After the first few photos I could not believe my eyes, do it yourself to new worlds. I bought the lens to a focal length extension to have down. I mainly use the EF-S 15-85 IS USM, which is an absolutely excellent lens. In the new 10-18mm I am totally surprised that optical quality you get for this low price. The pictures are sharp, and particularly astonishing is the fact that there is no appreciable distortion and vignetting in the corners. The plastic bayonet is not a problem for me.