What is the ISO setting on my camera?

Have you ever asked, “What is this button for?” Many people use a camera without understanding the function of some of the buttons and dials. Is that you?

The topic today is ISO setting. What is ISO? The initials stand for International Organizational Standard, but that doesn’t answer the question of how to use the ISO setting on your camera. The reason camera manufacturers include this feature is to allow the photographer to adjust the camera’s sensitivity to light.

Back in the days before digital photography, a rating system was established so film could be labeled with a number. The precursor to the ISO was the

American Standards Association (ASA). For a bright sunny day a photographer would load 100 ASA film into the camera. If the setting was cloudy or shady then 400 ASA film was used. A disadvantage was that the entire roll (36 exposures) was at that ASA (ISO) setting. What if you shoot half a roll of 400 ASA and then it stops raining and the sun comes out? An advantage of digital photography is ability to change the ISO setting for every shot if you like.

Thirty years ago film was available at ASA 64, 100, 160, 200, 400 and 800. Later the chemists at Kodak and Fuji developed films rated at 1600 and 3200. But a high quality digital camera nowadays can be set with ISO numbers up to 12,800. Now you have choices.

Why would a person want to adjust the light sensitivity on a camera? Are there disadvantages? Why not just crank the dial to the highest setting like 3200 for instance? There is a trade off. With a low setting like 100 ISO the images are smooth and pleasing. At the high end of the spectrum, such as 1600 and 3200 an issue with digital noise becomes apparent. This is the fuzzy or buzzy texture seen especially in the shadow parts of an image.

In film the problem with a high ISO was grain the equivalent of noise.

A rule of thumb, (and photographers like to break rules at times) is to use the lowest ISO possible. But, sometimes the choice is no photo or a slightly noisy photo. So turn the ISO dial up a notch or two and shoot. Some of the Pulitzer-prize winning photographs were a bit lacking in technical quality, but captured a moment in history for the whole world to see. It is fun to experiment with all different settings and compare the results. We learn by doing.

With less expensive point and shoot digital cameras the ISO is set automatically. So there is nothing to worry about. Even with more sophisticated cameras, when shooting in auto mode the ISO is set automatically going lower when there is plenty of light and raising to higher settings as the light decreases.

If you have lot of money to spend you can buy a pro camera with a better chip which will provide very low noise even at the higher ends of the scale. Also you can get software such as noise ninja to remedy the effects of noise. But if possible, get it right as you shoot it and eliminate the need for a software solution.

As you learn more about your camera and more about light you will understand how to override the camera and get some photos that you may have missed in the past.