Archived posting to the Leica Users Group, 1999/12/14

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Subject: RE: [Leica] B&W Scanning
From: "Jonathan Borden" <jborden@mediaone.net>
Date: Tue, 14 Dec 1999 10:19:35 -0500

> I think zones are frames of mind, what you make them, not logarithmic or
> numberical There are numbers involved. But they come later it think.
> Mark Rabiner
>

	By definition Zone O is pure black, Zone 10 is pure white and Zone 5 is
middle grey (the gray of an 18% gray card). When you create a step of values
between Zone 0 and Zone 10, *perceptually* it appears as each step is
getting linearly whiter. The difference in exposure for each Zone is roughly
1 EV, so the brain responds to increasing brightness in roughly the same
fashion as a calibrated meter.

Jonathan Borden