'Focal distance of a telescope' definitions:
Definition of 'Focal distance of a telescope'
From: GCIDE
- Focal \Fo"cal\, a. [Cf. F. focal. See Focus.] Belonging to,or concerning, a focus; as, a focal point. [1913 Webster]
- Focal distance, or length, of a lens or mirror (Opt.), the distance of the focus from the surface of the lens or mirror, or more exactly, in the case of a lens, from its optical center.
- Focal distance of a telescope, the distance of the image of an object from the object glass. [1913 Webster]