Click Thumbnails to Enlarge
How lenses affect depth-of-field
Techniques
24 October 2007 14:19
Your choice of lens plays an important part in how much of your image is sharp. The distance in front of and behind the subject that’s in focus is known as the depth-of-field, and is controlled by your distance from the subject, the focal length of your lens and the aperture used.
• The closer you are to the subject, the smaller the depth-of-field. This is particularly noticeable when shooting close-ups. If you move away from your subject, depth-of-field increases.
• The smaller the aperture you set on your lens, the greater the depth-of-field (and vice versa). So if you want only a limited part of your scene to be sharp, set a wide aperture such as f/4 or f/2.8. For great depth-of-field use a small aperture such as f/11 or f/16.
• The shorter the focal length of your lens, the greater your depth of field. If the aperture and subject distance remain constant, use a longer focal length lens for less depth-of-field and a shorter one for more.
We tried out different apertures on these shots of some flowers.
Using a wide aperture such as f/4 and focusing on the flowers in the foreground throws the background out of focus.
A mid-range aperture such as f/8 is a good compromise between keeping plenty of the shot sharp and still being able to handhold the camera.
For maximum depth-of-field set a small aperture such as f/16. Even though we focused on the foreground, the trees in the background are sharp as well.