Is the d4 better at focusing than the d800?

I have both...  And I use the D4 when I need to take advantage of the frame rate (duh).  I have, however, played with the D800 on traditionally difficult acquisition targets - birds in flight and whales breaching.   I was pleasantly surprised how well the D800 did.  The D700 isn't bad either.

The D4 might be a bit better and perhaps in certain circumstances might be significantly better (cf John Cole's posts above concerning motosports) but for the kind of photography I do, I won't hesitate to use the D800 for birds if that's what I've got on the lens.

Certainly if you need frame rate, the D800 is a bit of a slug.  But you really don't want 60 36 MB pix to shuffle through, do you?

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RG www.lostrange.com