Deep Depth of Field
A wide zone of sharpness in which foreground, subject and background all hold detail.
Measured in
m
In depth
Deep focus keeps every plane legible, which is why it suits landscape, architecture and documentary work where relationships between near and far elements carry the meaning. It comes from small apertures, short focal lengths and greater subject distance, though stopping down too far surrenders sharpness to diffraction — f/11 to f/16 is usually the practical limit on full frame.
Examples in practice
A 20 mm lens at f/11 focused at 1.5 m holds a foreground of pebbles and a distant lighthouse equally sharp.