Newbie here some questions about collimating flextubes

[Optic Nerve]

That's with a sheet of A4 covering the primary mirror, as well as a look down the focuser when there's no eye piece or cheshire in it.

https://imgur.com/a/lEm1CZj

Am I going in the right or wrong direction from what it was initially? Part of me is concerned I may have totally mucked it up.

[bosun21]

I’ve already posted how to position your secondary mirror. Your secondary is oval shaped and needs rotated.

[Optic Nerve]

36 minutes ago, bosun21 said:

I’ve already posted how to position your secondary mirror. Your secondary is oval shaped and needs rotated.

This is way to complicated for me. Sorry if that sounds stupid and I appreciate that people have put in the time to reply and try and help, but when it comes to altering the secondary mirror I mucked it up before and struggled to get things back to, I couldn't see either of the mirrors at one stage. I'm worried sick that tinkering with it much more and I'll end up mucking it up completely. I was ok with the views I had before, so at this stage I'll happily settle for an alignment that's about as good as that. Is it possible to look at what I had before, and what I had now, and say if I've at least made some progress in the right direction?

 

First two images are what it was before, through the Cheshire and also through the focuser with no eyepieces attached. This gave a view of the moon that I thought was quite good.

https://imgur.com/a/YvShjOV

https://imgur.com/a/H0joaLO 

 

The second two images are what I have now.

https://imgur.com/a/uDitdAO

https://imgur.com/a/lEm1CZj

 

Edited February 8, 2023 by Optic Nerve

[ollypenrice]

This link https://fedastro.org.uk/fas/members/members-location-by-county/  will take you to a comprehensive list of UK astronomical societies. (I'm not certain that you are in the UK but you write without an accent. ) I'm sure that, if you went along there, someone would sort out your Newt in no time and show you how to do it.

Olly

[SuburbanMak]

Hi @Optic Nerve -  in the words of Douglas Adams, first - Don't Panic!     Everything that can be adjusted is meant to be, so nothing you tweak is irrevocable. I went through (am going through) the same learning process last spring after buying a Dob for the first time with zero experience of collimation.   I got some great advice on here (from many of the same people contributing above) and from watching through a bunch of YouTube videos. 

Take it slowly, try and enjoy the process and the top tip is to make sure you only adjust the secondary when the 'scope is flat so you don't drop your allen key or screwdriver on the primary! Other than that tweak away - I found that I improved the view by increments eventually getting the views I expected.  I did all of my main alignment and secondary fiddling in the daytime and only adjusted the primary out in the dark. 

Here is the SGL thread where I asked for help, some of which you might find useful.  Good luck! 

 

[Optic Nerve]

14 minutes ago, ollypenrice said:

This link https://fedastro.org.uk/fas/members/members-location-by-county/  will take you to a comprehensive list of UK astronomical societies. (I'm not certain that you are in the UK but you write without an accent. ) I'm sure that, if you went along there, someone would sort out your Newt in no time and show you how to do it.

Olly

Yes in UK.

Does what I have now look better or worse than what I had before? Waiting for tonight when theres clear skies to see for myself. At this stage I'm just hoping for something like what I had before. I think everything looks a bit closer to what it should be but I've a bad feeling I missed something, if the secondary is rotated/tilted I guess that means any object I look at will appear tilted too?

[wulfrun]

9 minutes ago, Optic Nerve said:

 if the secondary is rotated/tilted I guess that means any object I look at will appear tilted too?

No, it means you won't get the clarity and sharpness that you could have got. I bumped one of my newts, knocking the secondary quite a way out (it was not locked properly and I'd failed to realise). It didn’t make much difference, for most targets but for things like planetary detail it did degrade the view.

Try this guide, it's one of the simplest I have found:

https://garyseronik.com/a-beginners-guide-to-collimation/

I also suggest you pause for a bit and don't worry too much. You can follow the guide above methodically but I think the best part of it is that he explains, in simple terms, the "whys" and "hows".

[Optic Nerve]

11 minutes ago, wulfrun said:

No, it means you won't get the clarity and sharpness that you could have got. I bumped one of my newts, knocking the secondary quite a way out (it was not locked properly and I'd failed to realise). It didn’t make much difference, for most targets but for things like planetary detail it did degrade the view.

Try this guide, it's one of the simplest I have found:

https://garyseronik.com/a-beginners-guide-to-collimation/

I also suggest you pause for a bit and don't worry too much. You can follow the guide above methodically but I think the best part of it is that he explains, in simple terms, the "whys" and "hows".

Its clear skies tonight so I'm going to have another look at the moon and see what difference my tinkering has made, hopefully I wont have made it any worse, I'd take that as a win at this stage.

