[pure-silver] Why Zone V at 50%?
- From: "Ralph W. Lambrecht" <info@xxxxxxxxxxxxxxxx>
- To: PureSilverNew <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 30 Aug 2006 18:57:23 +0200
I have listed the same question below on APUG and the Large Format site, so
if you check those, ignore this post. Nevertheless, the 'real' experts are
probably here, so I duplicated the post.
Why does a digital camera record a Kodak Gray Card (Zone V) as 50% gray?
A Kodak Gray Card represents an 'average' scene of 18% reflectance, but that
has nothing to do with a mean or medium on a grayscale. A gray card has an
absolute log reflectance density of about 0.75. Medium gray on a 2.2-gamma
monitor and a calibrated print thereof is about 0.66. So the image of the
card is lighter than the card itself. Why? Who came up with this assumption
or standard? Is it a mistake? Did someone assume 'average gray' meant 50%?
Disclaimer:
I'm aware that this is a mainly or exclusively analog forum, but I doubt to
get a satisfying answer for my question in a digital forum, since they
usually understand little about the Zone System. That's why I post the
question here. Besides, I need this to work out some details about making
digital negatives, which will be used to make pure-silver contact prints.
So, it's an analog question in a way.
Regards
Ralph W. Lambrecht
http://www.darkroomagic.com
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