Make it a notch or two below the highest setting. Your pictures may have graininess and other visual noise in the shadows, but you’ll notice it less at, say, ISO 800 than at 3200.
2. Hold Steady
The darker the scene, the slower your shutter speed has to be. So it may be pretty hard—or impossible—to freeze the action on stage. embrace the blur. But to keep from adding more, turn on image stabilization and brace your elbows against your sides to handhold steadily.
3. Don’t Get Distracted
Use spot-weighted metering (which meters a specific point or area rather than the whole scene’s ambient light) and single-area autofocus to keep your camera trained where you want it.
4. Use Exposure Compensation
The lighting designer may mix up effects throughout the show, so compensate by adding or reducing exposure manually as needed.
5. Go High and Low
Shoot from overhead and at waist level, even if you can’t see the lcd. Getting above and below the audience’s eye level offers new perspectives.
6. Shoot a Lot
You’ll be lucky to have one keeper for every 20 or 30 shots. don’t sweat it—just make sure that you’re packing plenty of memory.