Yeah, the concept is nice. I've been thinking of the same idea basically. I thought of taking night shots with a lets say 10 second exposure at a local 24h event. Thought of counting a certain flash exposure for let's say 5 meters, then set a right aperture and a long shutter speed with the camera on a tripod. Then I thought of acting as a human slave flash and going somewhere in the picture to manually trigger the flash at some rider passing by... Have to try that some time. Or I just gotta get a slave cell or a long sync cable.. Radio slaves or stuff like that would be too expensive for me..