This week’s discussion topic will attempt to answer the question:
Suppose your Newtonian reflector has a mirror with a diameter of 20 cm and a focal length of 2 m. What magnification do you get with eyepieces whose focal lengths are: a. 9 mm, b. 20 mm, and c. 55 mm?
From my textbook:
The magnification of a reflecting telescope is equal to the focal length of the primary mirror divided by the focal length of the eyepiece lens:
Magnification = Focal Length of Primary / Focal Length of Eyepiece
In the question stated above, the three different eyepieces will result in the following magnifications:
| 2000 mm / 9 mm = 222X |
| 2000 mm / 20 mm = 100X |
| 2000 mm / 55 mm = 36X |