The first video summarises the three crucial controls needed to get exposure right – Aperture, Shutter Speed and ISO.

This excellent interactive SLR camera simulator allows you to experiment with these controls on a virtual camera:

This second video sets us an assignment to create long-exposure photography. Here, the photographer uses a classic scenario – moving car lights. (the same technique could be applied to many scenarios where general light conditions are very low but bright lights are moving fast – think of some others for yourself). Notice first that one extra key ‘ingredient’ is needed … a tripod. Notice, too, that this technique involves all three controls (aperture, shutter speed and ISO)