Why is macro DOF so shallow?

DOF decreases with the square of magnification. At 1:1 (1x), DOF is measured in millimetres. At 2:1 (2x), it is even shallower. At 1:1 and f/8 on full frame, total DOF is only about 0.46mm. This is why focus stacking is essential for macro photography.

What is effective aperture in macro?

At magnification M, the effective aperture is N x (1+M). At 1:1 magnification and f/8, the effective aperture is f/16. This means 2 stops of light loss and diffraction equivalent to f/16. TTL metering compensates automatically.

What aperture should I use for macro?

Use f/5.6 to f/11 set on the lens. At 1:1, this gives effective apertures of f/11 to f/22. Beyond f/11 set, diffraction noticeably softens the image. For maximum sharpness, use f/5.6-8 and focus stack for more depth.

Does the DOF formula change for macro?

Yes. The standard DOF formula assumes focus distance is much greater than focal length. At macro distances, the simplified formula DOF = 2cN(1+M)/M² is more accurate. It shows that DOF depends only on magnification, aperture and CoC — not focal length.

PhotoCalcs

Macro DOF Calculator — Depth of Field at Magnification

Calculate depth of field at macro magnification ratios with effective aperture and light loss.

Magnification

1 = 1:1 life size

Aperture (set on lens)

Sensor (CoC)

How We Calculate This

Macro DOF Formula

DOF = 2 x c x N x (1 + M) / M²

Where c = CoC, N = set f-number, M = magnification ratio.

Effective Aperture

N_eff = N x (1 + M)

Light Loss

Stops = 2 x log2(1 + M)

Frequently Asked Questions

Related Calculators

DOF Calculator

Calculate near focus limit, far focus limit and total depth of field for any lens, aperture and subject distance combination. Free online calculator.

Hyperfocal Distance Calculator

Find the hyperfocal distance for maximum depth of field in landscape photography. Enter focal length, aperture and sensor size. Free online calculator.

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.

Bokeh Calculator

Estimate background blur disc size for any lens, aperture and subject-to-background distance. Predict bokeh quality before you shoot. Free online calculator.

Focus Stacking Calculator

Plan focus stacking sequences for macro and landscape photography. Calculate the number of frames and focus step distance needed. Free online calculator.

Last updated: February 2026

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