From: Sandy King (sanking@clemson.edu)
Date: 11/22/02-09:11:59 AM Z
Shannon wrote:
>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
Shannon,
The program depends on you having done your own film testing and
having determined the necessary CI needed for the ES of your process.
The way it works is as follows. In the the main program you first
choose whether you intend to work with the Zone system of SBR system.
You then choose one of the listed films, for which there are specific
reciprocity correction data, or choose a custom film, which uses
generic reciprocity correction data. The ISO value entered is that of
the manufacturer but actual exposure values recommended take into
consideration the time of development needed to reach a certain CI.
You then enter the focal length of your lens, the exposure scale of
your process, the low and high EV from your meter readings, any
filter factors, and distance to subject, and of course desired
shooting aperture. The program takes about 1/1000 of a nanosecond to
think and then recommends the best exposure for the situation. It
also recommends the necessary CI to which the film should be
developed to match the ES of your printing process. You can then save
all of this information to a separate Memo_Pad program for later
reference.
In an accompanying program, called the G-Bar, you enter your own data
compiled from film testing. This is done by entering the CI of film
at different times of development. If, for example, you tested five
sheets of film at five different development times you would enter
the five different CI values corresponding to this data.
Sandy
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