RC 10 collimation

[E_ri_k (Erik)]

Hey guys. So I mounted the new RC10 yesterday morning before work, and neatened up some cables and stuff. Had no instructions in the box, but thanks to RickS, who sent me some very useful info!

The only collimation tool I own is a Glatter Laser for my old Newt, and a home made collimation cap (Just an old 1.25" cap with a hole in the centre)

I'm still not 100% sure what I'm doing when it comes to collimating the RC. I had a look through the focuser and everything looked very symmetrical. Also read about the "Hall of mirrors" technique, which I could see very clearly when looking down the OTA. I wasn't expecting perfect collimation out of the box, but it looked pretty good. Did a quick star test after work last night, and it was off abit, but I couldn't get a pic.

So basically I'm having a bit of trouble figuring out what I should adjust. From the info that I have read, I figure I don't need to adjust the primary. This is pretty much what I'm seeing when I look through my collimation cap. I can see the centre spot on the secondary, and it appears to be off to the right a bit, which is also the direction in which the diffraction rings were heading in last nights test.

I'm thinking I need to adjust the secondary to centre that spot? Does that sound right?

Sorry for the long winded post, I am just a bit nervous when it comes to touching the wrong thing and messing it up.........

Any help would be great, thanks
Erik

[pluck]

Erik,

If this is a DSI RC10, then you should use Rich's method for collimation (if he hasn't sent it to you, it should be easily available). I've used it for an RC14C and the method works beautifully.

If this is not a DSI RC10 we're talking about, then apologies.

Paul

[E_ri_k (Erik)]

Sorry. should have mentioned it is a GSO RC10. Think I figured it out. star tested last night while adjusting the secondary and its getting really close. Still off the slightest bit. Im pretty confident ill get it spot on next time.

Thanks.
Eril

[TrevorW]

With a GSO RC you only adjust the secondary the primary is fixed\\

I adjust mine using a Cheshire which gets it fairly close then touch up using a star but it's very fiddly doing it by oneself. You only need to adjust the screws in very small steps otherwise you'll put it way out

Cheers

[E_ri_k (Erik)]

Thanks Trevor I really didn't want to touch the primary. It looks really well collimated anyway. I know what you mean when you say hard by your self haha! Found that out the other night, but I figured out which screw did what in the end. Only did VERY small adjustments, like 1/20 of a turn at a time, if that, and each time I noticed a small bit of movement, but it was an improvement. When you say the primary is fixed, does that mean it will never need adjusting if the scope is cared for properly? (i.e not dropping it or something)

Any thoughts on this website which talks about primary collimation? http://deepspaceplace.com/gso8rccollimate.php It is for a RC 8, found it quite interesting nevertheless, but if the primary doesn't need touching, I'm happy
Erik.

(Typically it's gone cloudy now, and is expected for the rest of the week.....)

[Paul Haese]

Originally Posted by TrevorW

With a GSO RC you only adjust the secondary the primary is fixed\\

Actually that is not true.

The primary is not fixed there are adjustment screws for primary collimation. It is recommended that you don't touch those screws unless a) you know what your doing and b) you have a tak collimation scope.

If you have the former and the tak scope then it is quite simple to adjust the primary.

However, most times the secondary is the only set of screws that will need adjustment.

Go to http://www.rcopticalsystems.com/support/resources.html and get Ken Crawfords video.

[E_ri_k (Erik)]

Thanks Paul, I did notice the screw on the back of the scope. Not game to touch them because, a, I know I'll mess it up, and b, I don't have a TAK scope!

I'll just work on the sedondary. That's pretty simple now that I got the hang of things.

Erik

[TrevorW]

Sorry, I should have said that the primary comes factory set and you are advised not to adjust for collimation

[ReaPerMan (Paul)]

You may find this helpful

http://www.davidcortner.com/slowblog/20110815c.php

I have tried some of these and they have helped me a lot.

all the best

Paul

[nobbygon (Angus)]

Has anyone used the tak collimating scope with any of the GSO RCs? I've got the 8" RC and am thinking of getting the Tak. Just wondering if anyone has had any success?

[RickS (Rick)]

Originally Posted by nobbygon

Has anyone used the tak collimating scope with any of the GSO RCs? I've got the 8" RC and am thinking of getting the Tak. Just wondering if anyone has had any success?

I use one with a RC10 and have been very happy with it. It gets me very close to perfect collimation.

Cheers,
Rick.

[allan gould]

I believe that the Tak scope is very good for getting you close to collimation. However I use Als collimation Aid which gets me spot on for collimation with round stars across the frame. I take a one second image of a bright defocused star and use als aid over the top of the defocused star to see if all circles are concentric. If not I adjust the secondary pivots as needed until they are absolutely spot on. Near enough is NOT good enough. I use the same system with my SCT and it works perfectly.
See NGC253 that I shot with the 10"GSO RC and collimation done this way was last touched ~6 months ago.
Allan

[E_ri_k (Erik)]

Thanks for the link Paul, very useful. Think I'm going to be spending a lot of time getting things spot on!

Came across this website the other day:
http://www.goldastro.com/goldfocus/details_plus.php
Looks pretty good actually, if it works?

Erik