The conformal gravity fit to observed galactic rotation curves requires {gamma}>0. On the other hand, conventional method for light deflection by galaxies gives a negative contribution to Schwarzschild value for {gamma}>0, which is contrary to observ
ation. Thus, it is very important that the contribution to bending should in principle be positive, no matter how small its magnitude is. Here we show that the Rindler-Ishak method gives a positive contribution to Schwarzschild deflection for {gamma}>0, as desired. We also obtain the exact local coupling term derived earlier by Sereno. These results indicate that conformal gravity can potentially test well against all astrophysical observations to date.
After the work of Rindler and Ishak, it is now well established that the bending of light is influenced by the cosmological constant {Lambda} appearing in the Schwarzschild-de Sitter spacetime. We show that their method, when applied to the galactic
halo gravity parametrized by a constant {gamma}, yields exactly the same {gamma}- correction to Schwarzschild bending as obtained by standard methods. Different cases are analyzed, which include some corrections to the special cases considered in the original paper by Rindler and Ishak.
