I'm having trouble figuring this out. I took a couple of long exposure shots with flash recently and they didn't turn out how I expected them to. Ok, so this was what the shot was. ---- A relatively dark alley end at night, pointing towards a street. I wanted to take a shot of my two friends in front (illuminating them using manual off camera flash), and then have them walk/run out of the scene and then I would expose the scene for 60-90 seconds to get some traffic blur behind them. I determined my aperture by focusing the lens on my two friends, and then looked at my flash's manual setting for feet/aperture guide and set it accordingly. I just basically wanted them fully visible and exposed properly in the foreground, with the blurred traffic behind them. The result: The two figures were see through ghosts and barely visible. This baffles me because if I would've had a much quicker shutter speed (say 1/60), they would've been exposed properly (though obviously no time exposure blurred background behind them). So obviously the very long minute or more exposure caused my ghost images. What happened? And how would I get two solid figures?