I picked up a new 100-400L lens while I was out of state doing a shoot. The lens was new, and wrapped up the way my other L lenses have been, and I have no reason to suspect it was a used item. The lens is nice and sharp while using autofocus, and I am pleased with its performance in that respect.
Sadly, there is a problem....
The manual focus ring moves the zoom tension ring. The tension ring will tighten the zoom, but it also tightens the manual focus ring. They will turn independant of each other if one or the other is held in place, but manual focus is not possible with this beast.
Is this a known problem? Is there anything I can do on this end aside from sending it back to Canon? I would be delighted to find out that it user error, but after using it for a few days, I doubt it.