Photography, by its very nature, is a calculated manipulation of light that produces a creative, out of the ordinary interpretation of something ordinary.
It is artistic expression and a joy that even the most amateur photographer can find in picking up a camera, pressing a button and developing a unique visual world.
In continuation of Photography in focus: What is shutter speed? this article explores the visual power of aperture, or the AV setting on a simple SLR or point-and-shoot camera.
Choosing to control your aperture allows you to choose how fast light flows into your camera.
I like to think of light as a liquid. In order to perfectly expose a shot, your camera needs exactly the same amount of light as your eye does in any given situation.
Lets say this is the equivalent of a glass of liquid light.
You can turn your tap to maximum and flood the glass almost instantly, or you can place the glass under a trickle of water and fill it slowly.
Either way you are left with a glass of water, or the correct amount of liquid light.
In real life the human eye contracts and expands, controlling light in much the same way that a tap can be turned to adjust the stream of water.
In photography, your camera uses aperture to control the flow of liquid light by opening and closing like a tap.
Although the final amount of light is the same, flooding your camera with light will have a very different effect to allowing it to slowly build up over time.
Creatively, aperture controls depth of field, which is simply a term used to describe how much of an image is in focus.
How does depth of field work?
During exposure, your camera uses light to paint a picture of what it sees, much like the brain does when the eyes are open.
As soon as the shutter opens, the camera starts to create the image in great detail from the focal point outwards. When the shutter closes, it stops.
If light flows into the camera quickly over a split second, the camera only has time to add detail to a small area, leaving the rest blurry.
When light is allowed to trickle in over a longer period of time, more details are added, creating an image that is sharp throughout.
This is known as depth of field and describes the depth of detail in your final photograph.
Shots for emphasis
Photographs that have a single story, an exciting moment, a main character or a cluttered background are best shot with a small depth of field.
Small depth of field is achieved by flooding the camera with light using a large aperture, such as f2.8 or f5.6, to allow for a fast exposure.
The smaller the setting number, the larger the aperture.
This creates a blurred background and lifts the subject to the foreground for emphasis.
Shots for endlessness
Scenes that go on forever are lost without the details. A herd of elephant will only be a herd if all are seen.
A small aperture, or a large setting number such as f16 or f22, will allow the camera to expose each member of the herd, telling a story that they are many and continue beyond the frame.
Choosing which truth to tell
The story of the migration in east africa can be told from the point of view of a wildebeest in two perspectives.
In scenario one, each wildebeest is one of ten thousand others making its way in life on the perpetual hunt for food.
It is a story of family, pilgrimage and crowds.
In scenario two each wildebeest is on a dangerous journey. Crossing vast rivers, crocs wait to snap up the weak and feed on their young.
This is a story of bravery, fear and survival.
Both stories in themselves are true.
In every scene a photographer feels compelled to share lies sub-stories, interpretations and visual truths. The art is deciding which to tell, which to create and which to leave out.
The choice is yours.