Skywatcher classic 200p 8inch dob won't focus

[bottletopbill85]

no idea what I'm doing wrong. can't get a clear view of anything (on earth or not). I've tried both eyepieces and they just won't focus, not even a little bit. photo attached w/ how I attached both eyepieces

[John]

Looks OK to me.

The scope won't focus on anything close to you. At least 100 metres away or more is the closest I seem to recall.

I assume that you have used the focus wheels to move the eyepiece and the focuser tube further out than that picture shows ?

The full range of movement of the focuser tube is around 50-70mm I think.

 

[vlaiv]

Yep, if focuser does not move - loosen screw underneath it - it could be focuser lock screw.

I don't remember having one on my 8" Dob, but it looks like focuser lock screw - and if it is tightened - focuser won't move when you rotate knobs.

[John]

This is the screw that vlaiv is referring to:

[joe aguiar]

Just wondering if that adptor under the ep needs to be removed 

Joejaguar 

[cletrac1922]

44 minutes ago, vlaiv said:

Yep, if focuser does not move - loosen screw underneath it - it could be focuser lock screw.

I don't remember having one on my 8" Dob, but it looks like focuser lock screw - and if it is tightened - focuser won't move when you rotate knobs.

 

I have had my 10" Dob for over 10 years, and has locking screw underneath as well

Just leave halfway out so do not lose it, never use it

Which eyepieces you have

Try starting with supplied 25mm

I am out a couple of times per month also with club doing presentation primary school, scout groups, and find 17mm wide angle ideal for viewing planets and other DSO's

For moon, definitely the supplied 25mm as fits moon in completely been closer to us

John 

[cletrac1922]

3 minutes ago, joe aguiar said:

Just wondering if that adptor under the ep needs to be removed 

Joejaguar 

 

Joe

Good pick up

I did not see that

Agree with you

John

[johninderby]

That’s the 1.25” eyepiece adapter. It’s supposed to be there. Pic from manual.

[bottletopbill85]

forgot to mention, it does move, but at no point does it focus. which is why I am so fonfused

 

 

[John]

As per the above illustration. Thats why I said that it looks OK - because it did !

The travel of the focuser drawtube (the tube that the eyepiece goes into) is around 50mm - 70mm. Try it around half way out on the Moon and it should be not too far out. It will need finer adjustment to get the moon sharp. Use the 25mm eyepiece while you find out how things work.

 

 

[bottletopbill85]

I have tried focussing on the moon, but like I said it doesn't focus at any point and is either extremely blurry or looks like it's not there at all

[John]

Was the scope purchased new ?

[johninderby]

Sounds badly oit of collimation if the focuser is moving that is. .🤔

Also with that focuser ypu have to buy an optional adapter to use 2” eyepieces. 

Edited December 18, 2019 by johninderby

[bottletopbill85]

yes (in response to 'was the scope purchased new?)

Edited December 18, 2019 by bottletopbill85

[John]

Well if there is anything wrong at least you will get a replacement.

These scopes work really well normally. I've owned one and many other folks on this forum own or have owned one as well.

Perhaps some pics looking down the scope tube from the top end, down the focusser tube with no eyepiece in it and of the bottom end of the scope where the primary mirror is would help diagnose what is amiss ?

[bottletopbill85]

hope this is what you were asking for

[Rob Sellent]

Just thinking outloud. But it might be worth placing the eyepiece's barrel a little way out of the focuser (cm by cm) and see if it comes to or near to focus. If so, it might be a 'problem' with the primary mirror's placement. If it is possible, raising the primary mirror just a small amount towards the secondary (mm by mm) might help.

P.S: If that sounds a but mad, it might be an idea to hunt down a local astro-club and get some of the regulars to check over your system. For sure, it will be purely a mechanical problem which shouldn't take too long to fix.

P.P.S: Looking at the photo, also make sure your secondary is at 90 degrees to your focuser and centered. If I'm reading the photo correctly it looks a tad skewed.

Edited December 18, 2019 by Rob Sellent

[joe aguiar]

Ok then isn't there a 2inch adptor that also comes with that model then the 1.25 inch adptor? I'm pretty sure it has 2 adaptors 

Maybe it will focus that way doesnt hurt to try

Joejaguar 

Edited December 18, 2019 by joe aguiar

[johninderby]

Worth a read.

https://neilenglish.net/test-diving-the-sywatcher-skyliner200p/

[John]

3 minutes ago, joe aguiar said:

Ok then isn't there a 2inch adptor that also comes with that model then the 1.25 inch adptor? 

Maybe it will focus that way doesnt hurt to try

Joejaguar 

If you use the 2 adapters together these scopes definitely wont come to focus. It's a common mistake that is made by new owners because, in the past at least, the manual was not clear that the adapters should not be used together.

The photos look OK to me but the focuser is still in its innermost position and sticking into the light path. Am I right in assuming that you have tried moving the focuser along its full range and it still will not come to any sort of sharp focus on the moon even when using the 25mm eyepiece ?

[johninderby]

According to the manual only the 1.25” adapter is included with the scope. Also the adapters are bigger than 2” at the bottom so not possible to fit the 1.25” adapter into the 2” one.

Why didn’t Skywatcher make the focuser drawtube openning 2 inches who knows?

Edited December 18, 2019 by johninderby

[joe aguiar]

Ok just trying to figure out different options 

Joejaguar 

[Ships and Stars]

I have (or had) a lot of different eyepieces that had different focal lengths. Some needed an extension tube, some didn't want anything, some would only work with a coma corrector because it provided a very narrow range (1.15x) not duplicated by my other extensions. If it doesn't seem to focus, the quick and dirty method I use to determine a rough idea of focal length is to just take out all the adaptors etc until you have a bare focusser tube and hold the eyepiece up to your eye and move your head in and out towards the focusser until you get a hint of pointy stars (my highly technical term). I'm assuming all caps and covers are off, and you are looking at the brighter stars like Capella, not a lorry parked over the road. Even if it's not properly collimated, you should get a decent idea of how far in or out the eyepiece needs to be.

Edited December 18, 2019 by Ships and Stars

[bingevader]

Where are you Bottletopbill85?

Are you able to get along to a local astro club for someone to have a look?

If it was purchased from a shop then take it back for them to have a look at.

As has already been mentioned, the 1.25" adaptor needs to be in place and the locking screw under the focuser released.

Then the draw tube should move freely in and out.

Try it out in the daytime on distant objects, you should get it in focus and this allows you to align the finderscope too!

[Louis D]

Alright, back to basics then.  Remove the eyepiece, point it at the moon, and look in the focuser hole from a distance of about a foot.  You should be able to see an aerial image of the moon in there.  Now, take a piece of white printer or notebook paper and move it outward from the focuser (which should be racked all the way in/down) until a sharp image of the moon is formed on it.  That distance is roughly where the shoulder of your eyepiece needs to be to reach focus at infinity.  If it's above the maximum outward position of the focuser, you'll need an extension tube or possibly both adapters stacked together.  If it just keeps getting more and more defocused as you move the paper outward, the telescope is reaching focus below it's most inward position.  That would mean your primary mirror needs moved upward in the scope's tube.  However, this shouldn't be the case for a new scope, and it should be returned for replacement for a properly spaced primary/focuser combination.