Everything has been said about the sharpness, high brightness, it really is all good. Its problem is its sensitivity to flare but there is no worse than the competition. Note that this goal, despite being designed for APS-C sensors, remains usable in full size at its maximum focal length, ie 16mm, and with a very slight vignetting. I had the opportunity to try on a 5D markII is very good. It is this detail and openness that made me prefer the good Canon 10-22, which it can adapt to a full frame camera. Given the rapid democratization of the full format, it is a detail to be considered for lovers of photography.