Aperture controls depth of field. The background may be blurred so the subject in the foreground is in clear focus, or the composition will be in sharp focus from the foreground to the horizon. Aperture also controls exposure.
The aperture is the opening created by a set of overlapping metal blades, known as the diaphragm, inside a photographic lens. This opening controls the amount of light, or exposure, of the photo. Aperture is measured in f-stops, which in turn, affects the depth of field and how much light passes through the opening.
As you move up the f-stop range towards the higher numbers, the amount of light coming through the lens decreases with each stop. As you move down towards the lower numbered f-stops, the amount of light coming in the lens increases with each stop.
Exposure and depth of field are the most important criteria for choosing the right aperture. You can choose to have the sharpest focus on the subject, or have the entire scene in clear focus. You also have to consider the amount of available light when you choose aperture to make sure your photo is correctly exposed.
Review the examples below and the situations when it's best to use the aperture setting.
f / 2.8 aperture setting best used for:
- Very dark environments
- Focusing on a specific point
- Pointing to a specific spot
f / 4 - f / 5.6 aperture setting best used for:
- Well-lit environment
- Creating blurred edges
- Creating a soft background on a portrait
- Creating a focal area
f / 8 aperture setting best used for:
- A midway point in f-stops
- Indoor and outdoor lighting
- Versatile with some blur but enough focus to capture the subject
f / 11 - f / 22 aperture setting best used for:
- Brightly-lit environment
- Majority of image in focus
- Landscape images