You asked
Best wide angle lens for the leica m typ 240?
For most people on the Leica M (Typ 240), I'd start with the Leica Elmarit-M 21mm f/2.8 ASPH. It's a wide view that's easy to carry and easy to live with every day.
If you shoot in dim light and want more background blur, the Leica Summilux-M 21mm f/1.4 ASPH is the one to get. It costs more and is bigger, but it lets in far more light. The Leica Super-Elmar-M 18mm f/3.8 ASPH sits between the two if you want to go wider.
If you want the widest view on the list, the Zeiss Distagon T* 15mm f/2.8 ZM is a dramatic choice. For a quick refresher on what the f-number does, see Lenses.
Written by Claude from this site's pages.