Often after buying a good digital slr cameras and point & shoot, we are fixated on auto mode for longer periods of time. Auto mode is most easily and quickly, but gave no creative satisfaction.
For those who want to “pass and go up a class” from the auto mode and want to channel the creative spirit into the photographs produced, it helps us understand the concept of exposure. Famous photographer, Bryan Peterson, has written a book called Understanding Exposure which includes the concept Exposure easily explained.
Member Peterson illustration of the three elements that must be known to understand the exposure, he named the three as a triangle relationship Photography. Each element in the photographic triangle is associated with light, how light enters and interacts with the camera.
These three elements are:
1. ISO – the measure of how sensitive the camera sensor to light
2. Aperture – how big the lens is open when the photo was taken
3. Shutter Speed - the span of time ‘window’ in front of the camera sensor is open
The third element of interaction is called exposure. Changes in one element will lead to changes in other elements.
Parable Exposure Triangle
Probably the easiest way to understand the exposure is to give a parable. In this case I like the parable of the exposure triangle like a water faucet. Shutter speed for me is how long we open the faucet, the aperture is how wide we open the tap and the ISO is the strong encouragement of water from the taps, and water flowing through the taps is the sensor receives light cameras. Certainly not a perfect metaphor, but at least we got the basic idea.