[pure-silver] Re: EI testing with Minolta Spotmeter
- From: "Ralph W. Lambrecht" <info@xxxxxxxxxxxxxxxx>
- To: PureSilverNew <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 23 Apr 2006 19:07:27 +0200
Paul
> So, if I understand you correctly, I take one reading and place on Zone
> V, make exposures at 1/2 stop increments from that reading, then check
> for 0.1 or 0.17 density.
Correct.
> From that, do I work back to my Zone V to judge
> what EI to use? How would I judge this?
Let's say you're using a film with an advertised speed of 400 ASA and your
meter is set to that speed, and expose the first frame as the meter suggests
for a gray card. Then give 1/2 stop less for the next frame, 1 stop less for
the frame after that, and so on. After 9 frames you can stop and fill the
rest of the roll with the first exposure setting. Process the film normally.
Now evaluate the film. Now starting with the first frame, count in the
following sequence 25, 35, 50, 70, 100, 140, 200, 280, 400, until you get to
the frame with a Zone I density. The counting sequence will reveal your EI.
Feel free to interpolate if the Zone I density is in-between frames.
Why does this work?
Zone V is 4 stops away from Zone I. That means the first frame was
overexposed by 4 stops in order to generate a Zone I, if the box speed is
correct. Overexposing a 400 ASA film by 4 stops is equivalent to exposing it
as 25 EI. With increasing frame numbers, the overexposure is reduced and you
are getting closer and closer to the advertised film speed.
Regards
Ralph W. Lambrecht
http://www.darkroomagic.com
On 2006-04-23 16:51, "Paul Mead" <paul.mead@xxxxxxxxxxx> wrote:
> So, if I understand you correctly, I take one reading and place on Zone
> V, make exposures at 1/2 stop increments from that reading, then check
> for 0.1 or 0.17 density. From that, do I work back to my Zone V to judge
> what EI to use? How would I judge this?
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