Gel to make household fluorescent bulbs 3200 K and 5600 K

M

Mike@AF

Veteran
I have some household fluorescent bulbs in fixtures that I'd like to add gel to so the light coming from them are as close to 3200 K and 5600 K (I'd change the gel depending on the situation) as possible. I think the color temp of the bulbs is about 2500 right now. What gel would I need to get? Thanks!
 
2500K would be really red. Are you sure these fluos are 2500K? That would be unusual.

Keep in mind that a full CTB takes away two stops of light and you'll probably dim any household fluo to the point where it won't be of much use lighting the scene.
 
See what it says on the tubes. I think soft white is the most common and it is usually about 2700K. You know that you can't turn a household fluorescent into a smooth spectrum source like a $25 Kino tube just by adding cooling gels, right? For example, the green spike won't go away.
 
+1 to what he says. Adding a gel won't change the CRI. swap the bulbs or angle the frame so the ceiling is not in the shot and fake it with kinos on a horizontal autopole
 
Mike@AF said:
I have some household fluorescent bulbs in fixtures that I'd like to add gel to so the light coming from them are as close to 3200 K and 5600 K (I'd change the gel depending on the situation) as possible. I think the color temp of the bulbs is about 2500 right now. What gel would I need to get? Thanks!
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Three things to think about. One is color temperature, which is just a measure of blue/orange balance. Note that this specifically excludes the green/magenta axis. And all fluorescent lights have a big green spike.

Which brings us to two, Color Rendering Index. The higher the CRI, the better the rendering in your video of the colors of the objects in the scene. To get acceptably high CRI from a fluorescent lamp typically requires six or seven phosphors in the lamp. Your typical "household" lamp has three or less. Which means you'll have holes in your spectrum and colors won't reproduce correctly. In particular, human faces may not reproduce correctly. Just sayin'.

Third, ballasts and flicker. Your typical household fluorescent fixture is powered by a cheap magnetic ballast and runs at "mains frequency" which is typically 60 Hz in NA, 50Hz in PAL countries. This frequency of flicker can easily interfere with video capture causing "strobing" which is nearly impossible to repair in post.

So, there's three reasons not to use household fluorescents for video capture.

If you still want to go this way, look at minus green filters to knock down the green spike. This will likely be a big improvement all by itself, but will cut your light output considerably. If you then add a CTB filter to raise the color temperature, you'll also cut light output again, and perhaps even worse. What you'll end up with may be dim to the point of being nearly useless for video. And it won't do anything about the flicker problem.
 
Rather than gel medium screw base (household type standard) bulbs, you should do what most movie electricians do, which is carry an assortment of inexpensive bulbs across several wattages and color temperatures.

Easier is to get Osram (or equivalent) 211 (~3200K, 75W); ECT (~ 3200K, 500W); 212 (~3050K, 150W); 213 (~ 3400K, 250W); BCA (~ 4800K, 250W); EBW (~ 4800K, 500W). All of these bulbs should set you back between $2 and $5 a piece.

For fluorescents, you can purchase StudioLine bulbs in T8 and T12 diameter that fit into many common fixtures. Also will add that if you can find the MovieTone MT3248 (3200K/40W/T12) or the daylight equivalent.
 
You can get 3200k and 5600k lamps at your favorite home improvement stores. They aren't that bad and compare somewhat to Kinos regardless of what people say.
 
As an example, the MovieTone bulbs have a CRI of 93. KinoFlo TrueMatch are CRI 95. Something like the GE Sunshine series is at CRI 90 / 20w / 5000K. Many of the bulbs you'll find at your local home center have CRI of 60.
 
Yeah as many others have said you're better off getting bulbs in the color temps you want rather than trying to gel them. I know there's a few guys around who have built fixtures with screw in CFLs and have found bulbs with decent temps and CRI.
 
Erik Olson said:
As an example, the MovieTone bulbs have a CRI of 93. KinoFlo TrueMatch are CRI 95. Something like the GE Sunshine series is at CRI 90 / 20w / 5000K. Many of the bulbs you'll find at your local home center have CRI of 60.
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That's some great info there Erik.
I have two questions. Where do you buy MovieTone? And have you ever gelled ge sunshine to bring it closer to 5600k?
 
Thanks for all the info everyone. I should probably give more info on what I'm trying to do. We're shooting a pilot in my apartment over the next few months and I let the producers paint my place. The decision was made by the art department to paint the living room a green color for the pilot. Normally I have fluorescent bulbs in 4 lamps and when those are on the walls are really really green. It's too much green for me and I'd like to gel the inside of the fixtures to get rid of the green. When I use a camera in the room with those lights on I can't go below 2700K, and it's almost just right, so I'm assuming they're 2500K. The bulbs don't say a color temp or CRI on them. But from what I've just read here it could just be a green spike which would mean I can get some minus green gel and put that inside the fixtures. I know that will cut down on the light, but I'd rather cut down on the green at this point.

When we shoot the pilot I'll replace them with incandescents, so this is just for my personal preference for everyday living.

Maybe I'll check out some of those bulbs Erik listed. Might be a better choice. Thanks for the info!
 
Erik Olson said:
As an example, the MovieTone bulbs have a CRI of 93. KinoFlo TrueMatch are CRI 95. Something like the GE Sunshine series is at CRI 90 / 20w / 5000K. Many of the bulbs you'll find at your local home center have CRI of 60.
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The GE sunshines are the ones that they sell at my local home improvement store.
 
And that's why you should call your local Barbizon store! :thumbsup:

MovieTone, the ones many electrics departments insist on come through our stores (and other fine retailers). The company that manufactures them is H&H Industries.

I would add a 1/8 or 1/4 CTB to the GE Sunshine if you want to be closer to 5600K - it won't be perfect, but within a couple hundred degrees, anyway.
 
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