1. APO 70-200mm F2.8 II EX DG MACRO HSM https://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3340&navigator=3 2. APO 70-200mm F2.8 EX DG MACRO HSM http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3316&navigator=3 What is the difference? The 2nd is on sale pretty cheap, but I can't seem to find any of the "II"'s... I just don't understand the difference between the two. I have done some looking and haven't seen a comparo. Any help?