How to use the angular resolution calculator
Find the smallest resolvable angle of a telescope or eye. Enter wavelength, aperture diameter in the fields above; the resolution is computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “how far apart can i see”, “telescope resolution”, “diffraction limit”, “calculate angular resolution”, “find resolution”.
Formula
Variables
- lam — Wavelength (nm)
- D — Aperture diameter (mm)
Worked example
With wavelength = 550 nm, aperture diameter = 100 mm, the calculator gives resolution ≈ 1.384038 arcsec.
Frequently asked questions
What is the angular resolution calculator used for?
Find the smallest resolvable angle of a telescope or eye. It helps with questions such as “how far apart can i see”, “telescope resolution”, “diffraction limit”.
What is the formula for the angular resolution calculation?
Resolution (arcsec) = 1.22 × lam × 1e-9 / (D / 1000) × 206265. Here lam is wavelength (nm), D is aperture diameter (mm).
What inputs do I need for the angular resolution (rayleigh criterion) calculator?
You need wavelength in nm, aperture diameter in mm. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the angular resolution calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the angular resolution result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.