Re: using a scanner as a densitometer?

Liam,
Stouffer makes what they call a "camera man's" target which is reflective --
probably because it's helpful in the world of off-set press. I bought a
couple just to use for reference for photographing. I have the R1215
(12-steps each at .15 du) but they also make a 21 step wedge that goes up by
.10 du. Stouffer says their reflective tablets go up to 2.05 dmax. By my
calculations this means the first step is .4 !?

~m

----- Original Message -----
From: "Liam Lawless" <lawless@bulldoghome.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, February 22, 2006 2:10 PM
Subject: RE: using a scanner as a densitometer?

Mark,

Doesn't the Stouffer have 21 steps? Each step 0.15, give or take a bit, and
B+F around 0.05, should make the top step 3.05. Or are you talking about
some other Stouffer?

Liam
-----Original Message-----
From: Ender100@aol.com [mailto:Ender100@aol.com]
Sent: 22 February 2006 19:09
To: alt-photo-process-l@usask.ca
Subject: Re: using a scanner as a densitometer?

It is not too difficult to get fairly accurate densitometer readings from
your scanner, as long as you have a standard reflection step tablet to use
as your standard comparison—these are available from Stouffers.

I included this feature in the new PDN Curve Calculator II just as an added
tool and it is surprisingly accurate—compared to my reflection densitometer
the values varied no more than about Log .02 reflection density. You just
enter a measured value between 0 and 255 and the software converts it to a
Log value for you.

The main trick is setting black and white endpoints properly using the
reflection steptablet and then saving that setting to use later with
whatever you are measuring. You then compare the Photoshop Values of the
print densities you are measuring to the known values of the reflection step
tablet. You can easily create an Excel Spreadsheet that will convert this
data for you.

Note that the maximum value on the Stouffers is Log 2.0 reflection, so
unless someone knows of a reflection steptablet that goes above that value,
you are limited to values between Log .03 and Log 2.0 when using this
method.

Best Wishes,
Mark I. Nelson
www.MarkINelsonPhoto.com
www.PrecisionDigitalNegatives.com
PDNPrint Forum @ Yahoo Groups

---
[This E-mail has been scanned for viruses but it is your responsibility
to maintain up to date anti virus software on the device that you are
currently using to read this email. ]