View Full Version : BTZS Powerdial

5-Mar-2007, 20:26
Hi- could anybody tell me what the 1.4 and the 0.8 on either side of the triangle on the ISO dial are for?

I was planning on sending some film to the View Camera store for testing but I was wondering if I might use the Powerdial without BTZS paper testing. For example, my Ilford MGIV RC documentation rates grades 00 to 3 all at 200. I just finished calibrating my RH Designs exposure meter and got ISO ratings for each paper grade that way. Can I use these numbers, rather than sending in paper to be tested as well? My confusion lies in that the graph on the Powerdial goes from ES 0.8 to 1.6 (ISO of 80 to 160, right?), and the Ilford ISO 200 won't fit on here, or my own calibrated grade 0 Value (which is above 160). Is it assumed you are printing on grades 1 through 3 when using the Powerdial?


6-Mar-2007, 01:54

You could use a factor of about 1.05 and that will get you close to a grade 2 paper.

The ES of a paper will vary quite a bit depending on the process you are using but if you use a range from 1.05 to about 1.15 you will get negatives that put you in the normal range of silver printing.

The lower the ES value the less "contrast" the film is developed to whereas the higher the ES number the more contrast in the negative.

It is a wonderfully controllable system. You will get good results straight away and tailor the system to the type of negatives you want in very little time at all.

If it satisfies your needs get the ExpoDev software and a palm. It does everything you need with reciprocity, bellows and filter factors. It is the power dial on steroids and much more.