Depth of Field & Hyperfocal Distance
Near and far limits of sharp focus, total depth of field and the hyperfocal distance from focal length, aperture, focus distance and sensor, in metres or feet.
Where sharp focus starts and ends, how deep the zone is and how much lies in front of the subject, the hyperfocal distance and its near limit, and the circle of confusion used — which you can change.
Example: 50 mm at f/8 focused at 3 m on full frame: sharp from 2.36 to 4.12 m, 1.77 m deep; the hyperfocal distance is 10.9 m, sharp from 5.4 m to infinity.
Sharp enough
is a choice.
How the near and far limits follow from the hyperfocal distance, what the circle of confusion is and why it is an input, and where thin-lens figures stop.
Hyperfocal first
Everything follows from the hyperfocal distance H = f² ÷ (N·c) + f: focused there, the zone of acceptable sharpness runs from H ÷ 2 to infinity. Focused at a distance s, it runs from s(H − f) ÷ (H + s − 2f) to s(H − f) ÷ (H − s), and the far limit becomes infinity once s reaches H. Closing the aperture or shortening the lens shrinks H and deepens the zone.
The circle of confusion
c is the blur spot the eye accepts as a point, and it is a convention, not a property of the lens: by the common rule it is the sensor diagonal ÷ 1500 (0.029 mm on full frame). A large print viewed close needs a smaller c and so has less depth of field. The divisor is an input, or enter c directly.
Front and back
Away from macro distances more of the zone lies behind the subject than in front — about a third in front at moderate distances, which is where the rule of focusing a third of the way in comes from. The page gives the split.
What the number does not settle
Thin-lens geometry measured from the sensor: focus breathing, the quality of the out-of-focus blur and diffraction at small apertures are not in it — see the diffraction page for the last. Inputs stay in your browser; the same anonymous usage counts as the rest of the site apply.