Like many others before me, I've owned the 17-40mm lens, but was never quite satisfied with the picture in the peripheral regions of my Canon 5D III. After a recommendation and the many positive reviews here on Amazon and I've bought the lens a few weeks ago and would buy it again at any time. Overall, it is significantly better than the mentioned 17-40mm, the border areas are very sharp and also the brilliance of the images in my experience is better. I tested the lens intensively on vacation and in the field of architectural photography and am completely convinced.
