Fuzbal wrote in post #15787304
I need sharp lanse with good AF. I compare your fotos with bobbyz but i dont judge sharpess but if they are hit. It does not matter if its crop or not when AF did not hit where should (unless you celowałeś the guy for 2 plan ...)
Its my old Pentax K-r + sigma 70-200/2.8 EX (non OS), first steps in sport ;]
Its crop (i dont remeber how much) but it was well-hit on f2.8 or 3.2. I need to be sure that the 120-300 can give me somthing like:
Its from my 7d + 70-200II. Im not afraid about sharpness of sigma (its very good for me) but AF is my only problem. It can be good enough but it can suck;/
As I keep saying those rugby shots were taken with the Sigma 500mm (and at 6-10MP jpgs before cropping, because media outlets and sponsors don't want their togs giving them a 1,000 x 30-45mb RAW files each !) and also as I said the 120-300 has even better AF, in my personal opinion.
I shot the rugby the year before (2011) too and that time with 2 x Pentax K5 and with the superb DA*300 and Sigma 50-150. The keeper rate was much lower (due to OOF shots from the AF of the camera and lens - 300 - not keeping up) than with the D800 and 500mm. I'm sure the Sigma 120-300 and 5DIII would blow the Pentax's performance away - as it should.
Your 70-200 is simply far too short for rugby, baseball, American football, football (soccer) on a full sized pitch (maybe for non-pro school events it would work). The pros use 400/2.8 most of the time.
When you are shooting to the far end/side of the pitch you are now dependant on your camera's AF, as well as the speed of the lens' AF. Anything except single point and the camera is not going to read your mind to pick out exactly who you want from a bunch of players (rugby, american football) whereas football (soccer) and baseball are much easier with usually not more than 2 players involved in the action most of the time (except for corners in soccer perhaps).
IMHO the 120-300 OS version more than meets sharpness criteria and it's AF performance on cameras of the level of a 5DIII or D800 is a lot more than adequate. YMMV.