Posted 17 January 2021 - 07:00 AM
Are the terms "visual back" and "eyepiece adaptor" sometimes used interchangeably?
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.
And here's a link to their visual back page.
Edited by SloMoe, 17 January 2021 - 08:20 AM.
- descott12 likes this
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.