ISO-less?

To determine the proper exposure, cameras generally use the concept of "film speed" - a number representing the film's sensitivity to light. For film, this number was a function of the emulsion and processing, changeable only in batches. However, digital cameras essentially process each shot individually, so most adopted the idea that the film speed of the sensor could be changed for each shot. The catch is that it isn't clear that the sensitivity of a sensor used in a digital camera can be adjusted at all: many digital cameras have been claimed to be "ISO-less," capable of producing similar images for the same exposure independent of the ISO setting used. This paper will present the results of testing the ISO-less behavior of various digital cameras, concluding with a simple proposal for how these results could be used to create a new paradigm for computing exposure and processing parameters.