Use of a gray card (fill the frame) is used to get an exposure similar to what an incident meter will give you. You lock exposure or set the camera on manual so the exposure won't change when you take the card out of the image..

Use a white card in the same way to set correct custom white balance..

Larry Bermanhttp://BermanGraphics.com..

It is too short to understand. Could you give explain the process ? .

Larry Berman wrote:.

Use of a gray card (fill the frame) is used to get an exposuresimilar to what an incident meter will give you. You lock exposureor set the camera on manual so the exposure won't change when youtake the card out of the image..

Use a white card in the same way to set correct custom white balance..

Larry Bermanhttp://BermanGraphics.com..

Put the gray card in the same light (in front of the subject) that you ill be photographing. Fill the frame and take an exposure reading. Input those settings in the camera with the exposure set on manual. Then remove the card and shoot..

Larry Bermanhttp://BermanGraphics.com..

In a nutshell: A gray card is used to set the correct exposure on your camera in various lighting conditions (via the custom white balance setting). By metering the reflected light off of the gray card - which represents mid tones - you let the camera know what luminance should represent midtones in that given light. The camera adjusts/corrects the WB settings accordingly..

This is the concept, however there is a small caveat to it: The gray card represents 18% gray, which geometrically lies in the middle between white and black. However you camera meter is not exactly calibrated to 'see' 18% gray, but more towards 12% gray. This means that if you meter off of 18% gray your camera is still slightly off and the image will be underexposed by about 1/2 to 2/3 of a stop. You can see this by looking at the histogram of your camera. If you use such a card you need to compensate by 1/2 to 2/3 of a stop in order to have the correct exposure setting..

Follow this link for more information and instructions how to use such a card:http://www.luminous-landscape.com/tutorials/dig-exp.shtml.

Cheers,becksi.

Athenamathew wrote:.

Could some body explain the usage of Gray Card ? I am beginner inphotography. I am using xti.

Thanks in advance..

I disagree with none of the previous posts. But to explain another aspect of the importance of this, ask yourself the question, "What is white?".

If I am at home with my incandescnet lights, I see white, or with florescent lights, my eye/brain combination still see's the same color. Outside on a sunny day? Once again I see white, cloudy day? White..

But the camera doesn't know what white is. This is what the white balance control is all about. Making sure that your camera see's the same "white" as you eyes do. In the days of film you could buy, "indoor" or "outdoor" film. Digital takes this ability much further..

Hope this helps.

Dave..