Bush League Question - How many shots...

I shot a university dance performance last week. The lighting was, well, awful.
a one foot move by a performer might take him or her from open white light to red cell to shadow. I tried shooting in P, hoping to get enough light for a clear shot. Result: maybe one in fifteen were in focus and not motion blurred (I did fill up the card, Dwight).
Any tricks to suggest?

here's one idea: you could meter for when the person is in the white light, dial in the camera's exposure using M for these settings, and wait patiently for them to return to the white light.

if the photos are blurry, it's likely because your shutter wasn't fast enough. what ISO were you using?

30d with 70-200 f4 and xt with 10-20 Sigma, both at 1600.
Thanks for the suggestion, I did test before the performance, but there was so much movement (students performed in groups of one to three persons) I didn't think to concentrate on a single spot.

caljimw wrote in post #3240899
30d with 70-200 f4 and xt with 10-20 Sigma, both at 1600.

f/4 and ISO 1600 likely won't give you fast enough shutter speeds under stage lighting. With that lens you'll want to use ISO 3200. Faster glass would help, too.