I try to read through these guides but they are really confusing. I get the feeling collimation is a bit like tying your shoes or learning to ride a bike, difficult to actually talk someone through it but straightforward once you understand. My only worry there is I fell on my bike loads when learning!

If the views I have tonight are similar ish to what I had before I'll be ok with that and then leave a proper collimation until ive gone over the guides again and again and it clicks. Its a bit of a frustrating start to the hobby, but it hasnt dampened my interests in looking up to space, its just a bit of a blow to my ego that I am basically being outsmarted by a mirror

Edited February 8, 2023 by Optic Nerve

[dark knight]

Nearly all reflector owners have been exactly where you are right now so dont give up, the astronomy learning curve can be quite steep but there is always help available, maybe say roughly what area you are in and someone maybe close enough to meet up and show you.

[Mr Spock]

What you need is someone experienced to demonstrate for you. If you put your approximate location, I'm sure someone will help.

[Xilman]

47 minutes ago, Optic Nerve said:

 its just a bit of a blow to my ego that I am basically being outsmarted by a mirror

You don't have to be a newbie to be outsmarted by a mirror, believe me.

I first used a Newtonian in 1975. I still loathe having to collimate them, especially bobbing up and down from one end of the scope to the other to see what difference twiddling a screw at the back of the primary has made and then trying to remember which screw and in which direction and by how much.

 

[wulfrun]

47 minutes ago, Optic Nerve said:

I try to read through these guides but they are really confusing. I get the feeling collimation is a bit like tying your shoes or learning to ride a bike, difficult to actually talk someone through it but straightforward once you understand.

Spot-on, yes much easier to do than describe in words. Once you get the idea behind it it does make sense. There's a multitude of adjustments on two mirrors, so it's not hard to get confused over what does what. Also easy to read too many guides & watch all the videos and make yourself more confused. Time for a pause if you've got there!

[Optic Nerve]

42 minutes ago, wulfrun said:

Spot-on, yes much easier to do than describe in words. Once you get the idea behind it it does make sense. There's a multitude of adjustments on two mirrors, so it's not hard to get confused over what does what. Also easy to read too many guides & watch all the videos and make yourself more confused. Time for a pause if you've got there!

Do you think the image through the cheshire now is better than what it was?

[JOC]

FWIW the apparent SGL standard reference for collimation is this one https://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/  I use this guide and no-one was more nervous than I the first time.  It works wonderfully

Edited February 8, 2023 by JOC

[wulfrun]

21 minutes ago, Optic Nerve said:

Do you think the image through the cheshire now is better than what it was?

Yes...but there's always the difficulty of the angle the camera was or might have been at, so it could look better (or worse) than it is. Assuming the camera was central, it's better but not right.

If I were in your shoes, I'd just use it for a while and take the time to re-read and absorb the principles before any more fiddling. That's not being unkind, most of us have been there! Amazing what a break from a task can achieve.

Also remember that the difference between "close" and "perfect" is unlikely to be noticed in real-life usage on visual astronomy. When you do tackle it again, aim for "perfect" but accept "close", don't obsess.

[Optic Nerve]

23 minutes ago, wulfrun said:

Yes...but there's always the difficulty of the angle the camera was or might have been at, so it could look better (or worse) than it is. Assuming the camera was central, it's better but not right.

If I were in your shoes, I'd just use it for a while and take the time to re-read and absorb the principles before any more fiddling. That's not being unkind, most of us have been there! Amazing what a break from a task can achieve.

Also remember that the difference between "close" and "perfect" is unlikely to be noticed in real-life usage on visual astronomy. When you do tackle it again, aim for "perfect" but accept "close", don't obsess.

Thats what I'm going to do. And yeah I'm not too bothered about getting it exactly right, I thought the views I had initially (with the secondary way off) were actually good.

 

By the way now that ive reangled the mirrors will my aim be off? I struggled to get my finder scope precisely aligned, the red dot had to be pointed to the moon and then about an inch to left. Will I maybe find its not in the right spot now, maybe instead its a bit to the right/down/up from the red dot?

[wulfrun]

1 hour ago, Optic Nerve said:

By the way now that ive reangled the mirrors will my aim be off? I struggled to get my finder scope precisely aligned, the red dot had to be pointed to the moon and then about an inch to left. Will I maybe find its not in the right spot now, maybe instead its a bit to the right/down/up from the red dot?

Yes, adjusting the mirrors will make a small difference to the finder, not usually much though. The finder is adjustable so you can just re-align it, Polaris makes the ideal target for that since it moves so little. If you're going to have another go at collimation though, maybe live with the finder for now?

