Most recent (20 years) camera strobe circuits include a high resistance
resistor in parallel with the cap to discharge it continuously once
power is removed. That said - do take precautions.
If possible connect a 10,000 ohm 10W resistor across the strobe
connection and leave it there for a couple hours. That should deplete
it. (Batteries out, of course). More aggressive discharge with a pure
short will create quite a snap - wear glasses).
(note that the cap and the strobe are in parallel, so putting the
resistor across there or in lieu of the strobe is the same as across the
cap).
(You can measure the voltage with a simple volt meter as well - set it
to 1000V or so - try to use one hand only).
See 2.6 of
http://www.repairfaq.org/REPAIR/F_strbfaq.html#STRBFAQ_007
--
"A Canadian is someone who knows how to have sex in a canoe."
-Pierre Berton