Collimation

[doughnuts729]

I don’t know if posting on the right forum but can someone help me with collimation? What is off in this picture or how do I fix it? I have a 10 inch skywatcher classic dobsonian. And howie glatter laser, parallizer and tublug.

[John]

Hello and welcome to the forum !

That looks pretty good to me.

What is the star test like ?

 

[doughnuts729]

7 minutes ago, John said:

Hello and welcome to the forum !

That looks pretty good to me.

What is the star test like ?

 

I do see a donut shape dark spot with ring of light around it when not focused and a bright NOT blurry light when focused. It’s just on the left side can you not see a part of it that looks like a waning crescent?

[Jamgood]

That's not bad at all. The secondary mirror could be tweaked a little but for observing, that should be pretty decent.

[doughnuts729]

22 minutes ago, Jamgood said:

That's not bad at all. The secondary mirror could be tweaked a little but for observing, that should be pretty decent.

Ok I guess I’ll have to trust you thanks

[doughnuts729]

58 minutes ago, Jamgood said:

That's not bad at all. The secondary mirror could be tweaked a little but for observing, that should be pretty decent.

Do you think the back and forth distance of my mirror is an issue or the issue?

 

2 hours ago, John said:

Hello and welcome to the forum !

That looks pretty good to me.

What is the star test like ?

 

 

59 minutes ago, Jamgood said:

That's not bad at all. The secondary mirror could be tweaked a little but for observing, that should be pretty decent.

 

[Sabalias]

Hi there,

I can see what you are referring to, the secondary looks very slightly off centre, but it still looks pretty good. If you are trying to adjust it then it think you might be right, the secondary could be moved slightly towards the front of the scope. Have you looked at Astrobaby’s site which explains the process really well?

Stu

[doughnuts729]

1 hour ago, Sabalias said:

Hi there,

I can see what you are referring to, the secondary looks very slightly off centre, but it still looks pretty good. If you are trying to adjust it then it think you might be right, the secondary could be moved slightly towards the front of the scope. Have you looked at Astrobaby’s site which explains the process really well?

Stu

I have looked the astrobaby page on collimating it’s a little confusing and I’m not good with technical things like this that’s why I posted here. But what people have told me is helping me understand.

[Spile]

8 hours ago, doughnuts729 said:

I have looked the astrobaby page on collimating it’s a little confusing and I’m not good with technical things like this that’s why I posted here. But what people have told me is helping me understand.

I read a few guides in order to find conflicts and identify those that suit me.

I like https://dbpeckham.com/Telescope/Collimation/Collimation.htm

 

[wookie1965]

I used this very easy to understand and step by step. 

http://www.schlatter.org/Dad/Astronomy/collimate.htm

[Spile]

I would work on the secondary tilt/rotation error and then align the primary.

 

[doughnuts729]

19 hours ago, Spile said:

I would work on the secondary tilt/rotation error and then align the primary.

 

Hey sorry for not replying and thanks for helping I gave up I ended up messing with the back and forth movement of the mirror to fix the issue. But just ended up making it worse and now am taking it to a telescope shop to get it somewhat right so all I have to do is small adjustments.

 

19 hours ago, Spile said:

I would work on the secondary tilt/rotation error and then align the primary.

 

 

[Peter Drew]

A bit late to this, I was about to give Spile's post a +1 and recommend that you didn't, at this stage, try and adjust the height of the secondary as this would likely lead to complications.

 

Never mind, providing you don't break or lose any of the bits, all can be put right.    🙂

[Stu1smartcookie]

On 14/06/2021 at 02:27, doughnuts729 said:

I don’t know if posting on the right forum but can someone help me with collimation? What is off in this picture or how do I fix it? I have a 10 inch skywatcher classic dobsonian. And howie glatter laser, parallizer and tublug.

I hope everything turned out right for you . This is easy to write but , don't beat yourself up over collimation . Honestly ,its easy to  get paranoid over it , and that can spoil the hobby. A star test is a really good way to learn if your mirrors are aligned , as was written earlier . 

 

[Jamgood]

2 hours ago, Stu1smartcookie said:

I hope everything turned out right for you . This is easy to write but , don't beat yourself up over collimation . Honestly ,its easy to  get paranoid over it , and that can spoil the hobby. A star test is a really good way to learn if your mirrors are aligned , as was written earlier . 

