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Visual Backs

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#1 Deepskyclusterstruck

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Posted 17 January 2021 - 07:00 AM

What is the difference between a visual back and an eyepiece adaptor and are visual backs always explicitly marked as such? Of the telescopes I have seen only my Schmidt Cassegrain 6SE has printed explicitly on the part in question "visual back." The purpose seems identical to a 2 to 1.25 inch eyepiece converter with the exception that the diameter of the drawtube seems too narrow to fully accomadate 2 inch diagonals & eyepieces.


Are the terms "visual back" and "eyepiece adaptor" sometimes used interchangeably?

#2 SloMoe

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Posted 17 January 2021 - 08:19 AM

Morning, no, not really, a visual back is used to hold the glass path optic's, diagonal and or eyepiece, 

and eyepiece adapters are used to be able to use a smaller diameter eye piece for a larger eyepiece holder in a focuser, like the most common 1.25" to 2" adapter.

 

Visual backs thread onto the baffle tube of the Mak  or SCT , eyepiece adapter's fit into eyepiece holders of focusers..

 

So if your scope has a 2" focuser eyepiece holder you'd use a 2" to 1.25" eyepiece adapter, there are variations of these, like .956"  to 1.25" or .956" to 2" or even 2" eyepieces to a 1.25" eyepiece holder..

 

Some Mak's use a different thread size & pitch than that of most SCT's and you can get thread adapter's for those too, to change the Mak thread to the standard SCT thread visual back

 

Here's a link to a vendors site that lists most of the common eyepiece adapters.

https://agenaastro.c...s/adapters.html

 

And here's a link to their visual back page.

https://agenaastro.c...apters.html?p=2


Edited by SloMoe, 17 January 2021 - 08:20 AM.

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#3 junomike

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Posted 17 January 2021 - 08:21 AM

Not usually.  A Visual Back is attached to the back of an SCT or Focuser (Refractor/Newt).  These almost always have a 2" opening to accept accessories (Diagonal, Barlowa, Etc).

An eyepiece adapter takes that 2" opening and stops it down (adapts) it to accept 1.25" eyepieces.

 

I can see how someone might confuse a 1.25" visual back with a 2" - 1.25" adapter but the threads are different as the  VB will have SCT threading and the adapter will have 2" threading.



#4 Deepskyclusterstruck

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Posted 17 January 2021 - 12:53 PM

Thank you both.

#5 Deepskyclusterstruck

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Posted 17 January 2021 - 12:53 PM

Thank you both.


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