Lesson

ISO is the sensitivity of the digital sensor or film. ISO is shown as numbers from 100 to 1600. On some cameras it may go up to 3200 or higher.

The lower the number (100) the less sensitive the sensor is to light.

The higher the number (3200) the more sensitive the sensor becomes to light.

When there isn’t very much light in the scene you are photographing, you may need to increase your ISO, making your sensor more sensitive, this means that your sensor won’t need as much light to still produce a well exposed image. This allows you to shoot in darker conditions, without your images being underexposed or blurred.

So when there is a lot of light in the scene you are photographing, you can use a low ISO, making you sensor less sensitive. This means that your sensor needs more light to produce a well exposed image, allowing you to shoot in brighter conditions, without your images being overexposed.