Quote:
Originally Posted by The1
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Dave, do you have an experience with the 300-800 F5.6 from Sigma? I'm curious how fast the auto focus is. That is mainly the reason I ended up with the 100-400mm back in the day when I was looking at their 120-500mm.
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No, no direct experience. I have read some reviews somewhere that complained about slow AF speed.
When I put my 1.4x TC on my 500mm f/4, the AF get marginal on my 7D. It might be ok on a 1D MkIV, but not on Canon's pro-sumer bodies. Shooting anything that moves fast, like birds-in-flight, I think that you need f/4 to really lock on and track BIF.
Believe me, I understand the "need" for a super-tele out at 700 to 800mm and that's why I'm considering Canon's latest mega-buck lenses. Getting length and speed without selling the M3 is tough. For now, I've resolved myself to using the 500mm naked for any BIF shooting and only use the 1.4x TC for static shooting.
The reach really does help with detail, so you can struggle with AF and get shots like this:
Great horned owl perches by her nest. by
dcstep, on Flickr
And then use a shorter lens and try to get close for something like this:
Big, handsome bald eagle juvenile by
dcstep, on Flickr
There's really no inexpensive answer that I know of.
Dave