I have this lens, and I also had the F 35-80 4-5.6, until I sold the latter last January, and the Tokina is sharper. In fact, it is very sharp for a zoom lens, its only disadvantages being noticeable barrel distortion at 28 mm. and that it is a flare prone lens, compared to SMC Pentax lenses.
Tokina must have put a multi-coating that is not as good as Angenieux's on its lens as the Angenieux "father" lens is said to be very good against flare.
Andre
