Help required for newbie.

[kyrol]

I have a Skywatcher 102 refractor telescope, if I look at any planets, the moon or stars I have to have the focus tube fully wound in & even then objects can be slightly blurry, any adjustment using the focus knobs to move the focus tube out & objects are completely out of focus. I am wondering if this scope is only good for deep space viewing or am I doing something wrong ?

Thanks in advance for any replies.

[oscar_camilleri]

Hi Krol

What eyepiece are you using when observing ? 

 

[kyrol]

I`ve tried it with a variety, from a 12mm up to a 32mm, with the 32 the moon is just about in focus with the focus tube wound fully in.

[wulfrun]

You should be able to get both sides of correct focus easily, so something's amiss. Post a picture of the focuser end of the scope, I'm not familiar with the scope but others will be and they should be able to diagnose the problem.

Do you wear glasses and if so, are you long or short sighted? Are there any extension pieces in the focuser? Within reason, eyesight should not affect your ability to achieve focus but extension pieces would. The difference between the Moon and other celestial objects is negligible (they are all near enough at "infinity", optically speaking), so that shouldn't influence anything.

[fifeskies]

Are you using a diagonal with the Skywatcher 102 ?

Depending on the exact model it may only give the correct focus range with the smaller 1 1/4 diagonal, but may still allow a 2 in diagonal to be fitted to it.

The longer focal path of the 2 in diagonal may then use up so much distance the focus adjustment can no longer move the eyepiece in far enough.

 

If you can post a photo (as a jpeg) this would allow others to give better advice.

 

Edited July 21, 2021 by fifeskies

[kyrol]

Image 1 is the only position I can have where I can see anything.

[fifeskies]

The adapter from the 2inch focuser to the 1 1/4 inch (for the diagonal) is a shouldered one with a fairly long length.

A "drop in" style reducer will give you extra in-travel distance for the eyepiece, looks like you would gain about 30mm travel.

Strange that it does not achieve focus if this is the supplied adapter however.

The longer "shouldered" adapter would probably be needed if using eyepieces without using the diagonal.

Did the telescope perhaps get supplied with 2 adapters (long and short) to give you the option of using it without the diagonal (ie for terrestrial viewing)

 

the short style adapter looks like this, and drops inside the 2in barrel.

 

[carastro]

Looks like there is an extra extension piece on the end of the diagonal.  Can you remove that, it should help with focus.

Carole 

[fifeskies]

Looking again, the diagonal seems to have a 2 inch end and a 1 1/4 inch end.

(Hard to be sure if that's the case as it might just be the angle the photo is taken at)

 

If is is 2 in one end , I think you need to reverse the diagonal and put the 2in end directly into the focuser.

Then you use the eyepiece in the end with the little screwlock.

This should then work fine.

 

The shouldered adapter is I think just for straight through viewing when used horizontal as a terrestrial scope when the diagonal is not used.

 

 

Edited July 21, 2021 by fifeskies

[fifeskies]

as Carole says, it may just be that you have an extra extension piece on the diagonal and that the 2 to 1 1/4 adapter is actually a short one , not shouldered as I was suggesting.

Only looks shouldered as an extension piece is in the adapter first before the diagonal is added.

 

[ollypenrice]

This looks very odd. Firstly that's not a star diagonal, it's an erecting prism. Note the 45 degree angle.

And then I can't work out which bits are which. Could we have a photo of all the components separated and placed on a table? I don't think the rear assembly is correct at all. For one thing, how do you put an eyepiece in that? It looks as if the eyepiece end of the prism might be attached to the scope. Just pull it all apart and take a photo first.

Olly

 

 

[kyrol]

Here it is seperated as far as it can be, I did try last night without the diagonal & it made no difference.

Thanks all.

