Thanks for the review and comments. I primarily do landscape photography and recently bought the 5DSR. Now I'm in the process of upgrading my glass. I'm blown away with the IQ of my new Canon EF 70-200mm f/2.8L IS II. Now I'm looking to upgrade my Canon 24 - 105 F/4 L, the kit lens that came with my 5DMII. I have been strongly considering the Canon EF 24-70mm f/2.8L II, and recently learned about the subject Tamron SP 24 - 70. Has anyone compared both lenses with the 5DS or 5DSR? I hear that you need super sharp lenses with the 5DSR. I don't want to be penny wise and pound foolish. At the same time, I hate to pay too much. Thanks.