AFTER: This is how the same hall appears when photographed with hand-held flashes. For this view, the door was closed and the only illumination came from the 580ex fired repeatedly from various angles. Although I didn't really keep track of the individual flashes (I was too busy feeling my way along the hall), I guesstimate this shot required 15-18 flash pops, some aimed at the walls and others flashed inside the rooms at right but aimed back out into the hallway to accentuate the doorway openings. I first became aware of this technique on a website called "Subterranea Brittanica" whose members explore and photograph abandoned underground British sites including fortifications, subway stations, coal mines, and other places I'd never venture into alone.