Variability and Quality Control in Photography

In addition to these differences, time creates variations in the properties of an object. The photographic speed of a roll of fi lm is not now what it was yesterday, nor will it be the same in a few months. Using this point of view, an object, say a roll of fi lm, is really a set of events that are unique and will never be duplicated. As the Greek philosopher Heraclitus long ago said, “You cannot step in the same river twice.”