why only 3 stars for an amazingly sharp lens which, with its useful 12mm equalized for full frame, stands quite alone on the market? The view angle is impressive, unfortunately the autofocus works sigma typically not reliable, neither on a 5DIII still on a 7d. Moves the focus in dependence on the distance from a back focus at a front focus. which can be even in a 5DIII not correct. My experience with the 50mm 1.4 from Sigma tell me that the service can not adjust. Unfortunately, Sigma builds interesting lenses, but can provide no suitable for Canon autofocus. Alllerdings which is at 12mm and an aperture of 4.5 is not nearly as tragic as a 50 1.4.
The maximum aperture of 4.5 is just not as famous considering the price and the 88mm front. For shooting outdoors in good light disturbs not, inside is necessary despite the 12mm fast artificial light. Otherwise a very nice lens.
