White balance cards

[israa_elmaddah]

Hello everyone,

I bought white balance cards and I found white and black cards with the grey one. When do I use the white and the black one?

 

What is the best way to use the card? Till now I put the grey card in the scene shoot the scene on auto white balance mode, and then I edit the color in Lightroom according to this photo.

 

Am I doing it right?

 

By the way I shoot mostly food and products.

 

Thanks in advance :)

[JDMvW]

Color control patches are used to help adjust the image when converting for color printing.

A gray-scale can be used with color, but also for adjusting "zone" manipulation.

 

In use

Dyes do fade and change, so don't expose the card to too much light.

Edited October 31, 2020 by JDMvW

[JDMvW]

BTW, in place of the "zone system", we also have what is known as the "ozone system" in which a first-approximation color correction can be started by touching the white "eye dropper" in Photoshop to the lightest location in the image, and the black eye dropper, to the darkest. Then tinker from there.

 

That's just one possible way to use a white and a black (0 and 255) card in a picture, though the trick can be done with naturally occurring shades and colors.

Edited October 31, 2020 by JDMvW

[DavidTriplett]

There are a number of different approaches. In my Nikon system I use white to set a custom white balance. Your camera instructions will tell you how to set a custom white balance. I use the grey to find or set a neutral exposure value, but there are also instructions on line regarding how to use the grey for white balance. (I have a fabric, folding, 2-sided card, grey and white, that I keep in my bag for unusual conditions. I find I rarely use it, but when I need it, I really need it, particularly with the advent of LED lights that don't fit any particular pre-set standard.)

 

Here is a LINK describing the system I use.

Edited October 31, 2020 by DavidTriplett

[paddler4]

Gray cards are used for two purposes: to set exposure and to set white balance. I assume you are interested in the latter because you referenced color.

 

If the gray and white patches are both spectrally neutral, it won't make any difference which you use to adjust color. Just put the white balance eyedropper in Lightroom on the neutral patch, and it will re-set white balance. Then adjust to taste.

 

If you're shooting raw, which you really should be if you are concerned with editing to get precise color, it will make no real difference how you set the white balance in the camera. That will affect how lightroom first renders the image, but it has no effect on the actual data, and re-setting the white balance with the method I described will produce exactly the same results regardless of the camera WB. for this reason, I haven't bothered with a custom white balance for many years. Instead, I get a white balance in Lightroom from a neutral card (I use a whiBal), and then I sync that color temperature to the other photos taken under the same lighting. Lightroom makes that very easy.

 

You can easily test whether your two patches are both spectrally neutral. Shoot an image with both, then adjust the white balance with each and see whether LR gives you the same color temperature with both.

[rodeo_joe1]

I use white to set a custom white balance. Your camera instructions will tell you how to set a custom white balance. I use the grey to find or set a neutral exposure value

+1 to that.

White card to set white balance, and grey card to set exposure.

 

Black card? Pretty useless unless you know its exact reflectivity IMO.

If it's just darkly pigmented matt card, it's not going to have a reflectivity much below 2%.

 

A square of black velvet fabric glued to a board would be far more useful as a 'deepest dark tone with detail' reference.

 

BTW, if you're going to include the white or grey card in the picture to poke with the 'eyedropper' tool, then make sure it's not parked next to something brightly coloured that'll reflect a colour cast onto it. It needs to be in the full beam of your key light.

Edited November 2, 2020 by rodeo_joe|1

[conrad_hoffman]

If I'm doing something like product photos I'll use a white card and set the camera's custom white balance. Other than that, the Nikon auto setting that maintains "mood" works great. For other things, if I have a white or grey target in the photo I'll usually waste a huge amount of time on the shot, getting that spot just right, dislike the result and just go with what looks good.

[Karim Ghantous]

Black card? Pretty useless unless you know its exact reflectivity IMO.

I'm not a printing or publishing expert, but black patches are used to set black points, I believe. The WhiBal card, which is one product among many, has a 12% WB gray patch, a white patch and a black patch. I'm rarely that fussy, and I would agree that the most important thing is WB, and even that isn't always necessary.

[rodeo_joe1]

black patches are used to set black points, I believe.

As I said, they can only reach a minimum reflectivity of around 2%, and that's not dark enough to be very useful. It's less than 4 stops below mid-grey, while shadowed areas of a scene can be much darker.

4 stops below mid-grey would be a widely accepted 'black point' and matt inks or pigments just can't get that dark. Gloss surfaces can, but only if positioned not to directly reflect light.

