I'm seriously considering either getting this lens or a 70-200 f/2.8 and a TC for my trip to Glacier. It's a tough call which of these two ways to go since they both pretty much put me in the same place. I am leaning toward the 70-200mm since it will double as a fast(ish) lens when off of the TC. But I do like the IQ this new lens delivers. Ugh...decisions, decisions.