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star diagnal with twist lock

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#1 ALMICHL

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Posted 18 August 2019 - 10:35 AM

I am currently looking at upgrading my star diagnal on my cpc 11 from an AstroTech 2", to a "twist lock" 2" diagnal. I have been searching and  have found a variety; especially in price. I see that Celestron has come out with a 2" twist lock. Orion also has one. Of course there is Baader. One consideration I am looking at getting in the future is a crayford style focuser to add to my sct. It would be nice if I could get one that would have a sct mount and a refractor mount, so I would not have to purchase another diagnal or an adapter. I would like any guidance on this issue. Thanks for any help, Al



#2 Don Taylor

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Posted 18 August 2019 - 11:31 AM

The Baader (standard) ClickLock dielectric 2" diagonal can be used directly coupled to the SCT visual back if you remove the 2" nosepiece (it's 48mm thread). Here's the Baader webpage:  https://www.baader-p...nal-mirror.html

 

And the lockring: https://www.baader-p...king-ring..html

 

There are several documents under "downloads" - especially the User's manual: https://www.baader-p..._connection.pdf

 

Once you add a Crayford focuser then you can re-install the nosepiece.  However directly coupling the diagonal will be closer to the optimum optical arrangement (primary to secondary mirror spacing the the resulting SA). Others more familiar with the C11 hopefully can add something here.

 

 

 

Hope this helps.


Edited by Don Taylor, 18 August 2019 - 11:38 AM.


#3 LDW47

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Posted 18 August 2019 - 07:41 PM

I am currently looking at upgrading my star diagnal on my cpc 11 from an AstroTech 2", to a "twist lock" 2" diagnal. I have been searching and  have found a variety; especially in price. I see that Celestron has come out with a 2" twist lock. Orion also has one. Of course there is Baader. One consideration I am looking at getting in the future is a crayford style focuser to add to my sct. It would be nice if I could get one that would have a sct mount and a refractor mount, so I would not have to purchase another diagnal or an adapter. I would like any guidance on this issue. Thanks for any help, Al

Antares makes an excellent Twist Lock for decent price of around $50 C, I have 3-4 of them for my 2” diagonals !



#4 dscarpa

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Posted 18 August 2019 - 09:29 PM

I use the Antares in all of mine too. David


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#5 csrlice12

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Posted 19 August 2019 - 08:56 AM

Meade makes a diagonal with two nose pieces.  One for refractors, one for SCTs.



#6 Jeff Morgan

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Posted 19 August 2019 - 09:13 AM

The only brand I have tried is Baader, the 2" BBHS diagonal (mirror). 

 

The Baader is very well made, excellent function. The twist lock is very nice to use. Fast, easy, and secure. Would be easy to use while gloves. The website shows a man lifting a C14 optical tube by the eyepiece and the ClickLock holding the load. Based on my testing, that is realistic.

 

I also tested how it performs on eyepieces with the Undercut Defect by removing the tape from a 27 Panoptic. After a couple of dozen trials in rapid succession, no snags!

 

The product works so well I ordered the 1.25" ClickLock adapter and a ClickLock for the Astro-Physics focuser on my TMB. When Baader releases a M54 male thread version in a couple of months, I will also order one for my Takahashi Epsilon.

 

I will look at the possibility of updating my two FeatherTouch focusers to use ClickLocks for them also.

 

Great product.



#7 25585

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Posted 22 August 2019 - 09:32 AM

Baader Diamond Steeltrack 2" focusers for SCTs are good. They allow swapping the 3 thumbscrew grip for a Clicklock, or T2 attachment with their diagonals, if you check the Baader site.



#8 Starman1

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Posted 22 August 2019 - 10:32 AM

I am currently looking at upgrading my star diagonal on my cpc 11 from an AstroTech 2", to a "twist lock" 2" diagonal. I have been searching and  have found a variety; especially in price. I see that Celestron has come out with a 2" twist lock. Orion also has one. Of course there is Baader. One consideration I am looking at getting in the future is a crayford style focuser to add to my sct. It would be nice if I could get one that would have a sct mount and a refractor mount, so I would not have to purchase another diagonal or an adapter. I would like any guidance on this issue. Thanks for any help, Al

First, a refractor-style diagonal, which inserts instead of threading on, is usable on SCTs and refractors.

Second, refractor-style diagonals are threaded on the front for filters (convenient).

Third, refractor-style diagonals have a larger clear aperture all the way through (desirable at low powers).

 

With a CPC-11, here is what I'd do:

1) replace the 3-1/4" plate on the back of the scope with a Baader Click-Lock rear plate. You get a 50.8mm clear aperture (better for illumination of low power eyepieces or large camera chips), and a great ease in inserting and tightening the diagonal.

2) Get a good 2" dielectric-coated diagonal, with Click-Lock or Twist-Lock as you prefer.  You can get a 2" to 1.25" adapter with twist-lock as well.

3) Replace the focus knob with a Starlight Instruments 2-speed focus knob.  This gives you very fine focus while also allowing fast focus: http://starlightinst...&product_id=261  and it doesn't add any length to the back end of the scope.

 

Unless you are using the scope solely for imaging, I would NOT add a rear-mount focuser to the scope.  SCTs' focal lengths get longer the larger the back-focus distance is.  Adding the length of the focuser would increase the focal length and f/ratio of the scope and reduce the field of view of every eyepiece.  On a CPC, the diagonal would no longer clear the base, which means no viewing around the zenith.

And it would add unnecessary weight for the gears to drive.


Edited by Starman1, 22 August 2019 - 10:33 AM.

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#9 luxo II

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Posted 26 August 2019 - 05:11 AM

APM sell 2” dielectric diagonals with a full unobstructed aperture and rotolock (equivalent to the clicklock)...

Edited by luxo II, 26 August 2019 - 05:13 AM.

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