SingAstro

Hi Bros, which focal ratio is better, i.e f/6, f/8, f/10 for refractor telescope?
Thanks

Hi,
Slower focal ratio Refractor is usually easier to manufacture, so usually slower focal ratio Refractor telescope will perform better than a faster focal ratio Refractor telescope of the same class from the same manufacturer.

Have a nice day.

Hi Weixing,, thanks for help

Depends on your aperture. You wouldn't want to stretch the focal length of small aperture telescopes, that will affect your image quality. Also depends on what you wish to do with the scope. If you would want to consider astrophotography, a f6 scope will do. Larger focal ratio means longer focal length, and that will be frustrating especially if you don't have a tracking mount. Yes, lower f-ratio scopes are more costly, but there is no free lunch. Get something that will last instead of something that will end up in the second hand market real soon.

Hi Chris, thanks for advice.