With the copy i got,i had such a bad experience,i will never buy a 'budget' lens again.
As i said the 70-300 kit lens had before the sigma was far better than the copy of the
120-400.Also someone says on this thread,that their 120-400 is'nt that sharp at 400mm,
Whats the point in having a 400 lens?,Anyhow,may be i am fussy,But to be able to go out
into the field and have confidiance in your gear is worth paying a bit more for,IMHO.
The sigma 120-400,just made me feel ill after i saw all of its images.I would recomend anyone
to look at other options,rather than the sigma,just my opinion.
The original poster wants a lens for sports action,I can recommend the canon 400 mmL prime
F 5.6,this is amazing lens for birds/wildlife,and pro surfer photographers use this lens.
Its very light,SHARP!,quick focus.causes no problems,a great daylight lens
hope this helps