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Telescope won't focus anymore

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#1 shrimpus

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Posted 15 August 2019 - 07:53 PM

I have a 2 month old 10" reflector, and for some reason it just stopped focusing. I transported it to a dark sky site and it worked fine, but when I brought it back, it stopped working. It's still collimation, so I don't understand why my image is still blurry. It's like that with all of my eyepieces.



#2 Jerome Ni

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Posted 15 August 2019 - 07:56 PM

How do you know if it's in collimation? Transporation may mess up the collimation.


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#3 shrimpus

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Posted 15 August 2019 - 07:57 PM

How do you know if it's in collimation? Transporation may mess up the collimation.

Because I checked with my laser collimator



#4 JamesMStephens

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Posted 15 August 2019 - 08:06 PM

What kind of scope?

 

Jim



#5 shrimpus

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Posted 15 August 2019 - 08:07 PM

What kind of scope?

 

Jim

Orion xt10 plus



#6 mashirts

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Posted 15 August 2019 - 08:11 PM

Farpoint uses Cheshire cap or what I call a colllimation cap and center dot for final
Collimation. And the accuracy needed goes up steeply with a lower focal ratio . Not saying a laser collimation
Is not accurate.
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#7 S.Boerner

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Posted 15 August 2019 - 08:13 PM

When you turn the focusing wheels/knobs does the eyepiece move up and down?

 

Is there a focusing lock mechanism?  the silver knob in this picture https://tinyurl.com/y3qwepsp

 

Look at the two (there are sometimes four) Phillips screws on this picture. https://tinyurl.com/y37kkz9c

Have yours come loose?


Edited by S.Boerner, 15 August 2019 - 08:18 PM.

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#8 shrimpus

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Posted 15 August 2019 - 08:15 PM

When you turn the focusing wheels/knobs does the eyepiece move up and down?

 

Is there a focusing lock mechanism?  the silver knob in this picture https://tinyurl.com/y3qwepsp

 

Look at the two (there are sometimes four) Phillips screws on this picture. https://www.google.c...rl.com/y3qwepsp

Have yours come loose?

2nd image doesnt work and yes the eyepiece moves



#9 John Fitzgerald

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Posted 15 August 2019 - 08:20 PM

Maybe the secondary somehow got covered with an opaque substance?

 

Are you focusing it on an object at virtual infinity?  If not, most reflectors IME will not focus closer than maybe 300 yards or even more.


Edited by John Fitzgerald, 15 August 2019 - 08:22 PM.

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#10 shrimpus

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Posted 15 August 2019 - 08:21 PM

Maybe the secondary somehow got covered with an opaque substance?

I doubt it because the laser from my laser collimator shows up perfectly fine on the primary



#11 S.Boerner

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Posted 15 August 2019 - 08:23 PM

I fixed the bad link with an edit above.  Looking at the Orion site your scope has a lock, but since your draw tube moves up and down it isn't the problem.

 

As a curiosity do things look better when focused in all the way or out all the way?


Edited by S.Boerner, 15 August 2019 - 08:23 PM.


#12 shrimpus

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Posted 15 August 2019 - 08:27 PM

I fixed the bad link with an edit above.  Looking at the Orion site your scope has a lock, but since your draw tube moves up and down it isn't the problem.

 

As a curiosity do things look better when focused in all the way or out all the way?

No, everything looks equally awful.



#13 Napp

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Posted 15 August 2019 - 08:27 PM

Is the focuser barrel moving through it’s full range?  If it is then something is obstructing the light path or the mirrors are misaligned - not collimated.  Well, there are a couple other possibilities.  How far away is the object you are trying to focus on?  If too close you will not obtain focus. Then there is the “clear eyepiece cap left on the eyepiece barrel mistake” that many of us have made.

 

Be sure you look through the focus barrel without an eyepiece to make sure there is no obstruction.


Edited by Napp, 15 August 2019 - 08:30 PM.


#14 jtsenghas

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Posted 15 August 2019 - 08:27 PM

I doubt it because the laser from my laser collimator shows up perfectly fine on the primary

Okay.... your focuser is aimed properly at your primary, but does the return beam return back to the center of your collimator? The aim of the primary is far more critical than that of the focuser and for your scope has a tolerance of about half a millimeter. That appears as a tolerance of a millimeter on the return beam of your collimator, though other tools better align your primary. 


Edited by jtsenghas, 15 August 2019 - 08:32 PM.


#15 shrimpus

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Posted 15 August 2019 - 08:32 PM

Is the focuser barrel moving through it’s full range?  If it is then something is obstructing the light path or the mirrors are misaligned - not collimated.  Well, there are a couple other possibilities.  How far away is the object you are trying to focus on?  If too close you will not obtain focus. Then there is the “clear eyepiece cap left on the eyepiece barrel mistake” that many of us have made.

 

Be sure you look through the focus barrel without an eyepiece to make sure there is no obstruction.

