Before posting a summary of some of Henry's acutance and granularity data for discussion, I thought it might help to post some "primer" definitions for anyone not entirely familiar with the terminology. I tried to keep it simple but welcome any feedback - and corrections. I'm thinking a few diagrams might help. Perhaps if this is well received we can post it as an article. As a second step I'm working on a kind of "map" showing the various variables (film characteristics, developer characteristics etc.) and how they are interrelated.