Shutter Speed, Aperture and ISO

Shutter Speed determines how long the shutter is open, and allowing light onto the film/camera sensor. A longer exposure can simply be used to collect adequate light in a low light setting, but in a normal setting can show ghosting, or afterimages of light/objects that have left the frame by the time the shutter closes.

A short exposure will allow for capturing events that are happening quickly, such as sports, animal movement, or lightning flashes. Alternatively, unlike long exposures, short exposures are very difficult in low light without a flash gun/module to temporarily illuminate the frame.

The long exposure on the left shows a waterfall to look as if there is more water, because of the ghosting effect of the exposure. The short exposure on the right could actually reveal an image that is impossible to see with the naked eye because cameras may take a photograph at faster than 1/1000th of a second.