[Tom Edgerton]

Marvin--

I've always understood the temperature of a north light to be around 6500K to 6800K, approximately in the middle between a regular fluorescent light and 5000K.

I've used the Lumichrome tubes in the ceiling of my studio for years, supplementing my northwest window, and found them to be generally very good. However, a complicating factor for me is that when I paint under any single overarching wavelength of light all day, my eyes get tired, especially at night--to the point where color discernment goes completely South. So I've used a cheap reflector on a stand and bounced another wavelength--sometimes regular tungsten household bulbs, sometimes the Sunwave corkscrew bulbs, sometimes blue-coated bulbs (whatever feels right)--off of the ceiling into the overall Lumichrome illumination. It's really just a "trace" of another wavelength, but the mixture helps immensely in avoiding the eye fatigue over long sessions.

Thanks as always for your thorough research and generosity in sharing it.

Best--TE