I took to replace the Sigma 17-70 2.8-4, which served me for 3.5 years and which I subsequently successfully sold on the Internet. Feelings - you switch to a technique of a really higher class. Firstly, the wide aperture is absolutely working, secondly, it shoots MUCH better against the sun, thirdly, the focus is much faster and more accurate, and fourthly, the picture itself is visually sharper and richer. And the fact that it is 20 millimeters shorter in zoom - so I have a telephoto lens for that. Also Sigma, 50-150, an excellent lens for "areal" reports and portraits. The only thing is an unconvincing stub, but this is the weak point of all sigmas, and I practically don’t use it.