Calibrating white balance using a white card..

Sports Illustrated recommends that their photographers set up their 10d's using custom white balance by shooting a white card..(www.siphoto.com)

Sorry if I sound like a moron but what is the best way to do that?


Thanks for your help

http://www.luminous-landscape.com/tutorial​s/dig-exp.shtml

By the way, I use grey card for setting white balance.

mcneguy wrote:
Sports Illustrated recommends that their photographers set up their 10d's using custom white balance by shooting a white card..(www.siphoto.com)

Sorry if I sound like a moron but what is the best way to do that?


Thanks for your help

I don't know which camera you use, but when you're camera is capable of using a custom white balance you can find out how to do that in the manual.

I thought it was supposed to be a grey card??

An 18% grey card is used to get an "average" exposure in average to high light levels.
Some meters aren't accurate at very low light levels, so a white card can be used. Don't forget to adjust the exposure down after taking the reading.

If you don't have a grey card with you, do this before you go out without one
Take a reading off the grey card. Take a reading from the back of your hand. Take a reading from green grass. See how they compare to the grey card reading. Now you don't have to carry one all the time!

For white balance, you can use a grey card, but I personally just use a white sheet of paper I keep in my pocket.
Have you noticed that "White" paper comes in different shades? Something to play with when you have extra time! Try pastel shades, too.

Yes, a white paper can be used for setting the white balance. Since I cut the grey card into a smaller size, I can always bring them. It is as convenient as using a white paper.

Why does it have to be a grey card in average to high light levels, does the camera get fooled or what? I always use a white piece of paper

I assume that you are asking why a grey card can be used. The name "white balance" may be misleading to some extent. The setting of white balance is to prevent colour shift due to different colour temperature. A white paper is used for setting white balance because white is 100% Red+ 100% Green+ 100% Blue, i.e. neutral. To set the custom white balance, we in fact are telling the camera what is neutral. A 18% grey card can be used because it is also neutral, 18% Red+18%Green +18% Blue. Therefore a 18% grey card can be used for setting custom white balance. And I assume that the grey card is better than white paper in some situations -- it is calibrated, it is less reflective in high light level.

Oops! Or are you asking why a 18% grey card is used for checking exposure level? Since you were using a white paper, I assume your question is white balance.

White card is used for colour temperature/white balance.
Grey card is used for measuring exposure.

you shouldn't set your white balance with a grey card and you shouldn't try to set your exposure with a white card.

To shoot for a custom white balance, just use a piece of white paper on lowest jpeg settings, then set it as the custom balance in your camera (see your cameras manual)

Please explain why a 18% grey card cannot be used for setting custom white balance.

For white balance, it doesn't matter if you use a white card, a gray card, or even a black card for that matter. The only thing that matters is that the colors on the card are "equally" red, green, and blue (as they are in pure white, gray, or black). Then, when your camera knows what RGB values are equal, it can go from there.

Excuse my ignorance but: How do you do that?

You just meter on the gray card. That will give you the correct exposure for the existing light level and the ISO you have selected. It doesn't really matter what your subject is or what color it is or isn't. Just put your gray card next to the subject and meter on it.

Yes they are used for that. It doesn’t mean that they MUST be used for that.

The only requirement for setting a neutral white balance is that the subject be neutral as sdommin & nosquare2003 point out.

Sorry evilenglishman, but on this, Kodak disagrees with you. In fact, when Kodak provided the “Neutral Test Card� (publication # R-27), one side is 18% reflectance (grey) & The other side is 90% reflectance (white). Both were to be used for determining exposure. Using white simply allows you to extend the capabilities of your meter in very low light levels. ANY COLOR can be used as a ‘standard’ to set your exposure as long as you have calibrated the ‘standard’ to suit your unique requirements. (I hope I haven’t opened a new bag of worms here.)

I do agree with you on “... and you shouldn't try to set your exposure with a white card.� to the extent that you shouldn’t use it if you don’t remember to compensate for the different reflectance & adjust the exposure before you shoot.

For mcneguy, who may be thoroughly confused at this point, here’s how to see why you use a grey card to set exposure. The meter “thinks� that whatever it’s pointed at is 18% grey, an average. If you point it at a white subject & take a reading, then take a pic, the white subject will be grey. If you point it at a black subject & take a reading, then take a pic, the black subject will be grey. Try it.

18% grey is designed to provide an average exposure that should (read SHOULD) allow both the blacks & whites to be properly exposed using FILM. Film has more latitude (ability to capture more shades of grey) than digital ‘film’, so it’s even more important to tinker with the exposure after you see the results of the first ‘test’ exposure. It’s also why some people take two pics at different exposures & combine them in a program like Photo$hop to get an extended range of tones. For more info on that goto:
http://luminous-landscape.com …/u-contrast-masking.shtml

Hang in there. You’ll get it!