How ISO affects shutter speed

7As previously mentioned, an increase in ISO makes the camera sensor more sensitive to light. And as well as an increase in noise, another side effect is that the shutter speed becomes faster. The result is that you can freeze movement if the shutter speed is fast enough for the speed of the subject. Another benefit with fast shutter speeds is being able to shoot handheld without a tripod in low light conditions. Every time the ISO is increased or decreased by a stop (doubled or halved), for example 200 to 400, the shutter speed will increase or decrease each time by 1 stop, such as 1/125sec becoming 1/250sec. If, on the other hand, you intend to shoot a moving subject such as a waterfall and wanted the water to blur, attach the camera to a tripod and shoot at a low ISO such as 100 or 200 in order to keep the shutter speed as slow as possible in the given light conditions.