Here at work (semiconductor engineering firm) I need a powerful off-camera battery-powered flash with umbrella on a tripod that can be set off by the on-board flash of a camera (Nikon D1.... no film... sorry). This is to photograph such things a DVD players, cell phones, TVs and such. I do not want to go with a full-fledge strobe due to mobility, need for AC and cost. I need something "unplugged" and easy to move around. Any suggestions?