Find the stops gained when changing ISO and the matching shutter speed.
Doubling ISO adds one stop of sensitivity, which can be spent on a faster shutter or a smaller aperture while keeping exposure constant. ISO is the exposure control you raise when you run out of shutter speed or aperture, though it adds image noise.
ISO Reciprocity
Stops = log2(target ISO / current ISO)
Stops = log2(target ISO / current ISO) Doubling ISO adds one stop of sensitivity, which can be spent on a faster shutter or a smaller aperture while keeping exposure constant.
ISO is the exposure control you raise when you run out of shutter speed or aperture, though it adds image noise.
This calculator takes 3 inputs: Current ISO, Target ISO, Base shutter (1/x s). The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.