What in the world is ISO and what does it have to do with digital photography? It’s important to have a basic understanding of ISO in order to better control the final result of your images.

Imagine that ISO is like the volume control on your stereo. The more you increase the volume, the louder the music, but the static is louder too. ISO is exactly the same, just with light and grain (otherwise known as noise, in the digital world). The more you increase the ISO setting, the brighter the picture, but the noise is brighter too.

So, in a low light situation, increasing the ISO either brighten the image, or increase the shutter speed allowing you to NOT use a tripod, or a little of both. You may be wondering, why not brighten the image with the flash? What if the subject is further than 12 feet (4m), the flash won’t be very effective. You may also want the look of soft ambient light instead of a hard flash casting a sharp dark shadow. Or you may want to increase the ISO and use the flash when photographing a night portrait.