Why would I change the ISO on my digital camera?

Why would I change the ISO on my digital camera?

Mark Comon (Vice President, Paul's Photo, Torrance, CA) gives expert video advice on: What does my digital camera's "manual exposure" mode allow me to do?; How do I change the shutter speed on my digital camera?; Which is worse to overexpose or underexpose pictures on my digital camera? and more...

You change the ISO on your digital camera to control the camera's sensitivity to light. In bright light we need the camera to be less sensitive, to give us a better quality picture. In low light where there's less ambient light, we need more sensitivity in the camera. So we raise the ISO from 1 to 2 to 4 or maybe 8 if you have to, to get enough light in so the picture looks good. Now, what's the payback? As you raise the ISO we get more noise or grain in the picture, and less color. So, you want to set the ISO as low as possible without having the ISO too low so we make blurry pictures.