Thanks for the comments!
I wanted to ask if you noticed some overexposure in the first and second shots did you have a chance to use this histogram?
There are a few blown highlights in all three shots, actually, but as they're things that 'should' be blown (chrome reflections, hotspots from stage lighting, etc.), I don't mind. I think the overall scne exposures are good, and in particular the DR at ISO 12800 is impressive, from the black shoes (with many shades of gray/black being distinguishable in the shadows) to the highlights on the shirt.
I know with that 70-200 2.8 lens we're all tempted in low light to keep the ISO as low as possible and the aperture wide open to get the best resolution but did you happen to notice a bit of blurriness in the hand of the first musician (1st pic)? I wonder if a narrower aperture with higher ISO would have helped or possibly Zone AF or the 61 Point AF? I had a similar instance where I was using a 70-300 L IS USM at 5.0 @ 221mm. I neglected to realize that 5.0 aperture still wasn't small enough as the focal range must be added in that equation as well to determine at what F stop would be the lowest I could go without sacrificing sharpness.
Well...wide open usually does not give best resolution from a lens - a couple of stops down from wide open is the resolution peak for most lenses. You're right, his hand is outside of the DoF on the first shot. Actually, the one that needed more DoF, IMO, is the third one - would have been nice to have both Nathan and my daughter in focus, but she's outside the DoF a bit. But...I was already at f/5 and ISO 12800. I may become comfortable shooting ISO 25600, especially if DxO's high ISO NR is better than DPP's (as it is for the 7D and 5DII).
There's something you may have heard of called Circle Of Confusion within each SLR that helps to determine the best aperture based on distance and your focal length. I did some reading on this yesterday..quite interesting.
CoC is based on sensor size (independent of MP count), and is what underlies the DoF calculators out there. After a time, you develop an intuitive feel for the aperture you need at a given distance/focal length to capture the DoF you want. There was a suggestion in another thread of using f/number = number of people in the group shot, up to f/8 or so, which was a nice way to put it.
Lastly, I wonder if the 61 point or Zone Af would have helped any (open for comment on this) with the 2.8 aperture making it any sharper..do you recall which AF selection you had on?
All of the shots posted here were in AI Servo mode with 61-pt auto selection (which also enables the iTR face tracking). Keep in mind when using auto selection in servo mode, you can pick the starting AF point, but when using auto selection in One Shot, the camera will lock into the closest subject, which may not be what you want.