Quote Originally Posted by polyglot View Post
PS I'm not seeing a formula in your post, just a list of variables... and u should cancel out entirely unless you want to include bellows factor for being focused at u. Which I don't.
Those variables were from the calibration equation which is too complicated to type out. Steve sent me the paper. I can e-mail it to you if you like. Calibration Levels of Film and Exposure Devices D. Connelly, The Journal of Photographic Science, Vol. 16, 1968.