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Two puzzling Newtonians!

Peter B

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I bought back into astronomy recently after a very long absence from the hobby with a Sky-Watcher 130P Newtonian reflector on the Sky-Watcher AZ GTi Wi-Fi mount. I knew that this telescope did not have primary mirror adjustment, only secondary mirror adjustment.  This scope had a lot of excellent reviews so I bought it despite the lack of primary mirror adjustment and I have to say that out of the box its collimation is spot on but I was surprised to see the primary centre spotted given that it isn’t adjustable.


Then a Celestron 130 Newtonian came up for sale locally on a Celestron EQ mount with a Celestron motor drive and with an extensive set of much better eyepieces than came with the Sky-Watcher. I wanted the EQ mount and eyepieces more than the scope but the lot was at a bargain basement price so I bought it. When I checked the collimation of the Celestron it was miles out and to my frustration the primary mirror was not centre spotted. I took the primary mirror out, centre spotted it and the scope collimated pretty well.


I just wonder why a) Sky-Watcher produce a scope whose primary mirror can’t be adjusted yet who centre spot the primary. and b) why Celeston don’t centre spot the adjustable primary mirror on their 130 Newtonian. Neither make sense to me!

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