Collimation screws for the primary mirror - RC scope

Equipment Ritchey-Chrétien Collimation
5 replies•523 views
IS_17m avatar
IS_17m avatar
Hi,
I have a RC scope. There are three pairs of these screws around the primary mirror (in the back of the telescope). I know that 3 screws are for adjusting the mirror position and the other 3 are for locking its position after adjustment.

I know that is "rare" that a primary needs to be adjusted on a RC scope, but I want to understand how it works the collimation with these screws, if I need to do it someday.

- the bigger screws are the ones for adjustment and the smaller screws are the locking ones, right?
- it is recommended to adjust ONE pair at a time, and avoid untightnening all the locking screws at the same time because that can mess up the focal lenght, correct?

The idea that I have (correct me if I'm wrong please) is that the procedure must be done in this order:
- untighten ONE lock screw
- adjust (tighten or untighten, depending on how much I want to adjust/move the mirror) the bigger screw of the SAME pair
- tighten the lock screw again of the first step
> move to the next pair

Thank you,
Clear Skies

Engaging
Chris Jensen avatar
Chris Jensen avatar
I dont have an RC scope, but this does appear to be a good tutorial. https://youtu.be/-iW_OmRDndk

Hope it helps
Ed Dixon avatar
Ed Dixon avatar
My iOptron RC6 was brand new and still needed to be collimated with adjustments to both ends.
Well Written
vercastro avatar
vercastro avatar
I think you're good to loosen all the locking screws at once by a bit then adjust the collimation screw. The collimation screw should hold on their own temporarily.

Having said that, this design looks different than what I'm used to (RC10 tube maybe?) and the mechanics might be slightly different.
Markus Gorski avatar
Markus Gorski avatar
Hello,
only two pairs of screws should be used to collimate the primary mirror, and always the same ones. Otherwise there is a risk that the distance between the primary and secondary mirrors will change. This resulted in a maladjustment that is not so easy to eliminate.
Best regards!
Helpful Concise
Isabela Chase avatar
Isabela Chase avatar
Hey there, I can totally understand your concern about adjusting the collimation screws on your RC scope. I am new to this forum, but I had a similar issue with my own telescope a while ago.
Well Written Respectful
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