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Altair 8"RC - Collimation.


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I acquired an Altair 8"RC. The stock focuser was upgraded to the Baader Diamond Steeltrack (BDS). During first light it was confirmed collimation was out. I suspect transportation was the issue. However, I am aware, and appreciate these scopes can be tricky to setup. From what I can see there are three elements one needs to be mindful of: Focuser / Primary Mirror / Secondary Mirror. 


I am awaiting delivery of an Ocal Collimator. I will use that for the bulk of tuning up, but will use the final Star Test following the DSI instructions for this to fix any final issues of on-axis coma and off‐axis astigmatism.


Regarding the focuser: I note some people invest in a Camera Tilting plate. If I have a BDS focuser is this still a recommendation? I ask this as the BDS is adjustable. Can I not just adjust the focuser to achieve the same result as a Camera Tilting plate?


Comments and suggestions welcome.



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On 2/13/2022 at 5:59 PM, len2376 said:

Baader have two pages of instructions showing how to adjust the focus tube. Two pages that made me invest in a tilt plate. YMMV.


Yeap... I am aware of this. Thanks. That wasn't the question. Thanks.

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  • 5 months later...

Late to this post but you're going to need a tilt plate for your RC8.

I've had a couple over the years & of you can get to grips with collimation, they're an absolute weapon. 

If you can't then you'll spend more time chasing errors than photos. 

In the end I couldn't be arsed with the faff & went back to Altair fracs because I don't get enough clear nights to waste.

I think I've still got the tilt plate somewhere

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