Theatrical/concert photography is about the most challenging there is, both in terms of pushing the equipment you use to the absolute edge of their capabilities and in terms of requiring every bit of skill and experience you might have as the photographer.
Photography is the art of capturing light. Most concerts don't offer much light to capture and what light there is to capture is changing rapidly and the subjects are usually very animated.
- The traditional solution to not much light (longer shutter speed using a tripod to hold the camera still) doesn't work because nobody on stage stands still for 10-15 seconds while you take a picture.
- The traditional solution to capturing motion (faster shutter speeds) doesn't usually work because there isn't enough light to capture a good image on a small sensor using a narrow aperture.
- In the end you have to balance the two as best you can AND use gear that allows you to capture as much of the scarce light that is present in the scene in as fast a time as possible.
That means fast lenses (wide apertures), larger sensors, and cameras that are highly responsive (fast handling).
It also means you must use impeccable timing when you release the shutter. If a performer is jumping you can get by with a slower shutter time if you catch the performer in the instant they stop going up and start going back down. If they're running back and forth across the stage, catch them in the instant when they transition from moving right to moving left or vice versa.
Manual exposure with Evaluative metering at about -1. EOS 5D Mark II, EF 70-200mm f/2.8 L IS II @ 200mm, ISO 1600, f/2.8 (notice only the front line is in sharp focus), 1/200 second. I'm right on the edge of subject motion blur at 200mm and 1/200 second even when timing the kick at it's apex. But the faces are sharp and that's what counts the most.
I've shot theatrical performances with both APS-C and full frame cameras. With even the best APS-C sensors I wouldn't try to shoot using any lens narrower than f/2.8. With a FF sensor I sometimes will use an f/4 zoom for the wider angle stuff where motion blur from slightly slower shutter times is not as much of an issue. For tighter shots using longer focal lengths I use an f/2.8 zoom or even a wider aperture prime such as a 100mm f/2 or 135mm f/2 to allow fast enough shutter times in such a setting. I often use a monopod with the 70-200 lens just to help with camera stability.
Shot from the orchestra pit during a dance number. EOS 5D Mark II, EF 24-105mm f/4 IS @ 24mm, ISO 1600, f/4, 1/160 second. Shot using Evaluative metering in Av exposure mode with -1 1/3 stop exposure compensation. I timed the shutter when the nearest briefcases were at the apex of their trajectory.
Manual exposure with Evaluative metering at about -1. EOS 5D Mark II, EF 70-200mm f/2.8 L IS II @ 70mm, ISO 1600, f/4, 1/125 second. The performers who are at the apex of their leaps are fairly sharp, those who were a little early or late show motion blur.
Notice that even though two of the three shots above, all shot in the same facility, were done using manual exposure the ISO, AV, and Tv combination are different for each shot. Learning your camera's controls enough to adjust ISO, Tv, and Av by touch without moving your eye from the viewfinder is critical to successful theatrical shooting. So is paying careful attention to the light meter and knowing which metering mode you are in and how each metering mode will affect the readings you are seeing.
If a large part of the scene is dark, then your meter should show that you're underexposing by one stop or more when you're using Evaluative or Center-weighted metering. The camera wants to make all of those totally black areas medium grey. You need to know how to tell it, "No, I want those areas to be fully black."
For tighter shots the needed Tv (time value i.e. exposure duration or "shutter speed") to freeze motion gets shorter. Sometimes you must concede that you won't be able to freeze every part of a performer's body with the options available to you (light, lens, camera's high ISO performance limits). In such a case the key thing to remember is to place the face at highest priority. Even if you have to pan a little to track the face during the exposure and blur the entire rest of the scene, it will look better than the rest of the scene sharp but the lead performer's face blurry.
EOS 5D Mark II, EF 70-200mm f/2.8 L IS II @ 200mm, ISO 1600, f/3.2, 1/200 second. (I could have gotten a slightly better result at f/2.8 and 1/250 if I'd been totally on my game!)
Shooting raw images so you will have latitude in adjusting color as well as exposure in post-processing is paramount. Having all the raw data from each image available opens so many more possibilities with regard to color, exposure, contrast, etc. than the much more limited information in a jpeg file (please see this answer to the last question linked below for a fuller explanation).
There are also a few other questions and answers that you might find helpful:
What are appropriate lenses for concert photography?
What kind of filter (if any) should I use when photographing a theater scene? (hint: Lose the filter on the front of your lens!)
Canon 70-200 f2.8 non IS or f4 IS
Regarding metering/exposure issues
What went wrong with this concert photo and what could I have done to make it better?
Blown out blue/red light making photos look out of focus (particularly this answer)