Vixen 80MF refractor +Achieving Focus

[johnb]

Hi

I recently got a Vixen 80MF refractor with the aim of using it for guiding, anyway played around to night and really struggled to achieve focus - not sure I understand why ?

Pointers appreciated

Regards

John B

[Peter Drew]

Hello JohnB. Have you tried a star diagonal on it yet, some of these refractors have a lot of back focus and won't work without. I've got a 80MF but having chopped 3" off it this afternoon I can't really double check for you!

[Merlin66]

You need either the diagonal in place or use a 50mm spacer.

[johnb]

thanks, advice appreciated

Regards

John B