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Diagonal for SCT and Refractor

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#1 Prima Luna

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Posted 03 April 2020 - 03:21 PM

I need to get a  single 90 degree diagonal that will work for 2 scopes.

 

What do I need to get if I have a telescope with a threaded 2" SCT and another telescope (a refractor) with a 2" eyepiece holder that is not threaded, but rather just accepts a smooth slide in diagonal.

 

I would like the diagonal to be threaded, and I guess I would need an adapter to adapt to the refractor?

I would rather have it the above mentioned way, instead of a smooth pop in with an adapter to make it threaded for the SCT.

A threaded one would be more secure, right?

 

FYI,

I am getting the Wegat plate for my ETX, which will has the 2" SCT threaded piece built in.

The refractor is the Astro-Tech 72EDii

 

Thinking to get this diagonal:

 

https://www.astronom...l-for-scts.html

10507_1.jpg

 

 

 



#2 bignerdguy

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Posted 03 April 2020 - 10:42 PM

Try here for a few diagonals like you mention:

 

https://www.highpoin...ories/diagonals

 

And here for the adapter (see visual adapters section):

 

http://www.scopestuff.com/index.html



#3 Prima Luna

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Posted 04 April 2020 - 03:29 AM

 

 

And here for the adapter (see visual adapters section):

 

http://www.scopestuff.com/index.html

Which adapter?

Either of these?

http://www.scopestuff.com/ss_taeq.htm

http://www.scopestuff.com/ss_adt2.htm



#4 Cometeer

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Posted 04 April 2020 - 03:35 AM

Which adapter?
Either of these?
http://www.scopestuff.com/ss_taeq.htm
http://www.scopestuff.com/ss_adt2.htm

Get the second adapter that you linked and a regular 2” slide-in diagonal rather than a SCT-threaded 2” diagonal. That adapter will allow a SCT to accept slide-in 2” diagonals.

Edited by Cometeer, 04 April 2020 - 03:36 AM.


#5 junomike

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Posted 04 April 2020 - 07:49 AM

WO offers both Diagonal Adapters for certain WO Diagonals (see 2nd row left & last row middle). Call Manish,  He might be able to help.



#6 Chevy5759

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Posted 04 April 2020 - 08:01 AM

Get the second adapter that you linked and a regular 2” slide-in diagonal rather than a SCT-threaded 2” diagonal. That adapter will allow a SCT to accept slide-in 2” diagonals.

This is this setup I use on the Edge 11. It works well.



#7 Prima Luna

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Posted 04 April 2020 - 01:31 PM

Get the second adapter that you linked and a regular 2” slide-in diagonal rather than a SCT-threaded 2” diagonal. That adapter will allow a SCT to accept slide-in 2” diagonals.

Thank you.  But as mentioned in my OP, I am  not  looking for a slide in diagonal.   

I am looking for a threaded SCT diagonal with an adapter to also allow me to use it on a refractor.

 

More often I will be using the ETX (the scope with the SCT thread).

I've put a lot of time in modifying the ETX, especially the rings, so I can de-fork it and use on my other 2 mounts.

And I probably spent more money than I should have (maybe should have just got another OTA) on making it work on regular mounts.

I purchased a back plate for the scope ($125) that has a 2" SCT thread which replaces the stock "slip in" EP connector.

So it  just seems counterproductive to replace the stock parts and not thread anything to it but instead buy another adapter.

 

I also do not want to add more weight to the heavier scope (ETX) so that my 2 mounts can do a better job with it.

So rather add the extra weight of the adapter on the already very light scope.

 

It seems from replies that there may not be anything like what I am looking for or is there a reason for not doing it the way I am trying to do it?

I can maybe think of 1 reason that I would like to ask you all about, but want to know if there are any others?



#8 Prima Luna

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Posted 04 April 2020 - 01:41 PM

WO offers both Diagonal Adapters for certain WO Diagonals (see 2nd row left & last row middle). Call Manish,  He might be able to help.

Thanks.

 

The nose piece mentions:

 

"With compatible diagonals, you simply unscrew the SCT adapter from the diagonal body, and screw this nosepiece on instead."

 

Compatible as in with any SCT or WO has something about theirs that makes it compatible?

And what SCT adapter?  Is this what they mean by being compatible?  Not sure why a specific adapter would have an adapter.

 

OK, will call Manish.



#9 Cometeer

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Posted 04 April 2020 - 02:50 PM

Thank you.  But as mentioned in my OP, I am  not  looking for a slide in diagonal.   

I am looking for a threaded SCT diagonal with an adapter to also allow me to use it on a refractor.

 

More often I will be using the ETX (the scope with the SCT thread).

I've put a lot of time in modifying the ETX, especially the rings, so I can de-fork it and use on my other 2 mounts.

And I probably spent more money than I should have (maybe should have just got another OTA) on making it work on regular mounts.

I purchased a back plate for the scope ($125) that has a 2" SCT thread which replaces the stock "slip in" EP connector.

So it  just seems counterproductive to replace the stock parts and not thread anything to it but instead buy another adapter.

 

I also do not want to add more weight to the heavier scope (ETX) so that my 2 mounts can do a better job with it.

So rather add the extra weight of the adapter on the already very light scope.

 

It seems from replies that there may not be anything like what I am looking for or is there a reason for not doing it the way I am trying to do it?

I can maybe think of 1 reason that I would like to ask you all about, but want to know if there are any others?

Reasons why I recommend the slide in diagonal ask over the sct diagonal. 
1. A SCT/mak has a larger focus range, so can accommodate any additional  length of a 2” diagonal. If you screw in a 2” nosepiece to the front of a sct diagonal, it adds a lot of length and may not be able to reach focus in your refractor. if you get a sct diagonal where the nosepiece completely unscrews and is replaced with a 2” nosepiece, you don’t have this issue. 

