One of the most important elements in photography.
Depth of field is a subjective quantity.
Remember this, adequate depth for one situation, application or photographers may be unacceptable for another. It is all a matter of personal preference when trying to determine the quantity. Depth of field is the amount of distance between the nearest and farthest objects that appear in acceptably sharp focus in a photograph. Generally, the closer the subject to the camera, the more evenly with the distribution of depth of field both in front and behind the subject. As subject distance grows, it extends more behind than in front of the subject.