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  1. #21
    wiltw's Avatar
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    Quote Originally Posted by Terry Christian View Post
    I use a pocket size Whi-Bal.
    Fine for WB adjustment, but wrong tonality for light metering purposes

  2. #22
    Bill Burk's Avatar
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    Quote Originally Posted by Trail Images View Post
    products offered up as 18% gray, but immediately followed up with statements of confusion and product reviews of more or less 12% gray and or used for white balance too. Say what? Is it a true 18% or not?
    There are some fun articles about 18%.

    Any known value could be used to determine exposure. In Zone System terms you can hold up a black card and stop down 3 stops to "place the reading on Zone II" for example.

    If you plan to take a photograph of the target itself, for example film testing... Then the actual reflectance is irrelevant...

    But to take a reading from a target as a "proxy" stand-in for the subject, the reflectance of the card should probably be about 12%.

    To make it neutral, I wouldn't do an inkjet (if the inkjet uses dye-based ink). Maybe something carbon based would be neutral, maybe a laser printer or artist's charcoal. For example, to make a target yourself... If you have a combination incident/spot meter, you could switch modes back and forth and color a board with charcoal until both modes read the same.

    Still, there are adjustments that may be appropriate if the subject is "predominantly dark" or "predominantly light shades". I guess there isn't a hard and fast "one percent solves all problems" answer.

    This is one fun article though not very indepth: http://www.bythom.com/graycards.htm

    For an explanation of K, which puzzled Ansel Adams and which I think may be responsible for the choice of 18%, I don't know a better write-up than Stephen Benskin's tutorial on the K factor:

    http://www.apug.org/forums/forum37/8...ancel-out.html

  3. #23
    RalphLambrecht's Avatar
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    Quote Originally Posted by Trail Images View Post
    Good point Alan, which leads to the question, where do you find a 12% card? 1/2 stop is not a deal breaker, but why not sell and advertise 12% cards I wonder.....thank you for your comment and the link too.
    it is not too hard to make your self any gray card%as long as you have a densitometer,some mount boardand weatherproof paint in neutral white and black.t's what i used for my zone cube:
    Attached Thumbnails Attached Thumbnails ZoneCube.jpg  
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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