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Collimating a Ritchey-Chrétien

Collimation Equipment
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#1 grkuntzmd

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Posted 08 April 2021 - 07:58 AM

I have a new Ritchey-Chrétien 254mm/2000mm telescope on order. I currently have an Orion laser collimator for my Dobsonian. Is it possible to use the Newtonian collimator for the new RC, or do I need to get one of the "fancy" collimators like the Howie Glatter?

 

Thanks.



#2 ElectricLungfish

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Posted 08 April 2021 - 11:16 AM

The Orion and similar lasers are not well enough collimated internally for RCs. Don't use it! However, there are many ways to collimate these things that don't require you to buy the expensive lasers. My recommendation would be not to touch anything until you get the scope under the stars and do a star test. The scope may come adequately collimated, and you don't want to mess it up in that case. Your experience with the Dob will not help you here; RCs are much more complex to collimate. Just search the forums here on collimation -- there are many, many threads on this topic.


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#3 jgraham

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Posted 08 April 2021 - 12:43 PM

+1

I highly recommend zeroing in the colimation of the secondary using the same technique that you would use for an SCT (centering the shadow of the secondary at high magnification using an out of focus star progressively closer to focus). If the stars at the center of the field look good (no on-axis coma) then you're good to go. Things get a bit tricky when you have to adjust the primary.

I luvs my 8" f/8 RC! Once I got the colimation zeroed in (and snugged the primary baffle) it blossomed into a fine performer.

#4 avarakin

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Posted 09 April 2021 - 10:33 PM

This document is all what you need to collimate you scope:

http://www.deepskyin...ure_Ver_1.0.pdf

Once you do this couple of times, it takes few minutes to fine tune collimation.

 

Alex


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