RC collimation and general impressions - Forums

Topic starter

Feb 9, 2018 · Edited: Feb 9, 2018

Hi guys,
A question for all the Rc owners: collimating this telescope is really as bad as it sounds? Is collimation needed often? How is the performance of this telescope compared to the one of similar scopes ( Visac, the edge HD series) and to that of bigger refractors?

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Michael Timm

Feb 9, 2018 · Edited: Feb 9, 2018

Hi Philoez98,

I own a 8" RC. I have collimated that scope once, but only the secondary mirror. The process is a bit more complicated compared to the 5" newton i have, but it is not as bad as it sounds, as long as you keep your hands off the main mirror. I collimated using a bright star and defocussed the camera. You can then see a small ring. That ring should be round. If it is not, you can use the screws on the secondary to adjust it. It took me about an hour and is very stable, no need to collimate again.

There are a lot of websites and manuals available. I am not an expert and my collimation is not the best, but it is okay for me.

The RC performs very well. I can only compare to a 8" Newton my neighbour owns and a 5" newton i own. The RC is more like a precise instrument. The focal length is superior when it comes to smaller objects (like PNs or galaxies far, far away…

but it is difficult to catch bigger objects like great nebulas.

My experience in astronomy is not very great, so take this post as the opinion of a beginner :-) But it was a good decision to buy that RC for me.

Best wishes,
Michael

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Chris Sullivan

Feb 9, 2018

I've only had mine up twice to date (just got it over Christmas) and the secondary was indeed out of collimation and it seems to lose collimation easier than my Newt (as I've colliamted it three times already…

. However: The scope traveled across the country and the primary arrived in perfect collimation. Astrotech used to void warranties if people adjusted the collimation of the primary (they don't do this anymore). In other words: You'd probably have to drop the scope to mess up the primary's collimation. The secondary can be collimated easily with a Cheshire. I'm sure collimating the primary is extremely difficult though - I'm keeping my fingers crossed that I don't ever have to do it.

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Philoez98

Topic starter

Feb 9, 2018

Well that seems scary. Furthermore I've read that if you want to accomplish a perfect collimation you may want to mess up with the primary mirror. But that can probably get thing worse if you don't know how to do it.

Matthew Enrietta

Feb 4, 2021

I have one and it is nothing short of miserable. I have been trying to collimate it for 8 months off and on . Finally discovered the primary mirror had a ton on slop. The retaining ring was so loose it was letting the mirror wiggle back and forth and you could even spin the primary with 0 effort it was so loose. I would not buy this again knowing what I do now

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Fabio Mirra

Oct 26, 2021 · Edited: Oct 26, 2021

I own my RC since four years now and I will never regret to own this scope :-) Collimation is not hard at all until you get the right tool.
Primary is collimated at factory so you better don't play with it, but for the secondary there are many tools available in the market.

I personaly use a simple takahashi collimator to center the secondary : https://www.pierro-astro.com/materiel-astronomique/accessoires-astronomie/collimation/oculaire-de-collimation-takahashi_detail

Once collimated and if you don't carry the scope in the car, you should not face any issue and scope remains collimated without problems.

You can then also add some more accessories to reduce the focal length and transfor it in a fast F/5.6

Definitely a great scope at for it's price range allowing multiple targets and lot of fun :-)

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