Depth of field is the photograph’s sharp zone, and it obeys exact optics — if you respect the one input everyone estimates and few understand. This Depth of Field Calculator takes focal length, aperture, focus distance and your sensor’s circle of confusion, and returns the near limit, the far limit, the total depth of field and the hyperfocal distance.
Worked Example: 50mm at f/2.8, Focused at 3 Metres
On full frame (circle of confusion 0.029 mm), the hyperfocal distance is H = f² / (N × c) + f = 2500 / (2.8 × 0.029) + 50 = 30.84 m. From a focus distance of 3 m, the standard thin-lens equations put the near limit at s(H − f) / (H + s − 2f) = 2.74 m and the far limit at s(H − f) / (H − s) = 3.32 m — a total depth of field of 0.58 m, split unevenly: about 0.26 m in front of the subject and 0.32 m behind. That asymmetry is a law of the geometry, not a rounding error — depth of field always reaches farther behind the focus point than in front at portrait distances (the folk rule of “one third front, two thirds back” is a rough portrait-distance approximation of it), and the split equalizes only at macro distances while inverting to front-heavy at long telephoto ranges. Read the hyperfocal number as the landscape photographer’s master key: focus at the hyperfocal distance and everything from half of it (15.4 m here) to infinity sits inside the acceptable-sharpness definition — the largest possible depth of field for that aperture and format. Stop down and H shrinks with the f-number: at f/8 the same lens hyperfocal is about 10.8 m, at f/16 about 5.4 m, each doubling of N halving H — the arithmetic behind the landscape habit of small apertures and a focus point a third into the scene.
The Circle of Confusion: The Honest Fudge at the Centre
Every figure on this page descends from one conventional quantity, and naming it plainly is the difference between using the calculator and believing in it. A lens focuses a point to a point only at the exact focus distance; nearer and farther points render as small discs — circles of confusion — and depth of field is defined as the zone where those discs stay smaller than a chosen threshold. The thresholds in the select box (0.029 mm for full frame, scaled by format) descend from the classic Zeiss convention: a blur disc looks sharp in an 8 × 10-inch print viewed at arm’s length. Three consequences flow from that pedigree. First, the numbers are perceptual, not physical absolutes — pixel-peep a 60-megapixel file at 100% and the zone of critical sharpness is far narrower than any standard CoC admits; print small and it is wider. Second, the format scaling is the real content of “crop cameras have more depth of field”: at the same framing and f-number, a smaller sensor’s smaller CoC threshold is applied to a shorter focal length, netting roughly the crop factor’s worth of extra depth — the equivalence this site’s Crop Factor Calculator states from the other side. Third, diffraction eventually taxes the small-aperture strategy: past roughly f/11–f/16 on high-resolution sensors, the aperture’s own blur grows into the budget the CoC set, and the calculator’s optimistic far limits stop arriving. Use the numbers as the standard convention they are — the same one printed on lens depth-of-field scales for a century — and they will predict your negatives faithfully at sane print sizes.
Field Craft: Placing the Zone Where the Picture Lives
The calculator returns a zone; the craft is in its placement. Portraits: focus on the near eye and let the zone’s front third cover the face — at f/1.4 and headshot distances the total depth can be under two centimetres, and the calculator’s near/far split tells you whether the far ear survives. Group photos: stagger rows inside the computed zone rather than stopping down blindly — two rows at 3 m and 3.4 m fit the f/2.8 example’s 0.58 m depth only if focus sits between them, and the arithmetic shows whether f/4 buys the margin or f/5.6 is owed. Landscapes: focus at the hyperfocal distance for the aperture you chose, then verify the near limit against your foreground subject — a foreground rock at 1.2 m with an f/8 hyperfocal near limit of 5.4 m is a composition that needs focus stacking or a different rock, and it is better to learn that from the numbers than from the contact sheet. Macro: at 1:1 magnification depth of field collapses to millimetres governed more by magnification than by the distance formulas’ usual shape — the equations here still run, but treat their macro outputs as optimistic and stop down or stack. In every genre the pattern repeats: decide what must be sharp, compute the zone that contains it, and let the aperture be the conclusion rather than the habit.
