Make:

• Make Projects - Volume 07
• Send GPS data to your computer without a microcontroller
• Homebrew iPod remote allows for easy control for the visually impaired
• Eglantine lamp
• Multitool keys
• HOW TO - Mod a VGA screen into a Chumby

My recommendation? Add red (and maybe some green) LEDs to taste.

In a twisted way, one could say that white light's "temperature" is really a measure of "the RGB value of your definition of white".

The kelvin number is defined as the temperature an incandescent object would have to be to glow that color. Naturally they're all fairly stratospheric since they are after all "white hot". This is very straightforward with incandescent bulbs, obviously-- whatever temperature the filament is, that's actually what color your light will be!

However, this goes all wrong when you start re-inventing the light bulb since you're not using good ol' incandescence anymore. Florescents have the same problem: their effective "temperature" is usually way hotter than any light we enjoy looking at.

For compact florescent lights, the solution has been a judicious fiddling with the phosphorescent coating: look around and you can get lower "temperature" bulbs that look less like the doctor's office.

LEDs could presumably benefit from the same treatment: white LEDs are phosphorescent-coated blue LEDs. However, I'm pretty sure you could game this system by "filling in" the lower wavelengths yourself with red and green LEDs, making the overall light look more yellow and thus, lower temperature.

Throwing in a few colored LED's won't work so hot because LED's have such a narrow beam that it will just put colored spots on your image. Even using a combination of warm white and "pure" white LED's would cause noticeable spotting, especially at macro distances.

My suggestion, is to make sure you are getting the best LED's you can, but most importantly, make sure they are all from the same production batch. That way, even if the color temperature is a little weird, it will at least be consistent across all the LED's. Then you can simply set the white balance on your camera accordingly, and take beautiful, clean shots.

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