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How to know if my refractor is misaligned?

beginner collimation imaging Meade
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#1 Hamlet

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Posted 21 July 2019 - 11:29 PM

Hi folks! I bought the Meade adventure, has 3 days in my home and i used in two nights, I saw the moon and jupiter, I think the viewing was good But when I use the lower magnification (that it came in the package) and when I look to jupiter or another bright star, it looks weird... I don't know if i normal or is something misaligned inside. There's some way to know that? Btw i don't have the cheshire collimator

 

I draw a picture of how it looks when i look through the EP 

Attached Thumbnails

  • IMG_20190722_002618.jpg

Edited by Hamlet, 22 July 2019 - 12:40 AM.


#2 oldstargazer

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Posted 21 July 2019 - 11:53 PM

Looks pretty much like a normal artifact in a short focal length refractor on a bright object, plus it isn't quite in focus.



#3 Jond105

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Posted 22 July 2019 - 01:33 AM

These are prone to pinched optics. Loosen the retaining ring a little a give it a tap, then put very little pressure back on the retaining ring. It’s hard to tell from your pic what is wrong, but it’s something that could be a problem.  



#4 Redbetter

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Posted 22 July 2019 - 01:55 AM

I assume this was taken with the included RACI diagonal.  Bright stars/planets will likely show some longitudinal blurring in line with the diagonal, usually as single line.  The diagonal might not be well aligned either, something I have seen in about half of the cheap achros.  As has been stated before...the accessories are bottom of the barrel, so you can't really trust them to evaluate the scope's focuser or optics unless everything happens to look great together.  If there are problems you have to try to eliminate various sources. 

 

It could be inherent to the eyepiece if the problem was not happening with the higher power one (usually such errors go the other way, they become more noticeable with magnification.)  Does the angle of the artifact change when rotating only the eyepiece?

 

If you are seeing the same thing with eye and camera then it rules out astigmatism in your own eye.  By 3.6mm exit pupil (the 18mm eyepiece in an f/5) even fairly minor astigmatism can be noticeable.  If the extension rotates when you turn your head to a different angle, then it is your eye.



#5 Chesterguy1

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Posted 22 July 2019 - 06:59 AM

I had a refractor that produced oblong stars that were quite noticeable at higher magnifications. The primary lens cell was misthreaded.

Chesterguy

#6 SeattleScott

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Posted 22 July 2019 - 08:15 AM

Sounds like astigmatism in your eye. LASIK should fix it. Or wear glasses when you are stargazing. At least at low power.

Where you see this stuff only at low power, the issue is with your eye. If the view is fine at low power but gets worse at higher power, then you need to worry about the scope.

Scott
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#7 MalVeauX

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Posted 22 July 2019 - 10:05 AM

Here's how it would look if your collimation was off.

 

You can check it by pointing it at a bright star (point light source) and move in and out of focus and look at the airy disc at high magnification.

 

50mmGuideScope_Collimation_Off_06032019.gif

 

Very best,


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#8 SteveG

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Posted 22 July 2019 - 01:43 PM

Hi folks! I bought the Meade adventure, has 3 days in my home and i used in two nights, I saw the moon and jupiter, I think the viewing was good But when I use the lower magnification (that it came in the package) and when I look to jupiter or another bright star, it looks weird... I don't know if i normal or is something misaligned inside. There's some way to know that? Btw i don't have the cheshire collimator

 

I draw a picture of how it looks when i look through the EP 

That spike you are seeing is likely an artifact from the correct image diagonal prism. A mirror diagonal would probably be much better for the scope, but unfortunately will cost almost as much as the scope. I would look for a used, 1.25” 90 deg diagonal.



#9 Hamlet

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Posted 22 July 2019 - 07:39 PM

Thanks so much for everyone!, i think is an issue with the terrestrial diagonal, the weird thing is when i use the 6mm eyepiece i don't see much of that problem and either so, with the cap on it. I will keep testing the scope


Edited by Hamlet, 22 July 2019 - 08:34 PM.


#10 rowdy388

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Posted 22 July 2019 - 09:38 PM

Compare the view with and without the diagonal (straight through). If the diagonal is the cause, you will know.


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#11 Hamlet

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Posted 22 July 2019 - 09:48 PM

Compare the view with and without the diagonal (straight through). If the diagonal is the cause, you will know.

You mean put the EP right in the focuser?



#12 tony_spina

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Posted 23 July 2019 - 05:22 AM

You mean put the EP right in the focuser?

Yes



#13 SteveG

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Posted 23 July 2019 - 01:47 PM

You mean put the EP right in the focuser?

What you might find is that there is not enough outward focuser movement to bring an eyepiece to focus without the diagonal. Give it a try and report back.



#14 Hamlet

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Posted 24 July 2019 - 09:29 PM

What I did was project the light of the cellphone's flashlight through the objective, passing through the ota to the focuser, without the diagonal, and project it on the wall, and the projection was similar to the image posted above #7




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