For those who do not have the possibility to offer 17-55 f constant of 2.8 at Canon, the Sigma lens is an excellent alternative, at least for an amateur. The product is "serious" in the hand and its operation on a CANON housing is fully compatible. The picture quality is, in my opinion, excellent, fast, quiet autofocus. Its openness is a big plus in low light and allows very good bokeh. Finally, it comes with a case and original lens hood and when we see how prices CANON sells these accessories, we said we had not made a bad deal.