Tonight I tried something new. Light painting with fire mixed with high speed photography. Basically I used a 4 second exposure, after blocking off all the light from the window and underneath the door of our garage. I put a tarpaulin on the floor to catch [most of] the glass and set up my 'studio' in the middle of the garage. Ignore the shoes please - they were comfortable. In this scene I am clapping my hands to make the sound activated flash trigger fire.
The basic principle is that if your background is dark enough then you can add as many exposures as you want as long as they don't interfere with each other. This can become quite challenging as you add new variables. The biggest variable here is the strength of the flame because it changes as it burns out. You think you have everything right, then you find out that after adding fluid to get your flame going again it is now too strong and exposes the garage door in the background.
Then when you have your aperture and shutter speed right you give the board a spin and realise that the subject wobbles a bit and gives movement when this happens - which leads to the decision to shoot the bulb and trigger the sound activated flash trigger at the beginning of the exposure, before moving the flames.
After you figure that out and get ready for a proper shot with the air pistol you're so excited that you spin the board too much and the flames go in front of the subject and "burn" the image out.
Now you think "Well I'm glad I worked that out and didn't use the only clear bulb I saved for this shoot, I'll have it all perfected for this shot". That's when you realise the microphone is too close and the flashes fire before the pellet even hits the bulb - and it's too late, the bulb is destroyed.
By this time the flames have burned down to a good intensity that doesn't light up the garage door and you get the spinning of the flames at just the right speed only to realise that in the time it took to remove the broken bulb and set this one up the flash has gone to sleep and you forgot to wake it up before firing the next shot. This was the test shot of the flames before I shot the bulb.
By now the ground made crunching noises when I walked, there was broken glass everywhere. I got a few reasonable results and learned that 'next time' I need more space behind the subject so as not to light the garage door - or I need to make a shield around the flames to direct the light only at my lens, not behind the subject. I got a few 'keepers' but there is a lot of room for improvement.
Here's a short video showing how it was done.