Sent my 28-70 lens in for repair costing me ($350!), and while it's now better than before, it's still not as sharp as my 70-200VR when shot wide open @f2.8. fwiw, I still haven't done a controlled test on tripod, only shooting it a little handheld. If I stop down even a little to f3.2, and esp a whole stop to f4, it's equal. Did I just get a bad example? Yes, there are times when one needs to shoot wide open, even though most times you don't. What do I do next just live with it, or send it back in? It's long out of warranty.