Difference between white card and grey card?


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rongwei82

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Oct 5, 2006
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#1
Hi ppl, just getting confused between a white card and a grey card.

1) Whats the difference?

2) Both are used in the same way?

3) White card use for custom white balance? ( Does that applies to the grey card as well?)

4) Grey card used to check correct exposure? ( The 18% grey refers to exposure or correct colour correction?)
 

Michael

New Member
Apr 5, 2005
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www.pbase.com
#2
Hi ppl, just getting confused between a white card and a grey card.
i presume you mean a whitebalance card and a grey card.

1) Whats the difference?
Both of them are grey, however a WB card needs to be of neutral gray (no colour at all) while a grey card used for exposure may have some tint

2) Both are used in the same way?
you can use a WB card for WB and exposure, a grey card only for exposure

3) White card use for custom white balance? ( Does that applies to the grey card as well?)

4) Grey card used to check correct exposure? ( The 18% grey refers to exposure or correct colour correction?)

both cards should be grey. if a card is fully white (or black) you do not have sufficient information for either WB and exposure since you overflood the sensor. 18% grey was specified for exposure cards as it matches well the average light on a frame. and it works fine for WB
 

catchlights

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Sep 27, 2004
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www.foto-u.com
#3
white card and gray card, white card or gray card, white card vs gray card............

For white balance need any objects with neutral tone, so you can use both cards for White Balancing

Gray card are calibrated to 18% gray, so it is a standard device for metering exposure, you also can use a white card to check correct exposure, since white card is two stops over (brighter) than a gray card, so you need to close down two stops to get the correct exposure, anyway, this is method not recommendable, unless you don't have access to gray card and know what are you doing.

btw, if you over or under exposed too much when you are using a gray card for white balancing, will have error massage, same thing will apply on using white card for white balancing.

Hope this help.
 

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