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Collimation disaster

JulianFR

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JulianFR

JulianFR

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I've just had a total disaster. Collimating the main mirror with my son, we got to within an ace of getting the little ring over the black dot under the Cheshire's cross hairs but could not get the ring to budge leftwards a tad. So my son turned two adjusters a bit ... And then the ring disappeared out of view and the black dot/cross hair circle were on the other side of my field of view.

I had no idea how to get the ring/dot even back to the same part of my view, so I slackened the lock nuts, which had become tight ... And one promptly came away from the mirror! So now all the lock nuts and all the adjusters are out of whack ... And nothing gets the ring/dot even close. Through a collimation cap I can no longer see the three equally-spaced mirror holders, only two.

Honestly, I came so close but I would have been better not collimating at all. I feel hopelessly frustrated as the mirror has obviously shifted so much it is beyond my capacity to fix it. 

Any suggestions? I don't think I'll be able to use it any time soon. I can't believe it as I've had some great views of Jupiter the last couple of nights.

I guess I'll need to drive to a telescope store and asking there ... My nearest is probably 50 miles away :-( I plan to join Swindon Stargazers now the seasons are changing. Maybe a kind person there would take pity on a beginner!

Maybe I should have bought a refractor as collimation seems beyond me :-(

Thanks for listening!

Julian

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Charic

Charic

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JulianFR........ Im trying to understand your dilema........

so I slackened the lock nuts, which had become tight ... And one promptly came away from the mirror! So now all the lock nuts and all the adjusters are out of whack

The Lock nuts (Hex Bolts) should rest against the assembly to prevent further movement by the adjusters. The Philips Head screws are the adjusters, can you not just screw it back in, and start again?

maybe some more info as I have the same telescope

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JulianFR

JulianFR

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Hi... Thanks for the quick replies. Yes, the screw is re-attached to the mirror housing... I pulled the mirror back towards the screw and it went back in ok.

The Phillips head screws are the adjusters? I thought they were the locking screws and the small holes house the adjusters, which are turned using a small allen key! That's what I've understood from the SW instruction manual, which covers two kinds of mirror end.

Since this happened I've been adjusting screw and allen key to get the ring/dot together but nothing seems to get them close.

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Avocette

Avocette

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Hi - its not a disaster if the mirror didn't come completely free! You should return to a safe starting position of releasing all three locking grub screws (Allen screws) well back and tightening all three cross-head adjusting screws to the point where the neoprene O rings are quite tightly and evenly compressed. The primary should then adjusted by releasing the cross-head screws by tiny amounts to get that donut in line with the black dot.

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Charic

Charic

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We have the same manual (Under Proper care of your telescope - Aligning the primary mirror) mine says the Hex are for locking.

So...... loosen the Hex Lock nuts. Then loosen the Adjusters (Philips)  If at all possible, between you and your Son, support the tube vertically, and then `screwdriver`  un-screw  all the adjusters until they are loose (now you know how to put them back in) . Now tighten them slightly, You need each screw to  be equally inserted, therefore the mirror is almost  aligned at this stage, and  its  little by little on the adjusters, until the mirror is central through the focuser ( the 3 mirror clamps should be visible) Make sure the secondary mirror  is  aligned  first. Caution when tightening the Hex nuts , almost guaranteed to upset the adjusters, so between your selves, one looking through the collimation (Device/cap) while the other adjusts. Not sure what guide you use for collimation, but  http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm is always recommended.

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laowho

laowho

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We've all been there. This is a good thing. You'll know your scope better than many after this and you will be a god-send to other new observers who aren't getting what they can out of their new scopes. Congratulations. This is a huge leap forward for you and you'll enjoy your scope even more...some (many?) people never even make it this far or bother to try.

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JulianFR

JulianFR

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All... Many thanks. After reading all your replies I feel less frantic. I'll go back to it tomorrow. I cannot believe I was so stupidly using the wrong things as adjusters  :eek: This in itself I'm sure will help.

I was following Astro Baby at the time, so thanks for forwarding the other instructions. The secondary is fine and, as mentioned, the three mirror clamps were equally in view ... And I was so close to having proper collimation (albeit using the adjusters!)

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Crebles

Crebles

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Bless ya JulianFR - I'm sure many of us have been there (and the others are fibbing!), so we do appreciate how frustrating it can be. I'll admit I was quite terrified! As Kirkster says - its part of the hobby, a bit of a rite of passage methinks. The Art of Collimation is talked about with a certain reverence around here! I read some people never pluck up the courage to have a go!

There's loads of good info here on this forum (taking your time is a good 'un) and YouTube as well. Astrobaby's guides are seminal.

If I may offer my one Top Tip: work with the scope in a horizontal position. That way if/when you drop your allen key / screwdriver / torch down inside - you'll not bust anything important. I know it sounds obvious - but its so easy to forget when you're in the middle of collimating and its all going star-shaped.

If you can't get it sorted alone, there might be someone at your local astronomy club that can help....

Hope that all doesn't sound patronising - I just really remember being in a similar pickle and feel for you!

Do let us know how you get on.

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JulianFR

JulianFR

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I've done it! Just 10 minutes of adjusting the screws instead of the hex nuts and it all came back into line ... It's so much easier with the screws for goodness sake. And I can even see the mirror clamps equally through the collimation cap. When we get a clear night I'll do a star test, but as the ring and dot are centred, I guess it should be ok.

You were right all of you ... I HAVE learned from what I thought was a disaster. Thanks again!

Julian

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wookie1965

wookie1965

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Congratulations people always think collimation is hard but once you have done it a couple of times it is easy, now you wont have to touch your secondary again unless you really bang your scope you will just have to tweak your primary from time to time.

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JulianFR

JulianFR

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Thanks ... I really will sleep better tonight [storm notwithstanding].

Many thanks again. The forum helped me solve a problem within a couple of hours when I thought I would be scope-less for days.

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