White or Grey

I also use a colorchecker and think it's a great little tool. As a backup, just in case I forget to bring it along, all of my cleaning cloths are Pearstone brand from B&H... which just all happen to be 18% grey and can be used for WB in a pinch.

Yes it does and thank you for your input it is much appreacated.

Thanks Lyndon looks like i off to the camera shop again,

DaviSto wrote in post #18346929
If you are using this for custom white balance. Is there also a way of getting the K value from the first white/grey shot or is this something that you adjust in PP, for example by using the eye-dropper in Lightroom?

I've a feeling there's something I've missed.

To answer my own question ... "Read the ******* manual!"

All clear now.

The one key point that was missed in this conversation is that a color reference used for white balance in a digital workflow has to be designed for digital image making.

There are several, my preference is the Color Checker which is now owned by Xrite. I use it primarily because the 24 square Color Checker has been the default reference for printing pre-press color calibration.

If the reference used is not specifically intended for digital use, it is likely to color casts that will throw off accurate reading by the camera.

I also do a custom camera calibration using Adobe DNG editor that generates a profile used by Lightroom and Camera Raw which is applied to the thumbnails generated by LR when the raw files are imported.

Considering this I leave my camera on auto white balance since the only place it makes a difference is on the LCD on the back of the camera.

When processing images there are two kinds of white balance; A)Technically accurate; B)Artistically meaningful. The second can be achieved by eye, the first requires a well thought out and careful workflow that starts with camera calibration and continues through to output from processing software for electronic or press use.

Wilt wrote in post #18347271
A cheap sheet of bond works, 'to get you close', but does NOT ensure color accuracy for color-critical reproduction.

exactly!

unless you really need perfect color accuracy, there is no need to overthink the issue.

I keep a few sheets of 'Brightness 90' printer paper in my bag. I've used paper napkins, tablecloths, back of some guys shirt. Anything white will work. 18% grey cards are for exposure, not WB. Two entirely different critters. You can use a grey card for WB. Using a white card for exposure will underexpose everything.

My WhiBal cards are of multiple sizes. Even a keychain size. Convenient and for white balance not exposure. I use color checker too.

Bassat wrote in post #18348744
I keep a few sheets of 'Brightness 90' printer paper in my bag. I've used paper napkins, tablecloths, back of some guys shirt. Anything white will work. 18% grey cards are for exposure, not WB. Two entirely different critters. You can use a grey card for WB. Using a white card for exposure will underexpose everything.

Why not just keep a Colorchecker Passport in your bag then? It's literally the size of a passport and weighs just a few grams. Then you can do light source profiles that take seconds. Or if that's too long you can use the Passport's light grey card as you would your paper, but know it's perfectly spectrally neutral.

Pippan wrote in post #18348808
Why not just keep a Colorchecker Passport in your bag then? It's literally the size of a passport and weighs just a few grams. Then you can do light source profiles that take seconds. Or if that's too long you can use the Passport's light grey card as you would your paper, but know it's perfectly spectrally neutral.

Because perfect/exact color reproduction is quite impossible anyway. Why bother? Close enough really is.

Bassat wrote in post #18348744
18% grey cards are for exposure, not WB. Two entirely different critters.

This is not necessarily true. The Kodak gray cards that have been made for eons can be used for both.

Bassat wrote in post #18348744
I keep a few sheets of 'Brightness 90' printer paper in my bag. I've used paper napkins, tablecloths, back of some guys shirt. Anything white will work. 18% grey cards are for exposure, not WB. Two entirely different critters. You can use a grey card for WB. Using a white card for exposure will underexpose everything.

You made conflicting statements.

An 18% gray card can be used for both exposure and white balance. There are other densities of gray card that are only for white balance and not exposure. But a photographic gray card can always be used for white balance.

Moreover, a gray card can also be positioned in the scene and used for more accurate white balance all the way down the chain beyond the utility of a custom white balance in the camera. When I've shot artwork, I've always included a gray card and color checker at the edge of the frame outside the artwork so that even a final lithographer will have a way to check his color accuracy...can't do that with only a camera custom white balance.

My usual method of balance is a gray card in the scene (not every shot, of course, but the first exposure-correct shot in the given light). White objects in the scene are practically useless for that purpose.

SkipD wrote in post #18349004
This is not necessarily true. The Kodak gray cards that have been made for eons can be used for both.

The Kodak gray cards that predate digital photography are not color neutral. They are poor white balance references.

Bassat wrote in post #18348954
Because perfect/exact color reproduction is quite impossible anyway. Why bother? Close enough really is.

I think there is probably a whole pre-press profession that would challenge that statement.
Perfect/exact are relative terms. I know from experience that using a color checker for reference I can produce digital images of art work and products that are visually identical.

dmward wrote in post #18349908
I think there is probably a whole pre-press profession that would challenge that statement.
Perfect/exact are relative terms. I know from experience that using a color checker for reference I can produce digital images of art work and products that are visually identical.

It's amazing that we get as close as we do. Considering we start with pixels captured by a camera, viewed as pixels on a RGB monitor, converted to CMYK, & then printed with dyes & pigments on varying grades of paper, isn't it?