Determining Field of View
Determining field of view: The actual field of view of an eyepiece roughly
equals its apparent field (the angular diameter of the circle of light you see in
the eyepiece when you look through it by itself) divided by the magnification provided
by the telescope and eyepiece combination. For example, if a 50o apparent field
eyepiece gives you 100x on a particular telescope, it will have a 1/2o actual field
of view (50 ,
100) – about the diameter of the Moon.