We introduce a new approach for investigating the weak field limit of vacuum field equations in f (R) gravity and we find the weak field limit of f (R) = R + μ4/R gravity. Furthermore, we study the strong gravity regime in R + μ4/R model of f (R) gravity. We show the existence of strong gravitational field in vacuum for such model. We find out in the limit μ → 0, the weak field limit and the strong gravitational field can be regarded as a perturbed Schwarzschild metric.
