Chris,
The 7D is an awesome wildlife camera. See some of the pictures I've posted from our recent Galapagos and South America trip for examples of what a bad photographer can do with it!
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http://www.iceinspace.com.au/forum/s...ad.php?t=89843
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With a modern tele lens (I have the 70-300 L) with fast auto-focus (your 400/5.6 also has fast focus) the ability to capture that quick shot is fantastic.
Cheers,
Jason.