grey card use for white balance

Ivan Lietaert wrote on 1/15/2009, 10:22 AM
Lately, with all the snow, I've been setting the white balance of my camera manually. I simply point to a white object, and set the white ballance. The result is clearly visible. http://www.vimeo.com/2794792
Someone pointed out that I should focus on an 12% or 18% greycard, rather than a white surface. So now, I'm confused. Can anybody help me?

Comments

musicvid10 wrote on 1/15/2009, 1:33 PM
Your white balance is fine. The big concern outdoors is are you setting it on sunlight, or on the reflection of the blue sky? In this case you did the right thing by setting it on reflected skylight from the snow near sunset ( I presume). It might have all been too blue otherwise.

Setting WB on a gray card is a legitimate technique, esp. when the color (gamma) curves tip wildly in situations where you want to maintain integrity in the midtones, while allowing some sacrifice in the whites. An example is facial tones under flourescent lighting. It all depends on what part of the tonal scale is most important to you. (Never white balance on a face, however, but a gray card).

Whatever method you choose, it is a photographer's trick to tilt the gray card so you are not actually balancing on a visible reflection. HTH
Strangeman wrote on 1/15/2009, 1:39 PM
I think this advice is a hangover from the days of film when a camera's exposure meter was set up to produce an 'averagely' correct exposure (ie 18% grey). This would mean that if you pointed your camera at something bright and white your camera would tend to underexpose it if you just relied on the camera's judgement. Hence you would use the grey card to judge the correct exposure.

I may be wrong, but I think that in the digital era, this no longer applies (because we have white balance).
musicvid10 wrote on 1/15/2009, 1:54 PM
No, it's not a hangover, but a legitimate use of a gray card for setting white balance to a midtone rather than white, and one which has absolutely nothing to do with the still photographer's use of a gray card to set the average exposure value; although it "could" also be used for that purpose if you were setting your video exposure with manual iris. Hope this clears up the confusion between two entirely different uses of an old tool.