For some basic advice on eyepieces see
http://www.televue.com/engine/TV3b_p...n=Advice&id=79
and
http://www.televue.com/engine/TV3b_page.asp?id=154
Camera lenses have a variable disphram hence focal length and minimum f stop is usually the reference. Telescopes do not have a diaphram and maximum aperture is usually referred to.
e.g. A 60mm f6 telescope (Tele Vue 60) has a focal length of 360mm. If this was a camera lens it would be referred to as a 360mm f6 with f6 being its minimum f stop and assuming it had a diaphram could then be stopped down further.
Focal length is the same term for either instrument.