Don't be afraid to use a high ISO when the moment calls for it.

Don't be afraid to use a high ISO when the moment calls for it. Yes its noisy, yes its grainy but you can capture the moment as it was.

In this image in a dark night environment this performer is lit from below with harsh blue light and similarly from above and behind. Using a high ISO let me use a fast shutter of 1/200th to stop his movement and the shallow depth of field from f/2.8 gives the ambiance of the crowd and street scene without distracting from the emotion of the musician by using a good depth separation between the sharp foreground and the blurry crowd.