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Robindonne

2” dielectric vs 1,25 star diagonal

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Posted (edited)

A short question i cant find an answer for.  What is the best option to mount to the back of a C8.  Does a 2” give a better view than a 1,25”?   I have just 1 dielectric diagonal.  And that’s the 2”.  My other diagonal is the stardiagonal that came with the C8, that’s the 1,25”.  
Most of my eyepieces are 1,25”, but of course fit the adapter of the 2”.  
 

thx for helping me out...

Edited by Robindonne

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Posted (edited)

With 1.25” eyepieces it doesn’t matter what size diagonal you use as long as it is decent quality. No real advantage in a 2” diagonal other than it lets you use long focal length 2” eyepieces.

Just get a 2” visual back. The Baader is nice but a bit expensive but good quality ones can be had for about £20.00.

https://www.firstlightoptics.com/adapters/baader-click-lock-2-for-celestron-meade-sct.html

Or cheaper alternative.

https://www.harrisontelescopes.co.uk/acatalog/revelation-sct-2-visual-back.html#SID=627

Edited by johninderby
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Posted (edited)
37 minutes ago, johninderby said:

With 1.25” eyepieces it doesn’t matter what size diagonal you use as long as it is decent quality. No real advantage in a 2” diagonal other than it lets you use long focal length 2” eyepieces.

Just get a 2” visual back. The Baader is nice but a bit expensive but good quality ones can be had for about £20.00.

https://www.firstlightoptics.com/adapters/baader-click-lock-2-for-celestron-meade-sct.html

Or cheaper alternative.

https://www.harrisontelescopes.co.uk/acatalog/revelation-sct-2-visual-back.html#SID=627

Ah thx.  Well i have some visual backs.  Some different types of 1,25 and 2”.   I was just wondering if the 1,25 diagonal wont show all. Dont know how to describe.....a cropped view?

So in my case, only having one decent diagonal, the 2”, its better to mount that one tonight.   
 

Just thought of it while assembling everything. I realised i dont have a good 1,25” diagonal.  Immediately added it to my to-buy list.  
But then a new question pops up: Does one really need a good 1,25” diagonal, while almost every scope supports a 2”?
 

Edited by Robindonne

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With a 1.25” eyepiece the field stop in the eyepiece is smaller than 1.25” so not problem with vignetting (cropping). using a 1.25” diagonal.

But as you have the 2” visual back and 2” diagonal then it makes sense to use that. You might want to get a long focal length 2” eyepiece some day.

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Does this help...?

867462112_re-moddedETX105SCTstardiagonal.thumb.jpg.0a8b2e97a3b9500b1a1ce91262c4a2e1.jpg2144000928_re-moddedETX105SCTstardiagonal(closeup).thumb.jpg.bd984209b84c1aca15aaaf7f00776cd4.jpg

I feel a lot happier with this on the backend of my ETX105; (or C6/SCT-xlt); than with a 1.25" push-fit, especially when using these 'old skool bad-boyz!'...

517405460_type1.jpg.6081a9d066256d23c85f03f0907fd47f.jpg548055074_series4000uwa.jpg.dfcf28115e9eb29ce73faa4351897806.jpg

That said, a 1.25" twist-lock maybe just as secure.

 

small_IMG_0385.JPG..jpg.96b510aeac1ce230208486066271a09d.jpgPIC011.JPG.d44aaf7659477cb4cf6a80da07ee9215.JPGPIC012.JPG.3b3b2b4aaf9826a35f9fd23345ee7b76.JPG

Just a few few images of my 're-modded' ETX105 with an ETX-SCT adapter ring and SCT-1.25" push-fit visual back. 

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