It is the capacity of the microscope to differentiate the images of two points that are close together on the object. The smallest separation (linear distance) that can be resolved by the midroscope is called limit of resolution (d0). It can be calculated by Abbe’s formula:
d0= 0.6λ/n sinα = 0.6λ/NA
As resolving power is inversely proportional to limit of resolution.
R.P= 1/d0 = NA/ 0.6λ
Here, is wave length of light used, in refractive index of medium between object and objective lens(i.e. air, sometimes oil is also used), α is the half angel of the cone formed by light rays entering the objective, NA is numerical aperture equal to sin α. Thus, the details (clarity) of the object depends on resolving power rather then magnification.