U of S | Mailing List Archive | alt-photo-process-l | Re: Measuring DMAX

Re: Measuring DMAX

  • To: alt-photo-process-l@usask.ca
  • Subject: Re: Measuring DMAX
  • From: Richard Knoppow <dickburk@ix.netcom.com>
  • Date: Tue, 15 Jan 2008 15:06:42 -0800
  • Comments: "alt-photo-process mailing list"
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  • References: <C3B18FE5.BE2E%henry.rattle@ntlworld.com>
  • Reply-to: Richard Knoppow <dickburk@ix.netcom.com>
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----- Original Message ----- From: "Henry Rattle" <henry.rattle@ntlworld.com>
To: <alt-photo-process-l@usask.ca>
Sent: Monday, January 14, 2008 2:17 PM
Subject: Re: Measuring DMAX

Somewhere I have a device marketed by Kodak many years ago. This is a sheet
of card, rather like a grey-card but printed with patches of different
reflection density. Each patch has a hole in it, so you can place it over a
print, find the matching density and read off the value. Fairly crude, but
effective ­ not least because when you do the match, both the print and the
reference are in the same illumination. Must be thirty years old, and if you
give me a week or two I might even be able to find it!


You can also do this using a reflection step tablet layed against the surface of the print. The eye is very good at matching areas of similar brightness or color. The problem is that the color of the step tablet and print may be different and the surface texture may be different making it diffult to get a reading. This is a way of getting at least an approximation of the density.

Richard Knoppow
Los Angeles, CA, USA