Indoors on 1.5x, like for basketball,volleyball,even wrestling and gymnastics, a 70-200 sucks...it's too damned LONG on a crop--frame body. This issue with Sigma has long,long,long been poor autofocusing on some examples of their lenses...with some camera models. When the camera makers update their AF protocols, the third-party lens makers have to reverse-engineer their lenses for the newer cameras; this is usually a fairly uncommon, rare occurrence, but say like, when the D200 came out and consumer Nikon's got back-button focus, Sigma's older lenses were suddenly, in many cases, not working right. Honestly...I got rid of my two big, high-end late 1990's Sigmas because my 2005-and-newer Nikons didn't focus "right" with them...wayyyy too many instances of severe focus hunts with the HSM EX-series 180/3.5 APO-Macro and the EX-series HSM 100-300mm f/4. I LOVED the Nikon 50-135mm f/3.5 Ai-S Nikkor manual focus on the D1,D1h,and D2x crop-frame d-slrs...the 50-135mm range was SUPER-handy!!! There is simply no comparison between the handiness of a 50-135 and a 70-200 or 80-200 on a crop-frame body; the shorter lens makes a HUGE difference in usefulness. So,so,soooooo much better for parades, events, and portraits/scenics, with the 50mm versus 70mm short end. Now that we've gone up to 24-MP on APS-C...there's less need for the 200mm top end all of the time, but for longer-range stuff, 200mm is better than 135mm was, and much longer than 100mm is.