My 15mm Voigtlander is back. The relationship with this lens started on the wrong note and I sold it. The first time I used it I had a Leica M4. The external viewfinder was quite off. I think it's very hard to create a decent viewfinder for such a wide angle lens. With Leica MM246 it's a different story altogether. It is a great lens. The vignetting is easily corrected in Lightroom, or not, if you like it. It's quite sharp and very easy to focus. It is also very small and light. 15mm gives you a lot of potential to play with surrounding shapes to create interesting compositions.