Астрорасчеты для окуляров
Eyepiece Apparent vs Real Field of View
Two methods, the first is an approximation but is often the easier to work out due to lack of information about field stop sizes.
Method 1
Method 2
Eyepiece Projection
Use this formula to calculate the resulting focal length and focal ratio when using eyepiece projection:
Where:
epid = Distance of CCD from Eyepiece
epfl = Eyepiece focal length
Note: This only gives an approximate value for the resulting focal length and focal ratio. The distance from the eyepiece is hard to measure, and the nodal point of the eyepiece (the point of its effect - which is usually internal to the eyepiece) is normally unknown.