Yikes, I wasn't slippery enough with my last post. Now you're trying to pin
me down. ;>
If what you've shot *so far* on a roll is important, and the photos may have
been significantly under- or overexposed (via incorrect ASA setting), I
think it would be better to continue shooting at the same ASA setting and
have the roll processed appropriately - push or pull - to compensate.
But what's significantly under or over? Depends on the film. Some of us
try to find the particular sweet spot for a given film and camera (due to
metering differences). So if for a particular film/camera the sweet spot is
320 (my preference for Agfa HDC 400 with my Can-not-an-OM-onet GIII),
despite the manufacturer's rating of 400, what's the equivalent of a
full-stop overexposure: ASA 200 or 160? I'd say it's 160. And two stops
over would be ASA 80. Which means, in a worst case scenario, if you
switched from Kodachrome 64 to Fuji Superia 400, but forgot to reset the ASA
- those photos might be salvageable, especially if the lighting situation
wasn't too contrasty. They'd only be a little more than two stops
overexposed (assuming we agree on the 320 ASA setting), which Fuji Superia
400 can tolerate fairly well, especially if the prints are done by a pro
lab.
Underexposure is another matter. Few films can tolerate much underexposure
without custom film processing. In my experience even Fuji, much as I love
its latitude, doesn't handle more than a full stop underexposure well. So
if your last roll was 800 and when you switched to 400 you forgot to reset
the ASA, a full stop of underexposure is workable without custom processing.
*But* if your particular combination of film/camera works best at 320,
then you've effectively exceeded a full stop underexposure and will see some
disappointing photos. Unless push processing is used.
So the short answer is, if there are no once-in-a-lifetime shots on the
roll, you can either:
1. Finish it at the "wrong" ASA and see how it comes out; or
2. Reset it to the "right" ASA and finish the roll so at least the rest will
turn out okay.
Otherwise, make a note of the ASA setting at which the first few photos were
exposed to help determine how much over or under they were, and have a pro
lab compensate.
Lex
===
Advice should not be taken with a grain of salt. That makes no sense. Take
it with a dose of salts (i.e., laxative) because the advisor may be full of
sh*t and trying to pass some along to you.
=====================================
From: Dan Lau <dlau@xxxxxxxxxxxxxxxx>
Subject: Re: [OM] What to do if ASA is set wrong
Date: Thu, 17 Aug 2000 15:31:16 -0400 (EDT)
On Thu, 17 Aug 2000 19:07, "Lex Jenkins" <lexjenkins@xxxxxxxxxxx> wrote:
>Depends on the film. If it's a typical color negative film and you've
>inadvertently set the ASA too low (in effect, overexposing the film), I
>wouldn't worry about it. Most 400 films can handle being set to 200; 200
>can handle 100; etc. Underexposure is trickier but many films can handle
up
>to a full stop of underexposure without significant loss of printability.
OK. From this (i.e., color negative film), can I take it then it is
better to reset the ASA to the proper value and continue with the rest
of the roll; then process the film normally? I am trying to figure
out whether it is better to shoot the whole roll with the same ASA
setting (even though it is not correct) or better to change ASA is the
middle of the roll. Thanks.
-Dan
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