For interested people, here are two related, detailed reviews on gravitational lensing in a variety of configurations, including Schwarzschild black holes, of course.
http://relativity.livingreviews.org/Art ... r-1998-12/
http://relativity.livingreviews.org/Art ... index.html
Contains lensing formulae for lots of concrete examples of interest and general presentation as well.
Bye Fridger
