  We consider an alternative formula for time delay in gravitational lensing.
Imposing a smoothness condition on the gravitationally deformed paths followed
by the photons from the source to the observer, we show that our formula
displays the same degrees of freedom as the standard one. In addition to this,
it is shown that the standard expression for time delay is recovered when small
angles are involved. These two features strongly support the claim that the
formula for time delay studied in this paper is the generalization to the
arbitrary angles of the standard one, which is valid at small angles. This
could therefore result in a useful tool in Astrophysics and Cosmology which may
be applied to investigate the discrepancy between the various estimates of the
Hubble constant. As an aside, two interesting consequences of our proposal for
time delay are discussed: the existence of a constraint on the gravitational
potential generated by the lens and a formula for the mass of the lens in the
case of central potential.
