For what it’s worth, I think most of us on this forum would strongly recommend the Televue 55/67 for the PVS-14, so it’s good you’re considering that. Keep in mind a 2x Barlow on the 55/67 will give you about the same focal length as your GSO Superview, and a 4x Barlow will be somewhere between the 20mm and 13mm EPs, so it is possible to accomplish close to what you’re thinking about using that approach (although it makes the stack even longer).
If you’re going to use a filter slider (instead of threading the filters on the eyepiece), then you could just acquire Televue plossls rather than another eyepiece brand for other focal lengths. All of the Televue eyepieces can be used with the same adapter, which is helpful. If you’re going to thread the filters on the eyepieces, though, then you should know the Televue 55/67 has a 2” barrel, while the rest of the Televue plossl line has 1.25” barrels, meaning you would need filters for both size barrels.
In the Televue line, the longer focal length panoptic EPs have 2” barrels, and you could pair these with a 2x or 4x Barlow to achieve the results you’re after.
If you’re set on going with another eyepiece manufacturer for afocal, I’d recommend checking with Joko about the OVNI adapter. He’s the owner and he’s on these forums. If he is still making them and they seem suitable for you, that’s another good alternative.
If the OVNI adapter doesn’t work out, I’d investigate what threads (if any) are present on the viewing side of the eyepieces you’re considering. A lot of eyepieces do actually have threads there, so it may be possible to acquire the adapters you need to connect the ENVIS threads on the PVS-14 objective directly to the eyepiece. You’d probably need this adapter (ENVIS to M42) to start, and then M42 to whatever thread is at the eyepiece (and maybe some spacers depending on the EP eye relief). https://rafcamera.co...f-to-m30-3x0-8m
BTW, the thread of the PVS-14 objective is an ENVIS thread (M30.3x0.8)
Hopefully this helps. Good luck!
Edited by stnagy, 10 October 2021 - 09:28 PM.