While a higher ISO means more sensitivity to light and brightens your image.
ISO (International Organization for Standardization) is most simply understood to control exposure or brightness and is arguably one of the most importantwildlife photography camera settings. A lower ISO value means less sensitivity to light, darkening your photo. While a higher ISO means more sensitivity to light and brightens your image. ISO is measured in numbers, typically from 100 to as high as 6400 (but can be much higher), through 200, 400, 800, 1600 and 3200. If your ISO value is too high you will end up with a very ‘noisy’ or grainy photo.