understanding exposure

How ISO, aperture and shutter speed affect your images

Shutter speed

This corresponds to the amount of time the tap is left on for. It works hand in hand with aperture – you can have the tap on full for a short time or open just a little bit for longer to get the same volume of water.

ISO setting

ISO is like the size of the glass. A small vessel (a high ISO) will fill more quickly than a big one.

Aperture

Think of the aperture as how many turns the tap is turned on by – do you want a trickle of light or a torrent?

Light intensity

This is like the water pressure. If the pressure is high, you don’t need to turn the tap on so far, or for so long, to fill the glass.

It’s a matter of taste

Exposure isn’t all about science: it’s also about artistic interpretation. Exactly how full do you prefer your cup of water to be?