Guide Scope

[Kenza]

Does it matter what the f-ratio is of a guide scope? I have an option of buying a 70/500mm or a 80/400 refractor, but i can get the 70/500 for a much cheaper price. Actually, which spec. of a guidescope is important?

[Tinker1947]

I would suggest you go for the lower f-ratio, more light going to the focus tube is better......

[Black Knight]

The Skywatcher ST80 (or the various clones) are very popular as guidescopes. At 80/400 they are f5, very useful for a guidescope. Relatively inexpensive too.