Aperture Diffraction Limit
Estimate the Airy disk size and whether diffraction softens your image.
About Aperture Diffraction Limit
Diffraction spreads each point of light into an Airy disk whose size grows with the f-number, softening detail when it exceeds the pixel pitch. Stopping down too far trades depth of field for diffraction blur, so there is a sweet spot aperture for maximum resolution.
Formula
Aperture Diffraction Limit
Airy disk = 2.44 x wavelength (550nm) x f-number
- pixel pitch
- Distance between sensor photosites in microns
Worked example
With the default values below, Aperture Diffraction Limit returns Airy Disk Diameter of 10.74. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Aperture (f-number)minimum 0.1
- 8
- Sensor pixel pitchminimum 0.1
- 4.3
Results
- Airy Disk Diameter
- 10.74 µm
- Diffraction Limited?
- Yes - diffraction softening likely
- Airy Disk vs Pixel
- 2.50
Step by step
- 1Values used
- 2Aperture Diffraction Limit
- 3Airy Disk Diameter= 10.74 µm
- 4Diffraction Limited?= Yes - diffraction softening likely
- 5Airy Disk vs Pixel= 2.50
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Aperture Diffraction Limit calculated?
Airy disk = 2.44 x wavelength (550nm) x f-number Diffraction spreads each point of light into an Airy disk whose size grows with the f-number, softening detail when it exceeds the pixel pitch.
Why does Aperture Diffraction Limit matter?
Stopping down too far trades depth of field for diffraction blur, so there is a sweet spot aperture for maximum resolution.
What values do I need to enter?
This calculator takes 2 inputs: Aperture (f-number), Sensor pixel pitch. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.