Not seeing anything in my eyepiece help!

[silkels]

Hello! I own an 8 inch Skywatcher dobsonian telescope. everything about the telescope has been great so far except the fact that I cant see through the eyepiece. I believe a 25mm and a 10mm came with the telescope and I cant use either. the finderscope works perfectly and has a great image. i have tried countless times aligning the finderscope just incase it is very exact, but i havent gotten anything through the eyepiece. I thought it was the mirrors not aligned and even got a collimation lens to make sure. playing with the focuser does not change anything either. Here is what im seeing through the eyepiece. The second image is my hand over the top of the telescope tube

[Mr Spock]

It's out of focus. Have you got the right attachments fitted to the focuser?

[silkels]

what would need to be fitted to the focuser? it came with the barlow lens and then the eyepieces. i thought that was all i needed 😂

[Steve Ward]

Check the focuser locking screw under the focuser tube. 

If locked the tube will not move in and out but the wheels will still rotate giving the impression that it's working.

[PeterStudz]

To reach focus on the Skywatcher 200p Dob you need an extension tube between the focuser and eyepiece. Are you using one? You should have got this with the telescope. 

[Moon-Monkey]

Take the eyepiece extension out (looks like a black tube in the focuser then try that 🙂

[RT65CB-SWL]

Hi @silkels and welcome to SGL.

As per @Steve Ward says, check the locking screw or screws under the focuser, assuming it is a ‘crayford’. There are usually two. Some are grub screws, some are thumbscrews or maybe one of each. I have attached this guide... Adjusting the Skywatcher Focuser.pdf

Below is an image of my ‘crayford’ focuser and its 1.25” adaptor [shown on right] that I use with my C6/SCT or ‘re-modded’ ETX105. As you can see, mine has two thumbscrews.

Edited October 9, 2022 by Philip R

[Knighty2112]

If you move the focus wheels does the Eyepiece you are using moving outwards or inwards in the focuser? If so and you still can’t reach focus when it is Fully wound outwards you need an extension tube fitted in the focuser first, then the EP fitted. That should allow focus to be reached.

If the focuser does not move at all when you turn the focus wheels then the knob highlighted in the picture is either set too tight, or possibly too slack. In which case alter this until you can move the focuser when turning the wheels. If this is a Crayford focuser you need to set this knob on the focuser to the right tension so that that focuser tube moves only when you adjust the focus wheels on the focuser. If too tight it won’t move. If too slack you can probably pull the focuser tube outwards by hand.

 

 

Edited October 9, 2022 by Knighty2112

[Knighty2112]

Just now, Knighty2112 said:

If you move the focus wheels does the Eyepiece you are using moving outwards or inwards in the focuser? If so and you still can’t reach focus when it is Fully wound outwards you need an extension tube fitted in the focuser first, then the EP fitted. That should allow focus to be reached.

If the focuser does not move at all when you turn the focus wheels then the knob highlighted in the picture is either set too tight, or possibly to slack. In which case alter this until you can move the focuser when turning the wheels. If this is a Crayford focuser you need to set this knob on the focuser to the right tension so that that focuser tube moves only when you adjust the focus wheels on the focuser. If too tight it won’t move. If too slack you can probably pull the focuser tube outwards by hand.

Just now, Knighty2112 said:

 

 

 

[silkels]

10 hours ago, PeterStudz said:

To reach focus on the Skywatcher 200p Dob you need an extension tube between the focuser and eyepiece. Are you using one? You should have got this with the telescope. 

I dont believe so, its the first ive heard of such a thing. the only thing that i received with the telescope is the barlow lens, eyepiece and actual focuser. 

[silkels]

10 hours ago, Philip R said:

Hi @silkels and welcome to SGL.

As per @Steve Ward says, check the locking screw or screws under the focuser, assuming it is a ‘crayford’. There are usually two. Some are grub screws, some are thumbscrews or maybe one of each. I have attached this guide... Adjusting the Skywatcher Focuser.pdf

Below is an image of my ‘crayford’ focuser and its 1.25” adaptor [shown on right] that I use with my C6/SCT or ‘re-modded’ ETX105. As you can see, mine has two thumbscrews.

yes, i checked if the focus was locked and it was not the issue. what extension would you recommend for the telescope I have?

