sigma 120-300 f/2.8 or sigma 300 f/2.8 prime

TooManyShots wrote in post #10455065
Birds or mammals? With birds, 300mm isn't long enough. You can consider the 500 F4.5 from Sigma. BTW, the 300mm zoom has better IQ.

I would be shooting mammals. Thank you all for the info, I am going to check the 500 too, but probably way out of my budget. This one would be pushing it.

True, but its only the brandname. I've made some pictures with this lens and 1(2) TC(s) attached.
klick

To prevent brandwars I don't say anything about the performance ( of the Sigma 300mm 2.8 ) compared to the 300mm 2.8 L IS.
I would prefer the Sigma 300mm 2.8 over the 500mm 4,5. ( 300mm + 2x TK =600mm f/5.6 vs Sigma 500mm 4,5 and dont forget its no canon, so you can easily use the Sigma with 2x TK wide open ). The Sigma 500mm has some problems with teleconverters and it seems not to be as sharp as the 300mm.

Very ni ce thanks for the effort