OK, here we have something I've been doing because the 70-400mm SSM and A77 combined really frustrate my attempts to get exactly the results I need in very poor light conditions from a long distance - but that after all is why I bought the lens...
First of all, a family of cormorants. This was not some easy spot with close access, birds in Scotland don't stick around when humans come into sight unless there's a couple of hundred feet of river between us and them. So this involved scrambling into undergrowth and flood debris on their side of the river. Although the sun was out, this spot they choose is in shade from cliffs beside the river all day.
This is a 100% section of this f/8, ISO 800, 400mm shot sampled down to 17.5 megapixels. At 24mp, none of my autofocused shots looked good enough especially those at full aperture. This was in the morning. I was still trying, after first attempts yesterday which just produced a soft mess of aberrations and focus error, to get the A77/70-400mm combo to produce an acceptable AF shot ourdoors, after fine tuning the Micro AF and checking sharpness on indoor subjects at low ISO. Those proved there is nothing wrong with the lens at 400mm wide open, in the place of focus, though it's not pretty just outside the sharp zone.
This may surprise you, because it's from the A55 fitted with a cheap Sigma 70-300mm APO Macro DG at full aperture - and I've blown up the image to 25 megapixels during raw conversion. It's a lower ISO of 250 (about twice the light level) but even so, my tests on the Sigma APO Macro show it to be much sharper.
Then, using MF Peaking to set the focus (I'm learning now always to approach peaking from a closer distance - never make the adjustment from further away than the subject, you'll end focused on the very back of anything solid instead of the front, as peaking will tend to select only the outline of the subject). This time wide open on the 70-400mm at 400, and better light again, ISO 200 though ACR corrections made it more like 400.
Good enough? I'm not sure. I want the 24 megapixels on APS-C to enable me to pull in subjects like this with the 400mm, better than a good 300mm lens on the A55 can manage. I took some at ISO 50 by mistake (moved a control while scrambling around to find a clear shooting position) and they, though unsharp due to marginal shutter speeds, tell me that any kind of higher ISO on the A77 is really killing both shadow and sharpness detail.