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White Balance function question

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  • White Balance function question

    Has anyone used this? I could not find anything in the archives about it.

    I'm using pro 7, by the way. My specific problem is I'm shooting wildlife (moths) in an environment of UV, MV and a 6x6 "flood" LED lamp. I nearly always shoot RAW. So, WB becomes pretty important. I have procured a set of white, gray and black cards to assist with white balance. If I shoot the gray card using just the LED lamp, I get a different result from the white card.

    Process is Develop, White Balance, eyedropper most anywhere in the card. The gray card gets results that are much more natural, to me.

    I can't find anything in the manual that is... illuminating . Any suggestions?

  • #2
    In my experience, whites tends to not be very good for setting white balance with the eyedropper because they tend to clip one or more channels and hence don't represent the color of the light as accurately as a gray card. So I'd say, keep using the gray card.

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    • #3
      As Marc said and I think it's true that most if not all cameras assume that the world is 18% grey (not a spelling mistake!) on average and quite often they are right. I'm a fan of Michael Tapes WhiBal.

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      • #4
        Sometimes, the eyedropper can only get you 'close'. When, some manual White Balance tweaking is required, here are some additional suggestions:

        The Red-Green slider affects tint and should be used very delicately, or not at all. The only time I ever touch the Red-Green slider is when I can visibly see a pink or greenish cast in an image. Only then, I might nudge that slider a click or two to offset a slight color cast.

        The Yellow-Blue slider is the important slider when your image suffers from off-color lighting. This is the slider you want to work with to get the lighting in your images just right. Add more yellow to make an overcast day look less grey and gloomy. Add more blue to offset the yellowish tint on indoor shots taken in incandescent light (no flash). Conversely, add yellow to offset the excess blue in Fluorescent lights.

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        • #5
          My understanding is that 18% grey cards were originally intended for exposure checking in the days of film. I’d guess, then, that when digital cameras came along people used them for white balance purposes simply because they were available, and that manufacturers continued to make them because they still sold.

          As has been pointed out, one problem with using a white card is that one has to be careful not to overexpose the card, because the procedure is invalidated if any of the RGB channels “clip”. On the other hand, using a white (or very light grey) card will offer finer graduation in the RGB values (i.e. a difference of 1 is a smaller % of the total).

          So perhaps a light grey card (rather than a mid-grey or white one) would be the best compromise. That seems to be what Sam’s WhiBal is – it certainly doesn’t look like a mid-grey, and an image I grabbed from their website measured between 210 and 240 (out of 255) in RGB terms.

          Of course, having said all that, there’s really no such thing as “perfect” or “correct” white balance, and ultimately it all comes down to what you (or the client, if you have one) like and/or are trying to achieve. (For example, I don’t think many people would “correct” the colour balance of a sunset shot by reference to a card, because in that light they wouldn’t want a white card to look white.)

          I’d also guess that if you included both the grey and white cards in an image and “corrected” it by one the other won’t appear perfectly neutral (all RGB values the same).
          Last edited by JohnRadcliffe; 11-26-2013, 06:11 AM.

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          • #6
            How come this thread shows as having 5 posts (it will be 6 now!) but there are only 4 (well 5 now!)?

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            • LV_Bill
              LV_Bill commented
              Editing a comment
              Hi Sam - The 'missing' post is mine. It was "forwarded to the Moderator for approval". Another vBullietin bug/quirk. IMHO, the ACD Forum is not being served very well by this difficult to use software. That said, it does get credit for ridding us of the Asian spammers.
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