Circles of confusion, Day 37

I teach beginning photography for Continuing Education at CU, Boulder. My favorite technical topic to discuss is aperture and how it relates to depth of field. Most students take the class because they have a new camera they want to learn how to use, so the first class can be a bit overwhelming. When I was sixteen I took a trip to Japan with my father and brother. I clearly remember my dad attempting to explain aperture and depth of field to me as we sat in a cafe...I didn't get it. It wasn't until many years later that I was thrust as a grad student into the world of teaching as a beginning photography instructor that I had to tackle my technophobia. So if you want to know what "circles of confusion" are and how they relate to depth of field I would be happy to discuss the subject with you.