photography is an art of observation. it has little to do with what you see and and everything to do with the way you see them.
depth of field definition
The area within the depth of field appears sharp, while the areas in front of and beyond the depth of field appear blurry. In optics, particularly as it relates to film and photography, depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.