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# Help needed with eyepiece.

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Posted (edited)

Hi all.

I have setup me evolution 9.25.

The mount legs are out as far as possible. And it is perfectly flat when the telescope is mounted.

Because of the height I had to turn the diagonal 45 degrees to the right so I can see in to it.

I followed the instructions and put the 40mm eyepiece in.

All I can see is a perfect circle with a black hole in the middle!

I was trying to align the scope to the top of a tree. The round circle was so small I could not see a thing.

So I took out the 40mm and just used the diagonal. I could then see the tree top and lined it up.

I put back the 40mm and I see just a very small round disc in the middle of the eyepiece still with a black hole in the centre.

I had 6 friends come round and all asked why the white disc was so small? and why is there a black round space in the middle.?

What am I doing wrong>

Thank you for your time.

EDIT= When I see a roof of a house, its at and angle. Is that because I have the diagonal at a angle?

Edited by tezz
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Posted (edited)

It seems that the view through the eyepiece is out of focus.  As a novice, and with the telescope out of focus, it may take some time to figure out which way to wind the focus knob to get it in focus.  Note also that if you point the telescope at a bright point source (e.g. Venus) and it is out of focus, you will see a bright donut with a black hole in the middle (the shadow of the secondary mirror). In this case finding focus is a no-brainer - just wind the focus in the direction that makes  the donut smaller.

24 minutes ago, tezz said:

EDIT= When I see a roof of a house, its at and angle. Is that because I have the diagonal at a angle?

Yes. the view will also be reversed L-R.

If the 40mm eyepiece is a 1.25" fit, the field of view circle is going to be quite small anyway.

Edited by Cosmic Geoff
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Posted (edited)
8 minutes ago, Cosmic Geoff said:

It seems that the view through the eyepiece is out of focus.  As a novice, and with the telescope out of focus, it may take some time to figure out which way to wind the focus knob to get it in focus.  Note also that if you point the telescope at a bright point source (e.g. Venus) and it is out of focus, you will see a bright donut with a black hole in the middle (the shadow of the secondary mirror). In this case finding focus is a no-brainer - just wind the focus in the direction that makes  the donut smaller.

Yes. the view will also be reversed L-R.

If the 40mm eyepiece is a 1.25" fit, the field of view circle is going to be quite small anyway.

Thank you for your answer.

The image I see is very small. And yes it's the 1.25 thatcame with the scope.

If I do as you say, will the image become bigger?

What eyepiece should I buy to see a bigger image?

Thanks again.

Edited by tezz
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16 minutes ago, tezz said:

Thank you for your answer.

The image I see is very small. And yes it's the 1.25 thatcame with the scope.

If I do as you say, will the image become bigger?

What eyepiece should I buy to see a bigger image?

Thanks again.

The image should become a lot bigger! If the tree is very close you might not be able to get it into focus - try and pick something at least 100m away, and preferably a lot further - when testing my telescope I use a water tower around 3 miles away.

On a SCT it can take a lot of turns of the focus knob to travel the full length of the focus range so don't give up if nothing immediately changes - it can feel a like a really long time when using the focus motor!

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11 minutes ago, Shimrod said:

The image should become a lot bigger! If the tree is very close you might not be able to get it into focus - try and pick something at least 100m away, and preferably a lot further - when testing my telescope I use a water tower around 3 miles away.

On a SCT it can take a lot of turns of the focus knob to travel the full length of the focus range so don't give up if nothing immediately changes - it can feel a like a really long time when using the focus motor!

Could you advise on a eyepiece to make the image bigger?

Thank you very much.

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Hi @tezz Maksutov’s and SCT’s do require a lot of turning of the focus knob, either clockwise or anti-clockwise. Think of the focus shaft as a length of threaded rod.

To get a higher magnification you will need eyepieces with lower numbers. Also the higher the magnification then you may have to place your pupil directly over the centre of the eyepiece, otherwise you may end up with a ‘blackout‘ when looking thought it if not centred. Also what is budget for individual eyepieces? Some wide-angle eyepieces may/will induce vignetting.

Have you got a 90 degree star diagonal? 45 degree diagonals are normally used when viewing nature/terrestrial objects.

Another tip… I don’t fully extend my tripod legs… vibrations will take longer eliminate/calm down if they are fully extended.

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Posted (edited)
1 hour ago, tezz said:

EDIT= When I see a roof of a house, its at and angle. Is that because I have the diagonal at a angle?

Yes! the image will be right way up and left & right reversed.

Edited by Philip R
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Posted (edited)
21 minutes ago, Philip R said:

Hi @tezz Maksutov’s and SCT’s do require a lot of turning of the focus knob, either clockwise or anti-clockwise. Think of the focus shaft as a length of threaded rod.

To get a higher magnification you will need eyepieces with lower numbers. Also the higher the magnification then you may have to place your pupil directly over the centre of the eyepiece, otherwise you may end up with a ‘blackout‘ when looking thought it if not centred. Also what is budget for individual eyepieces? Some wide-angle eyepieces may/will induce vignetting.

Have you got a 90 degree star diagonal? 45 degree diagonals are normally used when viewing nature/terrestrial objects.

Another tip… I don’t fully extend my tripod legs… vibrations will take longer eliminate/calm down if they are fully extended.

It's the 90 degree that came with the scope.

I do have a 2X barlow that I haven't tried as yet.

There is no vibration as I have celestron anti vibration cups and the floor under the mount has soft rubber squares.

I was just surprised at the minute image I got in the centre of the eyepiece .

I do have a ZWO camera and a focus motor to fit.

But I will get used to using it first this way, and learn a bit more.

Maybe one day they will have auto focus like my 150-800 zoom lens has.

Edited by tezz
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Posted (edited)

Was there a reason you needed to set the mount so high that you had to put the diagonal in sideways rather than the normal way of straight up? I have a Nexstar SE goto mount whichis similar to your mount, and never set it up at maximum height as this impedes viewing through the EP when viewing things low down in the sky,  unless of course you are a 6’ 10” high basket ball player! 😆

Edited by Knighty2112
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16 minutes ago, tezz said:

Could you advise on a eyepiece to make the image bigger?

Thank you very much.

There are two ways in which you can make the image 'bigger'. One is to see a wider field of view (so you see more of the tree) and the other is to increase the magnification. You can of course combine both of these at the same time. To increase  the field of view you are looking for eyepieces with a higher field of view, measured in degrees - the Celestron 40mm eyepiece is probably around 45-50 degrees. You might want to consider 68/70 degree eyepieces or 82 degree eyepieces. To gain increased magnification you want an eyepiece with a lower mm measurement - there is a trade-off though at which the magnification is too high and you don't gain anything in image quality.

You might want to start off with a cheaper set of eyepieces while you work out what sort of objects you prefer looking at - the Svbony 68 degree range are well regarded at the budget end and a full set is £144 on amazon. Alternatively the BST starguider range from FLO would also be a good choice.

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1 minute ago, Knighty2112 said:

Was there a reason you needed to set the mount so high that you had to put the diagonal in sideways rather than the normal way of straight up? I have a Nexstar SE goto mount whichis similar to your mount, and never set it up at maximum height as this impedes viewing through the EP when viewing things low down in the sky,  unless of course you are a 6’ 10” high basket ball player! 😆

Tezz is a wheelchair user and also has his mount in roll off observatory - I suspect it is a combination of those factors that causes the issue with the eyepiece.

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3 minutes ago, Knighty2112 said:

Was there a reason you needed to set the mount so high that you had to put the diagonal in sideways rather than the normal way of straight up? I have a Nexstar SE goto mount whichis similar to your mount, and never set it up at maximum height as this impedes viewing through the EP when viewing things low down in the sky,  unless of course you are a 6’ 10” high basket ball player! 😆

I have it high because it housed in my specially made shed.

I am disabled in a chair. So it's a bit hard

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Just now, tezz said:

I have it high because it housed in my specially made shed.

I am disabled in a chair. So it's a bit hard

OK. Hope you get some great views with it. 👍🏻

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10 minutes ago, Shimrod said:

There are two ways in which you can make the image 'bigger'. One is to see a wider field of view (so you see more of the tree) and the other is to increase the magnification. You can of course combine both of these at the same time. To increase  the field of view you are looking for eyepieces with a higher field of view, measured in degrees - the Celestron 40mm eyepiece is probably around 45-50 degrees. You might want to consider 68/70 degree eyepieces or 82 degree eyepieces. To gain increased magnification you want an eyepiece with a lower mm measurement - there is a trade-off though at which the magnification is too high and you don't gain anything in image quality.

You might want to start off with a cheaper set of eyepieces while you work out what sort of objects you prefer looking at - the Svbony 68 degree range are well regarded at the budget end and a full set is £144 on amazon. Alternatively the BST starguider range from FLO would also be a good choice.

I will look at both the eyepiece sets now.

Sorry to be a pain to you all.

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Posted (edited)

I bought the SVBONY 1.25" 68-Degree Ultra Wide 6mm/9mm/15mm/20mm Eyepiece Set for £110

Edited by tezz

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