One of the biggest mistakes people make when shooting concerts or events is to try to use their flash. A friend of mine shot a concert once and hated the results he got (he used flash). He emailed me some of the images, and I saw exactly why. I wrote him back, "So let me get this straight—there were around 275 of these huge 1,000-watt stage lights aiming right at the performers, but you thought there just needed to be one more?" We laughed about it, but there's a lot of truth to it. You want to see the color and vibrance of the stage lights, and you want the scene you photograph to look like what it looked like when you were there at the concert. Using flash wipes all that out (besides making the performers angry), and reveals all sorts of distracting things like cables, cords, plugs, duct tape, etc., that would never have been seen under normal stage lighting (in fact, if you shoot big name acts, they forbid the use of flash, and you generally only get to shoot for the first three songs of the concert, if that!). Since you absolutely shouldn't use flash, the key is to shoot at a high enough ISO that you can get your shutter speed around 1/125 of a second (to give you sharp shots in lower light—and yes, the stage is often very dramatically lit, and the lights are constantly changing, which is why shooting performances is so tricky). Since you may get some noise at these higher ISOs, be prepared to use a noise reduction plug-in (I've been using Nik Software’s Dfine 2.0), and take along the fastest (lowest possible f-stop) lenses you've got (f/2.8, f/2, f/1.8, etc.). If you're close to the stage, take both a wide-angle lens and something like a 70–200mm f/2.8, or even an f/4 if you've got a good, low-noise camera.