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The AGFA data sheet actually does show some reciprocity info, up to 100
seconds exposure. With this film it calls for an adjustment of +2
f-stops.
Walter Willis
Life without chocolate is too terrible to
contemplate
----- Original Message -----
Sent: Monday, August 25, 2003 2:57
PM
Subject: Re: [APML] Agfa Optima Prestige
film
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>>>>>
"Bert" == Bert Katzung <katzung1@comcast.net>
writes:
Bert> I've never used Optima Prestige,
but recommendations of
Bert> daylight photographers,
professional or otherwise, are
Bert> generally
worthless for astro applications. The reciprocity
Bert> characteristics of films are generally unknown to them
(and
Bert> sometimes to the manufacturer as well,
when it comes to 1
Bert> hour exposures) and
reciprocity is critical for our stuff.
As a small footnote to this, I
recently picked up a book on large
format photography. Interestingly
enough, it has a set of charts
showing reciprocity adjustments for a large
number of films. The
chart only extends to about 120 seconds
(nominal, the adjusted
exposure may be much longer). So *some*
professional photographers
are at least aware of the problem. Too bad
Kodak, Fuji, Agfa,
etc. don't publish similar
charts....
regards,
roland
- --
PGP Key ID: 66 BC 3B CD
Roland B.
Roberts,
PhD
RL Enterprises
roland@rlenter.com
6818 Madeline Court
roland@astrofoto.org
Brooklyn, NY 11220
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