HAVRILIAK wrote:
believe "oil immersion objectives" are a feature of microscopes, not
telescopes, right?


Yes. There is a technique in microscopy where oil (don't remember which one)
is placed between the objective or nose piece and the specimen being examined.
I believe it increases the contrast of the object.
More about immersion that you might want to know;-)

http://micro.magnet.fsu.edu/primer/a...immersion.html