In photography, when we refer to compression we are speaking of a phenomenon involving lenses and the distance from the subject to the background and the subject to the camera. Compression is the “compressing” of a scene - a phenomenon in which the background appears to be closer to a subject and larger in comparison than it actually is. This compressed effect is achieved with telephoto lenses. The longer the lens, the further back the photographer must step back from the subject to keep them the same size in the frame and the larger and closer the background will appear. Some really interesting images can be created this way, for example in which the moon looms larger-than-life over a subject.