Sigma made three 70 to 300s, the bottom of the line non APO, the APO red ring and VR APO versions. I have the non APO in Sigma SA mount, came as a kit along with a 28 to 80 and SA7 camera body, optically good, AF is very slow, small motors. I also have the APO version in Minolta A mount, and Sigma SA mount. The Minolta version is gear driven while the Sigma is micro motor driven. Both are very good with color, a little soft at 300, but ok up to a 8X10. The gear driven Minolta Mount version is fast on my Minolta 9 and 800Si and digital Sony A900, slower on entry level bodies. The micro motor driven Sigma SA mount is faster than the non APO, but not lighting fast. I do not have an VR model so can't comment. I assume you are going to shoot on a Nikon body. Don't know if you are looking at a gear driven or micro motor body, might make a difference with AF speed.