Upgrading to Plotter for Windows
If you're a BTZS old timer you'll remember
the original BTZS software—the little program (now called ExpoDev) for the
Radio Shack PC-6, and the Plotter and Matcher programs for DOS PCs and Macs.
Those old programs were relatively crude but they did the job well enough,
and made the BTZS testing and metering methods possible.
have now been refined and enhanced by three volunteer professional programmers
using modern computer languages, but the basic functions of the original
programs have remained unchanged. Well, almost; the new programs do everything
the old ones did, and more, but they sometimes use different methods. In
almost every case (that I'm aware of) the results are the same and the old
and new data are interchangeable; but recently I've discovered that in some
unusual cases there is a noticeable difference in the speed point calculations.
Briefly, the old Mac PlotterPlus calculates slightly lower EFS values
than WinPlotter does. In most cases this difference is insignificant, but
in preparing the extra-low contrast film development data recently, I was
surprised to discover EFS differences of up to about 1/2 stop. These differences
are probably not important because they affect mainly the extreme low gradient
curves that represent almost outlandish subject ranges, but there are also
minor differences in some of the more normal curve families. I don't believe
any of this is cause for concern, and I'm not suggesting that you should
abandon your old data. In fact, I don't even know which program is providing
the "best" information; but I mention this to answer in advance any possible
questions about "why don't the data agree?"
All of which brings
us back to square one; BTZS data are relatively objective so anyone can
use them with reasonable confidence. But test methods do vary somewhat,
and if you want to eliminate that uncertainty, do your own careful testing
to produce personalized working data.