I second that. 2 mm tops. This lens doens't feel solid, but 5 mm is waay to much. Get it changed.
Optically, I agree with your observation too, Don. I find it from quite good at 80 to good at 200, above that becomes soft and contrast degrades quite a lot. Closing down for a stop or two helps, of course. Matja� > Don - > > Given these same conditions, my 80 - 320 moves about 2mm > > Paul > > > > With it set at 320mm and focused as close as possible (longest > > extension) very gentle pressure on the very front by the filter > > threads will deflect the front over 5mm. > > >
