Want to move beyond taking point-and-shoot snaps? Trying to figure out how to recreate some of your favorite photos? Pick up your camera because in this series, we’re introducing you to some essential elements of photography that will make your snaps picture perfect.

Photo by Antoine Buchet


Possibly the least understood factor of photography, ISO is a standard system of measurement (International Organisation for Standardization) to tell how sensitive a camera sensor (or a roll of film) is to light. Selecting the correct ISO based on the shooting conditions helps photographers ensure proper exposure in their images.

When shooting on a digital camera, increasing the ISO (or the sensor’s reactivity to light) means that you need less light (natural or artificial) to capture an image.

However, increasing the ISO also increases the graininess in an image, often referred to as “noise.”


In the two pictures below, you’ll notice that the one on the left is clearer than the other. It has less “noise” than the photo on the right.

Photo by Jack Cain

In bright daylight, you’ll only need an ISO reading of 100 to 200. In cloudy conditions or indoor settings (in which a subject is well illuminated by natural light), set the ISO to about 400.

On the other hand, if you’re shooting indoors and aren’t close to a window, adjust the ISO to roughly 800. For dark settings (performances and other low-light events), you might consider setting the ISO at 1600 or higher. High ISO settings (1600 and above) can also be used to capture an object in motion — because the sensor is so reactive to light, the time needed to properly expose the image is a fraction of what it would be at a lower ISO. As a result, the shutter speed is extremely quick, allowing photographers to capture moments as they happen.

Photo by George Turner

Use the built-in light meter on your camera to determine the optimal exposure — it’ll also suggest the appropriate ISO setting. Most DSLRs also have partially-manual modes in which the aperture and shutter speed can be manipulated. In these modes, the camera will adjust the ISO automatically, so you can photograph with peace of mind.


  • ISO measures the sensitivity of a camera sensor (or a roll of film).
  • In bright light, set the ISO to a low number (100 or 200). As the setting grows dimmer, set the ISO to 400 and above.
  • Increasing ISO increases grain.
  • A high ISO can also be used to capture action as it happens.