I would like to buy a photometer to measure Kelvin degrees. Kan anybody recommend me a good and affordable one?
By the way, I need to buy the photometer to be able to get the same white balance -using CTO and CTB filters- different days while filming a production. I'll be filmng with a Beta camera. Any tip for somebody with experience about how to be able to maintain color temperature stable in different days and light conditions? You are most welcome....
Thanks in advance
A professional video camera with an auto white balance (AWB) feature is as accuare a method of reading relative color temperture as any meter! All you need do is white balance off the same target, preferably a grayscale chip chart, which is what the preset and auto white circuitry is adjusted to in the engineering lab.
But the question begs a discussion of why white balance at all? Many folks, myself included rarely white balance (with single camera production) once we know and are satisfied with the presets of our camera. You'll notice if you compare the preset and a white balance of the same scene (including flesh) that the preset is usually warmer and better looking. By using this same preset setting and same lighting everyday you provide the postproduction folks matching material.
Of course if you are shooting under fluorescent or otherwised mixed or discontinuous light sources you might want to auto white, but still if you're able to, compare the resulting color with the preset on an accurate monitor.
With multicamera shooting, in lieu of complete engineering controls (charts, waveform/vectorscope, ccu's and a skilled engineer) the best quick matching method is to turn off the matrixes and white balance on the same chart.
You'll find that in general white balancing "takes the color out" of the picture. especially in early morning and twilight, when the sun turns warm. This is a very pleasing and interesting look, unless of course you're trying to match scenes from midday, in which case, yes, you should be taking the color out. Even under fluorescents or sodium vapor street lights, the off-color can sometimes lend the proper effect to the scene, by recreating what the eye sees and the mood of the location that's lit that way (like a large warehouse)!
The few times that accurate color must be achieved, like when doing a Campbell Soup commercial, or an automobile commercial with crs of a distinctive hue, it'll take more than white balance to do so. In these cases careful engineering of the matrix to the standards of a chart like the Chroma de Monde from DSC with a properly calibrated Vectorscope are called for, but remember even in these cases powerful post production color correction on a Da Vince or the like is almost always budgeted too!