Chapter 3: Camera Settings, ISO

ISO

• The International Organization for Standardization (ISO) established a numerical scale to rate how sensitive different kinds of film were to light. This scale was retained for digital cameras. When you change the ISO value on a DSLR, you can think of it as changing film to  something more or less light sensitive to what is currently in the camera. A big advantage of a digital camera is that you can change the ISO from shot to shot, instead of only per roll of film.
• Higher ISO numbers are more light sensitive, meaning the camera will be able to take pictures in darker environments. However, higher ISO numbers also tend to produce grainier images.
• Examples:
  • ISO 100: suitable for a bright, sunny day
  • ISO 800: indoor spaces when not using a flash
  • ISO 1600: dim or even dark environments

This short video shows how to set ISO on the Canon EOS 5D Mk IV. 

For a more in depth explanation, visit Chapter 2: Elements of Exposure, ISO