Patti (whipartist) wrote,
Patti
whipartist

Tell me if I said something stupid

This is primarily directed at my friends who actually showed up for freshman physics when they were in college.

In a photography discussion forum, someone was asking where to get a good bulb for a lightbox, so that colors were rendered correctly. A respondent said not to worry about it-- to just use any old light, shoot raw, and then correct the colors later. This seemed like a bad idea to me, since you ran the risk of losing some of the colors. As I was typing, though, I realized I was only about 95% certain of what I was saying so I sprinkled caveats liberally around my message. Tell me if I'm right or wrong.

You might be able to find a daylight bulb at Home Depot. Try looking for things that are intended for plants.

It's entirely possible that I'm wrong about what I'm about to say. If so, I hope that the people who correct me do so diplomatically. :-)

It seems to me that even if you can correct the white balance later using RAW processing, it makes sense to use the best spectrum light you possibly can, so that the camera can see all the colors. Imagine for example that you had a bulb that produced a lot of red and yellow light, but almost no blue. If you use that to take a picture of something that had the full range of colors, it seems like the blues and greens would come out too dark since little to no light would reflect off of them.

I believe this is the reason that red cars look black under sodium lights in parking lots.

In reality, you're probably not going to find a bulb that's completely deficient in one area, but rather one that has strengths and weaknesses. Still, it seems like it makes sense to start with the best possible light source, rather than one that is known to be deficient in a particular area. I'd rather use RAW processing to solve problems that I couldn't otherwise fix, rather than relying on it as a primary tool.

I was googling around as I was writing this, and found this potentially useful page: www.assumption.edu/users/bniece/Spectra/Complete.html It shows the spectra of various light sources. It's interesting to see how much more red there is than blue in an incandescent bulb.

How about it, lazyweb?
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