Scope with larger focal lenght as guide scope?

[jmdharkness]

Hi,

My first scope was a Celestron XLT 120, however, when I have since got an 80ED with the CG5 GT mount. I was wondering if you can use a larger focal length scope for guiding. I want to do my imaging, for the most part, through the Celestron 80ED, but i am unsure of the consequences of using scopes which such larger focal differences.

Thanks all,

John