It's been 10 months since release, now that (I'd hope) more people have this lens in their hands, what are the strengths and weaknesses of this lens in comparison to the original 100-400? My primary use would be birds and wildlife, and later BIF but that's just a pipe dream until I upgrade from my T1i to a 7D.
I'm probably going to wait for the sigma 150-600 contemporary to release before making a purchase of a zoom, but that's not going to stop me from thinking about these two in the meantime
I'll keep it simple:
Optically as good.
600mm > 400mm. Not even a debate.
1lb weight difference only
Focus limiter & modern VC (IS)
Fantastic for wildlife on any camera.