Geometrical approach to strong gravitational lensing in f(R) gravity

We present a framework for the study of lensing in spherically symmetric spacetimes within the context of f(R) gravity. Equations for the propagation of null geodesics, together with an expression for the bending angle, are derived for any f(R) theory and then applied to an exact spherically symmetric solution of R-n gravity. We find that for this case more bending is expected for Rn gravity theories in comparison to general relativity and is dependent on the value of n and the value of the distance of closest approach of the incident null geodesic.