The 50mm Hyperfocal Ladder
One lens, every aperture — the landscape photographer’s pocket table, computed from the same formula (full frame, this page’s CoC): at f/1.4 the hyperfocal distance is 61.6 m; f/2, 43.2 m; f/2.8, 30.8 m; f/4, 21.6 m; f/5.6, 15.4 m; f/8, 10.8 m; f/11, 7.9 m; f/16, 5.4 m. Read the pattern rather than the rows: past f/4 the distance roughly halves every two stops, because H tracks 1/N once the focal length’s own contribution fades. The practical reading: at f/8, focusing at 10.8 m keeps everything from 5.4 m to the horizon inside the convention — most landscape compositions live comfortably inside that window, which is why f/8 became the landscape default long before it became an internet proverb. The rows above f/4 tell the portrait story in mirror image: at f/1.4 the hyperfocal sits sixty metres away, meaning at any human working distance the depth of field is a thin shell around the subject (the worked example’s 0.58 m is at f/2.8 — at f/1.4 and 3 m it narrows to about 0.29 m), and no placement cleverness widens it; only the aperture does.
Macro: Where the Zone Becomes a Sheet of Paper
At life-size magnification the depth-of-field formula changes regime, and its verdict is severe enough to plan around: total depth at 1:1 is approximately 2 × N × c × (1 + m) / m² with m = 1 — at f/8 on full frame, 2 × 8 × 0.029 × 2 = 0.93 mm. Under a millimetre of sharpness, at an aperture already flirting with diffraction, on a subject that breathes — the three facts that built focus stacking into the macro discipline: shoot a rail of frames at stepped focus distances and merge the sharp slices, because optics offers no single exposure that holds a beetle. The calculator’s distance-based output at macro ranges should be read as an upper bound for the same reason (the classic formulas assume a symmetric lens; real macro lenses’ pupil asymmetry shifts the zone) — run it for orientation, then trust the stacking rail for the result. Product photographers meet the same wall at less extreme magnification and answer it with the view camera’s older magic — tilting the lens plane (the Scheimpflug principle) to lay the sharp zone along the subject rather than perpendicular to it — a geometric rearrangement of the same zone this page measures, available in miniature from tilt-shift lenses.
Common Mistakes
Entering the equivalent focal length instead of the lens’s true focal length (the CoC already carries the format; entering both crops double-counts the format). Expecting the printed zone to guarantee pixel-level sharpness at 100% — the CoC is a print convention. Believing depth of field splits half-and-half around the focus point. Chasing depth with ever-smaller apertures until diffraction eats the sharpness the stopping-down bought. And hyperfocal folklore: focus “a third into the scene” is a mnemonic, not the hyperfocal distance — compute H and focus there.
Related Tools
Continue with the Crop Factor Calculator, the PPI Calculator, the Upload Time Calculator, or browse the full Other Calculators hub.
Frequently Asked Questions
What is the hyperfocal distance?
The focus distance that maximizes depth of field for a given aperture: H = f²/(N × c) + f. Focus there and everything from H/2 to infinity is acceptably sharp. For a 50mm at f/2.8 on full frame, H ≈ 30.84 m.
How much depth of field does a 50mm at f/2.8 give at 3 m?
On full frame, sharp from 2.74 m to 3.32 m — 0.58 m total, split about 0.26 m in front of the subject and 0.32 m behind. Depth of field always reaches farther behind the focus point at ordinary distances.
What is the circle of confusion?
The largest blur disc that still looks like a sharp point at the intended print size and viewing distance — the threshold that defines “acceptably sharp.” Standard values scale with sensor size (0.029 mm full frame, 0.019 APS-C, 0.015 MFT).
Do crop sensors really have more depth of field?
At the same framing, f-number and subject distance, yes — roughly the crop factor’s worth, because the smaller format uses a shorter focal length and a tighter CoC. The Crop Factor Calculator states the equivalent aperture that makes the comparison exact.
Why do my f/16 landscapes look soft?
Probably diffraction: at small apertures the aperture itself blurs the image, and on high-resolution sensors the effect arrives around f/11–f/16, cancelling the depth-of-field gains the formulas promise. The optical sweet spot balances both.
Should I use the marked focus distance or measure it?
Focus distance is measured from the sensor plane (the ⌀-like mark on the camera body), not the front of the lens — at portrait and macro distances the difference changes the computed zone, so measure or read the lens scale with that origin in mind.