I always work out my exposure plan with smaller paper. I use multi contrast for this even if I plan to make the real (large) print on fixed contrast.
To get from small to large paper I don't use any mathematics. That does not work for me, the remaining differences are too large. One or two test strips form the real paper and I have brightness and contrast there where it is in the smaller.
It helps very much if you count burning and dodging times not in seconds but in fractions of a stop. I think in third stops, that is my base unit.
Another hint: Way Beyond Monochrome recommends controlling contrast and exposure time from the beginning looking at the highlights. This makes sense: Highlights are more important than shadows. But if you change contrast the exposure time changes too (to a large amount) and you start from the beginning with your test strips. I always make the first steps with the minimal time for maximal black or in the near of it. That is in effect looking at the shadows first. If you change contrast this time remains nearly the same which makes the life with text strips much easier. If you in the near of the final exposure plan you have to look at the shadows of course. Change of the contrast should not be an issue then.
Last edited by piu58; 11-21-2012 at 02:09 AM. Click to view previous post history.