The gray card and its use - Photography Course - Lesson 30

This article is part of the online digital photography course.

Related article: The white balance - Photography Course - Lesson 29

Foto by Wolfgang Lonien Flickr.com/photos/wjlonien/
In conditions of mixed light our camera may have many problems in balancing the white, in this case it comes in help the 18% neutral gray thin cardboard that is used to calculate the exposure. Some photographers use a gray card that is 5% neutral, a compromise between the total white and the darker grays.

Massimiliano Albani, a user of the board forumdifotografia.it, wrote:

“I find pretty useful the 18% neutral gray thin cardboard in conditions of mixed light, the colors are more close to reality than those obtained by using a simple white paper.

I use the thin cardboard this way:

  1. I place the paper on the scene in the way that it reflects the light as the subject.
  2. I take a picture of the entire paper.
  3. Then I remove the paper and take normally all the other pictures.
  4. In post-production I open the picture with Lightroom.
  5. In the BASE section of the Development module I take the sector of the white balance and I click on the zone with the uniform light of the paper.
  6. Done! Lightroom gives me the right color temperature value that I can apply to any picture.
While making the white balance during the shot with the gray card depends on the brand of your camera, the conceptual procedure is the same for every camera.

  1. Place the paper on the scene making it reflect the light like the subject.
  2. Take a picture of the paper so that it takes most of the frame. Possibly with a manual focus and a correct exposure (important to obtain a correct color temperature).
  3. In the camera menu go on "custom WB".
  4. At this point the picture previously taken must be selected.
  5. For the subsequent shots choose from the WB settings the option "custom". This options are set based on the previous picture.
I honestly find more convenient and accurate the post-production procedure.

Another user called sinXphotography answers:

I use the ColorChecker ( a tool divided in colored squares that have the primary colors). Basically it works similarly as the gray thin cardboard, but is more accurate in the closeness to reality of the obtained colors.

It’s used in the same way:

  • You have to take a picture of the color checker on the set, with the same lights.
  • In post-production, with its software, is produced a DNG file that will be used with Camera RAW or Lightroom for the balance.
It’s provided also with gray and white squares, with which you can do a classic balance.

It's very useful for the Still-life, but it can be used pretty well for exteriors and studio services as well.

Regarding the thin cardboard, you should take a picture just to it, always lighted by the set light, then try to set the custom WB on that shot and it should work on all the subsequent shots.

Translation by Nina Kozul

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