both shot handheld with the 120-300 os, minimal processing.
the heron (shot this morning): 300mm f3.5 iso400 1/1600s 50% crop (os wasn't switched to pan, but it didn't appear to affect the outcome significantly).
the squirrel (the first 'real world' test shot when I got the lens): 200mm f2.8 iso200 1/640s
Sheesh you must be Mr Muscles! The Sigma AF 120-300mm f/2.8 APO EX HSM DG OS (isn't that a nice long name for a lens?) weighs in at a beefy 2950g vs 2400g for the Canon 300 f/2.8 vs 1490g for the 70-200 f/2.8isII. Hand-holding the Sigma would deliver the dual advantage of being a great lens and a gym weights workout rolled into one. As an 80Kg weakling, I'd be packing the monopod. The 70-300L is a svelte 1050g.
I was very interested in this lens about a year ago when the new OS model started shipping, but there was so little information about it that I let the whole thing slide. But if it works as advertised, it's a very compelling lens. I have read that the older model Sigma 120-300 actually does not make it all the way to 300mm, it's more like 280 at the long end. Is this also true of the 120-300mm f/2.8 APO EX HSM DG OS?
At just a bit over $2k it's very very tempting. http://www.shopbot.com.au/m/?m=Sigma%20AF%20120-300mm%20f/2.8%20APO%20EX%20HSM%20DG%20OS