I have tried the "Plastic Fantastic" Tokina 19-35mm before once, but ONLY in the camera shop, so I cannot comment on its image quality. But the feel of the lens is pretty good. The zoom ring is nicely damped, surprisingly so.
I was contemplating this and the Tamron 19-35mm f3.5-4.5 and in the end I bought the Tamron instead due to the BETTER ratings it got on
www.photographyreview.com . However, I am terribly disappointed with the Tamron. From Wide Open to f9, there is visible vignetting. The colours are rendered warmer than Nikon lenses, almost slightly too contrasty. It is lighter than the Tokina but it feels cheaper as well. It comes with a hood which the Tokina does not provide for free. On paper, it beats the Tokina FLAT because of its closer focusing, more aperture blades (cant remember if its true) and lighter weight. Sharpness is good in the centre, but my lens had a TERRIBLE softness at the edges ( anything out of a 2 CM radius from the centre on 4R photo paper). This was more evident at the lower left portion. At first I thought it was due to a shallow DOF when I shoot at wide apertures, BUT from f3.5 to f22 , this softness is evident. TERRIBLE !!!!! It has a poor resistant to flare and ghosting as well. I flashed a rock once and the reflection off a POROUS nonreflective rock caused some ghosting. However, it may be due to a lemon that I got, but it was so terrible ... I decided not to get another one.
I have heard that the Tokina is good.... but, I suggest you do some research on DPreview.com . A lot of people use it, but take note that they use DSLRs with a crop factor that does not show the soft edges. I use film.
Wide angle photography is awesome. I love the effect. But , I will AVOID the Tamron, and MAY give Tokina a chance. If you have the Cash, go for a Nikon 18-35mm or a 17-40L if u use a Canon. But if you are a poor student like me, I will not hesitate to go for the
SIGMA 20mm f1.8 EX ard $500 . Freaking sharp f2.8 on. If you own a zoom lens in the 28-105mm range.... you dont really need a wide angle zoom, because you'll probably use the Wide End of a wide angle zoom anyway 99% of the time. Wide angle zooms (consumer ones) arent good at telephoto end.