Originally posted by Tommot1965 no worries,,I amused you bought the 50-135 locally....Id have still gone the extra $500 though for the sigma...did I mention its also sharp at F2.8
try that same shot with the axeman running towards you full tilt..then abruptly changing direction before delivering the final blow...you have a similar situation to shooting a footy game/soccer/hockey.....taking a static subject and saying AF is fast enough isn't quite the same..that subject being sharp would come down to shutter speed rather than AF speed ,,
I was pretty sure I was offered less than A$900 for the sigma at the shop I tested it on - but no, I wasn't impressed with it.
As for your scenario - sorry I don't buy it. It doesn't make that much of a difference in my experience - most of the time in a situation like that, I will be shooting at 7fps and the lens should already be mostly focused so it's just a case of tracking focus from shot to shot.
And I already mentioned I did a test shooting a moving car (same scenario as selar) and the DA*50-135mm tracked each shot perfectly.