How do I calculate the aperture for a specific DOF?

Rearranging the DOF equation: N ≈ DOF × f² / (2 × c × 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.

Aperture Calculator — Find Aperture for Target DOF

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

Focal Length

Actual lens focal length in millimetres (e.g. 50 for a 50mm prime).

Subject Distance

Distance from the sensor plane to the point you focus on.

Target DOF

Total front-to-back depth you want acceptably sharp.

Sensor (CoC)Choose your sensor format (sets the circle of confusion), or pick Custom to enter a CoC in mm.

How We Calculate This

Aperture Formula

N ≈ DOF × f² / (2 × c × 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 hyperfocal-distance DOF equations (H = f²/(N·c) + f, with near and far limits from H).

Frequently Asked Questions

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Circle of Confusion Calculator

Calculate the circle of confusion for your sensor size, viewing distance and print dimensions. Essential for accurate DOF calculations. Free calculator.

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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.