Gray cards : the 12% - 18% controversy

Started Apr 13, 2013 | Questions thread
xpatUSA
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Re: Gray cards : the 12% - 18% controversy
In reply to Roland Karlsson, Apr 15, 2013

Roland Karlsson wrote:

xpatUSA wrote:

Not only that, ISO gives what they call "latitude" so, when you set ISO 100 on the camera, it could be anything between about 75-125. A good indication might be to shoot a gray card metered to zero plus half a stop and check the histogram (with as little processing as possible, esp. brightness and saturation) - it should show a narrow distribution in middle of the horizontal axis.

The middle? How do you define that?

A trick question, I suspect

I define the middle of the histogram's horizontal axis (assuming 0-255) as 127.

Of course, it could also be defined as 118 depending how gray you like your mid-gray . . .

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Regards,
Ted http://kronometric.org
SD9, SD10, EF-500, GH1.

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