I'm recently into IR and its difficult to find the right focus. The 70-200 VR is of course a great lens, but Nikon did not put any IR reference mark on this lens and apparently it focuses IR somewhat closer than the visible spectrum. I've experimented and caught somewhat of a focus occassionally, but it seems very difficult. Landscapes and long depths are no problem to focus for infinity, or a tight aperture when it works, but I'm trying to do portraiture! It is harder than I imagined to find the right mark. There seems to be a very small margin for error at about 10 feet away. Nikon has not even published any IR focus conversions for this lens. Does anyone else have this problem? Any suggestions?