Graham - I take it you were firing off several flashes per pic in the larger chambers?
The big progress these days is in LED technology - I've recently been using a Fenix P3D to light some big chambers with surprisingly good results. Given that the torch is smaller than an AA Maglite and uses only a pair of CR123A batteries (3v versions of an AA give or take), it's all the more impressive.
That said... I don't think that light painting will give as clean a photo as using a big flash gun for a couple of reasons:
- the flash gives you a more diffuse spread of light without 'puddling'
- something odd in digital cameras seems to introduce a lot of purple with a long exposure: with a flash you've got far less time when the shutter is open and light is going in
- most LED of halogen torches have a tint to their light output. The Luxeon Rebel 100 is the whitest I've seen yet, but you can get some LEDs which produce a very odd tint
I think I may have wondered off-topic... anyway: I'll take my Metz CT60 and have a play if I get a chance over the Cwmorthin work weekend (this weeked) and post up some pics using it.
Hello again darkness, my old friend...