secondary adjustment on a 10" gso dob

[Starkler (Geoff)]

Originally Posted by Hotkey

My 10 inch Dob is proving very difficult to collimate. I spend hours adjusting then when I take it out at night I find I can just split easy doubles. I have read heaps of articles but must be doing something wrong still.

Have you checked your scope for pinched optics ?

Is the scope properly cooled when you observe? This time of year it should be outside for an hour at least before its anything like cooled close to ambient assuming you dont have a fan.

[Starkler (Geoff)]

Originally Posted by astro_nutt

G'day hotkey,
Have you checked to see if the focuser is collimated..

If you have a laser, the easy way is to adjust the secondary so that the laser dot falls into the middle of the secondary donut. This ensures that the focuser is square to the optical axis and your focal plane is not tilted at the focuser.