With mixed feelings (because of partly. Rather negative reviews) I ordered anyway and am very happy now. With my previous WW (Canon 16-35 1: 2.8 L II 1DS Mark III) I just come across too often at the borders (motives: rooms, kitchens, large machines and always damned little space). The maximum aperture of only 4.5 / 5.6 is (in this case) completely wurst I always ausleuchte with up to 10 flashes and because of the sharpness eh at least Bl 11 - must dim 16 (also the Canon).. Thus, the sharpness, even at 12mm, top. Even at the edges. A spirit level and a grid matte screen in the way, help me adjust, otherwise still tripod, mirror lock and cable release. Distortion is when shooting "from the center" out not worth mentioning and easily correctable. Incidentally gibts also designs where dynamics are quite desirable by distortion. Otherwise: eg ISO3200, and at 12mm, you can take pictures even without shaking up to 1/12 sec Easy out of hand. So fact: you can use this lens make Hervoragende recordings. By the way, if the AF times does not apply: completely disarmed manually pull and refocus. Then passts again.