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Old Mar 1, 2004, 3:15 AM   #1
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Default Using a greycard!

I think I understand why a greycard is used, for white balance? But can someone explain it in a bit more detail. I.e. How it helps? How to use it? and What type/depth of grey is needed? Is there a website I can go to?

Thank you for your help,

Yours ignorantly ops:
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Old Mar 1, 2004, 6:21 AM   #2
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I suppose it could do white balance, and maybe I'm mistaken, but personally I thought a grey card was used more for accurate exposore. It is 18% grey - same as what your camera meters all scenes for. I've been told if you have a trickly lighting scene, you can meter your camera off the card in the light you'll be using and it helps ensure the exposure is correct. I know for my camera, if I want to set my white balance, all I need to do is set the wb against a white sheet of paper.
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Old Mar 1, 2004, 7:58 AM   #3
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Yes, a grey card is for exposure not while balance.

The meter is expecting you to point to something that is 18% grey, or at least reflects light like that. The problem is that the user doesn't always do that (I'm guilty too.) It isn't always possible.

Imagine if you meter off a white wedding gown. The camer will think the light came from something grey and pick the proper exposure.... for something grey, not white. The end result is that it will expose too dark and overexpose the dress.

The exact opposite happens when you meter of the grooms black tux. It will lighten the entire scene.

The nice thing about a grey card is that you know that if you put it in the same light as your subject... the exposure will be right.

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Old Mar 1, 2004, 8:35 AM   #4
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A grey card can be used for white balance in all but the lowest light: your camera will simply see it the same as a white card with less light on it. The key point for using any card for white balance is that the RGB values all be the same, not what the particular value is.

A grey card will give a good starting point for setting exposure, but it is not enough to guarantee good exposure. If you use it to set the exposure for a white wedding dress, likely you will blow out large parts of it (R=G=B=255). With most digital cameras (Fuji's new sensor might be different) there is a very sharp cut-off on the high end. Trying to get the groom's tux and the bride's gown exposed properly in the same shot is a bit more difficult than just metering off a grey card.

Using a grey card is almost always the best single exposure reading that can be done. Almost never will a single exposure reading produce the best exposure for the whole scene.

I only wish I could get the exposure and white balance right every time.
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Old Mar 1, 2004, 9:50 AM   #5
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Thanks Guys, think IŽll get me one of them there grey cards!

I am actually photographing my cousins wedding in July, although, as strange as it sounds, it is a "Wiccan" Wedding, and the ceremony will be in the New forest in Southern England. Should be a good opprtunity to get some good shots!

Thanks again....
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Old Mar 1, 2004, 10:20 AM   #6
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Merry meet.
Have fun at the handfasting, and chances are the bride and glooms clothes may not be black & white
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