I'm considering changing my Nikon 16-85 and 70-300 following a recent shoulder operation purely to cut down on weight to an 18-300, what is confusing me at the moment is looking at various reviews, some have the filter size as 67mm and others as 77mm. Does anybody know when and why there was a change, obviously 67mm would suit me better as that is the filter size I already have, and I know when I buy one, hopefully on here, I only have to ask the seller, but it does seem strange. Any ideas?