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From: beyer@houxs.UUCP (J.BEYER)
Newsgroups: rec.photo,sci.electronics
Subject: Re: Homebuilt transmission densitometer?
Summary: Check ANSI standard
Message-ID: <663@houxs.UUCP>
Date: 9 Feb 88 14:10:42 GMT
Distribution: na
Organization: AT&T Bell Laboratories, Holmdel
Lines: 14

R
eferences: <2659@dcatla.UUCP>


There is an ANSI standard on transmission densitometry that you should
look up. While you could make a densitometer in ignorance of the standard,
and while you could calibrate it to serve your personal needs, your
numbers will not agree with anyone elses unless your machine conforms
fairly closely to the standard.
The light color is fairly important as is the sensitivity curve of the
detector. Of greater importance is the angle of acceptance of the
detector and the angle of illumination of the source. If you don't
get these right, you will not be measuring diffuse density, but something
else. THis will confuse you and everyone else.