I did something similar, I just took teh inverter and the capacitor out of the camera and used a relay to discharge the capacitor across an old lawnmower ignition coil. It works pretty well save for the fact that the trigger relay spot welds itself closed and you have to apply some inpact recalibration to get it to open and let the capacitor recharge. The best part, it all runs off a battery and if you excluded the trigger relay and just had the switch there, it woud all run off one "AA" battery.