For those of you that never shot film, every role of film comes with an emulsion number that indicated date of manufacture, coating plant etc. The photos, below, show the process I used to test the effective film speed (versus stated ISO) of film as part of some workshops I taught on adapting the Zone System to 35mm photography.
I should add that by knowing the effective speed of your film when recorded by your standard lenses and developed in your standard developer, you essentially were eliminating any of the variables in your equipment thus allowing you to instinctively compose and read a scene quickly then "expose for the shadows and develop the film to control where your highlights fell".
This got me thinking about another practice in the film days that has seemingly been forgotten or not appreciated in the current age of being able to immediately review images taken with a new camera or new lens, and instantly make snap decisions on the performance of your gear. I remember a maxim a well known editorial photographer shared with me at a workshop I was attending about how he related his lenses as equivalent to the fine bristle brushes he used for his other passion - oil painting.
Just like new brushes, he pointed out that with any new lens, he had to spend many hours getting accustomed to how it captured light just like how he'd have to practice with a new brush on scratch canvas to understand how it lay down his favorite oil paint. His maxim was that it typically took him "100 rolls of film" to thoroughly test any new lens in all the various lighting situations and conditions that he typically shot. He explained that he would never use a lens on an assignment until he fully understood it's characteristics and traits.
Note: I've been meaning to write this post for awhile, and I still have some additional comments from my old photo journals that I need to find time to review in order to complete this essay. Stay tuned.
(Data on color photo: DA*55mm lens / K20D / F4.0 1/20 sec. Japan, April 2009)
