Camera Tech: I.S.O

ISO is the measure of how sensitive the camera becomes to incoming light and effects how exposed the image or film is light. An example would be using a high ISO is areas with limited light sources or whilst filming at night and a low ISO for areas that are well lit such as a high volume of natural light, however a high ISO also increases the amount of image noise which distorts the image by giving it a very grainy, static appearance, so a low ISO is often the best option, especially when used with either a low shutter speed or wide aperture as using a high ISO in this circumstance would overexpose the image.

Most digital DSLR cameras have the option to alter the ISO manually depending on the situation you are shooting in and generally have ISO values that range from 100 to 3200, 100 ISO in the right light conditions would give a very crisp clear shot whereas an ISO of 3200 would dramatically increase the film grain on the image. Below is an example of how ISO affects an image.

The image on the left uses an ISO of 100 so the shot is very crisp and clear whereas the image on the right is shot using an ISO of 3200 which has increased the amount of grain on the image, distorting it slightly. Generally a low ISO would be used for high density light conditions however it can also be used in tandem with a wide aperture or a low shutter speed to limit the amount of film grain on the image while still being brightly lit as the wide aperture would allow more light into the camera so a low ISO making the light sensor less sensitive would be appropriate.