SW AZ 130P -- Collimation nightmare -- help! :(

[perseid68]

Hi

Ok, so I was stupid. I decided to collimate my telescope for the first time in the middle of nowhere (went there for clear skies) and I have very successfully decollimated the scope (i.e. if there is an ideal perfect collimation, I managed to achieve the exact opposite). Right now stars look like massive blotches through the scope.  If I don't manage to fix this here on my own with what I have at my disposal ("civilisation" is about 350 kms away) then this entire trip was for nothing. Ok, now that I have painted the general picture of despair, here are the particulars. And yes, I have read through a million tutorials (Astro Baby, etc etc).

The telescope is a Skywatcher SynScan AZ Goto 130P, and I have a Hotech SCA laser collimator that was supposed to overcome the general problems of laser collimators needing alignment of their own as well as a collimation cap which I made yesterday out of an eyepiece protector. (The Hotech YouTube videos and the demo by the salesperson in the shop made it look so incredibly easy...)

The problem is that no conceivable combination of wiggling and turning the front centre screw and the three allen screws around it is now able to align the secondary mirror straight in front of the eyepiece. It is a complete mystery to me how these four screws logically affect the position of the seconday mirror because they just randomly jump round. Also, nothing I do will bring the red laser dot anywhere near the centre - it seems to be limited to the top left corner. (I may soon not need a telescope because the red dot has now accidentally shone in my eyes more times than I can remember).

Right now I am feeling incredibly sorry for myself and after hours and hours and hours of failure I am seriously contemplating taking a hammer to the telescope or myself.

Any advice from somebody who has overcome a similar experience will be welcome. *Sobs*.

[Astrosurf]

Are you collimating the screw at the front of the scope, in the aperture? That's for the secondary and that's the most difficult to do. It's best done during daylight, I'm afraid. I would have only started with the primary mirror (at the back) as the secondary isn't always off. Once it's collimated it tends to stay put.

I don't know your scope but my SW 200P primary has three Allen key holes and three screws. The Allen key holes are for loosening the grip on the mirror so only loosen them about 1/4 turn then adjust the mirror with the screws. I imagine that the screw, as it's tightened, 'pulls' the donut towards its direction, if that makes sense?

I gave up on my laser and now use a combination of collimation cap and Cheshire. But they need light, hence my collimating during the day.

Sorry you're having this problem.

Alexxx

[perseid68]

Thanks for replying. I started with the secondary because the collimator dot was quite a bit removed from the centre If I'd known this was going to happen I probably wouldn't have collimated it at all...

The SW 130P has one screw in the middle and three Allen key holes around it. (Talking about the front of course). Still can't fathom what the relation between the three Allen key holes and the screw in the middle is. Do I loosen the screw in the middle and then adjust the three Allen key screws around it? Or vice versa? I have gone through all the different combinations and permutations, I think. I also managed to get the primary all out of kilter. The laser dot doesn't even appear on the collimator cross hairs on the outside that you use to adjust the primary mirror any longer.

[NGC 1502]

Hi and welcome to SGL......we can feel your pain.

First, please put away the hammer (post #1) and take a break for as long as it takes to feel as calm as poss.

Make sure you have well fitting tools. Keep the telescope tube as horizontal as you can so if you drop a tool down the tube it won't damage the primary mirror.

Secondary collimation (front end) the centre screw is a lock screw, and also can be used to shift the secondary nearer or further from the primary mirror (the larger mirror) the 3 outer screws adjust the tilt of the secondary.

One common issue is the 3 screws that adjust the secondary can dig a small hole in the secondary holder making adjustment a VERY frustrating process. The fix is to add a large washer between the inner end of the 3 screws and the secondary holder (dismantling needed for that)

One of the best tutorials for Newtonian collimation is here - http://www.garyseronik.com/?q=node/169

Good luck ! Ed.

[perseid68]

Thanks for the words of encouragement. Unfortunately I ended up completely unscrewing the screws from the secondary mirror, which is now wobbling freely in its tube. If I can't collimate a telescope, I doubt if I will be able to get the secondary mirror back in the correct position and aligned with the four screws. I guess that's almost as good as a hammer. I was having a lot of fun with this telescope, but this aspect of it all unfortunately made me realise that I am in need of another hobby.

[AdeKing]

Collimating the secondary is very time consuming and frustrating the first time around, but stick with it and you will get there.

Have you read AstroBaby's guide to collimation, it's the clearest guide I've found.

http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

Basically the large screw in the centre of the spider at the open end of the scope moves the secondary mirror up and down inside the tube and so will move it up and down when you look through the collimation cap.

The three Allen bolts surrounding the central screw adjust the tilt of the secondary mirror to align it with the primary.

When making changes keep the changes small. When adjusting the three Allen bolts on the secondary, remember that as you tighten one bolt you may have to very slightly loosen one or both of the others to line up the reflections.

Read the AstroBaby guide, work through it slowly and try not to get too cross, you will succeed in the end.

Good luck.

[Astrosurf]

Also google YouTube Orion Optics Collimation. I wish I could give you a link now but YouTube is barred at work. You should find a vid with an American giving instructions. I found that very good. If I remember rightly, the central screw also allows forward and backward adjustment of the secondary. Take care not to put your fingers on the secondary mirror.

