I bought it to replace kenon 28 2.8. Aperture 1.8 decides. Here is my review andcomparison: . Ua/index. Php/kto-kogo-canon-28mm-f2-8-vs-canon-28mm-f1-8-usm/ Different pros: Very convenient focal length in full frame. Lightweight, light, relatively inexpensive. Extremely convenient for travel or reporting. Cons below: At aperture 1.8, it lathers very strongly. Since 2.0 it's sharp. Sharpness is generally good, but not stunning.