Its better to use flash during this event. Since its just a party not drama, flash is normally allowed here. ISO 400 with flash is much much better than ISO 800 or 1600 without flash. (it will look very urgly, if the pic is under-exposed in this kind of situation)
Try not to use the tele-photo, as its really difficult to take sharp pics with hand-held. Or maybe you can find a mono-pod for help. Use shutter-speed 1/30 abvoe unless for some special effecrt.
Also, make sure battery is fully charged, make sure you have list of show table, make sure you change your roll before importent importent moment.
In a word, just make sure your pic is not under-exposed, not blur, and consider a bit of framing. That's the basic requirment for the event pictures. Good Luck :-)
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