Digital BW, The Print

----- Original Message -----
From: "Craig J. Sterling" <craig@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, October 19, 2002 2:56 PM
Subject: Re: [Digital BW] My Spectrocam as a Densitometer


> Greetings,
>
> I have checked the Archives, but cannot find an answer.
>
> I have a Spectrocam Photospectrometer that I use in conjunction with
> ProFiler Pro software for generating colorsync profiles when printing from
> my 7000.  I have just discovered how to measure densities using the
> Spectrocam...WOW!
>
> While I can read the densities of my gray scale step wedge printouts,
these
> numbers are sensless without a reference.  Any suggestions on how I can
come
> up with a set of "base-line" numbers or values for each of the steps on a
21
> step grayscale?
>
> Appreciate any advice you folks might have...Craig

Craig,

I am not sure what you are looking for as a base-line number. The Spectrocam
is giving you Visual or Neutral density and this is an actual measurement in
log form of how much light is reflected from what you are measuring. Density
= log10(1/Reflectance)

As a guideline, paper white is usually in the range of 0.06 to 0.08. Silver
fiber prints have a Dmax values ranging from 2.0 to as much as 2.8 depending
upon brand, development and toning. Carbon pigment inkjet prints have Dmax
values in the 1.4 to 1.9 range depending upon ink, paper and workflow. 1.6 -
1.7 would be a typical values.

A word of caution on the Spectrocam. It does not accurately measure
densities above 1.7. Antonis did a comparison between a X-Rite 810, X-Rite
Digital Swatchbook and a Spectrocam. Both the Spectrocam and the Swatchbook
read low as the density exceeds 1.7. It may be that these hand held units do
not have a bright enough light source to get good readings when the matte
blacks get really dark.

Martin Wesley

http://www.borderless-photos.de/guests.html