A pro walks you through shooting live music in small- to medium-sized venues.
Shooting stage light is a bit like shooting a stormy sky at sunset: with ever-changing light and high-contrast colors, it is a spectacle for you to capture, not control. Make use of backlighting, side lighting, and smoke caught in spotlight shafts, but try to make sure the lighting draws attention to rather than from the performer or performers. If you are able to move around the venue, you will have more opportunity to find unusual lighting, but even if you are restricted to a single spot, you can wait for a moment when the light is most evocative.
I tend to use manual mode when shooting live music. But if the light show is particularly dramatic, I often switch to aperture priority to keep up with the ever-changing light (if I feel the shutter speeds will be high enough). I always use partial or spot metering (metering off the main subject's face), and my exposures are usually fine in this mode if the light is adequate. You may need to play around with exposure compensation. Some dramatic light shows have quite a bit of back-lighting, and the meter will tend to underexpose. Trial and error, and some practice, will help you come up with a system that works.
This is often much easier at smaller venues where you may be freed from the three-song rule. High-interest moments usually happen later in the gig. The more you shoot live, the more you will get the feel for when something is going to happen. If you are familiar with the act or the music, you may be aware of a signature move (a jump, spin, or a dramatic guitar move, for example), which you can capture. Otherwise, you may hear a build-up in the music that leads to a dramatic gesture, as in the case of this shot of one of The Wailers.
Remember to pay attention to details, as you may notice something interesting to keep an eye out for. Seeing a birthday cake left onstage early on, I made sure to save some space on my memory card for a shot of Neil Hannon of The Divine Comedy blowing out his candles near the end of the show. Even then, I made sure I shot a burst of ten during this key moment, with only one turning out exactly as I'd hoped.
Key moments need not always be so obvious, so don't ignore the expressions or poses more subtle performers make. When shooting quieter, mellow acts, the best shots are often between the songs when the musicians are interacting with each other and the audience.
Here's where your own style and shooting eye come into play. Many of the compositional tricks that apply to other areas of photography work well here, or you can experiment and try to come up with something new. Shooting close and wide allows for some interesting compositions with multiple performers, performers and the audience, or even performers and the stage. If a concert is less than full, you can use your increased mobility to find interesting angles and vantage points. Using a longer lens close might seem limiting, but it can make for striking, detailed photos of the performers filling the frame. Acquire all the equipment you feel you need and can afford, but also remember to make the best of what you have.