Bulbs, Globes, and Easter eggs...

So today I helped out on a spec short at Mole today and I learned a little bit about bulbs. I am going to try and regurgitate the info that I got today. (...by the way, I'm going to try and use all 7 names for a bulb in this story)So it all started out with a burnt out 5K globe, and the gaffer asked me and Kate is we new the difference between an incandescent bulb and a Quartz-Iodine bulb? I, of course, said no and so we went out into the hallway to the old heads. He pulled a huge, old halogen bulb out of the classic 5K head and showed us the difference.

They used to make big bulbs because the glass was fragile so it had to be a certain distance away from the filament. Also, as the filament burned, carbon particles would stick to the inside of the glass, causing their color temperature to turn red over their life-span. To clean the inside of the bulb without disturbing the vacuum(to keep out oxygen which fuels fire), little grains of graphite was put in the bottom of the fixture and the old guys would turn the egg over and swirl it around. But they had to make sure they shock all the graphite to the bottom of the fixture so it was off the filament because the graphite grains were conductive.

Then, quartz-iodine lamps were introduced. Basically, the glass on these bottles are made from quartz, which has a much higher melting temp then the purer glass previously used. This allowed the glass of the bubble to be closer to the filament and they made them much stronger... but the filament is still fragile. Also, they started using iodine gas in the Easter eggs, which is a re-generative element that pulls the carbon particles back to the filament so they don't stick to the inside of the glass. This extended the life of the lamp as well as allowed it to keep its same color temperature. However, as the filament decays, color temp is eventually lost slowly, but the lamp, globe, bulb, bottle, bubble, egg, Easter egg, or what ever else you want to call it usually goes out before the color temp changes too much.

The PhillM tip-of-the-day:
When bringing a light to set, always make sure it has at least these three things: barn doors, scrims, and a bulb.