For some reason, most film technicians find sensitometry either boring or frightening. This is unfortunate, since with only a basic knowledge of the photographic process and the ability to do your two times table, you can master all you need to know to gain considerably more control over your picture making.
Sensitometry, as the word would suggest, is the technique we use for measuring and evaluating the sensitivity of a film emulsion to light. The important part of the evaluation, to cinematographers, is to know how much light arriving at the emulsion is needed to produce the required density of image on the film after development. The relationship between the amount of light, the exposure and the darkening, the density, ...