 

I concur. Once you grasp it, it becomes a very easy tweak here and there to make everything line up.

I was literally pulling the last few strands of my hair out when I first started, convinced I was doing more harm than good. The good thing is you can't really break anything and anything you do wrong can be restored. Just take your time and it'll be fine.

The best thing I did was give my laser to my cats for a toy. A collimation cap and a cheshire are all you really need. Maybe a concenter eyepiece if you're struggling with the secondary. Once the secondary is sorted, leave it alone.

Nowadays, I just use the cap. 

[Pixies]

2 hours ago, Jamgood said:

The good thing is you can't really break anything

Unless you over-tighten the secondary bolts and gouge grooves into the soft metal of the secondary holder that then prevent you from making any fine adjustments again 🙄

[John]

13 minutes ago, Pixies said:

Unless you over-tighten the secondary bolts and gouge grooves into the soft metal of the secondary holder that then prevent you from making any fine adjustments again 🙄

I have a large washer between the secondary bolts and the secondary holder to stop that happening. I have also added the milk carton washers to the arrangement:

https://www.cloudynights.com/topic/446178-secondary-mirror-milk-jug-washers/?p=5775875

 

 

[Jamgood]

16 minutes ago, Pixies said:

Unless you over-tighten the secondary bolts and gouge grooves into the soft metal of the secondary holder that then prevent you from making any fine adjustments again 🙄

There is that but you forewarned me about that when you helped me when I was a puppy at that stuff. 👍

[Pixies]

21 minutes ago, John said:

I have a large washer between the secondary bolts and the secondary holder to stop that happening. I have also added the milk carton washers to the arrangement:

https://www.cloudynights.com/topic/446178-secondary-mirror-milk-jug-washers/?p=5775875

 

 

Yep - that's how I fixed it

[BrendanC]

4 hours ago, Jamgood said:

The best thing I did was give my laser to my cats for a toy. A collimation cap and a cheshire are all you really need. Maybe a concenter eyepiece if you're struggling with the secondary. Once the secondary is sorted, leave it alone.

 

Agreed on all counts (including giving the laser to the cat!). I was struggling, got a Concenter, sorted the secondary, never touch it now. Just a quick check with the Cheshire to get the primary centred. The Concenter was more than I wanted to pay for a pretty much one-off fix, but I would still be getting frustrated with collimation if I hadn't bought one.

[doughnuts729]

12 hours ago, Stu1smartcookie said:

I hope everything turned out right for you . This is easy to write but , don't beat yourself up over collimation . Honestly ,its easy to  get paranoid over it , and that can spoil the hobby. A star test is a really good way to learn if your mirrors are aligned , as was written earlier . 

 

I haven’t taken it to the my local telescope place yet but I’m confident I’ll get it fixed he knows what’s wrong with it as I talked on the phone. Yeah I tend to get paranoid and overthink things.

[doughnuts729]

10 hours ago, Jamgood said:

There is that but you forewarned me about that when you helped me when I was a puppy at that stuff. 👍

Actually I may have tightened the 3 adjustment screws pretty tight like creaking scratching metal tight.

[doughnuts729]

11 hours ago, Pixies said:

Unless you over-tighten the secondary bolts and gouge grooves into the soft metal of the secondary holder that then prevent you from making any fine adjustments again 🙄

I may have done that I tightened the bolts pretty hard like creaking scratching metal hard. It looked like there’s a deep scratch but its not as deep as it looks.

 

 

Edited June 19, 2021 by doughnuts729

[Pixies]

4 hours ago, doughnuts729 said:

I may have done that I tightened the bolts pretty hard like creaking scratching metal hard. It looked like there’s a deep scratch but its not as deep as it looks.

 

 

You need to see whether it affects your ability to adjust the secondary. I found that the secondary kept slipping back in to the same position whenever I tightened the bolt and I couldn't get it into a position I wanted 

Easy to fix though. Like John said, you need to insert a large steel washer. I'll find a link to my old post from last year.

[doughnuts729]

34 minutes ago, Pixies said:

You need to see whether it affects your ability to adjust the secondary. I found that the secondary kept slipping back in to the same position whenever I tightened the bolt and I couldn't get it into a position I wanted 

Easy to fix though. Like John said, you need to insert a large steel washer. I'll find a link to my old post from last year.

Ok yeah there is not to much of an issue when I adjust the secondary can get it centered easy but good to know all I gotta do is put a washer in.