 

Besides, a digital black point of 0,0,0 RGB is a mathematically meaningless state, since any increase above that represents an infinite increase in brightness. Division by zero being 'disallowed'.

[paddler4]

White card to set white balance, and grey card to set exposure.

 

What matters for setting white balance is that the reflection in spectrally neutral, not how bright it is. If the gray card is neutral, e.g. as it is on whiBal cards, it's fine for setting white balance.

 

As a practical matter, I never find a need to use my whiBal to set the white or black point. I meter off the scene for that. I use it solely to set white balance.

[israa_elmaddah]

Gray cards are used for two purposes: to set exposure and to set white balance. I assume you are interested in the latter because you referenced color.

 

If the gray and white patches are both spectrally neutral, it won't make any difference which you use to adjust color. Just put the white balance eyedropper in Lightroom on the neutral patch, and it will re-set white balance. Then adjust to taste.

 

If you're shooting raw, which you really should be if you are concerned with editing to get precise color, it will make no real difference how you set the white balance in the camera. That will affect how lightroom first renders the image, but it has no effect on the actual data, and re-setting the white balance with the method I described will produce exactly the same results regardless of the camera WB. for this reason, I haven't bothered with a custom white balance for many years. Instead, I get a white balance in Lightroom from a neutral card (I use a whiBal), and then I sync that color temperature to the other photos taken under the same lighting. Lightroom makes that very easy.

 

You can easily test whether your two patches are both spectrally neutral. Shoot an image with both, then adjust the white balance with each and see whether LR gives you the same color temperature with both.

Great information thanks

[israa_elmaddah]

+1 to that.

 

 

BTW, if you're going to include the white or grey card in the picture to poke with the 'eyedropper' tool, then make sure it's not parked next to something brightly coloured that'll reflect a colour cast onto it. It needs to be in the full beam of your key light.

 

So if I am shooting a burger sandwich for example, should I use the card on the background then add the Item? or do you mean I have to make sure the Item doesn't reflect any colors on the card?

Edited November 17, 2020 by israa_elmaddah

[rodeo_joe1]

or do you mean I have to make sure the Item doesn't reflect any colors on the card?

Yes.

Any strongly coloured part of its surroundings can cause a colour cast on a grey or white card and upset the white balance got from it.

 

Ideally you want your white balance reference to be lit only by the main light source, or at least in the same light as the most important (colour-critical) part of the subject.

 

For example: You can often see a green or blue cast in the shadows of poorly-shot TV productions that use a virtual 'green screen' background. That's a good example of colour contamination from a strongly-coloured adjacent surface.

Edited November 17, 2020 by rodeo_joe|1

[paddler4]

Yes.

Any strongly coloured part of its surroundings can cause a colour cast on a grey or white card and upset the white balance got from it.

 

+1

 

It depends on your setup, but in much of the studio work I do, all of the light is the same temperature, and the walls are primarily white, so the reflected light is largely free of color casts. Under those conditions, holding the card between a light source and the subject, just in front of the subject, works fine.

[q.g._de_bakker]

Since you're setting white balance settings for the light used to illuminate your subject, the card does not have to be close to the subject as long as it is in, i.e lit by, the same light.

 

(Reminds me a bit of a photographer preparing to take a photo of a large statue outdoors, in full sunlight, who used a hydraulic hoist/reach arm to be able to hold his incident light meter as close to the statue as possible, even leaning out of the basket to get even closer. )

[paddler4]

Since you're setting white balance settings for the light used to illuminate your subject, the card does not have to be close to the subject as long as it is in, i.e lit by, the same light.

 

That's right, as long as the lighting is uniform and you don't have non-neutral surfaces nearby. If that isn't the case, then holding the card near the subject will more accurately reflect the lighting that actually reaches it.

[paddler4]

Quote

Most digital cameras nowadays, including your smartphone camera, are proficient at manually adjusting the white balance.

I think you mean "automatically."

If they do well enough for you, then don't bother with a neutral card. However, even though my main camera has very good AWB, it often isn't close enough for my taste.

Of course, you can adjust in postprocessing. That's the point of a neutral card. It gives you an easy and accurate way to get a neutral WB. using Adobe software, the quickest way to do this is to use the WB eyedropper in either Lightroom or Adobe Camera Raw. It's a lot faster and more accurate than the method in the article you posted, which is "Play around the available options to find the right adjustment out of the RGB colors." Once one has a neutral starting point, one can fiddle to adjust to taste.

Without a neutral card, one can sometimes find a reasonably neutral area in the image as a starting point. I often use the whites of eyes or white in clothing. Not as good, but often good enough.

Edited October 18, 2022 by paddler4