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Problem with new eyepieces

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#1 Cptcrunch

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Posted 27 July 2021 - 01:12 AM

Hi, I’m fairly new to astronomy and I’m not sure what I’m doing wrong. Any advice would be very appreciated.

 

I have an 8” dobsonian, skywatcher 200p, and I’ve been using 1.25” eyepieces until now. It has been working great. I recently purchased a set of 2” eyepieces and all I can see out of it is a disk with the silhouette of the secondary mirror in it. Unfortunately This is the first time I’ve used it in months, but it isn’t handled roughly.

 

 In the photo I have a 2x Barlow lens and a 26 mm eyepiece. But it’s the same exact problem without the Barlow lens.

 

 Any idea what I’m doing wrong?



#2 javad

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Posted 27 July 2021 - 01:22 AM

Hi, I’m fairly new to astronomy and I’m not sure what I’m doing wrong. Any advice would be very appreciated.

 

I have an 8” dobsonian, skywatcher 200p, and I’ve been using 1.25” eyepieces until now. It has been working great. I recently purchased a set of 2” eyepieces and all I can see out of it is a disk with the silhouette of the secondary mirror in it. Unfortunately This is the first time I’ve used it in months, but it isn’t handled roughly.

 

 In the photo I have a 2x Barlow lens and a 26 mm eyepiece. But it’s the same exact problem without the Barlow lens.

 

 Any idea what I’m doing wrong?

Maybe your focuser does not have enough back or in focus for 2" EPs.



#3 DHEB

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Posted 27 July 2021 - 01:38 AM

It sounds like you need to change the lenght of the optical train at the eyepiece end. Perhaps you need to add or remove an extension so the eyepiece can reach focus.

I do not see any photo.

#4 Jon Isaacs

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Posted 27 July 2021 - 02:42 AM

Hi, I’m fairly new to astronomy and I’m not sure what I’m doing wrong. Any advice would be very appreciated.

 

I have an 8” dobsonian, skywatcher 200p, and I’ve been using 1.25” eyepieces until now. It has been working great. I recently purchased a set of 2” eyepieces and all I can see out of it is a disk with the silhouette of the secondary mirror in it. Unfortunately This is the first time I’ve used it in months, but it isn’t handled roughly.

 

 In the photo I have a 2x Barlow lens and a 26 mm eyepiece. But it’s the same exact problem without the Barlow lens.

 

 Any idea what I’m doing wrong?

 

Are you doing this at night or during the day?  If you are doing this during the day, you will need to pull the eyepiece out.. 

 

When you focus, does it seem like it's better with the focuser all the way in or all the way out?

 

Jon



#5 sixela

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Posted 27 July 2021 - 09:21 AM

Those Skywatcher come with two adapters, a 1.25" one and a 2" one, which is an extension tube. If you just remove the 1.25" one and replace it with nothing, then your 2" eyepieces will not come to focus.

 

 

Skywatcher-Crayford-focuser-2-voor-Explo

On the left the 2" adapter. On the right the 1.25" adapter, and if you unscrew that little barrel it becomes a T2 adapter for cameras.


Edited by sixela, 27 July 2021 - 09:22 AM.

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#6 Cptcrunch

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Posted 27 July 2021 - 10:11 AM

Thank you all for replying so fast. I don’t know why my photo didn’t upload, but Hubble had it. I had misplaced my 2” adapter and completely forgot about it. Thanks again, I really appreciate the help.


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#7 Bill Weir

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Posted 27 July 2021 - 02:44 PM

Then don’t forget to take the 2” adapter out when you inset the 1.25” one. Diagnosed this problem with someone who was new to the game and couldn’t get their 1.25” eyepieces to focus.

 

Bill



#8 Frenchy

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Posted 28 July 2021 - 01:46 PM

What's interesting to me with this subject, with the newts I've owned, they have all been different when it comes to focus and they all have had similar focusers. Zhumell z8 (gso dual speed crayford), needed 35mm extension tube for 2" eyepieces, not for 1.25". 12.5" meade starfinder (gso dual speed crayford), needed 35mm extension tube for 2" eyepiieces, not 1.25". 10" meade lightbridge plus (synta dual speed crayford), needed 35mm extension tube for both 2" and 1.25" eyepieces. 12' 1st gen lightbridge (gso dual speed linear bearing crayford), no extension tube needed at all.  


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#9 aeajr

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Posted 28 July 2021 - 02:15 PM

What's interesting to me with this subject, with the newts I've owned, they have all been different when it comes to focus and they all have had similar focusers. Zhumell z8 (gso dual speed crayford), needed 35mm extension tube for 2" eyepieces, not for 1.25". 12.5" meade starfinder (gso dual speed crayford), needed 35mm extension tube for 2" eyepiieces, not 1.25". 10" meade lightbridge plus (synta dual speed crayford), needed 35mm extension tube for both 2" and 1.25" eyepieces. 12' 1st gen lightbridge (gso dual speed linear bearing crayford), no extension tube needed at all.  

That is interesting.  I have an Apertura AD12 (GSO).  It came with a 35 mm extension tube, but it lives in the unused equipment bin.   My 2" eyepieces don't require it to come to focus.

 

 

 

Hi, I’m fairly new to astronomy and I’m not sure what I’m doing wrong. Any advice would be very appreciated.

 

I have an 8” dobsonian, skywatcher 200p, and I’ve been using 1.25” eyepieces until now. It has been working great. I recently purchased a set of 2” eyepieces and all I can see out of it is a disk with the silhouette of the secondary mirror in it. Unfortunately This is the first time I’ve used it in months, but it isn’t handled roughly.

 

 In the photo I have a 2x Barlow lens and a 26 mm eyepiece. But it’s the same exact problem without the Barlow lens.

 

 Any idea what I’m doing wrong?

Try this.

 

When you put the 2" eyepiece in, get it as close to focus as you can.  Now unlock the eyepiece and pull it out slowly and see if it comes to focus.

 

My Orion XT8i never needed an extension with any of my eyepieces EXCEPT for a 25 mm Explore Scientific/Bresser eyepiece.  That one I had to pull out of the focuser about 1/4" to get it to come to focus.  

 

 

I am not familiar with what kind of focuser is on that Dob. Some focusers have a built in adjustable height adapter so you can raise or lower the eyepiece within the focuser.  I had an Antares dual speed focuser that was like that.   I had to play with it a bit until I got it to the right spot so that all of my eyepieces would come to focus.  


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