Wow, thanks for all the great replies. There are so many large brains here, and seeing the same goal approached from so many different directions really helps the understanding. That, after all, is entirely the point of my pursuit of film photography. It is an intellectual challenge to learn and understand an activity that pretty much appears to be pure magic from the outside and to hopefully become skilled at it. Think Zen Archery (Kyudo). As far as getting an app, if I wanted to follow that approach to photography, I would be shooting digital.