  We investigate gravitational lensing in the Palatini approach to the f(R)
extended theories of gravity. Starting from an exact solution of the f(R) field
equations, which corresponds to the Schwarzschild-de Sitter metric and, on the
basis of recent studies on this metric, we focus on some lensing observables,
in order to evaluate the effects of the non linearity of the gravity
Lagrangian. We give estimates for some astrophysical events, and show that
these effects are tiny for galactic lenses, but become interesting for
extragalactic ones.
