Apertia · Library
Calculate · Airy-disk diameter (mm)
A thin-lens plan using distances from the sensor plane. Real lens behaviour, focus breathing and computational photography are outside this model.
State the wavelength and acceptance threshold
The ideal circular-aperture model uses Airy-disk diameter 2.44 × wavelength × f-number. The wavelength and circle of confusion are entered in millimetres. The result compares that diameter with the chosen circle-of-confusion threshold.
The aperture at which the disk equals the threshold and the app’s half-threshold planning heuristic are different outputs. Neither is a universal best aperture or a sharpness cutoff for a real camera.
Use a comparison, then inspect the image
Sampling, demosaicing, lens aberrations, contrast, motion and output size affect perceived detail. A wavelength assumption is not a full spectrum model, and diffraction geometry does not capture every source of softness.
Method and reference context
A thin-lens plan using distances from the sensor plane. Real lens behaviour, focus breathing and computational photography are outside this model.
Results
Example calculation
Airy-disk diameter (mm): worked out from the values already filled in the form above.
Inputs
- Aperture: 8
- Circle of confusion: 0.03
- Assumed wavelength (mm): 0.00055
Result
- Airy-disk diameter (mm): 0.010736
- Airy diameter / CoC: 0.357866667
- f-number where Airy diameter equals CoC: 22.3546945
- Half-CoC planning f-number: 11.1773472
Related tools
Geometric blur diameter (mm) · Horizontal angle of view (°) · Focus-stack plan