ISO should be one of the easiest aspects of digital photography to master, but many beginners in photography still have a hard time understanding this fundamental camera setting.
I suspect this is because of the way it is being taught. You see, ISO started out as a property of film, and it was much easier to visualise it in terms of the old technology. So that’s where I want to start my explanation, before bringing you into the 21st century with ISO today.
ISO actually started out as ASA, which stands for American Standards Association. Decades ago, a commercial film manufacturer came up with a set of numbers to define the sensitivity of different types of film. That set of numbers was accepted by the American Standards Association, so all American manufacturers could use the same system. Later, the American standard was adopted by the International Standards Organization, so ASA became ISO.
What does all that mean? Well, it means that the letters ISO didn’t really stand for anything except for the name of an organization.
