Spark image
Refracting telescopes

The main purposes of a telescope are:
(a) to gather as much light as possible – this is done by using a large aperture lens or mirror.
(b) to resolve fine detail – this is also done by using a large aperture lens or mirror.
(c) to magnify the image of a distant object – this is done by using a lens or mirror with a long focal length.

Magnification = Focal length of the objective (F)/Focal length of eyepiece lens (f)


Notice that the image formed by this type of refracting telescope is upside down.

 
 
 
© Keith Gibbs 2011