Yes it's moving through its full range, I live on a lake and I was looking at the horizon, and I looked through the focuser with no eyepiece and it looked fine to me.


Edited by shrimpus, 15 August 2019 - 08:33 PM.


#16 shrimpus

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Posted 15 August 2019 - 08:34 PM

Okay.... your focuser is aimed properly at your primary, but does the return beam return back to the center of your collimator? The aim of the primary is far more critical than that of the focuser and for your scope has a tolerance of about half a millimeter. That appears as a tolerance of a millimeter on the return beam of your collimator, though other tools better align your primary. 

Yes, it does.



#17 Jon Isaacs

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Posted 15 August 2019 - 08:41 PM

Some thoughts andvquestions:

 

Is your collimator collimated? It's more likely the collimator shifted collimation. Are you using a Barlowed laser to align the primary?

 

What are you looking at to evaluate the image sharpness?

 

How steady is the seeing? 

 

Jon


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#18 Garyth64

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Posted 15 August 2019 - 08:47 PM

Some thoughts andvquestions:

 

Is your collimator collimated? It's more likely the collimator shifted collimation. Are you using a Barlowed laser to align the primary?

 

What are you looking at to evaluate the image sharpness?

 

How steady is the seeing? 

 

Jon

Forget the laser, and look in the eyepiece holder with your eye.  Does everything look aligned?

 

A telescope does  not simply decide that it no longer wants to be in focus.  Obviously something is out of wack.


Edited by Garyth64, 15 August 2019 - 08:48 PM.

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#19 havasman

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Posted 15 August 2019 - 08:53 PM

Since transport was involved, look to see if your mirrors may have shifted. Be sure the primary sits on all the mirror supports and that nothing is holding it closer to the objective aperture. See that the secondary stalk hasn't been bumped and that the mirror is in position.

See that your focuser is still securely in place and that the tube is not shifted in or out in the focuser bore.

Grasping at straws here but there's a cause out there & it'll show up pretty soon.

Try pointing at the moon, racking the focuser all the way out and then slowly pulling the eyepiece further out of the focuser to see if it approaches or achieves focus. If it does that'll at least indicate a direction to a component's movement.



#20 Bean614

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Posted 15 August 2019 - 09:55 PM

The OP wrote. ,"I live on a lake and I was looking at the horizon,"

 

I think some have realized that he might be looking at objects far too close, and with short focal length EP's.  He never actually answered the question of what he was looking at, but his above quoted statement seems to indicate that it wasn't in the sky, but on this planet, and close by.


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#21 N3p

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Posted 15 August 2019 - 09:56 PM

One thing I noticed about the XT10, you need to use the right extension tube with some eyepieces. 

 

On a couple of occasions, we had to pull the eyepiece out of the extension tube of about 1/8" to reach focus because the stock drawtube of the focuser along with the extension tube were too short for some eyepieces to even reach focus.

 

Try it during daylight, if you can't reach focus, pull the eyepiece out and see.

 

I was disconcerted when I discovered that... and complained in the dark quite a bit against the XT10i Orion.


Edited by N3p, 15 August 2019 - 09:59 PM.


#22 havasman

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Posted 15 August 2019 - 09:59 PM

One thing I noticed with the XT10, you need to use the right extension tube with some eyepieces. 

 

On a couple of occasions, we had to pull the eyepiece out of the extension tube of about 1/8" to reach focus because the stock drawtube of the focuser along with the extension tube were too short for some eyepieces to even reach focus.

 

Try it during daylight, if you can't reach focus, pull the eyepiece out and see.

 

I was disconcerted when I discovered that... and complained in the dark quite a bit against the XT10i Orion.

You've likely discovered by now that the coma corrector, which it needs anyway, solves the matter.



#23 havasman

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Posted 15 August 2019 - 10:01 PM

The OP wrote. ,"I live on a lake and I was looking at the horizon,"

 

I think some have realized that he might be looking at objects far too close, and with short focal length EP's.  He never actually answered the question of what he was looking at, but his above quoted statement seems to indicate that it wasn't in the sky, but on this planet, and close by.

That's a big reason why I suggested the moon, in addition to it being impossible to miss in an eyepiece if its light is hitting both mirrors and they're even nearly aligned.



#24 cookjaiii

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Posted 15 August 2019 - 10:09 PM

". . .  I live on a lake and I was looking at the horizon, . . ."

 

Looking over the surface of a lake whose temperature may be very different than that of the air + looking low on the horizon, those two could combine to create a thermal atmospheric turbulence that would look out of focus, even if looking at something far away.

 

Look at something near zenith to rule this out as a possible cause.



#25 N3p

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Posted 15 August 2019 - 10:09 PM

You've likely discovered by now that the coma corrector, which it needs anyway, solves the matter.

Ah oki oki, bah I think it's usable without the coma corrector the XT10i, but I have a good tolerance for coma apparently.

 

We installed a better focuser on it and the problem was solved like that, the new one can go a bit higher obviously.




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