What is ISO in photography?

ISO is the setting that determines how sensitive your camera is to light. The term comes from the the system developed by the International Standards Organization used to indicate the light sensitivity of photographic film, hence ISO.

While digital cameras don’t use photographic film, you can still adjust the sensitivity to light with ISO.

The higher the ISO, the more light the camera will receive.

However, ISO also affects the quality of your final picture. When you turn up the sensitivity, ISO, you also reduce the quality of the picture with what’s called noise.

Noise is the color and pixel distortion that you see when looking at a picture shot at a high ISO, it looks sort of like grain in an old film picture, with the exception that the “grain” (noise) is also made up of different colors, causing it to be distracting to the eye, and also unflattering for your subject.

When shooting at a high ISO (I consider anything over ISO 800 high), it is particularly important to get your picture properly exposed. This will reduce noise because noise mostly shows up in darker areas or underexposed parts of the picture, and becomes very apparent when brightening pictures up in editing software.