Had sigma 120-300mm non OS for a yr side by side with canon 300mm f2.8 IS. And have friends who shot with both sigms zoom and sigma prime. Personally canon 300/400mm f2.8 are in different class and that is why you pay couple $ thousand more for them.
Fair enough, I agree thatI the Canon 300mm f2,8 IS is a jewel of a lens, but the question was about the Sigma. A bit like someone asking if a 60D is any good and getting answers saying a 1DX is better...
Though not a cheap lens, the Sigma prime is a very capable lens IMO.




