About camera flash units: A typical strobe flash capacitor can put out 60 Joules at 500 volts. Don't be fooled by the fact that only 2 or 4 AA batteries are used. Typical capacitor will be 480 micro Farads. To put that in perspective, a typical CDI ignition will use a 1 to 2 mF cap. There's a lot of zap storage in a strobe cap. I don't know about throwaway cam voltages, but the older hot shoe strobes put out a dangerous amount of power. More than ignition systems. Remember CDI's can put out over 60 sparks a second. A camera cap takes about 15 seconds to charge because of the much greater power needed to work a strobe flash.
If you want to learn about high voltage, don't start by repairing strobe flashes, wear rubber gloves, and keep your left hand in your pocket.