You cannot create a photograph without using light. Light paints the image. Light gives the image depth and movement. It can also ruin an image.
The amount of light that creates the image is important. That is why we have different shutter speed and aperture variables too much light causes over exposure: underexposure is the result of too little light.
But other factors are important too. Where is the light coming from? If from behind the subject you could create a silhouette. If from the front, the subject could appear flat and washed out and human subjects may have to squint.
Angled lighting gives depth and shadow detail. Great for texture and a 3D effect.
Flash can give a harsh rendition to the subject almost bleached sometimes and the amount of light may need altering (if your camera has flash exposure compensation, use that).
Morning sunlight is rich and orange and casts long shadows. The same goes for the end of the day. Midday light is intense and harsh and not very flattering. Moonlight is soft and romantic.
Diffusing the light for example using netted curtains at the window or a cloth over flash, gives a more romantic and softer effect and the use of coloured gels or filters can make a normal subject appear unusual and exciting.
Whatever light you have, you need to use it to its potential to get the best images
Eric Hartwell runs the photography resource site http://www.theshutter.co.uk and the associated discussion forums as well as the regular weblog at http://thephotographysite.blogspot.com
