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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.

Those programs 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.


© 2002 Phil Davis