Quote Originally Posted by Chan Tran View Post
I wouldn't use the exposure factor at all since the aperture is known (i.e. f/333) the film speed or rather paper speed is known as ISO 3.2. What else does one need except for the reciprocity characteristic of the paper?
Reciprocity failure is a big problem. Each paper and film has different reciprocity failure characteristics. Tech specs for film usually include reciprocity compensation factors; but since they are not needed for enlargements onto paper, the manufacturers don't publish them. The easiest way around the dilemma it is to test. Also, the 3.2 ISO mentioned in the original post seems to be little golan's light meter's lowest setting. People usually rate paper anywhere from ISO 2 to ISO 6. One advantage of testing is that when the basic daylight exposure for the tested camera / paper or camera / film combination is known, adjustments to the it, like giving three or four more stops of exposure, are linear. For practical purposes, doing the test in the pinhole range incorporates reciprocity in determing the basic exposure and no further compensation is needed.