Reflecting telescope how it works:


1) In this case a concave mirror is used and this acts as objective of the telescope.


2) When lights from the distant object enters in a direction parallel to the principal axis of the mirror they focuses at the principal focus of the mirror.


3) Now if you place a convex mirror the focal plane of the objective mirror, you can collect incoming lights into an eye piece as shown below:

 


 



In this way a reflecting telescope works.

 

 

Advantages of reflecting mirror telescope:

 

1) Reflecting telescopes are free from chromatic and spherical aberration.


2) Reflecting telescopes are much less weigh than the refracting telescopes, because there is only one reflecting surface or a mirror. So reflecting telescopes are easy to handle and set up.


3) The image formed in reflecting telescopes are much brighter and have high resolution power than the refracting type telescope.


4) A high quality reflecting telescope can easily be constructed with cheap rate.