Photographing with gray card

Of course, all digital cameras can perform automatic white balance. As a rule, you get good photographic results this way.

However, there are situations in which the automatic system produces incorrect results. A gray card helps here for correction. The gray card is a seemingly overpriced piece of cardboard - the special thing is that the cardboard reflects exactly 17,68% light. Because of the necessary accuracy, the gray card is also correspondingly expensive.

What was the effect of working with a gray card? Here is a simple test image that I took at the beginning of May at around 19 p.m. - well before dusk, which is visible to the eye.

As you can clearly see, the image has become too blue. This is particularly noticeable on the head of the blue tit, because the plumage on the side of the head is actually white.

Our human eye compensates for the changed light composition and sees the situation without the color cast. However, the camera's automatic system is overwhelmed at this point. Getting the color shift out again later in image processing is very laborious. It's quicker and much easier with a gray card.

There are two ways to work with a gray card: either you hold it in the picture and then correct the white balance in the usual RAW editing programs or you calibrate the camera using a gray card - but this is not possible with all cameras. (Please take a look at the user manual.)

In the first case, ideally you hold the gray card directly next to the object - only a small part of the gray card needs to be visible in the image. Of course, this doesn't work with an image like the one above. Then you can help yourself by taking a photo of the gray card, roughly in the same way that the actual object of desire will later be photographed. In both cases, the correction happens afterwards during image processing by taking the color temperature on the gray card using the usual pipette and transferring this value to the other images. Depending on the program, there are corresponding automatisms for this.

Of course, it is nicer if the camera allows individual calibration. You should photograph the gray card out of focus. To find out how the rest of the calibration works, please refer to your camera's operating instructions. The advantage is that you can also take photos in JPG, because the white balance is then adjusted exactly to the lighting conditions.

In both applications, care should be taken to ensure that the light composition changes quickly in the evening hours and that the white balance should therefore be done more often.

The result of the individual white balance looks like this: