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I can't see anything clearly trough my telescope, I need help.

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#1 Polaris0000

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Posted 02 July 2020 - 09:50 AM

Hello, I am Sebastian. I am new to astronomy and telescopes.

 

Links:

 

-The site that I bought the telescope from : https://astromagazin.ro (The site is in romanian, not in english)

-Link to the telescope on AstroMagazin.ro : https://astromagazin...31200-dob-.html

-Official Omegon site : https://www.omegon.eu/

-Link to the telescope on Omegon.eu : https://www.omegon.e...ab_bar_0_select

 

 

Details:

 

-I bought it from AstroMagazin because the transport was way cheaper.

-I took the telescope and eyepiece covers/caps off.

 

 

Story:

 

So I bought my telescope a couple months ago and I waited some time, until the sky was clear (it wasn't clear when the telescope came).

One day, the sky was clear and I decided to test my scope. I expected having a hard time figuring out how to use it, I was right, I had some problems but I figured it out, I decided to go to sleep.

Next day, clear sky, I tried it again, everything was set up, I pointed it at a star (it was in the shape of a donut) and I tried focusing. I tried doing it fast, going back and forth. But I realized I was doing it wrong, and I started doing it slower and slower. (and it still looked like a donut)

Well, I have been trying for a long time, so I stopped and went to sleep.

(Another day)I kept trying for a bit, but it didn't work. I thought that my telescope wasn't collimated, so I watched some tutorials on how to collimate your telescope, but I failed collimating it.

Again, I tried it for some days, but it didn't work, so I decided to buy a cheshire eyepiece and a laser collimator (I heard people saying that they are using both).

The same happened and I didn't know what to do.

Some time ago I decided to go and look at something that is really far away, but it is on the ground (I know a reflector inverts the image). I saw the objects, I did this as a little test. But when I tried looking at a star, it was still a donut.

 

 

In my opinion, I just don't know how to collimate the telescope, but maybe it's not that.

I hope you can help me!

 

 

Thank you!



#2 MikeTahtib

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Posted 02 July 2020 - 10:00 AM

Are there multiple holes in the tube to mount the mirror?  Maybe the mirror is in the position for imaging rather than visual observing.

When focusing, does the star donut get smaller smaller, then start getting bigger? or is it getting smaller all the way to one end fo the  focuser travel, but still isn't in focus?  If you focus until the focuser tube is sticking all the way out as far as it can, but you still aren't in focus, I would try loosening the eyepiece screw, and sliding the eyepiece slowly out of the focuser tube to see if it focuses while being held a little farther out.  I have a telescope like this, I have to use a 1.5" extension tube to achieve focus.


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#3 coopman

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Posted 02 July 2020 - 10:03 AM

Often the laser collimator needs to be collimated.  


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#4 Richie2shoes

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Posted 02 July 2020 - 10:05 AM

It really sounds like your scope isn't properly collimated.  When collimating you want to start with your secondary mirror.  When you look into the focuser (without an eyepiece), the secondary mirror should appear to be a perfect circle.  Once you get that lined up, then you move on to the secondary using a cheshire, collimation cap or laser.  If using a laser, you need to make sure that the laser is collimated or use a barlowed laser.

 

Here is an excellent post on the subject with more detail:  https://www.cloudyni...your-newtonian/

 

I used this site when I was teaching myself the process:  http://www.astro-bab...nian-reflector/

 

The first time I tried it, it took me a couple of hours to get it right, but once you figure it out, it gets easier and quicker.  Now I check it each time I take my scope out and I'm ready to go in less than 5 minutes.  Once set, the secondary rarely needs adjusted and the primary mirror only needs minor adjustment.


Edited by Richie2shoes, 02 July 2020 - 10:09 AM.

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#5 KTAZ

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Posted 02 July 2020 - 10:06 AM

Hello Sebastian, and welcome to astronomy. You will get past this.

 

I am not an expert on Dob's, but there are many here that will help shortly. There is a specific subforum for "Reflectors" that might be another spot to post this question. However, I expect that a moderator might do it for you.

 

This sounds like a focus issue where you may not be achieving full focus. That can happen if the eyepiece is not at the right location in the focuser, or perhaps the focuser is simply having a problem. I will let others provide you with better advice.

 

The donut indicates that the star is out of focus on one side or the other. In general, simply turning the focuser in the direction that shrinks the donut will eventually get you to a pinpoint focus. If not, you may need an extension tube.


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#6 Polaris0000

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Posted 02 July 2020 - 10:07 AM

Often the laser collimator needs to be collimated.  

Hello, the laser collimator seems collimated to me, but thank you!



#7 Polaris0000

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Posted 02 July 2020 - 10:10 AM

Hello Sebastian, and welcome to astronomy. You will get past this.

 

I am not an expert on Dob's, but there are many here that will help shortly. There is a specific subforum for "Reflectors" that might be another spot to post this question. However, I expect that a moderator might do it for you.

 

This sounds like a focus issue where you may not be achieving full focus. That can happen if the eyepiece is not at the right location in the focuser, or perhaps the focuser is simply having a problem. I will let others provide you with better advice.

 

The donut indicates that the star is out of focus on one side or the other. In general, simply turning the focuser in the direction that shrinks the donut will eventually get you to a pinpoint focus. If not, you may need an extension tube.

Alright, thank you! Really love the community here, the people are nice. I will try everything, I hope something will work!


Edited by Polaris0000, 02 July 2020 - 10:19 AM.


#8 Polaris0000

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Posted 02 July 2020 - 10:14 AM

It really sounds like your scope isn't properly collimated.  When collimating you want to start with your secondary mirror.  When you look into the focuser (without an eyepiece), the secondary mirror should appear to be a perfect circle.  Once you get that lined up, then you move on to the secondary using a cheshire, collimation cap or laser.  If using a laser, you need to make sure that the laser is collimated or use a barlowed laser.

 

Here is an excellent post on the subject with more detail:  https://www.cloudyni...your-newtonian/

 

I used this site when I was teaching myself the process:  http://www.astro-bab...nian-reflector/

 

The first time I tried it, it took me a couple of hours to get it right, but once you figure it out, it gets easier and quicker.  Now I check it each time I take my scope out and I'm ready to go in less than 5 minutes.  Once set, the secondary rarely needs adjusted and the primary mirror only needs minor adjustment.

Hello, thank you! I think the same, the problem is probably that I didn't collimate it properly, I will try to collimate it again, but I will read more about collimating a telescope!



#9 cookjaiii

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Posted 02 July 2020 - 10:15 AM

Poor collimation won't cause donut-shaped stars.  You are not able to reach focus because either the eyepiece is too close or too far from the primary mirror.  The solution to the problem depends on which it is, too close or too far.


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#10 Polaris0000

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Posted 02 July 2020 - 10:17 AM

Are there multiple holes in the tube to mount the mirror?  Maybe the mirror is in the position for imaging rather than visual observing.

When focusing, does the star donut get smaller smaller, then start getting bigger? or is it getting smaller all the way to one end fo the  focuser travel, but still isn't in focus?  If you focus until the focuser tube is sticking all the way out as far as it can, but you still aren't in focus, I would try loosening the eyepiece screw, and sliding the eyepiece slowly out of the focuser tube to see if it focuses while being held a little farther out.  I have a telescope like this, I have to use a 1.5" extension tube to achieve focus.

Hey! I will try to follow your instructions, if nothing else works, I will probably buy an extension tube, also I will answer the : "Are there multiple holes in the tube to mount the mirror" question, but I can't look at the scope right now, I will answer that question in a couple hours, thank you!



#11 Polaris0000

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Posted 02 July 2020 - 10:22 AM

Poor collimation won't cause donut-shaped stars.  You are not able to reach focus because either the eyepiece is too close or too far from the primary mirror.  The solution to the problem depends on which it is, too close or too far.

Maybe you are right, but my scope still isn't collimated properly so I will need to do that first.



#12 coopman

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Posted 02 July 2020 - 10:23 AM

Do you know any other local astronomers that could help you?  I doubt that there is anything seriously wrong with your telescope.  It's probably just out of collimation.  See youtube for videos about collimating a newtonian.


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#13 Taosmath

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Posted 02 July 2020 - 10:25 AM

Maybe you are right, but my scope still isn't collimated properly so I will need to do that first.

Not actually that's the wrong way round.  You need to get to good focus before you can collimate.  The changes  you make to let you reach focus are likely to affect the collimation, so do whatever you need to get good focus THEN collimate.


Edited by Taosmath, 02 July 2020 - 10:25 AM.

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#14 Polaris0000

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Posted 02 July 2020 - 10:27 AM

Do you know any other local astronomers that could help you?  I doubt that there is anything seriously wrong with your telescope.  It's probably just out of collimation.  See youtube for videos about collimating a newtonian.

Hi again! Well, there are some astronomers in my area, but they are far away and I can't really travel in these times, they actually own a planetarium, they have a lot of scopes there. So if nothing works

I will need to get in contact with them. Thanks!



#15 Polaris0000

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Posted 02 July 2020 - 10:31 AM

Not actually that's the wrong way round.  You need to get to good focus before you can collimate.  The changes  you make to let you reach focus are likely to affect the collimation, so do whatever you need to get good focus THEN collimate.

Oh, thank you! I didn't know that I need to get to good focus before the collimation. I think that's why I couldn't collimate my scope properly, I followed the tutorials but it wasn't working so this may be a good advice!



#16 sg6

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Posted 02 July 2020 - 10:40 AM

Doughnut stars are that you cannot get the eyepiece at the right position to get a focused image.

Really suggest you leave collimation.

If you can see doughnuts then you are looking at stars, just unfocused stars.

 

With the eyepiece in - the one with the biggest number on it, so low power, does the doughnut appear to get better or worse as you wind it outwards.

 

If it gets a little better like a less doughy doughnut (all I can think of as a description) then I would half suspect that in with some bits is a small extension tube that you need to add to the focuser to move it all outwards a little.

 

Would imply that the focuser is set for you to add a camera. But as cameras and eyepieces have to sit at apparent different place you need to add an extension tube. My Bresser is the same.

 

Other options:

Haven't read the links but does the scope take 2" eyepieces as well as 1.25" ones ?

If so the you could have a 2" adaptor in there with a 1.25" adaptor sat in it, Take them both out and put the 1.25" one back in. Put the 2" one somewhere safe where you can find it in 6 months time. This is common on Skywatcher reflectors and so on rebrands of them.

 

If it is this then with the low power eyepiece the doughnut gets better as you would wind the focuser inwards.

 

Suspect this one is the reason.


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#17 havasman

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Posted 02 July 2020 - 10:44 AM

It is good to consider collimation as it is very critical but this is not your main problem. You are not reaching focus.

 

You should have tried all the way in and all the way out for focuser travel and one should make a smaller clearer "donut". Likely that is all the way out. Try sliding your 25mm eyepiece out of the focuser tube a bit when it is racked all the way out. This is common for these Dobs.. You should be able to find focus that way. Some of these scopes come with a 35mm extension tube and you may want one some day. They are not expensive.

 

You have a powerful scope that will work very well for you as soon as these initial matters are cleared up. Keep us involved in your solutions if you like.


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#18 Polaris0000

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Posted 02 July 2020 - 10:50 AM

It is good to consider collimation as it is very critical but this is not your main problem. You are not reaching focus.

 

You should have tried all the way in and all the way out for focuser travel and one should make a smaller clearer "donut". Likely that is all the way out. Try sliding your 25mm eyepiece out of the focuser tube a bit when it is racked all the way out. This is common for these Dobs.. You should be able to find focus that way. Some of these scopes come with a 35mm extension tube and you may want one some day. They are not expensive.

 

You have a powerful scope that will work very well for you as soon as these initial matters are cleared up. Keep us involved in your solutions if you like.

Hi, thank you! I will keep you guys involved in my solutions, gonna check my scope.


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#19 dcollier

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Posted 02 July 2020 - 10:57 AM

You will likely need an extension tube between the eyepiece and the focuser to reach focus.  This is not un-common on some Newtonians  a couple of inches should work.  Also, get in touch with your local astronomy club.  They can be a source of a good bit of help in getting you going.

 

              -Dave


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#20 Polaris0000

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Posted 02 July 2020 - 10:58 AM

Hey guys, I just wanted to ask you something, should I put a video where I try to focus on a star, or is it alright?



#21 Ulmer Spatz

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Posted 02 July 2020 - 11:01 AM

If the scope has a so-called Crayford focuser and a focusing tube lock screw, make sure the lock screw is loose. If it's tightened down, it's possible to turn the focusing wheels with the focusing tube not moving because of slippage.. Sort of like a car wheel in a mudhole--it turns and turns, but the car isn't going anywhere. 


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#22 Polaris0000

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Posted 02 July 2020 - 11:10 AM

You will likely need an extension tube between the eyepiece and the focuser to reach focus.  This is not un-common on some Newtonians  a couple of inches should work.  Also, get in touch with your local astronomy club.  They can be a source of a good bit of help in getting you going.

 

              -Dave

 

 

It is good to consider collimation as it is very critical but this is not your main problem. You are not reaching focus.

 

You should have tried all the way in and all the way out for focuser travel and one should make a smaller clearer "donut". Likely that is all the way out. Try sliding your 25mm eyepiece out of the focuser tube a bit when it is racked all the way out. This is common for these Dobs.. You should be able to find focus that way. Some of these scopes come with a 35mm extension tube and you may want one some day. They are not expensive.

 

You have a powerful scope that will work very well for you as soon as these initial matters are cleared up. Keep us involved in your solutions if you like.

 

 

Doughnut stars are that you cannot get the eyepiece at the right position to get a focused image.

Really suggest you leave collimation.

If you can see doughnuts then you are looking at stars, just unfocused stars.

 

With the eyepiece in - the one with the biggest number on it, so low power, does the doughnut appear to get better or worse as you wind it outwards.

 

If it gets a little better like a less doughy doughnut (all I can think of as a description) then I would half suspect that in with some bits is a small extension tube that you need to add to the focuser to move it all outwards a little.

 

Would imply that the focuser is set for you to add a camera. But as cameras and eyepieces have to sit at apparent different place you need to add an extension tube. My Bresser is the same.

 

Other options:

Haven't read the links but does the scope take 2" eyepieces as well as 1.25" ones ?

If so the you could have a 2" adaptor in there with a 1.25" adaptor sat in it, Take them both out and put the 1.25" one back in. Put the 2" one somewhere safe where you can find it in 6 months time. This is common on Skywatcher reflectors and so on rebrands of them.

 

If it is this then with the low power eyepiece the doughnut gets better as you would wind the focuser inwards.

 

Suspect this one is the reason.

Hi guys, a quick update, I found an Omegon extension tube (I will not buy it yet, but I want to get your opinions on it, also I will test the scope a little bit more but if it doesn't work I will buy it), do you thing it is worth it, what are your opinions on it? If you have a better one at a good price, reply to this.

Link : https://www.omegon.e...on-tube/p,33231



#23 Star Geezer

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Posted 02 July 2020 - 11:14 AM

If the scope has a so-called Crayford focuser and a focusing tube lock screw, make sure the lock screw is loose. If it's tightened down, it's possible to turn the focusing wheels with the focusing tube not moving because of slippage.. Sort of like a car wheel in a mudhole--it turns and turns, but the car isn't going anywhere. 

Following your link to the scope I noticed the lock nut right away. My money is on that being the problem.


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#24 JohnBear

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Posted 02 July 2020 - 12:14 PM

First of all welcome to CN Sebastian! 

 

As you can see from the many different individual responses here, there are many possible reasons for the problem(s) you are having. We simply do not have enough specific information to really narrow it down for you. Usually doing this online requires several pictures (that have to be taken a specific way with some precision). 

 

This is a common problem with first telescope owners (newbies). They don't know enough about their telescopes (which have a fair amount of optical complexity and require precision adjustments), and the try to fix a perceived problem by trial and error without really understanding what they are doing - making things much worse. This happens a LOT if you read the Beginners Forum. So you are not alone.

 

Probably the simplest reason for the 'focus' problem you described is the "locknut on the focuser" being too tight (a simple easy to fix problem if you are aware of it), but if you have tried to collimate the telescope, that could have created several new problems to deal with.

 

Fortunately you have a nice basic Dobsonian (Newtonian) telescope. So, almost any experienced astronomer should be able to quickly analyze the problem(s) you have and show you how to fix them and use the telescope properly in a matter of minutes (really) if they are there in person.  

 

So i suggest that you contact your local astronomy group(s) via email and ask if there is someone in your area that would be willing to help you.  There probably will be someone nearby that will offer to help you, and it will take very little time to do so. This is probably is the fastest way to get your telescope back in shape again, and you will also learn how to collimate and fine tune you telescope optics in the future. That is a fairly complex procedure, requiring precision that is extremely hard to learn via online forum discussions from multiple sources. But someone right there with you can teach you how to do it very quickly in person.

 

Best of luck, clear nights, and stay safe!


Edited by JohnBear, 02 July 2020 - 12:16 PM.

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#25 MikeTahtib

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Posted 02 July 2020 - 12:16 PM

So what would help a lot is if you could describe what happens when you try to focus on a star. As you look through the eyepiece at the donut and turn the focus wheels, the donut should get bigger turning teh wheels one way, smaller turning the other way.

-If it doesn't change at all, then the problem is as described by Ulmer Spatz, the focuser is locked and you're not actually changing the focus.  As you turn the focuser wheels, you should be able to see the focuser tube move in or out.  It should move a couple centimeters.

-If the donut gets smaller as you move the focuser in, but doesnt' get to full focus by the time teh focuser runs out of travel (is as far into the scope as it can get), then the mirror needs to be closer to the focuser, or the eyepiece isn't properly seated in the focuser, or there is some extra adapter between the focuser and the eyepiece. 

-If it gets smaller as you move the focus wheels so the tube comes outward, but doesnt' get to focus when you are as far out as the focuser gets, then you need an extension tube. 


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