Explanation

This formula comes from the Rayleigh criterion for the minimum resolvable angle (θₘᵢₙ) in optical systems like lenses or telescopes:

$$theta_{min} = frac{1.22 , lambda}{D}$$

Where:

• $lambda$ = wavelength of light

• $D$= diameter of the lens aperture

This equation gives the angular resolution or resolving power of the lens.