In Photography, Depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. Creating a professional depth of field (DOF) effect in your photos is a quite difficult task and requires some practice and the right equipment. For any given lens setting, there is only one distance at which a subject is precisely in focus, but focus falls off gradually on either side of that distance, so there is a region in which the blurring is tolerable. The challenge in DOF photography is managing to let the sharpness gradually decrease on each side of the main subject. The DOF is determined by the camera-to-subject distance, the lens focal length, the lens f-number, and the format size or circle of confusion criterion.