[bosun21]

If you stick with the hobby I’ll wager that in a years time you will look back and laugh at the predicament you are in at the moment, and wonder what all the fuss was about. The secondary mirror can be seen much better with a coloured sheet of paper between it and the primary mirror. A second sheet of white paper slid into the tube directly opposite the focuser will help you a great deal. If it’s all getting too much for you I second what @Mr Spock has advised and state where you are situated so that a member can possibly drop in on you and guide you through the procedure step by step. I wish you well.

[Optic Nerve]

23 minutes ago, bosun21 said:

If you stick with the hobby I’ll wager that in a years time you will look back and laugh at the predicament you are in at the moment, and wonder what all the fuss was about. The secondary mirror can be seen much better with a coloured sheet of paper between it and the primary mirror. A second sheet of white paper slid into the tube directly opposite the focuser will help you a great deal. If it’s all getting too much for you I second what @Mr Spock has advised and state where you are situated so that a member can possibly drop in on you and guide you through the procedure step by step. I wish you well.

Yeah probably, that seems to be the consensus in everything I've read about collimation. A massive headache to start with then it just clicks in your head and becomes straightforward. It hasn't put me off the hobby, although I've decided that if the view I have now ends up being about as good as what I had before, I'll just leave it at that for now. Spend time familiarizing myself with the scope and observing what I can, and then return to collimation after studying the guides until I'm more confident in what I'm doing.

I'm in the north of England

 

[CraigT82]

There are two main aspects to beginner collimation to get your head around, secondary and primary.

• Secondary is (as the name suggests) adjusting the position of the secondary mirror so that the entire primary mirror can be seen in the secondary mirror as you look through the cap. Secondary collimation isn't that important for a beginner to master, the consequences of getting it wrong is mainly uneven field illumination, it wont have much effect on the sharpness of the image.
• Primary collimation is adjusting the tilt of the primary mirror so that its optical axis is exactly aligned with your eye.  This is the important one to get right as the sharpness of the views can suffer if it's way off because of something called coma. Looking through a collimation cap or cheshire, you're trying to place the dot in the centre of the donut and this is done mainly by adjusting the three screws on the bottom of the scope behind the primary mirror,

In the last images you posted the dot and donut are quite far apart. which is bad... I've annotated it below.  Try to sort this out first and you can worry about your secondary later.

[Optic Nerve]

21 minutes ago, CraigT82 said:

There are two main aspects to beginner collimation to get your head around, secondary and primary.

• Secondary is (as the name suggests) adjusting the position of the secondary mirror so that the entire primary mirror can be seen in the secondary mirror as you look through the cap. Secondary collimation isn't that important for a beginner to master, the consequences of getting it wrong is mainly uneven field illumination, it wont have much effect on the sharpness of the image.
• Primary collimation is adjusting the tilt of the primary mirror so that its optical axis is exactly aligned with your eye.  This is the important one to get right as the sharpness of the views can suffer if it's way off because of something called coma. Looking through a collimation cap or cheshire, you're trying to place the dot in the centre of the donut and this is done mainly by adjusting the three screws on the bottom of the scope behind the primary mirror,

In the last images you posted the dot and donut are quite far apart. which is bad... I've annotated it below.  Try to sort this out first and you can worry about your secondary later.

Couldn't quite get it bang on but https://imgur.com/a/DJDjZUq

[CraigT82]

19 minutes ago, Optic Nerve said:

Couldn't quite get it bang on but https://imgur.com/a/DJDjZUq

How come? Did you run out of travel on the primary screws? 

[Optic Nerve]

25 minutes ago, CraigT82 said:

How come? Did you run out of travel on the primary screws? 

No it just wouldn't sit nicely, it was sort of like I was chasing it around the dot.

[CraigT82]

12 minutes ago, Optic Nerve said:

No it just wouldn't sit nicely, it was sort of like I was chasing it around the dot.

Keep at it! See if you can get that ‘dot in the donut’. It might help just to stick to using two of the three primary screws rather than using all three? 
 

In any case it’s a lot better than what it was last time and also better than what it was in your first post.

 

 

[ollypenrice]

Just pick a moderately bright star, high in the sky, centre it and focus on it. About 100x magnification is recommended but isn't compulsory at this stage. Now rack it inside focus and outside focus. When you do so, you should see concentric circles rather than shuttlecocks. These are the bare bones of the 'star test' which, surprisingly, is a brutally demanding test of optics because its underlying value is the wavelength of light - which is very short indeed!

If you get ovals out of focus, you are somewhere near. The trick is to refine them into circles.

Olly