Quote:
Originally Posted by M54
Hi all,
I've been reading about eyepieces and the author is talking about long focal length telescopes and short focal length telescopes.
My telescope is a 130cm, 900mm focal length, f/7 reflector.
Is this a long or short focal length, I don't know what is considered long and short. 
Thanks in advance,
Molly. |
Yours is medium focal ratio, a good all-rounder. Long enough to provide good high power views of the moon and planets, yet also able to give wide fields of view provided you use some pretty big eyepieces like Vixen's LVW42 or LV50mm.
f/3 to f/5 is short, suitable for low power wide field views but nt much good at high power,
f/6 to f/10 are the all-rounders, and
f/12 to f/15 are long focal ratios - high powers suitable for lunar and planetary but not so good for low power wide field stuff.