----- Original Message ----- From: "Jason Russell" <jruss...@wishtv.com> > > The corrected time you gave me worked very well. Thank you! > > However, I want to clarify one thing... > > Did you go to the Polaroid website to get the numbers to plug into the > WinCurveFit program? Did you just pull the numbers from the displayed graph > and plug them into the program and extend the curve? Is that how that > works.
Jason, altho I could have used the graph to get some "indicated versus corrected" values, that graph is just too coarse and since some values are already given in the "Reciprocity Performance" table, that's what I used. Now, that table (or graph) gives you corrected values in terms of extra stops of Exposure Adjustment, so we need to translate the indicated exposures to corrected exposures in seconds. For full stops it is easy, you double the indicated exposure for each stop of adjustment, but what about, for instance, the corrected exposure for an indicated 16 secs and an adjustment of +1 2/3 stops? To do it, you have to use the following equation: I = indicated time T = corrected time n = exposure correction in stops ^ = raised to the power of (need scientific calculator to do it, I use CALC98, freeware program downloadble here http://www.calculator.org/download.html) T = I * (2 ^ n) In the case of 16 secs and 1 2/3 stops adjustment, it would be: T = 16 * (2 ^ 1 2/3) T = 16 * (2 ^ 1.6666) T = 16 * 3.17465 T = 50.79 secs Once you have all the corrected values in seconds, feed the indicated and corrected values to the WinCurveFit program. I have to mention that I don't bring a calculator with me when I go out to make exposures, I prefer to make a graph, very much like this one http://www.kodak.com/global/en/professional/support/techPubs/f9/f002_0062gc. gif and use that to find corrected times. Guillermo