I had the chance to compare my Sigma 30mm 1.4 Canon lens to that of my friends original Canon 50mm 1.4 and I must say that I was impressed. In terms of build quality the Sigma actually seemed like it had the edge over the Canon which is not something I see every day. When it comes to the actual image quality I think the Canon has a slight edge but not much. Considering the price difference I would say that it is quite an achievement. My friend is a landscape photographer primarily and he said that he has used the Sigma in the past but the results did not satisfy him. I do not have any problems with the lens but I guess corner sharpness is not as important to me as it is to him. Unless you are a serious professional I think you will be more than satisfied by the quality of this lens.