This is an outstanding lens for the price, but I encountered some difficulty getting it to perform. There is a focus shift on the lens that made it difficult to use at wide open (f/1.5). The lens I received was calibrated for spot-on rangefinder coupling at f/2.8 (admittedly a mistake on Zeiss' part). I sent mine back to the factory in Germany, where they re-calibrated it (to spot-on at f/1.5, not 2.8) for free after some paperwork. Now, it is very nice, but it doesn't get fully sharp until somewhere between f/2 and f/2.8. Overall, a very nice lens that compares favorably to some of my vintage Leitz lenses.

By Star_navig8r from Behind the Cheese Curtain-Milwaukee Wis. on 6/18/2008

I chose this lens for the basic reasons:
1. Low-light capable
2. Extremely sharp wide-open
3. Aperture increments 1/3 stop clicks
4. Zeiss build quality, guarantee, reputation
5. Price was significantly lower than Leica equivalent
6. My previous experiences with Zeiss optics have been perfect!

My only negative is the Zeiss hood is relatively expensive...but it fits & works perfectly!!