Aperture and Depth of Field

• Digital SLR cameras and some point-and-shoot digital cameras allow the user to adjust aperture. Aperture is the opening inside the lens. The wider the opening, the less depth of field a photo will have. Depth of field is the amount of a photo from front to back that will be in focus. A shallow depth of field can result in a blurry background. Using lower numbered f/stops will give you larger apertures and shallower depth of field. Use the lowest f/stop your camera/lens will allow.
  
  

Distance and Focal Length

• The greater the distance between a subject and a background, the greater the potential is for background blur. Shorter distances between camera and subject will also increase potential for background blur. The larger an f/stop number is, the greater the distance between subject and background needs to be to achieve background blur. Zooming out or using a telephoto lens compresses the depth of an image and can result in background blur.
  
  

Panning and Flash

• Images with moving subjects can have blurry backgrounds. Panning, or moving the camera with the motion of the subject, results in blurry backgrounds. Moving at the same relative speed as the subject is important to keep the subject in focus. Using a flash set to rear curtain will help keep the subject focus strong while accentuating the background blur.
  
  

Digital Photo Editing

• There are factors that will limit the ability to blur a background at the time the image is captured. Digital photography gives photographers options to blur photo backgrounds after the image is captured. Different editing software programs have different methods. Some will give the user a tool to simply work back and forth over the area of the image where blur is desired. Some require the user to apply a mask over the subject followed by a blurring step that will affect unmasked areas of the photo. Users should search the help section of their software for specific instructions.