Hey all- I'm new to this forum, in fact I'm a brand new to the Nikon Family! Just purchased my first Nikon -- bought a D700 and am pumped to start getting the right lenses for it! I upgraded from a Sony Alpha, which I got into by way of having many Minolta 35MM lenses. Long story short , I am a family and children outdoor portrait photographer. I'm budget conscious, but also want to ensure that I am making the best possible choice in the long run, as we all know how glass holds its value. Here is my dilemma-- I found a used 28-70 2.8 for roughly $1000 and a used (cannot believe I found this used right now) 24-70 2.8 for about $1600. Given what I'm shooting, is the extra $600 and additional 4mm worth the spend? Any advise would be greatly appreciated! Thx!