----- Original Message ----- From: "Shannon Stoney" <shannonsto...@earthlink.net>
> This is interesting, a variation on the formula I was given. Where did you > get this formula? I wonder if such formulas exist for all films? > I have been using this formula successfully for about a month. It seems to > give good times. I have no idea why this "works" mathematically. The formula you use is known as "Best Curve Fit", it works by finding a formula whose curve fit best to all the points in a graphic of "metered vrs reciprocity corrected values". In other word, you first find by experimentation as many values as possible and then apply the "Best Curve Fit" method of choice (there are many, BTW) to find a formula that matches them best. Once you have a formula, you can inter and extrapolate to find any other corrections you want. There are shareware programs available that allow you to find the formulas w/o having to do it manually and w/o having to like or to be good at math. Guillermo
