Re: BTZS ExpoDev software for reciprocity corrections

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From: Jim Strain (jstrain@iquest.net)
Date: 11/22/02-02:08:01 PM Z


Sandy's explanation is quite right for the version mounted on a Palm Pilot.
With the version I have (mounted on a simple calculator), you input your own
EI, your high and low EV measurements (either incident or reflective), if
reflective, the Zone you wish to assign, your preferred ES (achieved from
testing), the f-Stop and whether you are doing a close up. The critical
output then is the subject brightness range (the "SBR") which I compare to
the curves I generated from film testing to determine development times. It
will also give you the depth of field and, of course, the shutter speed.
Phil had predetermined and programmed reciprocity for TMX and TMY. Since I
use TMY, I have been able to rely on his curves for reciprocity. I have
used it for all of my b&w negs for many years and it is always right on
(within whatever reasonable range of error there is in shutter speeds and
developer activity). The program really works and I am sure it is even
better in the Palm version. Hope this helps. Jim
----- Original Message -----
From: "Shannon Stoney" <sstoney@pdq.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, November 22, 2002 10:05 AM
Subject: Re: BTZS ExpoDev software for reciprocity corrections

> Sandy wrote:
>
>
> >Just a short while ago we had some discussion about reciprocity
> >correction charts for various films.
> >
> >I would like to suggest that some of you may be interested in using
> >the BTZS ExpoDev software for exposure calculations in the field,
> >especially when dealing with complicated situations that involved
> >filter factor corrections, reciprocity corrections, and/or
> >corrections for bellows extension. I have been using the ExpoDev
> >software now for about 6 months, and during the last month or so
> >have made heavy use of it in work that often involved significant
> >reciprocity and filter factor corrections, and sometimes bellows
> >extension corrections. I am very pleased with the results, with
> >excellent exposures on nearly every shot. In fact, I very much doubt
> >that I could have done as well in making these complicated
> >calculations manually as did the program automatically upon entry of
> >just a few pieces of information.
>
>
> Can you plug your own ISO and development times, based on your own
> curves, into the program?
>
> --shannon
>
>


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