Matching north light with fluorescent bulbs

[Richard Monro]

Marvin,

When I was setting up my new studio I researched lighting extensively. Hopefully the following will help. Color Rendering Index is very important as is the Kelvin temperature. Both must be considered together to get the best light compromise...and it is a compromise. North light is about 7500 Kelvin according to some sources and tends to be more blue and balanced in spectrum than south daylight. However, the reflected color from your studio walls and ceiling will influence the color you see. Hence my statement about chosing the best compromise.

Lumichrome flourescent bulbs at 6500 kevin and 98 CRI seem to be the best compromise of both criteria for bulbs on the market for the studio artist. Going with lights that are between 5000 and 7500 kevin and with a CRI greater than 92 should work well in any case.

If you want to get very technical you can do prismatic spectral analysis to verify that your new lighting reasonably matches your north light. In the end though it will come down to what pleases you as your art will ultimately be displayed in lighting that will be anything but north light.

Wish you success.

[Richard Monro]

Garth must have posted his reply as I was writing mine. Way to go Garth. Your diffraction grids show that there is a reasonable spread of light Kevins that can be chosen.

[Michele Rushworth]

Chris, thanks for posting that link for the screw-in 6500K bulbs. I have two light stands in my studio that I like to move around depending on what I'm doing and it would be great to have decent bulbs to put in them. I'll check out the TCP bulbs.

[Richard Monro]

Chris, I checked your link and could not find the 6500K bulb. What was the CRI for this bulb?

[Chris Saper]

http://www.1000bulbs.com/search.php

You'd have to ask them about the CRI

[Timothy C. Tyler]

And here's what happens. We paint under perfect lights. Then (some of us) send our works to galleries who place them under hot spots about 3800k. Then someone buys them and you have no control or idea of how they will be hung.

This was the long view when the CAA's began discussing this 10 years ago. Perfect circumstances are for perfect worlds. Compromise is the reality. As many of you know, the galleries may never even give you the name of the buyers. Selling directly to a portrait client, you can nudge them and try to educate them-but everyone won't listen.

The bulbs also change their temperatures as they age-just like in the tanning booths. But take heart, Sargent, Whistler, Monet, Titian, Zorn, Sorolla and Vermeer did okay without these.

[Marvin Mattelson]

Sun-a-lite makes a bulb that is 6500 degrees Kelvin with a CRI of 98.

Actually Sun-a-lite sells the bulbs. They are made in Germany and Sun-a-lite is a dealer. I have ordered these bulbs and will post the results when they arrive.

[Timothy C. Tyler]

Sounds like none of us are ready to trust those selling to judge how true their product is. The trouble is that we can't easily compare "stereo A" with "stereo B" which is always very informative when comparing other products. Holding a white card up doesn't really do it either.

I wonder if the curve here is lower than we suspect. When you wish to insulate your home once you pass R-value of 38, any improvements are moot and certainly a poor investment. North light in Iceland in April is very different from North light in Madrid in June. I rather think that if we can get from 5500-6000k, even if this involves mixing of bulbs, then that is likely as good and certainly more constant than northern light which we all concede varies.

On a related subject, too much light in a studio is wicked. Photograghers measure "how much" light all the time. Seems we painters should ask this question too.

[Marvin Mattelson]

Tim I am happy to report that your theory doesn't apply to light bulb manufacturers. I just received the bulbs I ordered on Friday. The name on the bulbs is Lumichrome made by Lumiram. They are spectacular. In comparison Ott lights are too green and Ott true color are too yellow. They are not precisely the same as true north light but are so close that the difference is negligible, to my eye anyway.

In addition I've never seen any lights that are better.

Here is the description from their site:

Lumichrome

[Tony Pro]

[QUOTE=Marvin Mattelson]
In addition I've never seen any lights that are better.

Here is the description from their site:

Lumichrome