Photography technique - Exposure
Photography taken at 1/20 Same picture with longer exposure
In modern cameras the exposure is usually set to automatic by default and, most of the time, it can be left there and will produce beautiful pictures. There are times though, when the lighting conditions are difficult or we want to produce a particular effect and it would be nice to understand what is going on 'under the hood'. So there's when we go to MANUAL mode on our camera settings and leave the automatic garbage behind :)
Overall: The amount of light falling on the film is governed by three things.
- The amount of light reflected from the scene which, if you are outdoors, you can do very little about.
- The 'shutter speed' which is the amount of time the shutter is open, measured in fractions of a second.
- The 'aperture setting' which is the size of the hole through which the light enters. If you look at the lens of your camera you will see a diaphragm in the middle of the glass which the camera adjusts according to the light. This does exactly the same job as the iris in your eye. Aperture settings are measured in 'f stops'. (more about this in following posts)