While I was searching for information on daylight balanced fluorescent tubes, I found this article. http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00Futx&tag= I've been playing with spiral lights and was thinking of going to tubes for backlighting. Hmmm, looks like I might want to rethink that and go with flash and soft boxes or diffusion. Good thing to remember: The effective length of the exposure is determined by the duration of the flash, not by the shutter speed of the camera. No matter how obvious, it only makes a difference when the ambient lighting can become a factor in the exposure.