The Leica Summilux 21mm f/1.4 is the fastest and widest lens available for Leica M mount cameras. It is a surprising performer and often found in my camera bag. The wide angle truly allows you to capture the scene around you. If you are looking for a wide angle lens and have the means I wouldn't look any further. I am extremely pleased with the results I have been able to get with the Lecia Summilux 21mm f/1.4.
I recently brought only this lens on a trip to Singapore and was amazed with what I was able to capture. I don't think any other lens would have done justice to the views from the top of the Marina Bay Sands Hotel.
21 shots at 21mm with the Leica Summilux 21mm f/1.4.