[fifeskies]

well spotted Olly, I think that is indeed a 45 degree prism

 

Kyrol, the piece at the right hand side looks like it does have a 1 1/4 adapter that should be removable but that is needed for the 1 1/4 eyepieces

 

The LHS piece is the one that looks a bit unusual to me , tho I have never used this scope, as I mentioned before replacing this with the low profile style drop in adapter for the 2in focuser to 1 1/4 diagonal may work , but you should have got a working kit as supplied.

ie another like the one at the RHS eyepiece end to connect the silver tube part directly into your telescope.

 

It might make sense if the LHS piece unscrewed into 2 parts but if it doesn't then it's a bit of a mystery to me.

 

[ollypenrice]

OK, that's good.

If you can't get the eyepiece in far enough to reach focus then the distance indicated is too long. The problem item is called a two inch to inch and a quarter adapter and this is a very odd one, the like of which I have never seen before. The narrower part of the body is very long and has an inexplicable bulge in it before the chromed lock screw. Like Fifeskies above, I suspect it may be in two parts. Does the bit to the right of the bulge (the bit underneath the world 'long' in my image) not separate from the rest? Fifeskies posted a picture of a conventional 2 inch to 1.25 adapter and you can see how much shorter it is

Can we just check that the eyepiece is going in as indicated and that you are pushing it right down into the item on the right.

I would contact your supplier and link them to this thread.

Olly

Edited July 21, 2021 by ollypenrice

[Alan64]

You want something like this, rather...

That long adaptor looks like what's provided with the Sky-Watcher Newtonian-Dobsons, and another animal entirely.

That diagonal is an Amici, and for daytime/terrestrial use; birds in trees, ships at sea, that sort of thing.  At night, a star-diagonal is suggested, and in this case a star-mirror.

You can get a 2" star-mirror, or this 1.25"... https://www.rothervalleyoptics.co.uk/antares-90-star-diagonal-125.html

Edited July 21, 2021 by Alan64

[fifeskies]

I found this image of an older 102 , this does seem to show the extended adapter as being the correct one for this scope unless they changed the design when they went to the new black and white style.

This wont help any I know , but it may point to the problem being elsewhere in the scope, but I personally cant see how a focus issue can be anything other than something to do with the back-focus distance.

 

Kyrol,      with the eyepiece just direct into this adapter , nothing else in the system , can you get to focus by racking the focuser a long way out.

If you can , then measure how much of the silver tube is showing, this will tell us how much light path is available to be used by a diagonal or prism.

Ideally it should be around 110mm as a 2 inch star diagonal will need 100mm (a prism needs about 85mm) , the extra being needed to let you move through both sides of focus.

 

Edited July 21, 2021 by fifeskies

[kyrol]

Thanks, I`ll give that a go tonight & let you know the outcome.

[Cosmic Geoff]

Very odd. First of all, '102' does not define the scope as there are long and short versions.  I have the 102mm f5 'Startravel'.   It came with a 45 degree diagonal, which proved not fit for astro use. However it came into focus just fine.   I  substituted a 90 deg 1.25" star diagonal - a stock skywatcher/Celestron type, and it focuses just fine with the eyepieces with around an inch of focus travel available either way.  My 2"/1.25 adapter is not the same as the one in the photos and is rather short - about 1.5cm of it is visible when assembled.

As the others say, it looks like you have got too much length between the focuser and eyepiece.  And stop using the 45 deg diagonal and buy a 90 deg mirror diagonal right now - even a cheap one will work better for high powered astro views than the 45 deg erecting prism.

[kyrol]

Thanks all, I have ordered a 90degree diagonal & a stubby 2" to 1.25" adaptor, hopefully that`ll get me going.

[Kimboman]

The image of the telescopes looks very similar to my Celestron 102 GT .this scope works fine with both types of diagonal .

The reducer is tapered and it is removed to take the 2 inch eyepiece

 

 

[Cosmic Geoff]

11 hours ago, Kimboman said:

The image of the telescopes looks very similar to my Celestron 102 GT .this scope works fine with both types of diagonal .

The reducer is tapered and it is removed to take the 2 inch eyepiece

I have the same reducer as Kimboman.