Understanding How Your Digital Camera’s Exposure Settings Work
Taking great digital photos requires an understanding of how to use your digital camera’s exposure settings, whether you have an SLR camera or a point-and-shoot camera. The combination of shutter speed and aperture determines how much light hits the digital sensor in your camera, and the ISO setting determines how quickly the sensor responds to the light.
A simple way to illustrate how the three exposure settings work together is to think of filling a water bucket. Here are the components of this analogy:
A full bucket = a good exposure
The size of the bucket = the ISO
The size of the garden hose = the lens aperture
The amount of time it takes to fill the bucket = the shutter speed
Say you’re in your yard with a bucket and garden hoses of different sizes. The bigger the garden hose, the faster you can fill the bucket. You can fill the bucket by using any size garden hose you want, but the size of the hose determines how much time it takes to fill the bucket. If you want the bucket to fill up faster without using a bigger garden hose, you can use a smaller bucket.
To put the water-bucket analogy in photography terms, think of your camera’s digital sensor as a light bucket. Large apertures “fill” your sensor with light faster than small apertures. If you set your sensor to a faster ISO (in other words, if you make the bucket a smaller size), it’ll fill up with light faster than it would at a slower ISO setting. Large apertures (as well as high ISOs) call for faster shutter speeds. Small apertures (or low ISOs) require longer shutter speeds.