Very bright lens with pro-level build quality. The sharpness between f / 5.6 and f / 16 is excellent even in the corners. Between f / 2.8 and f / 4 it's very good in the center but softer in the corners: especially visible if we made a test dive, much less on the ground. I can not compare against other UGA because I've never had that there. The constant aperture of f / 2.8 is significant, especially for indoor shots or low light. The autofocus works perfectly on my D90 (careful, it is not compatible with all housings). The zoom is narrow (11-16) but it does not bother me more than that because I use it mainly to 11mm, and I see the 12-16 ranks as a small margin of maneuver in handy in certain situations. Be careful not Tokina SAV in France.
