This was meant to be a private letter.
On 2/8/2021 10:01 AM, `Richard Knoppow wrote:
You are right. This is my problem at my age. I draw blanks on words and have to paraphrase them. Both of these effects are probably more easily explained with illustrations. In any case, some photographers seem concentrated on getting exaggerated versions of both while a great deal of historic research was aimed at getting rid of them. Fascinating.
I never actually forget anything but it may take hours or even days before the missing word pops into my head. When I have learned anything in an organized manner it may take a while for it to percolate down if I have not had to use the knowledge for a while. Then a whole flood of stuff comes back. When I begin to write about something it triggers or cues my memory and I must sometimes stop to organize what I want to say.
Forgetting words is not new but has gotten worse as I have gotten older. My doctor assures me its not dementia.
On 2/8/2021 9:43 AM, Robert Shanebrook (Redacted sender makingkodakfilm for DMARC) wrote:I think you have interchanged "adjacency effect" and "acutance".
My off the cuff definitions are:
*Adjacency* is an enhancement at a density border documented by microdensitometry trace showing a decline in density and an increase at the border. The narrow decline and increase is at a level more extreme than the adjacent broader areas.
*Acutance* is a MTF based subjective measure that estimates the visual response. It is usually referred to CMTAcutance. There is a paper published on this in JOSA or SPSE Journal.
As a photographer, film designer, and film manufacturer I am not an advocate of still development. It creates more problems than benefits.
Bob Shanebrook
On Monday, February 8, 2021, 12:22:48 PM EST, `Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
Acutance is the word I was drawing a blank on. Thank you.
The idea of high acutance developers is that they effectively
draw lines around things by increasing the contrast at the border
between high and low densities.
It should be understood that the acutance effect is not the
same as resolution or the ability to record fine detail. In fact,
it is an optical illusion and can result in a loss of resolution.
The acutance effect can be created either by the generation
of a restrainer at the border or by the generation of a
development accelerator at the border. In either case lack of
agitation tends to keep reaction products near the source of
their generation and encourage the diffusion throught the
emulsion by increasing the concentration at the source. A
restrainer will interfere with development at the border, an
accelerator will increase it and a microscopic examination of the
image will show that the denser part is more dense right at the
border and the low density side is less dense, both because the
activity of the developer there has changed. These effects
probably take place under all conditions but are exaggerated by
"stand" development. Where agitation is insufficient the same
causes will produce streaking, or either an increase or decrease
in the density of the image immediately adjacent to a high
density area. When the film is vertical gravity can cause this by
cause a flow of the reaction products where they are of slightly
different density. These are sometimes known as motion effects
and used to plague motion picture processing by causing streaking
in the direction of motion of the film in the processing machine.
Anyway, "acutance" was the word hiding behind the curtain in
my memory. Thank you.
On 2/8/2021 4:11 AM, BOB KISS wrote:
>
> "Acutance"?
>
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>
WB6KBL
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