Bob Andersson wrote:
at first glance you'd think that would be better as f/1.4 is brighter than f/1.8 but, if I've got my sums right, that Panasonic lens is actually letting about 1/3rd as much light from the scene onto the sensor as the Sony.
Well, this should be interesting. I'm going to go out a limb and disagree with Bob. While I agree that Depth of Field will be doubled on an m4/3 sensor, I believe light gathering power stays the same. i.e. theoretically, if a scene is properly exposed on a full frame camera at, say, 1/60, f1.4, ISO200 it should also be properly exposed on an m4/3 camera with those same settings. Yes, the Field of View and Depth of Field will be different, but exposure shouldn't be. (Of course, in actuality, there would probably be a slight difference due to different light transmittance (unless you use T-stops instead of f-stops), different manufacturers' ISO ratings, etc.)
If my understanding is correct, then to the OP:
This is an advantage for m4/3 for concert photography because you can achieve proper exposure in lower light while still having usable Depth of Field (say, a foot or two). On the other hand, full frame sensors generally have less noise at higher ISOs. So on a full frame camera, you could stop down the lens and bump up the ISO, which could get you similar results.
And just to echo Bob other advice, for concert photography
, you generally want to use a shutter speed of 1/120 or faster. So, assuming decent photographic technique, image stabilization (in either the body or the lens) is unnecessary for wide angle and normal field of view lenses.