Virbhadra-Ellis lens equation
Encyclopedia
The Virbhadra-Ellis lens equation relates angular positions of the unlensed source 
, the image 
, the Einstein bending angle of light 
, and the angular diameter lens-source 
and observer-source 
distances.
.
This lens equation is mainly useful for studying gravitational lens
ing in a strong gravitational field (see here for more information.)
, the image , the Einstein bending angle of light , and the angular diameter lens-source and observer-source distances..This lens equation is mainly useful for studying gravitational lens
Gravitational lens
A gravitational lens refers to a distribution of matter between a distant source and an observer, that is capable of bending the light from the source, as it travels towards the observer...
ing in a strong gravitational field (see here for more information.)