The 180 in. (4.57 m) diameter mirror of a telescope has a focal length f = 14.9
ID: 2299304 • Letter: T
Question
The 180 in. (4.57 m) diameter mirror of a telescope has a focal length f = 14.9 m.
(a) When the detector is placed at the focal point of the mirror (the "prime focus"), what is the f-number for this telescope?
(b) The coude focus arrangement uses additional mirrors to bend the light path and increase the effective focal length to 134.1 m. (Coude is French for elbow, since the light path is "bent like an elbow." This arrangement is useful when the light needs to be focused onto a distant instrument.) What is the f-number of the telescope when the coude focus is being used
Explanation / Answer
a) f number = F/D = 14.9/4.57 =3.26
b) f number = F'/D = 134.1/4.57 = 29.34
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.