Hi -- Slower lens speed (smaller maximum aperture), a tendency toward pincushion distortion at the long end and barrel distortion at the wide end, more darkening at the corners, heavier and sticks out farther. In other words, all the usual zoom characteristics. 🙂MelanieC said:What is the functional difference between this and the non-zoom model (other than the obvious)? My understanding is that lens quality in the "zoom" models is lower but I don't understand why.