What is ISO?

ISO (International Standards Organisation) is a rating for the sensitivity of the film or digital plain to light(I will just refer to the sensor, but this is the same for film). The higher the number of ISO, the more sensitive the sensor is to light. Equally, the lower the number, the less sensitive the sensor is to light. This means that we need to change our ISO rating depending on the time of day, the location, and type of feel we want for the shot.

How does ISO Work?

On traditional cameras, you would buy the film stock of the ISO you wanted. This meant you had to finish the reel of film before you could change ISO. With digital cameras, you can change ISO at any time, so you can always change to the correct film stock.

So why not just use the Highest ISO?

You may be asking yourself why doesn't your camera just leave itself on the highest ISO, or does it indeed just stay on the highest ISO available. ISO controls sensitivity to light, but it can make it too sensitive. When taking images in the dark, and having a high ISO, the image is almost amplified, much like music is amplified through speakers. When you turn up the speakers, you hear the quality go down, and this is true of having a higher ISO setting. The lower the setting, the better quality your image will look and the less noise that will be there.

What is Noise?

Noise is much like film grain, dark/light/coloured specks will appear on your image. Some photographers make use of this, especially in black and white photography. Most the time however photographers try to keep away from having these specks, and so they use the lowest ISO possible, without allowing the camera to have image blur.

How to prevent noise?