Tragedy - I got a FF camera and was assuming my 50-135 Tokina would work on that - which it does to a point but can leave a "crop circle". I have a 70-200 Canon but am in the hunt for a 24-70 - I love Tokina so am drawn to that rather than Tamron or Sigma - but not with senseless blind passion. Lenses aren't footy teams! Anyone using this lens? Comments?