🔭 Angular Resolution Calculator
Enter the light wavelength and telescope or lens aperture diameter to find the smallest angle it can resolve, using the Rayleigh criterion.
What is angular resolution?
Angular resolution is the smallest angular separation between two points that an optical instrument, like a telescope, camera lens, or eye, can distinguish as separate rather than blurring into one.
The Rayleigh criterion
This calculator uses the Rayleigh criterion: θ = 1.22 × λ ÷ D, where λ is the wavelength of light and D is the aperture diameter. The constant 1.22 comes from the diffraction pattern of light passing through a circular aperture.
Real-world resolution can be worse than this diffraction limit due to optical aberrations, atmospheric turbulence (for ground-based telescopes), or sensor pixel size. This calculator gives the theoretical best-case limit for general reference and educational purposes.