It sounds like you are speaking of "exposure" in terms of the amount of light the subject is exposed to, where in still photography, most of us think of exposure in terms of the amount of light allowed to strike the film.
Still photographers have a lot of flexibility in adapting to the light hitting the subject, we have both duration of exposure (to the film/sensor) and intensity to work with. OTH, cinema photographers have a fixed shutter speed, and so control exposure by the amount of light placed on the subject, which is why even when shooting in daylight they have truckloads of lights, reflectors, and shading panels to exercise that control.
In both cases, the ISO of the film is a "tweak", that is, we can choose a faster or slower film, which then influences the other choices. A faster film will allow the use of small lens apertures, or shorter shutter speeds, to yield increased depth of field or reduced movement blurring, for example.
Does this address the point you are making?
Last edited by bdial; 01-05-2014 at 07:03 AM. Click to view previous post history.