Good luck!

EDIT: try here:

http://www.youtube.com/watch?v=YAVGcGEBmCE

[spike95609]

Firstly, take your time, don't panic, and have a think about everything you're going to do before you do it. Make only small adjustments at a time, and think about what those adjustments are likely to achieve before you do them - this way if anything goes wrong it can be easily reversed. The first thing to do is to reconnect all the allen screws with the secondary. Don't tighten one completely and then move onto the others, tighten each by about a quarter of a turn in succession so that they all go on evenly.

The next thing to do is to align the secondary with the focuser. The large screw moves the secondary towards and away from the primary, but in order to move it at all you'll need to loosen, only a bit, all of the allen screws first. It's not a sensitive screw and so will move the secondary quite a lot with each turn. Once it's central with the focuser, leave it be and move on to the allen screws.

These control the tilt. Again don't think of the three of them as individual screws to be tightened or loosened independently, it's a three-way balancing act and they operate in unison. Look through your collimation cap in the focuser and adjust the screws until you can see the primary mirror clips (I think there will be 3 of them in your scope) evenly positioned around the edge. That's all you need to do with the secondary. If you can't see them, give one of the allen screws a small turn and see if it is starting to bring things towards alignment. If you're going the wrong way, just reverse what you did and play around with another screw. It will be a bit awkward because three screws will alter the alignment along an axis of 120°, rather than a nice and easy to understand 90° that you'd get from four screws. But by playing around with all three you should gradually be able to align it until you see all the clips. Once you're satisfied, tighten them up. As before though, do not tighten them up individually, but tighten each by small fractions of a turn at a time, otherwise you'll knock it out of alignment again. Keep tightening them by the same amount until everything is, well, tight. Your work here is done.

[Astrosurf]

Excellent description, spike.

[Charic]

........that's pretty good advice from spike9560, also the comments from other members too.

One of the  main issues with collimating any telescope, is understanding the principle and the theory behind it? A good way to learn is to totally take the thing apart, which may sound strange to you as a struggling new user, but I often learn how things work by this very method. total strip down, visualise the parts and study their purpose  and reason. 

If this is too much to attempt, don't put a hammer to it, try the suggestions from Spike, maybe look for other information on the web, check out astronomy shed here,

 ( dont try the modifications just yet, but just look at how the parts assemble and work together )  and keep studying/reading here, and continue to ask.

Take this with a little humour, You could always wrap the whole thing back up and return it to the store, but I doubt you'll get your money back, unless you have just bought it in the last few days or so, but  that would be the easy way out?

Keep at it and keep studying. Your not the first to have these issues, and  won't be the last. and When it clicks into place, and you understand what happens, why it happens, and  you succeeded in collimating your scope, you'll wonder what the fuss was all about, but for some folk, its just not so easy to grasp, your not alone!

[cuivenion]

Thanks for the words of encouragement. Unfortunately I ended up completely unscrewing the screws from the secondary mirror, which is now wobbling freely in its tube. If I can't collimate a telescope, I doubt if I will be able to get the secondary mirror back in the correct position and aligned with the four screws. I guess that's almost as good as a hammer. I was having a lot of fun with this telescope, but this aspect of it all unfortunately made me realise that I am in need of another hobby.

I've been there mate, with exactly the same scope. I actually managed to disengage the secondary, it dropped off and fell down the tube. The secondary was chipped and the primary was scratched, I felt like drop kicking the thing!

Collimation is a steep learning curve that is best compared to tuning a guitar, it takes practice but you will get there. As others have said you need to be calm, practice in daylight and make sure the scope is horizontal! I will say that the 130p while a fine scope optically, can be awkward to collimate because of the small aperture.

It's hard to get your hand in to rotate the secondary and also to get paper in to block the reflection of the primary.

Don't give up on it! I'd have missed some cracking sights if I'd have given up at that point.

[perseid68]

Hi everybody,

Thank you very much for all the support. Wish I could have had all of you here with me in the Kalahari desert, where, quite frankly, the night sky is so amazing you don't need a telescope.

This will not get me down. Unfortunately like Cuivenion the secondary actually became disengaged. At that point I realised that any further attempts to fix the telescope might lead to me inflicting permanent damage, and half my holiday had already been swallowed up by this frustration, so I just decided to enjoy what was left of it with my naked eyes and not to stress any more. Will probably take the scope in to have somebody (with smaller hands) reassemble the secondary mirror, which seems to be fine (and no, it didn't drop on the primary). I'm just terrified of smudging it or hurting it, but without some serious handling it seems impossible to realign the mirror inside its tube with the holes for the screws so I can screw it back into place.

What doesn't kill you, makes you strong At least I now know exactly how everything is set up inside the scope. So this will hopefully help me in future.

Thanks again for all the moral support

L.

[Astrosurf]

I love your philosophy! And it's absolutely true. Please let us know how the collimation goes.

[Moonshane]

astro-baby's guide is excellent and thorough. I take a slightly simpler approach. http://stargazerslounge.com/topic/197640-collimation-and-star-hopping/