What is ISO

ISO stands for International Organization for Standardization, and is a measurement of sensitivity to light. The ISO of a camera is usually expressed as an integer number. The lower the ISO number, the more sensitive the camera will be to light, and the higher the ISO number, the less sensitive the camera will be.

ISO is one of the most important settings to understand when it comes to manual photography. Along with Aperture and Shutter Speed, it is something you need to master.