[Cosmic Geoff]

3 hours ago, silkels said:

yes, i checked if the focus was locked and it was not the issue. what extension would you recommend for the telescope I have?

If it's a new scope, check the packaging.

If it's used, ask the seller what he did with the extension tube.

[silkels]

2 hours ago, Cosmic Geoff said:

If it's a new scope, check the packaging.

If it's used, ask the seller what he did with the extension tube.

gotcha. i got it in june so i dont have the box anymore but i made sure there wasnt anymore parts in there. am i missing something?

[Ricochet]

The two parts shown in your first photo are the extension tubes, or eyepiece adapters as described in the manual. One is for when you use 1.25" eyepieces and one is for when you use 2". You only ever use one at a time. In your photo you have both stacked into your focuser, which is why you can't focus. 

[Mr Spock]

When I owned a 250mm Flextube I only used one of those at a time.

[JOC]

2 hours ago, Mr Spock said:

When I owned a 250mm Flextube I only used one of those at a time.

Me too, one takes 2" EP's and one takes 1.25" ones.  I suspect the OP just needs the smaller one directly in the focuser (the one on the right hand side in their picture) and then a 1.25" EP on top.  Since we have determined that the locking nut is not the issue, i.e. when the focus knobs are turned the focussing turret goes up and down then I think more enthusiastic turning of the focus knobs might be needed.  I would suggest that the OP sets up the telescope during the daytime (please point it away from the sun though) and then find a distant tree or aerial to experiment with - it will be upside down and back to front in the EP, but this doesn't matter)  Watching the image through a 1.25 EP fitted into the JUST the 1.25" turret mounted into the focuser drive the focus wheels from one end of travel to the other when I would be very surprised if you can't achieve a perfectly focussed image at some point - if you can't then come back and tell us.  The only possible hiccup being if the OP actually has a flex tube Skywatcher like the one in your photo @Mr Spock (or like the one I own) where the OP might not have realised that there are two clicks needed to unlock the flex tubes to the longest extent and that both clicks are needed - focus won't be achieved unless the tube is drawn out to double click position and locked in place with the small twisty locking nuts.

 

 

[silkels]

3 hours ago, JOC said:

Me too, one takes 2" EP's and one takes 1.25" ones.  I suspect the OP just needs the smaller one directly in the focuser (the one on the right hand side in their picture) and then a 1.25" EP on top.  Since we have determined that the locking nut is not the issue, i.e. when the focus knobs are turned the focussing turret goes up and down then I think more enthusiastic turning of the focus knobs might be needed.  I would suggest that the OP sets up the telescope during the daytime (please point it away from the sun though) and then find a distant tree or aerial to experiment with - it will be upside down and back to front in the EP, but this doesn't matter)  Watching the image through a 1.25 EP fitted into the JUST the 1.25" turret mounted into the focuser drive the focus wheels from one end of travel to the other when I would be very surprised if you can't achieve a perfectly focussed image at some point - if you can't then come back and tell us.  The only possible hiccup being if the OP actually has a flex tube Skywatcher like the one in your photo @Mr Spock (or like the one I own) where the OP might not have realised that there are two clicks needed to unlock the flex tubes to the longest extent and that both clicks are needed - focus won't be achieved unless the tube is drawn out to double click position and locked in place with the small twisty locking nuts.

 

 

okay thank you so much, i will try these suggestions when i get home. another small problem though, i may have messed with the mirrors a bit. i saw using the laser that it wasnt exactly in the middle of the circle on the back mirror. i just don't understand how to adjust either mirror. the screws don't seem to move the mirror and change anything, i have no idea if im doing it right or not. 

[JOC]

17 minutes ago, silkels said:

the screws don't seem to move the mirror and change anything, i have no idea if im doing it right or not. 

