Most people, when they ask this kind of question, don't really want a particular lens, but specific effects. Rather than buying a special piece of glass for that, try experimenting to get the effect with your existing lenses, such as:
- Haze: Smear some vaseline on a clear piece of glass, hold it in front of your lens.
- Vignetting: Cut a ring from cardboard with a hole slightly smaller than the front element, hold it in front of your lens.
- Flare, low contrast: Make some deep scratches into a clear piece of glass, hold it in front of your lens.
Advantages: One less lens; effect can be achieved with all lenses you already own; you can control the degree of the effect.
Disadvantages: None.
The Leica is not the best system for this kind of experimentation because you don't get in-viewfinder verification of what you're doing. Best do these experiments with an SLR, then when you know how to get good effects apply them to your M lenses. 🙂
Philipp
