I have a full set of 2" 100 degree eyepieces, and some 82s, but I find myself hardly ever using them anymore. When I pop in the binoviewers and have a look, then take them out and look through say, my 20mm 100 degree, I struggle to find much advantage to mono viewing. It's uncomfortable, and has no depth. Even with the 100 degree eyepieces I find it appears as a wider field to just be looking through 2x24mm eyepieces in the binos. It also seems like despite the fact that the light from the telescope is being split between the two, using two eyes seems to make up any sensitivity to faint objects. Do others find the same?
Perhaps my eyes are just not well suited to mono viewing? I am not a serious visual observer, quite casual really, mainly due to not having easy access to a dark site (Bortle 5 home). But in any case I am thinking about selling all my mono EPs and going with a few nice bino pairs instead.
Has anyone just gone full binoviewer and gotten rid of all mono eyepieces? If yes, did you end up missing having them, perhaps even buying them again? Are there any certain times where you would absolutely not want to use a binoviewer and instead prefer to view with one eye? I am trying to avoid seller's regret...
My circumstances are similar to yours - except I do most non-outreach observing from dark skies (SQM: 20.8 to 21.75 - mostly the latter), and I do most visual observing with a Explore Scientific 127mm APO and an Obsession 20 F/5.
I also use Denk II with 3x switch, and I have one of the now-discontinued Denk "Newt focal reducer" switch-in lenses (Why did he ever drop those?). Thus I have only two eyepiece pairs: D21's and Brandon 16mm's. The "switches" provide all the power changes I need - and end the need to carry eyepiece pairs up a ladder.
I was almost totally 'bino' until I 'discovered' 100 degree eyepieces - and now use a set of 100's mono a lot, plus a Paracoor II (at F/5). I have never been that happy with 'bino' for deep sky on my 10-inch and smaller telescopes. However any dimming effect is not of much concern in a 20-inch under dark sky -- 14th mag galaxies can be observed - altho going to the absolute 'dimmest' of deep sky requires mono.
I have every intention of doing more bino in the future - at least with the 20-inch, and solar/lunar/planets with the 127mm APO.
I much prefer observing with two eyes - bino-viewer, true binoculars, or just 'eyeballs'. When doing several nearly all-night sessions in a row - using two eyes is far more relaxing. Views of things like the 25 brightest globular star clusters are much better 'bino'. Alto I don't own those 3-D eyepieces.
Only work for 'outreach' if you are dealing with small groups, maybe 8 at most - and about 1 in 5 'public' just can't get it to work. It takes time to de-case and assemble my Denk II - and even worse, at the end of the night I have this big honking thing that is 'fiddly' to disassemble and put away - so I often just leave it assembled and somewhere like in the house or on my truck's passenger seat until 'the morning after'. For short 1 or 2 hour sessions it is just too much work. They do dim the view slightly - especially noticeable in 10-inch and smaller scopes (again, mostly not an issue with a 20"). Even with my "Newt focal reducer lens" the bino can never provide the widest views - so if the object needs the widest possible view - then mono with a 41mm Pan is the way I go. One final minor issue - switching bino to mono requires re-balance of my scopes.
I have one friend with an 18-inch F/4 Dob (with Stellarcat GoTo and tracking) who almost never removes the bino (was Denk II, now Binotron) from his Upper Tube Assembly - even for transport and storage. He is 100% bino, and has been for years. He did, like me, 'discover' 100 degree eyepieces - so, at rare times I now see him 'mono' with something like a Ethos 21 (ane PII of course).
Bottom line: Bino most of the time -- but you still need a good set of mono eyepieces. Stay flexible. This advice is more appropriate as one moves up in telescope aperture.
Edited by George N, 18 April 2019 - 11:47 AM.