the (Canon) 70-200 2.8 IS even with some "softness" at 2.8 is still
the only option you get in a low light situation. That's out of the
question
Then it's "deeper" than the f/4
It's true that many had the IS locking the camera and Canon still
didn't do much about it (yet) - I mean, they do replace the IS but
when you buy a new one you may have the problem ... (in other words
Canon will wait until you have the camera locked to be clear)
the f/4 is sharper
I had some problem with the autofocus but now is fine. Still it
goes completely OFF (of focus) for no reason, once in a while. LOL
What I find "odd" with the f/4 is the stabilization. The 2.8 may be
a stop slower (about IS) but it gets it right at the first shot
while the f/4 still needs two or three shots to stabilize. It's not
me because I hold the camera/lens in the same way as I do with any
lens.
The 2.8 is still a better lens, all considered.
but I have the f/4 now. to be honest. Sharpness comes first (for me
of course).
--
fun while shooting, always
the new & improved shy & adorable MarkLe