70-200 2.8 IS vs 300 F4 IS

Which one do you think would be sharper stopped down? Or rather, which one SHOULD be sharper stopped down? Personally I think the prime should be sharper across all apertures, based on others information and photozone.de. I might need to send mine in and would just like some opinions.

edit*
I'm talking track here...Perhaps the 300f4's AF speed isn't as fast or up to snuff for runners and sporadic action?

I have both, and they are pretty comparable.

If you need 300mm, the 300/4 is faster focussing and sharper at f/4 than the 70-200+1.4X TC is at f/4.

JeffreyG wrote in post #7887632
I have both, and they are pretty comparable.

If you need 300mm, the 300/4 is faster focussing and sharper at f/4 than the 70-200+1.4X TC is at f/4.

I haven't tried that combo yet but I would think it would be no contest. However, both lenses at f6.3 seem pretty close and at f4 it's almost the 70-200 that LOOKS better.

I would think the prime would, or at least should, best the 70-200 in all situations.

Perhaps the lens isn't up to par with the hype or I'm expecting too much?

What's strange, and makes me think I should send the 300 in, is that it almost looks better when I'm using the 1.4 on it.

I had the 2.8 zoom for a short while (took it back) and while it has very good contrast the actual resolving power is not as good as the 300 f4 IMO

I use both for sports and to me there is nothing between them, both do the job.

ICee wrote in post #7888301
I use both for sports and to me there is nothing between them, both do the job.

That's what scares me A 2.8 zoom is as good/better than a f4 prime? Something seems amiss...