[Eric48]

Has anyone any tips on how to work out whether the OTA on a dob mount is at 90 degrees to the base? Do I ensure the base is horizontal using a spirit level and then use the spirit level on the OTA's dust cap to see if it is horizontal too? And then somehow put some kind of a stop in between the OTA and the dob mount to set it at 90 degrees? I have to move my 12 inch dob around quite a bit on a trolley depending on which bit of sky I want to look at - lots of trees on the small farm where I observe (but wonderful dark skies).

Eric