2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/211409Keeping the exact general relativistic treatment of light bending as a reference, we compare the accuracy of commonly used approximate lens equations. We conclude that the best approximate lens equation is the Ohanian lens equation, for which we present a new expression in terms of distances between observer, lens and source planes. We also examine a realistic gravitational lensing case, showing that the precision of the Ohanian lens equation might be required for a reliable treatment of gravitational lensing and a correct extraction of the full information about gravitational physics.11 pages, 6 figures, to appear on Physical Review DGeneral Relativity and Quantum CosmologyAstrophysicstext