Re: Dynamic Range testing
Re: Dynamic Range testing
- Subject: Re: Dynamic Range testing
- From: Rudy Harvey <email@hidden>
- Date: Thu, 6 May 2004 12:39:54 -0700
Hi Terry, It was called the Q' Factor.
You are correct , it is a very real effect, caused by dispersion of the
light path
by film grain. It is another good reason to scan using oil. Using oil
in effect , reduces
the number of surfaces to 2 instead of 6(mylar-2 , film-2,drum-2)
Yea, have not heard that mentioned in over 10 years.
I just love terms like this , they only mean something to about 20
people on the planet.
All the Best
Rudy Harvey
Adobe Certified Expert
Certified Photographic Consultant
Custom Scanning Services
Why not scan a Stouffer Certified 21 Step Transparent Calibration
target
T2120CC? It's piece of black and white film that goes from .04d to
4.07d.
That would definitely be less expensive than the Kodak ST-34 that Jim
Rich and I suggested (I mistakenly called it the T-34 step wedge).
However, the Stouffer scale is a silver-based step wedge instead of
being of the dye/carbon variety. I'm reaching back almost twenty years
(oh, hey, I wondered where I put that...) but I thought the issue with
silver scales was that they would APPEAR more dense to the scanner as a
result of the light getting blocked by the relatively large silver
grains as opposed to being nicely diffused by the carbon dye material
in the more expensive step wedges. I forget the term for this effect
but it was "real" and the reason why you couldn't use a plate exposure
step wedge on a scanner. The silver scales worked fine when used in
contact (such as plates) but not so well when light was projected
through them. Just a thought.
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