 

2. I find a screw in diagonal more prone to slipping than one attached via compression rings. You need to really tighten it down which also makes it harder to unscrew. 

 

3. Leave the visual back attached to the ETX at all times. No unscrewing components when you want to use the diagonal in the mak vs in the refractor. 

 

 

 

If you REALLY want to still get a 2” SCT threaded diagonal, purchase a William Optics one. Then you can buy this: https://agenaastro.c...-nosepiece.html

That component requires you to unscrew the SCT adapter and thread on the 2” smooth barrel. A much better method than screwing a 2” smooth barrel to the front of the SCT adapter. 


Edited by Cometeer, 04 April 2020 - 02:52 PM.


#10 Prima Luna

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Posted 04 April 2020 - 03:36 PM

Reasons why I recommend the slide in diagonal ask over the sct diagonal. 
1. A SCT/mak has a larger focus range, so can accommodate any additional  length of a 2” diagonal. If you screw in a 2” nosepiece to the front of a sct diagonal, it adds a lot of length and may not be able to reach focus in your refractor. if you get a sct diagonal where the nosepiece completely unscrews and is replaced with a 2” nosepiece, you don’t have this issue. 

 

2. I find a screw in diagonal more prone to slipping than one attached via compression rings. You need to really tighten it down which also makes it harder to unscrew. 

 

3. Leave the visual back attached to the ETX at all times. No unscrewing components when you want to use the diagonal in the mak vs in the refractor. 

 

 

 

If you REALLY want to still get a 2” SCT threaded diagonal, purchase a William Optics one. Then you can buy this: https://agenaastro.c...-nosepiece.html

That component requires you to unscrew the SCT adapter and thread on the 2” smooth barrel. A much better method than screwing a 2” smooth barrel to the front of the SCT adapter. 

Thanks for your reply.  I am considering your suggestions and have been looking at your options now ever since your post.  

 

While looking, I found this unit below.

 

It has what I am looking for:

"Two interchangeable adapters allow you to switch between a Schmidt-Cassegrain thread adapter and a 2” barrel adapter so you can use this diagonal with a wide variety of telescopes"

 

Plus, it has this nice additional feature:

"Twist-lock keeps the eyepiece centered in the diagonal to provide better optical alignment"

 

https://agenaastro.c...lock-93573.html

 

It's a new item, so no reviews at Agena so far.

Will search around.

93573_twist-lock_dielectric_star_diagona



#11 Cometeer

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Posted 04 April 2020 - 03:59 PM

Thanks for your reply.  I am considering your suggestions and have been looking at your options now ever since your post.  

 

While looking, I found this unit below.

 

It has what I am looking for:

"Two interchangeable adapters allow you to switch between a Schmidt-Cassegrain thread adapter and a 2” barrel adapter so you can use this diagonal with a wide variety of telescopes"

 

Plus, it has this nice additional feature:

"Twist-lock keeps the eyepiece centered in the diagonal to provide better optical alignment"

 

https://agenaastro.c...lock-93573.html

 

It's a new item, so no reviews at Agena so far.

Will search around.

93573_twist-lock_dielectric_star_diagona

That Celestron looks like it will work. Seems similar to the William Optics one, though I’d personally get the William Optics diagonal at a slightly lower price and better quality. 



#12 Prima Luna

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Posted 04 April 2020 - 04:31 PM

That Celestron looks like it will work. Seems similar to the William Optics one, though I’d personally get the William Optics diagonal at a slightly lower price and better quality. 

I'm not sure which WO one you are referring to, but the 2 that I was looking at that has the twist-lock is a little more $ (with the adapter). 

What is it about the WO that I need to look at that indicates it is of better quality?  And which model? 

 

I'm now also leaning on getting the product below (along with a refractor slide in diagonal - opposite of what I wanted in my OP :) )

"Baader 2" SCT Click-Lock Eyepiece Adapter / Visual Back (with 2" SCT Thread) # CLSC-2 2956220"

https://agenaastro.c...sct-thread.html

paar-bp-clsc-2-1_1.jpg



#13 Prima Luna

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Posted 04 April 2020 - 04:36 PM

WO offers both Diagonal Adapters for certain WO Diagonals (see 2nd row left & last row middle). Call Manish,  He might be able to help.

Agena (Tom) reached out to me earlier during this thread and provided me a link to help me out with all this.

Pretty good article written my Manish!

 

"Choosing and Using 2" Diagonals for Schmidt-Cassegrain and Maksutov-Cassegrain Telescopes"

https://agenaastro.c...-diagonals.html



#14 junomike

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Posted 04 April 2020 - 05:04 PM

Thanks.

 

The nose piece mentions:

 

"With compatible diagonals, you simply unscrew the SCT adapter from the diagonal body, and screw this nosepiece on instead."

 

Compatible as in with any SCT or WO has something about theirs that makes it compatible?

And what SCT adapter?  Is this what they mean by being compatible?  Not sure why a specific adapter would have an adapter.

 

OK, will call Manish.

 

 

Agena (Tom) reached out to me earlier during this thread and provided me a link to help me out with all this.

Pretty good article written my Manish!

 

"Choosing and Using 2" Diagonals for Schmidt-Cassegrain and Maksutov-Cassegrain Telescopes"

https://agenaastro.c...-diagonals.html

No, I meant to call Manish to see if any current WO Diagonals are compatible with both nosepieces.  If not the Celestron would work, but I'd prefer WO myself (nothing wrong with the Celestron, just a preference)




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