Jaap, Thanks so much, great demonstration of the capabilities of this lens. Looks like a must have.
You know I used to have it in the film days and remember making some 24"prints. I remember they look good. Just that digital have different demands.
But as I see here it behaves very good, provably the little soft in the edges is due to focus curvature as all wide angle this wide usually have, meaning that if the wall was a bit curved toward the camera, you provably get a thoroughly sharp image.