Archived posting to the Leica Users Group, 2000/09/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Guy, I've always used a similar system based on the fact that the change in intensity of light falling on the paper is inversely proportional to the change in magnification. The problem with the formula below is that w1 and w2 should be measured from the widths of your negative (or negative mask) projected on the easel rather than the width of your print. Any size print that falls within the negative's projected light will require the same exposure regardless of the width of the print. I usually find it easier to measure H1 and H2 where H = the height of the negative above the easel (shown on my enlarger column). In either case H1/H2 = w1/w2 = the change in magnification. Mike Quinn Guy Bennett wrote: > the next question is related, and it concerns the extrapolation of new > printing times when making another, different-size print of a given > negative. he offers the following equation for making the calculation: t2 = > t1 x (w2/w1)2 [i.e. squared], where t2 = new initial exposure, w2 = new > print width, t1 = initial time of the original print, w1 = width of the > original print. my question: do any of you use this, or any other system to > extrapolate new print times for enlargements? is such a system reliable, > given the variables involved (different batch of paper/new chemicals/etc.)?