[pure-silver] Re: Here's one for the head scratchers
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 16 Jan 2005 14:01:52 -0800
----- Original Message -----
From: "Helen Bach" <helenbach@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, January 16, 2005 8:58 AM
Subject: [pure-silver] Re: Here's one for the head
scratchers
> "I think that you'll find" that it is simply local
> disturbances in the
> Zugzeit-Luftkopf continuum.
>
> Well known to all those snappers who have one of those old
> folders
> with a little door in the back that enables one to write
> on the film
> by pressing through the paper with a stylus. Who needs a
> databack?
>
> Best,
> Helen
You are thinking of the old Kodak Autograph film and
cameras. The writing was not recorded by pressure effect but
by light. The paper film backing was such that the metallic
stylus would scrape away a layer of opaque material allowing
light to come through. I think Autographic film must not
have had an anti-halation coating on it. Kodak did not make
Autographic cameras or film for very long, evidently the
system was not really very satisfactory. Autographic cameras
took standard size roll film so the cameras stayed in use
after the special film was discontinued.
A sort of very early data back.
BTW, pressure effects on photographic emulsions has
evidently been widely studied. There is a mention of the
effect in _Theory of the Photographic Process_ 3rd edition,
Mees and James, with a number of citations to research
papers. The explanation given there is that the image is
produced by heat effects (see p.17), however I have a vague
recollection of an article attributing it to electron
release due to deformation of the crystal shell but have no
idea now where I saw this.
Modern emulsions contain additives for the purpose of
reducing or eliminating pressure effects.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you subscribed,)
and unsubscribe from there.
Other related posts:
