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I normally photograph landscapes. However I am dabbling in photographing some friends' artwork and I am quite pleased with the printed results, when you consider the nightmare of colour matching paintings to print.

I use a set of daylight balanced fluorescent continuous bulbs at 5200k. I place in the picture a gray card which gives me my correct white balance in Photoshop CC raw. The pictures are beautifully lit so why when I click on the gray card does it change it to 6500k-6700k which does make it correct? I would have thought the correct white balance would be at 5200K and that clicking on the Gray card would not really make a difference. It doesn't really make a difference to me because I am happy with the result. I just don't understand, with being new at this.

  • What, if any, other sources of light are present and adding to the light reflected by the artwork? – Michael C Mar 5 '16 at 22:03
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Daylight (in photography) is not an absolute color, it's more a vague wishful dream. Liberties are taken. :)

The various light bulbs will simply vary greatly, each brand and type. Your gray cards will vary slightly too, and 18% gray cards are really too dark. Gray WB cards are much lighter, and I'd suggest a "white" white balance card, the Porta Brace is only $5 at B&H.

Your work is OK if you have the reference to correct it. You click on the neutral card, telling computer "This spot is neutral, make it be neutral", and it does, and removes the color cast there (result has equal RGB components, no color cast).

Here is a sample of several cards, with the same one flash illumination.

enter image description here

It is JPG now, and it's been corrected once, but you can still click around on it.

Clicking in Raw, on 4 gray card brands at top, from top left to right, I get

6300K -13 tint
6400K -3
6300K -4
6450K -4

The two small gray cards down at left

6600K -3
6750 -3
The WhiBal card in center 6350K -6

The large white foam board everything is mounted on 5750K -4

Across the bottom, left to right:

The two white Porta Brace WB cards at bottom

6400K -5
6350K -8

The sheet of plain white copy paper 6500K -11

The cheap white envelope 6300K -9

Clicking around on the same card often gives slightly different results. Not so much that it actually matters. About any try is greatly better than no try at all.

Flashes all vary too. They claim Daylight, and they're usually halfway close, but they could be a little low, or 1000K high, and also with a color tint. Flash color WILL vary with their power level. They also age and shift. Light bulbs too. Excepting perhaps bright direct sun, we always need to correct white balance. The flashes and light bulbs will vary more than the gray cards do.

But any situation can be made pretty good if you have a reasonable reference to correct it.

  • Thank you for taking the time for such a comprehensive answer. It is greatly appreciated! Cheers. – John Trewen Mar 6 '16 at 14:20

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