No problems I under exposed the ambient light using my camera settings and it was the flash that lit the suject. I placed one behind with the snoot to make the smoke stand out. The background is actually the white tiles on my laundry wall but I have underexposed dramatically to turn them black. The flagged flash stops the light from spilling onto the background. I used my 100mm macro lens, 1/200 sec @ f10. Then for post all I had to do was in Lightroom 3, an adjustment to the blacks to make the background darker and added some luminance to the blues. Hope that is more helpful

Thanks very much Darkrider