Increasing Background Blur in Photographs
Blurred backgrounds in photos taken with digital cameras are often difficult to achieve. This article explains some techniques for increasing background blur. For a technical discussion of this topic, see Igor Yefremov's article "Blurring the Background - A scientific approach."
Here are some techiques to use that will help increase the background blur:
Focusing in front of the subject moves the subject to the far end of the depth of field. Objects in the background will have more blur, but the subject will still be acceptably sharp in the photo.
For example, with a 7.1 mm lens set to f/2.8 and focused at 5 feet, the depth of field extends from about 3 feet to 16 feet:
If you focus at 3 feet, the depth of field extends from about 2 feet to 5 feet:
So, your subject at 5 feet is still acceptably sharp, but you'll get more background blur.
The main drawback of this technique is that your subject isn't in perfect focus; it's just acceptably sharp. However, this technique will work for some subjects.
DOFMaster can be used for printing a depth of field scale for a camera that doesn't have a scale on the lens.
© 2002 Don Fleming. All Rights Reserved.