View Full Version : 200k difference?
200 kelvin that is...
I'm sure someone here has pondered this before. I am interested in creating a cheap lighting setup using 28 watt 5000k compact flourescent lamps. I figure 4 per bank of lights.
My digital camera has settings for 5200k white balance as well as 3500k. I think color film will tolerate 5200k.
Is 5000k too short a wavelength for good color? Am I even on the right track?
I believe this will work fine for Black and White.
Fundamentally you're on the right track; with the camera at 5200K and the lights really pumping out 5000K, the pictures will have a warm cast to them, but this can be easily corrected in post processing.
Most important though is to make sure that all the lights that you're using have indeed the same colour temperature. And, given that they're fluorescent, have a suitable spectrum.
You can't really colour correct a spectrum that has two or more significant bumps at very different wavelengths. In that case you'd always end up with some colours off.
The whole idea of colour temperature is related to black body thermal radiation. Essentially it's comparable to what you get when you heat a piece of iron. The hotter it gets the whiter it radiates because more and more shorter wavelengths of radiation start to contribute. But all the time, the spectrum starts with the highest output at long wavelengths and tapers off towards shorter ones.
The white balance of the camera basically reshapes the spectrum from one black body radiation shape to another, and is only able to do so if the shapes are basically the same form..
Unless the lamps are intended for photographical use, you may have to try one out before jumping in and/or spending $$ on them.
Great input Peter, and great explanation thanks!
These are th elamps I had in mind-
These appear to be household energy saving lamps. And, electricity bill aside, they're false economy. You'll need a lot of lamps to get enough light.
Moreover I can't imagine they're particularly suited to colour photography.
Their output varies over time, both w.r.t. light level as well as colour. At first they give a low light with a decidedly orange cast, and only after a while give higher and whiter output. This may take 15minutes to settle each time they're switched on. That'll be a tough job getting consistent lighting and colour.
Photo hot lights typically are ca. $50 per bulb. But here less is more. One bulb per studio stand/fixture is more than enough. And their output is tailored to studio use.
Good pointers thanks again.
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