A friend of mine has the Sigma 150-600mm Contemporary (on a 7D2) and in all but quite dark situations (think rainforest just after sunrise) I can’t pick much/any difference to my 200-400mm with teleconverter engaged (also on a 7D2), although if I stop down to even f/6.3 the Canon sharpness takes over. At 10% of the price and just over half the weight I’d call the Sigma Contemporary the best value bird photography lens on the market. My research back when he bought it also indicated that the Sigma at 600mm f/8 had equal or slightly better image quality to the new Canon 1-4 with a 1.4x tele at 560mm f/8. The Canon won on weight though. And close focus.

The clear downside though: in low(er) light the Sigma needs too much ISO boost to hold it at f/8. The Canon 100-400mm II (albeit only at 400mm) is a step up in lower light. And the 200-400mm is yet another step up.

Been there, done that. In spades 🙂

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