In camera shopping, this is the second most touted number after megapixels. 400, 800, 1600… all these numbers signify the sensor’s sensitivity to light. It takes a lot more light to photograph by candlelight than by sunlight, and cranking up your ISO is an easy way to shoot in the dark. But like everything in photography, there is a tradeoff – higher ISO produces more noise. If you are set on shooting in a low-light location, or don’t want to invest in in lighting, look for a camera that performs well with a high ISO. Generally you want to keep your ISO as low as possible, as you can probably tell from this handy set of images below.