Ok, thank you! That's what the manual tells too but it's another thing to hear it from someone, using it in the fields. :) Is the opening aperture (4.5) a problem sometimes? As the weather tends to be not that great over here most of the time, this can be a point for the 70-200 (2.8)? The gap between 70 and 100 shouldn't be a problem at all .. me thinks. But (very slowly) i do believe, i should forget about that converter ... sigh Tom