[pure-silver] Re: Speed rating of glass plates
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 29 May 2009 18:34:41 -0700
----- Original Message -----
From: "Bogdan Karasek" <bkarasek@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, May 29, 2009 6:06 PM
Subject: [pure-silver] Speed rating of glass plates
hello,
Hope everybody is out burning film or sniffing hypo in the
darkroom . :)
I have a number of exposed 5x7 glass plates, they are
portraits, family, children, couple, single, done in a
studio. From what I can make out, i.e people sitting in
cars... probably 1920's?????
Does anybody know what would have been the ISO of these
plates? I also have boxes of 4x5 and postcard size
SEED's glass plates that are marked, "High Speed" which
would be what speed?
Any historians out there???
Cheers,
Bogdan
Any markings on the other plates? I have a little stuff
on very old plates and will look. About the only way to get
an idea of speed in modern terms is to look at the
recommended exposure chargs and use the "sunny 16" rule.
While there were several speed rating methods beginning with
Huerter and Driffield none was very reliable and
manufacturers often exagerated the speed. The exposure
charts _must_ be reasonably accurate.
A good source of information on at least British stuff
are old eiditions of the _British Journal Almanac_ The
advertising is often the most interesting part and some
manufacturers included short form catalogues with film data,
etc.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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