Depth of field (DoF) is the distance range in a photo where objects appear acceptably sharp. A shallow DoF blurs the background (ideal for portraits), while a deep DoF keeps everything sharp (ideal for landscapes). Three factors control DoF: aperture (f-stop), focal length, and subject distance.
- At 85mm f/1.4 on full-frame, DoF at 10 ft is only ~3.5 inches – ideal for isolating a portrait subject
- At 24mm f/11 on full-frame, DoF can stretch from 4 ft to infinity for landscapes
- Moving closer to your subject narrows DoF more than changing aperture by one stop
- Longer focal lengths compress perspective and produce thinner DoF at the same distance