I am ready with three pinhole cameras for the world day. Using the 'pinhole calculator' I have the f # and the exposure factors. I have a light metre that will let me say iso 3.2.... but I cant quite understand how to change my information into exposure times. I could use film, I can use the calculator for that, but I want to use paper. So can anyone help me tranlate it? F333 / exp factor 229.1 F230 / exp factor 109.3 F358 / exp factor 264.8. thankyou.