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Hello to everyone im new to the forum and the astronomy side of.things..

Just purchased a 12inch dob the other day....set it all up, was really excited, had a clear night sky too...

One issue im having is that my images are completely blurry no matter how much i try focusing the image, it remains blurry..the lenses provided are a 25mm plossl and a 10mm plossl...both produce blurry images...i have aligned and collimated the scope...i really dont know what the issue is....when i remove the eye piece and look just straight down the barrel of where the eye piece goes...i can see images that are close as clear as crystal, however when i look at further objects they become blurry....ive literally tried and read everything i can, i thought someone might be able to help me on this forum??

I have taken the lenses apart checking to see if that will make a difference.  Theirs no barlow with this scope.  So i really dont know.

Thanks guys and girls, look forward to a reply.

Jov

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Are you letting the scope acclimatise outside for a bit before use? This really helps. Also check the focuser is actually moving when you turn the wheels.

Is there an extension you are not using that you should be? Perhaps some photos of the scope set up would help.

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Hey, 

Thanks for the reply, ye it sits outside for a while, ill put up some pics....i have put all parts on that have come with it, ive tried reassembling things...but it only assembles one way from what i can see...tomorrow im thinking of taking the eye pieces back to the store as they have a demo 12inc dob there...see if they work differently on theirs...dunno what else to do

 

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Posted (edited)

As Moonshane has said - the scope is not coming to focus within the amount of focus travel you have so you may need to put an extension tube on the focuser - you could test to see if this is correct by extending the focus travel all the way out whilst looking at a distant object during the day and then slowly pulling the eyepiece out to see if your scope comes to focus.

Or if you already have an extension tube in the focuser take it out and try the above.

Edited by dweller25

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I have extended the focuser all the way...the only way i see a clear image is when i literally move back from the eye piece and stand at a distance...but then the image is literally the size of the end of cigarette butt...which to me really doesnt make sense to stamd that far back...i even put my phone camera on top of the eye piece and zoomed it to get a larger clear image which worked...but doesnt seem logical to do that...an extension sounds good...but my question is shouldnt some else be having the same issue with this scope if an extension is required..or even saxon suggesting an extension coz images are blurry?? Dunno...just makes me think...but i think ur both right an extension might be an answer.

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7 minutes ago, Cornelius Varley said:

Hello and welcome to SGL. Does your telescope use a 2" focuser with a 1.25" adapter ? 

Hey,

Im fairly new to the telescope terminolgy, i believe the focuser is 2inch...as in it goes in and out about 50mm...and by adapter i think you mean eye piece...i have 2 that are provided...a 25mm (1inch) and a 10mm so just under half inch

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Just now, Jov said:

Hey,

Im fairly new to the telescope terminolgy, i believe the focuser is 2inch...as in it goes in and out about 50mm...and by adapter i think you mean eye piece...i have 2 that are provided...a 25mm (1inch) and a 10mm so just under half inch

Actually i think i know what adapters your taking about...they are 2 additional adapters and then the eye piece goes into it....ive tried disembarking these adapters..but then the eyes piece doesnt fit into anything else

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The point of focus is when the image is at its smallest. Find which way the focuser turns to make the image smaller and keep turning until you reach the point where the image is about to start becoming larger again. You should do this at night on a celestial target. These types of scopes typically do not have enough focuser travel to focus on terrestrial targets, unless they are very far into the distance. Saxon tend to sell rebranded Skywatcher scopes. The Skywatcher dobs are supplied with two extension pieces, one for when you use 2" eyepieces and one for when you use 1.25" eyepieces. Many people have problems because they try stacking both together. If you post a photo of your focuser we can tell you if you have it set up correctly.

If you do have it set up correctly, then thermal currents are most likely to blame, either inside the telescope tube because it has not cooled down sufficiently, because you are observing over man made objects which release heat later into the night, or simply the atmosphere, which will be worse at lower altitudes.

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10 minutes ago, Ricochet said:

The point of focus is when the image is at its smallest. Find which way the focuser turns to make the image smaller and keep turning until you reach the point where the image is about to start becoming larger again. You should do this at night on a celestial target. These types of scopes typically do not have enough focuser travel to focus on terrestrial targets, unless they are very far into the distance. Saxon tend to sell rebranded Skywatcher scopes. The Skywatcher dobs are supplied with two extension pieces, one for when you use 2" eyepieces and one for when you use 1.25" eyepieces. Many people have problems because they try stacking both together. If you post a photo of your focuser we can tell you if you have it set up correctly.

If you do have it set up correctly, then thermal currents are most likely to blame, either inside the telescope tube because it has not cooled down sufficiently, because you are observing over man made objects which release heat later into the night, or simply the atmosphere, which will be worse at lower 

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28 minutes ago, Ricochet said:

The point of focus is when the image is at its smallest. Find which way the focuser turns to make the image smaller and keep turning until you reach the point where the image is about to start becoming larger again. You should do this at night on a celestial target. These types of scopes typically do not have enough focuser travel to focus on terrestrial targets, unless they are very far into the distance. Saxon tend to sell rebranded Skywatcher scopes. The Skywatcher dobs are supplied with two extension pieces, one for when you use 2" eyepieces and one for when you use 1.25" eyepieces. Many people have problems because they try stacking both together. If you post a photo of your focuser we can tell you if you have it set up correctly.