You need this guide https://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/ which is the SGL favourite resource.  You will note that perfectly collimated 200P (at the end of the article) still looks slightly off centre.  However, I think even with the mirrors not ideal you should get something visible better than your pictures, unless of course the secondary has taken a bit of a bash.  If you follow Astrobaby's guide to the letter (even including the odd sounding instructions about bits of paper etc. ) you will end up with a collimated scope (I did and there was no-one more worried about shifting stuff than me - give yourself plenty of time, if you know what you are doing it can be done in minutes - it took me over an hour the first time).  What I did find was that you have to allow for the final tweaks of the nuts to finally position the mirrors and allow for that movement before you tighten them.  However, although mine was a bit out, they have to be really out to get an image truly un-useable IMO.  FWIW (even given that you've clearly had a fiddle) I doubt collimation is the issue unless your secondary is at an odd angle (the one below the EP).  The guide is done with a 200P so is directly applicable to your own scope.

17 minutes ago, silkels said:

i saw using the laser

What you need to know is that the lasers themselves can be off-centre and need collimation themselves and there are methods of introducing them into the focusser that make them more central than others.  I bought and experimented with a laser - decided that the output was proverbially bad, bought a cheap Cheshire collimator (which Astrobaby uses) and never looked back, but even those need placing centrally between the focussing nuts to be err.... central!

Edited October 10, 2022 by JOC

[Dark Vader]

It sounds like you've put both adapters in. The supplied eyepieces are 1.25" so take out the 2" one. Your focusser should look like this...

[silkels]

Hello everyone again, so sorry for not updating as I had lost the motivation to try and get the telescope working. since this post i have tried astrobaby’s guide twice and nothing has changed. okay while i was taking photos of the finderscope vs the eyepiece my phone camera was able to see the picture clearly. is this because of the mirror or my phones just better than my eyes?

[StarDuke82]

Well the mirror has to have a clear image in order for the camera to be able to focus properly on it that’s just how cameras work, now phones do have adaptive focusing that focus an image but that applies more to taking photos where something is either in the background or foreground and the camera is trying to focus on one or the other, so I would say that your scope is in focus and you may need some glasses or if you wear glasses wear them while using your telescope, I wear mine when using my scope and it doesn’t hinder it’s use though you do have to look for eyepieces that accommodate people that wear glasses as they offer better viewing and eye relief for people that wear them. 

[michael8554]

I'd guess that those tree branches are too close.

Try a really distant landmark.

25mm eyepiece and no Barlow.

You might get an image by sliding the eyepiece in the holder.

Michael

[JOC]

On 10/10/2022 at 00:35, silkels said:

gotcha. i got it in june so i dont have the box anymore but i made sure there wasnt anymore parts in there. am i missing something?

One thing I have spotted is that in the photo with the comment I've copied here (October 2022) the picture shows the blanking plate still in the back part of the telescope.  Clearly this needs removing before it will work.  Though the pictures of the trees would not have been possible if it had not been removed in the photos just above. 

The other thing that hasn't been noted in the above thread is that it can take a little experimentation to look through some eye pieces.  Sometimes your eye needs to be right on top of them and sometimes you can hover a cm or two away from them.  You also need to be looking directly down the EP's and make sure that all the covers have been removed from each end of them (when I first started I did occasionally forget to remove covers etc.) 

Another thing is if the enquirer is using a Flex tube that there are TWO stops that the tube needs to be extended by.  You pull it forwards once and it goes click.  You then need to pull the tube up again and a second click will be found.  That is the position it needs to be used in NOT the first click only.  Pull it up both clicks and then tighten the locking screws.  If you don't have the tube fully extended it won't be the right length and I think this could explain all the problems above.

Edited May 10, 2023 by JOC

[JOC]

Also, it is possible that the earlier problems could have been caused by mirrors and EPs covered with dew/condensation.  Condensation wipes out everything really quickly and sometimes you don't spot it.  The OP realy should experiment during the daytime with the scope pointed at a distant object a mile or so away away from the sun on the ground.  If the above trees could be seen through the EP then I suspect the scope is functional.