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As to Nikon's current 80-400 VR zoom: There is still little competition, only the Sigma 120-400 OS came out after my test. For a review of that lens look over
here. The Sigma is cheaper than the Nikon and larger, the OS did not convince me and bright light produced visible haloes around dark edges. The other lens that comes to mind is the Sigma 100-400/4.0: unfortunately my copy was heavily decentred (see my review
there), but it is pretty bright with a constant f/4.0 aperture (which also helps subject isolation) an could have been sharp if Sigma QC were better.
And this is one of the recurring themes all over the internet: If you go Sigma make sure you buy at a dealer where you can swap the lens w/o a prohibitive restocking fee because there is quite some risk that your first copy is a lemon.
So all in all even today the Nikon 80-400 would be on my recommended list because it's sharp, not too heavy/bulky and zooms back to 80mm which gives you quite some flexibility in the middle of a wedding shooting.
On a more personal note, as I have no experience with weeding shots myself, I'm a bit sceptical whether you really need 400mm or even 300mm focal length on these occasions. Because as an invited photog you normally can get close enough to the action. That in turn would lead me to recommend Nikon's fabulous 70-200/2.8VRII, my review of which is
here.
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Thomas (beware: Nikon-fanboy and moderator!)
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