitors are over 40 years old and usually softer and more open. The Nokton is very sharp at f/1.5, which is the main reason for buying a fast lens. It's a Leica threaded mount, which is good because there are no other modern lenses for older M39 mount cameras like the Leica III. or Canon P. You can also use it with an M mount with an adapter. (However, you cannot use an M-mount lens on a screw mount camera.)