How do I calculate the aperture for a specific DOF?

Rearranging the DOF equation: N ≈ DOF x f² / (2 x c x u²), where N = f-number, DOF = desired depth, f = focal length, c = circle of confusion, u = focus distance. This gives an approximate aperture, accurate when the focus distance is much greater than the focal length.

What if the required aperture is wider than my lens allows?

If you need f/0.7 but your lens opens to f/1.4, you cannot achieve that DOF at that focal length and distance. Options: use a longer focal length (shallower DOF per f-stop), move closer, or use a larger sensor (smaller CoC per equivalent framing).

What if the required aperture causes diffraction?

Apertures smaller than about f/11-f/16 (depending on sensor pixel pitch) cause diffraction softening. If you need f/22 for your DOF target, consider focus stacking at f/8 instead for sharper results with the same total depth.

Does this work for macro photography?

For macro distances (close to the focal length), the approximation becomes less accurate. Use the full DOF calculator for precise macro results. At macro distances, DOF becomes very shallow regardless of aperture.

PhotoCalcs

Aperture Calculator — Find Aperture for Target DOF

Find the aperture needed to achieve a target depth of field at a given distance.

Focal Length

Focal length of the lens in millimetres

Subject Distance

Distance from camera to subject

Target DOF

Desired depth of field

Sensor (CoC)

Enter the sensor (coc)

How We Calculate This

Aperture Formula

N ≈ DOF x f² / (2 x c x u²)

This is an approximation valid when the focus distance is much larger than the focal length. The calculator also verifies the result using the full DOF equations.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.