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Altaf

Very blurry primary mirror on Skywatcher skyliner dobsonian 200p

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Hello, 

 

Am very new to this so apologies right from the start. I have recently just bought a skywatcher akyliner dobsonian 200p and i set it up. However the image is very blurry even when i remove all magnification and just look into the primary mirror eveything looks very blurry including the moon or nearby trees etc. I am unsure what the issue could be as i am eager to get started on my stargazing! 

Could someone please assist me or at the very least point me in the right direction. 

 

Kind regards

 

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What does the primary mirror look like when you look straight down the front of the tube?. Can you see your face reflected in it? If the telescope is new the problem will most likely that the telescope is not focused, you may have the adaptors for the eyepiece incorrectly assembled, this is a common problem.  :icon_biggrin:

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If it looks blurry just looking through the eyepiece holder into the tube (without an eyepiece fitted of course), it could be that the secondary mirror and/or the primary mirror are just misted over. If not, the problem is most likely what Peter suggests.

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The 200P's come with a focuser for 1.25" eyepieces and 2" eyepieces. In the focuser there are 2 adaptors and for shipping the 1.25" one is fitted inside the 2" one. This means the 1.25" oe is at the wrong position. You may therefore need to remove any eyepiece, then look to remove the adaptor that the 1.25" eyepiece would slide into, then look again and you should find a second adaptor but for 2" eyepieces, remove this, then put just the 1.25" adaptor back in. Put the 2" one somewhere dafe where you cannot lose or forget it.

For a scope "near" is sort of The Moon, so a nearby tree is way too close, by several thousand miles.

The problem with the adaptors if that is the cause is almost normal, at a guess 30% of people do it. It would help if Skywatcher made a specific section in the manual and even better if they were 2 different colours, as in: Remove the Blue EP adaptor, remove the Red EP adaptor, put the Blue EP adaptor back in on it's own.

Try the above and if it solves it then great otherwise ask again with any further information.

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If it all still seems puzzling plenty of us beginners and otherwise all have your telescope, so a fair idea might be to post some pictures of the bits you have and how you have it all joined together and folks should be able to tell you what goes where.  NB.  There is also a larger than you might think amount of travel on the focusser knobs and sometimes it take cranking them a good long way before things change.  Additionally there is a tensioner screw on the focuser which is very easy to tweak by accident and if it is too tight no amount of twiddling of the correct knobs will get the focus unit to go in and out.  So if the focus tube isn't travelling up and down give the extra screw a tweak in either direction and see if things change.

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Hello and thank you all so much for your help. I have played around with the focuser and it was moving in and out and i completely removed the adapters and looked down the scope and the image was still very blurry. I have looked down the scope and looked into the primary mirror didnt look misty but any idea of how i could demist it? Also would i need a collimator for focussing the telescope and if so what one would be best suited?

 

Apologies for the extremely amatuer questions.

 

Kind regards

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If you look down the big opening can you see your face reflected? If you can the mirror is fine your problems lie elsewhere.

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This is what the end of your focuser should look like. If it has an extra part you need to remove it. Once the focuser is correct you will be able to focus on astronomical targets without issue. 

4HD8B1_2_720x600.jpg

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Also the telescope focus range is designed for objects very far away like the Moon, you'll never focus on close range objects.

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10 hours ago, happy-kat said:

you'll never focus on close range objects

Well...........that depends on what you means by close.  With my 200P (with an eyepiece in)  I can focus on trees that are 300-400 yards away - of course I have to change the focus when I look into the sky, but its quite possible to focus on a tree in the next field (albeit its upside-down).  It may even be possible to focus closer than that - I've just not tried.  I can also see my face reflected clearly if I peep into the top end of mine.  After all its only a mirror, albeit curved.

Altaf - is the telescope new or could it have been stored somewhere?  You say mirror doesn't look misty, but I wonder if it has been somewhere and deteriorated in some other way. 

For collimation you want a £25 Cheshire collimator and Astrobaby's collimation guide (Google it - or I am say someone will find the find and post it - someone on SGL does have a decent PDF, but I always forget who it is) - that's the combination I won with in the finish the first time I tried it.

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It's Moonshane PDF collimation guide that is good too.

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