What is the usual ratings for a capacitor in a disposable camera?

I am wondering so that I can calculate the output power of my small capacitor bank-in amps and joules.

Typically 470 uF with 350 wV rating.
Seconded. Those numbers are a bit squishy by manufacturer -- I've seen everything from 300uF @ 450V to 500uF at 300V. Remember of course engineers should be building in safety margins on these things so they don't usually charge to 100% capacity.