Understanding the Concept of Exposure
Often after buying a good digital SLR camera and point & shoot, we are fixated on auto mode for longer periods of time. Auto mode is the most easy and quick, but do not give satisfaction creativity.
For those who want to “pass and first class” of the auto mode and want channel creative spirit into the resulting photographs, it helps us understand the concept of exposure. Renowned photographer, Bryan Peterson, has written a book titled Understanding Exposure which includes the concept of exposure are easily explained.
Peterson member illustration of three elements that must be known to understand the exposure, he was named the relationships between the three as a triangle Photography. Each element in the triangle of photography 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 much the lens open when the photo was taken
3. Shutter Speed - the time span “window” in front of the camera sensor is open
The interaction of these three elements is called exposure. Changes in one element will result in changes in the other elements.
Parable Exposure Triangle
Perhaps the easiest way to understand the exposure is to provide a parable. In this case I like the parable of the exposure triangle as well as a water faucet.
- Shutter speed for me is how long we open the tap.
- Aperture is how wide we open the faucet.
- ISO is the strong encouragement of water from the taps.
- While the water flowing through the faucet is received light camera sensor.
Certainly not a perfect metaphor, but at least we got the basic idea. as you can see, if the exposure is the amount of water coming out of taps, means we can change the exposure value by changing one or a combination of all three constituent elements. You change the shutter speed, means changing how long the water tap open. Aperture change means changing how much water flow, while changing how strong encouragement from the water source.