[toni-a]

Hmm...
I did choose the f/4 flavour of the 16-35 on the Canon side of life, and it looks like I would've done the same in the Sony scope.

For weddings, especially the dance floor f2.8 is practically a must have, for the rest f4 is just enough.
Wedding guys are major customers at least here, so naturally every manufacturer would make one, it's up to us to choose what we want.
Myself I bought tokina 16-28f2.8 used twice at weddings on 5D classic, it did really well, for the rest 10-18 on 7D never failed me.