Re: Optical Density ?
Re: Optical Density ?
- Subject: Re: Optical Density ?
- From: Terry Wyse <email@hidden>
- Date: Thu, 05 Sep 2002 10:28:54 -0400
on 9/4/02 6:22 PM, Jim Rich wrote:
>
I find that using either a carbon dye grayscale as well as an IT8 to measure
>
density and density range provides realistic density readings
Jim took the words right out of my mouth. Back in the days of process camera
separations (yes, I'm that old!), we learned that normal transmission
*silver* grayscales APPEARED to have a much higher density when making
separations than was actually measured with a densitometer and that a carbon
dye scale was the way to go. The reason had something to do with collimation
of light/diffusion of the silver particles, something light that (is that
close Jim?). Anyway, the silver halide grayscales behave differently when
measured with a diffuse light source as opposed to being photographed.
If you're going to do experiments like this based on density, then you'll
want to use a carbon scale as they behave consistently whether they're
measured by a densitometer, photographed or scanned. The only one I can
think of off-hand is the Kodak ST-34 that's been around for a while. Only
drawback is that it pretty much peaks at around a 3.2 - 3.4 density. The
trick here is to purchase a square of Kodak neutral density filter material
in either 1.0 or 2.0 density and lay this over half of the carbon scale to
extend the density beyond 4.0.
Terry
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