If you do have it set up correctly, then thermal currents are most likely to blame, either inside the telescope tube because it has not cooled down sufficiently, because you are observing over man made objects which release heat later into the night, or simply the atmosphere, which will be worse at lower altitudes.

I tried viewing mars and jupiter the other night, they were blurry, i tried viewing during the day today..at trees and things in the distance, im in melbourne its winter here...12degrees celcius today...so i dont know if heat is playing a factor here...i just hope your going to tell me ive done the set up wrong hahaha...

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Posted (edited)

Looks like two adaptors and an eyepiece! take off the fattest adaptor, keep the middle one and the eyepiece, see if that works.

The fattest adaptor is for 2" eyepieces only, it looks to me that your inserting the 2" to 1.25" adaptor in to the 2" adaptor than fitting the eyepiece. that is your problem. You don't need both adaptors at the same time, it's  one or the other.

Edited by Charic
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Just now, Charic said:

Looks like two adaptors and an eyepiece! take off the fattest adaptor, keep the middle one and the eyepiece, see if that works.

It doesnt fit...to small...wants to fall right through...ive tried reassembling it like a million times...it seems it only works the way ive got it...i could be wrong...and might not be seeing something...but ive seriously tried all combos

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34 minutes ago, Ricochet said:

The point of focus is when the image is at its smallest. Find which way the focuser turns to make the image smaller and keep turning until you reach the point where the image is about to start becoming larger again. You should do this at night on a celestial target. These types of scopes typically do not have enough focuser travel to focus on terrestrial targets, unless they are very far into the distance. Saxon tend to sell rebranded Skywatcher scopes. The Skywatcher dobs are supplied with two extension pieces, one for when you use 2" eyepieces and one for when you use 1.25" eyepieces. Many people have problems because they try stacking both together. If you post a photo of your focuser we can tell you if you have it set up correctly.

If you do have it set up correctly, then thermal currents are most likely to blame, either inside the telescope tube because it has not cooled down sufficiently, because you are observing over man made objects which release heat later into the night, or simply the atmosphere, which will be worse at lower altitudes.

I tried viewing mars and jupiter the other night, they were blurry, i tried viewing during the day today..at trees and things in the distance, im in melbourne its winter here...12degrees celcius today...so i dont know if heat is playing a factor here...i just hope your going to tell me ive done the set up wrong hahaha...

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Posted (edited)

Despite your million attempts, it still looks like the adaptor Ive marked with yellow X is one too many, only the middle adaptor required?

 

Focuser edited.png

Edited by Charic
  • Like 1

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Hahaha alrighty, ill give it a go tonight when i get home...ill put a pic up of it...and hopefully ive failed a million times hahah

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59 minutes ago, Jov said:

.i have put all parts on that have come with

Looks like Charic is right, you don't need both adaptors, this is a common mistake with new Newtonians, just use the 1.25" one.

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2 minutes ago, Charic said:

Despite your million attempts, it still looks like the adaptor Ive marked with yellow X is one two many, only the middle adaptor required?

 

Focuser edited.png

Quick question to that though?? Wouldnt that increase my magnification, ultimately bring it close and reduced focal length of the eyepice...enhancing more

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Posted (edited)

More often than not, focuser issue, ie. blurring is down two both adaptors fitted where only one is required, and the other issue is the focuser lock, the grub screw beneath the focuser wheels, visible in your image. If this is too tight the focuser wheels will still turn, but there'll be no movement in the focuser itself?

Edited by Charic

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1 minute ago, rwilkey said:

Looks like Charic is right, you don't need both adaptors, this is a common mistake with new SW Newtonians, just use the 1.25" one.

 

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In addition to @Charic's post, it looks like the 1.25" adaptor (the one on the right hand end of the image) is partially unscrewed. You don't unscrew this part. The thumbscrew in the 2" adaptor should be loosened and then the whole 1.25" adaptor can be removed. 

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2 minutes ago, Jov said:

Hahaha alrighty, ill give it a go tonight when i get home...ill put a pic up of it...and hopefully ive failed a million times hahah

If you don't know, you wont know, plus you wont be the first to fall for this trap!

Lets hope it is just the simple task of removing one adaptor.

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2 minutes ago, Jov said:

Quick question to that though?? Wouldnt that increase my magnification, ultimately bring it close and reduced focal length of the eyepice...enhancing more

No, that isn't how focal length works. The telescope mirror has a fixed focal length and the eyepiece has a fixed focal length. All the focuser does is move back and forth so that you can position the focal planes of both components at the same place and get an image. Adding or removing accessories does not change the focal length. 

  • Like 1

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Okay, thanks for informing me on that...that would make sense...whats the additonal adaptor for?? If one needs to be removed like some of the guys have stated...what would it be used for in that case? Is that when your using longer eye pieces??

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