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Alternative visual back

eyepieces
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#1 sor

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Posted 19 September 2020 - 05:45 PM

I’m wondering if there are any recommendations on possible alternatives for a visual back on Celestron 9.25” SCTs.

It just really annoys me how loosening the thread on the visual back and tightening it again can leave the back in entirely different positions, as shown by huge variances when trying to use a laser collimator.

Is there any visual back with less “play” than the stock one, or maybe I’m worrying about nothing? I’ve got a decent investment in 1.25” eyepieces, so I’d need something that allows me to continue using those.

#2 BQ Octantis

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Posted 19 September 2020 - 06:07 PM

For years, I've used a Blue Fireball dual-screw brass clamp, like this one:

 

https://agenaastro.c...-back-e-15.html

 

They make a 2-inch version, too:

 

https://agenaastro.c...-2-adapter.html

 

But the crème de la crème du jour appears to be the Baader Click-Lock visual back:

 

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

 

Here's a testimonial for that one…he had me convinced!

 

https://www.youtube....h?v=oYoymtIT0ww

 

Cheers,

 

BQ

 

P.S. I linked to the smaller Celestron rear SCT thread. I don't know if the 9.25 uses that or the larger one in the video…

 

P.P.S. Truth be told, I start my optical chain with an SCT-thread to T-thread adapter:

 

https://agenaastro.c...ad-adapter.html

 

I can then screw on T-threaded accessories (including a T-threaded dual-screw brass clamp visual back) for a rigid optical chain that stays put in a wind storm.


Edited by BQ Octantis, 19 September 2020 - 06:23 PM.


#3 Bean614

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Posted 19 September 2020 - 06:20 PM

Get the Baader.  It's  SO much better than everything else, there isn't even a second place.



#4 Echolight

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Posted 19 September 2020 - 06:25 PM

I wanted the Baader. But got the Celestron. $22.

celestron_93661_sct_to_2_visual_1572549762000_1512119.jpg

Brass compression ring. It works.


Edited by Echolight, 19 September 2020 - 06:26 PM.


#5 BQ Octantis

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Posted 19 September 2020 - 06:31 PM

It doesn't look like Baader makes an SCT-Thread to 1.25-in Click Lock visual back. (Please correct me if I'm wrong.) But they do make a T-thread to 1.25-in Click-Lock holder (probably intended for their T-threaded prism diagonals):

 

https://agenaastro.c...hread-t208.html

 

So with the SCT-thread to T-thread ring I mentioned above, you could have a 1.25-in Click-Lock visual back without needing a 2-in to 1.25-in adapter.

 

BQ


Edited by BQ Octantis, 19 September 2020 - 06:32 PM.


#6 sor

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Posted 19 September 2020 - 06:33 PM

Thanks everyone!

I think I can get the 2” “SC/HD” model and the 2” to 1.25” click lock reducer for now.

Later I might want to buy the 2” click lock diagonal and perhaps some 2” eyepieces, or attach a DSLR to the 2”z

#7 Redbetter

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Posted 19 September 2020 - 06:36 PM

If you are going to replace the visual back it might make sense to go to 2" diagonal (it will still work with your 1.25" eyepieces, that is why they have 2" to 1.25" adapters with the diagonals.)  The rear baffle on the C9.25's is 46mm per Celestron.  However, I don't know if a 2" diagonal will clear the mount on whatever set up you have though, when pointed at zenith.  I prefer how solid 2" set ups are compared to 1.25". 


Edited by Redbetter, 19 September 2020 - 06:40 PM.


#8 sor

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Posted 19 September 2020 - 06:56 PM

I’m going to buy the 2” click lock and the reducer for now. Later I may pony up for the 2” diagonal and place it in between the two, but that thing is a bit more than I want to spend. Maybe next spring.

#9 Radiotel78

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Posted 19 September 2020 - 07:41 PM

BQ,

 

Thanks for your post.  I'm looking at the Baader Click-Lock to replace the stock visual back on my NexStar 6SE. The SCT-thread to T-thread ring you mentioned checks another box. I'm also looking at the T2 Zeiss prism. My understanding is that I must purchase a 1.25" nosepiece adapter. Also, I would add a click-lock for eyepieces.  Does that all work together? Make sense? I'd like to invest now so I may move the equipment as I (someday) move to another telescope.  Again, thanks.



#10 BQ Octantis

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Posted 19 September 2020 - 07:50 PM

BQ,

 

Thanks for your post.  I'm looking at the Baader Click-Lock to replace the stock visual back on my NexStar 6SE. The SCT-thread to T-thread ring you mentioned checks another box. I'm also looking at the T2 Zeiss prism. My understanding is that I must purchase a 1.25" nosepiece adapter. Also, I would add a click-lock for eyepieces.  Does that all work together? Make sense? I'd like to invest now so I may move the equipment as I (someday) move to another telescope.  Again, thanks.

Makes perfect sense. I've had the same setup in my AgenaAstro cart for several weeks. The optical train would go

 

  1. OTA → SCT-thread to T-thread ring → Baader T-thread to 1.25-in ClickLock
  2. 1.25-in nosepiece to T-thread → T-thread Baader Zeiss prism diagonal → Baader T-thread to 1.25-in ClickLock

 

Agena Astro carries both a safety-ridged Baader nosepiece and a smooth Blue Fireball nosepiece.

 

The most challenging part of the setup is trying to convince myself to buy it! smile.gif

 

Cheers,

 

BQ


Edited by BQ Octantis, 19 September 2020 - 08:18 PM.

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#11 KTAZ

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Posted 19 September 2020 - 07:55 PM

This is what I bought. includes a case and a 2” to 1.25” adapter. Very solid, rotates easily, and threads tightly for no sag connections.

 

Also holds your eyepieces very tightly.

 

https://agenaastro.c...lt-coating.html


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#12 Redbetter

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Posted 20 September 2020 - 12:47 AM

I use the AT version for my 127 Mak.   It is a 99% dielectric with the SCT threaded connection.  Link.  It has worked well. 




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