sing the mid-range numbers the depth of field will again be different. An aperture of f/2.8 will have a very shallow depth of field while f/32 will show sharp focus throughout the whole image.
4. Focusing distance
How far you are to the point of focus is another factor to consider. When using any lens, the depth of field will increase the further the focusing distance. If you focus on an object three meters away, and if you focus on something 300 meters in the distance, the depth of field will be greater. So in other words, when the subject is far away from the camera there will be a greater depth of field and more of the image will be in focus.
5. When to use depth of field
Most of us have taken landscape images where most of the scene is in focus. This is true when you’re shooting scenes of fields and trees and boats on the sea. The way in which this is achieved is by setting your aperture to the highest number, e.g. f/22 and above, which means the smallest aperture. Virtually the whole scene from foreground to background is in focus. But this changes when choosing a wide aperture or a small f-number on the lens. Here you would only use this setting to shoot something you want to isolate such as a face in a portrait. The background gets blurred out and the face is in crisp focus. You would also use this when shooting close-ups of flowers or animals in a zoo where you don’t want to see the background or the bars or fence in the foreground.
So, as you can see, depth of field is really quite simple. Blurred out backgrounds use a large aperture and landscapes that need to be in focus from foreground all the way through to the background use a small aperture. The key as you learn digital photography is to experiment with all settings and then practice, practice, practice!
About the Author:
Wayne Turner has been teaching photography for 25 years and has written three books on photography. He has produced 21 Steps to Perfect Photos; a program of learner-based training using outcomes based education.
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