People are always asking what is "Depth of Field" and "Why is this concept important when taking photographs?" Depth of Field involves the visual content that exists in front of or behind the subject of our photograph (that is, the person, building, animal, or object that we want to photograph). The question of how much depth of field is also important. When composing a picture, it is important to ask yourself "What am I trying to communicate in this photo?" Am I trying to display a beautiful scenery on a vacation trip where a far depth of field will provide the viewer with a full appreciation of the location? Am I trying to focus on a particular airlines to promote a particular company. The focus clearly will be on the airlines and not the scenery. Too much background can distract from the intent of the photographer. Depth of field, therefore, is important because it conveys the intent of the photographer. Too much depth of field can be distracting or too little depth of field might not tell the whole story. As one can see this idea is a critical question that the photographer needs to consider when taking a photograph.
Hint: In order to blur the bacground of the photo or develop a narrow depth of field use a smaller aperture number (e.g. F/5.6). To set up a long depth of field ( everything is sharp)use a larger aperture number(e.g.,f/22).