06-02-2014, 08:25 PM
I own Canon 17-55 a very robust lens with excellent image quality one of the best I have used, myself I see such a move as irrational.
IS is great easily 3 f stops I don't expect sigma OS to do the same
Never had AF problems with this lens, none of my ex sigma lenses (24-70f2.8 20mmf1.8 and 14mm f2.8) had such a good precision.
Also AF is blazingly fast much faster than HSM on my ex sigmas.
So I recommend you think twice before such a move
IS is great easily 3 f stops I don't expect sigma OS to do the same
Never had AF problems with this lens, none of my ex sigma lenses (24-70f2.8 20mmf1.8 and 14mm f2.8) had such a good precision.
Also AF is blazingly fast much faster than HSM on my ex sigmas.
So I recommend you think twice before such a move