I know the exact model number of photo flash I have and they don't even list a ESR There's a reason for that, they're produced in bulk and cheaply with wide variances to reduce cost, so the individual device to be used would have to be tested in order to determine if it were okay for use under anything but short pulses infrequently. Even a badly manufactored capacitor is going to last a pretty long time when used at the rate that a disposable camera flash is. I've never taken any apart (they're expensive obviously) so I don't know what kind of capacitors higher end cameras use.