I took a chance and orderd a Linear Polarizer (by accident) for my new AF lens (Sigma 24-70mm EX f/2.8 DG-DF) and it does work GREAT! Even though the owners manual itself says to use a C-PL (Circular Polarizer). My theory was, that if, the front element does NOT rotate (which this one does not) why can't you ues a standard (MF only) Linear PL? Well . . . I had a couple cocktails one night and foolishly orderded the cheapest PL filter I could find for 82mm only to find the very next day that it was a linear and not a C-PL. OK I thought "What the Heck? I'll try it and if it doesn't work my theory will be junk and I'll just re-sell it" well it does seem to work thus far. Has the same qualities that I find in my much more expensive C-PL for other lenses (with rotating front element) but half the cost (granted that was more than paid for in the lens cost). I WILL post pics to prove this when I get a chance. In the meantime, please, any pro's or people in the past that have tried this tell me what problems I may find or that I am being dumb now! This was a VERY shallow test so far ( so I still could be proved wrong ) but so far we are all good, it delivers razor sharp focus and very good contrast in cloudy skies as well as zoomed reflections Disclamer: A no rataing front element lens means that the very front of the lens does not ROTATE at ALL during autofocus operation.