How to Blur Background in a Videoby Erick Kristian ; Updated September 22, 2017
Blurring the background in a video is done by changing the depth of field. The depth of field is used to define the focus of the lens. For example, a shallow depth of field would display objects in the foreground in focus and the objects in the background blurred. Adjusting depth of field while filming is much easier than attempting to blur only the background of a shot in post production.
Block the shot. Make sure that everyone in the scene is in place.
Place the video camera in the location from which it will be shooting.
Turn on the camera and look through the view finder.
Find the subject that will be in the foreground of the shot.
Focus on the object in the foreground. Some video cameras have an o-ring on the lens that lets the user control the focus or depth of field.
Record the shot once the depth of field is adjusted accordingly.