The Tamron 17-28mm f/2.8 Di III RXD has only been available for pre-order one week, but already Tamron has had to issue an apology about availability. Apparently demand for the new Sony E-Mount lens has been so high that even those who have already placed an order might have to wait a little while longer to receive their unit—to say nothing of new orders. The apology was published by Tamron Japan, who made it pretty clear that not all pre-orders…