When light from the concave primary mirror of a telescope is reflected by a small secondary mirror through a hole in the primary to its focus, it is called the
A) Cassegrain focus.
B) Newtonian focus.
C) coudé focus.
D) prime focus.

Question

Quizplus · Accepted Answer

The Cassegrain focus involves light being reflected from a telescope's concave primary mirror to a smaller secondary mirror, and then through a hole in the primary mirror to its focus. This configuration is characteristic of Cassegrain telescopes.

When Light from the Concave Primary Mirror of a Telescope