Maybe I am alone with this discovery, but just in case I let you know.
Few weeks ago, I was wisiting the Giant's Causeway in Northern Ireland. Those who were there know about the spectacular formations, and dramatic landscapes. Unfortunately I arrived too late, the sun was down, and the moon wasn't strong enough to lighten the surroundings. Even with exposure times as long as 4-5 minutes, I could not get any decent pictures.
I was always wondering how good is the lightning of landscape photographs in the National Geographic. I had thought that they used lots of powerful flashes and huge reflectors to enlighten the foreground. It was too late when I realized few days ago the trick, which could have saved the day when I was visiting Northern Ireland.
The trick was to use long time exposure (just as I did) and walk around with a flash, and fire it many many times until the foreground is uniformly enlighted.
I am sort of disappointed now - because I might not have a second chance to visit Northern Ireland. I am also glad that I have learnt something new, and I can't wait the opportunity to try it out.
I've never tried it, but there was an article in View Camera sometime around the summer of this year (can't remember exactly when or who wrote it) about photographing trains and railroads that mentioned this trick.
I've done quite a bit of landscape and architectural work using both flash and continuous light sources to paint with light. If you'd like a real eye opener on the possibilities - look at work by William Lesch.
I did it to light a cave once. I was able to print the negative, but I should have doubled the number of flashes I used.
I've seen photos of building interiors and exteriors in which multiple flash or light painting was used to get excellent results. In the case of the exteriors, the shots were made at dusk, and the light gave tonal variation to large blank surfaces. The light was hidden behind bushes near the building and resembled permanent landscape illumination. The photographer claimed that the building's owner like the effect enough to replicate it with actual landscape lighting. It's an intriguing technique that allows you to simulate complex lighting setups with only one instrument.