I purchased this lens in September the images it produced were amazing. I used it at Christmas and was again very happy with the quality. In January I was surprised to find the images lost the sharpness. After changing lenses and comparing it was equal to a 2.8. I sent it to Nikon; they returned it saying "Could not repeat issue". I'm sure they just shot and few and figured it was good enough. Nikon choose to ignore my emails. BAD lens BAD customer service....back to Cannon.