There are two types of depth of field. Shallow depth of field is when the subject of the photo is in focus and the background is blurry. Greater depth of field allows the photographer to make the entire photo in focus. You would use shallow depth of field when you dont want the viewer to be distracted by the background.You would use greater depth of field when you want everything in focus for example when your taking a landscape photo.This could be a leaf and the branch so the leaf would be in focus and the branch wouldn’t. This makes the photo look professional and it is good to show focus on a particular object. It would look good in black and white. As it makes the object in the foreground look crisp. Another good way to use depth of field is to use it in wildlife photography if you wanted to focus on one bird in the flock.