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Which binoviewer eyepieces for outreach?

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#1 npapouts2


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Posted 16 March 2024 - 10:44 AM

Hello all,


a question for the combined expertise of this wonderful forum: I use a Maxbright I with twin Nagler 11T6s and a 2.5 Powermate (to reach focus) on my 80/560 apo refractor. I have found this just fits the entire moon/sun (with herschel wedge) in the FOV and the views are very pleasing…but eye positioning is critical to avoid blackouts and kidney beaning. When I try to show others, we spend several minutes adjusting the bino, having them try to get in the right position etc, not always successfully (especially with kids). In fact last time I tried to show a friend how to binoview, she spent a lot of time observing, only to tell me afterwards she couldnt see both images but the view was so nice she just closed one eye lol.gif


With that in mind, what would you recommend in terms of eyepiece pairs for ease of use alone in non-glass wearers  (think binoculars-you just bring them towards you and focus)? Also, what other factors besides eye relief affect this? Is it exit pupil, FOV? Thanks!

#2 betacygni



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Posted 16 March 2024 - 10:55 AM

In my experience 20-25mm Plossls will be your best bet. They are physically narrow so will fit people’s various sized noses/faces, and offer a medium AFOV that will be easy to take in. The eye relief tends to be just right for most (not slamming into eyepiece, or having to float above). They don’t have any significant geometric distortions or kidney beaning, etc.

Edited by betacygni, 16 March 2024 - 10:56 AM.

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#3 mikeDnight


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Posted 16 March 2024 - 11:12 AM

I'd suggest a pair of Kson 24mm & 16.8mm ortho's. They are as cheap as chips and truly top class in a binoviewer. With a cheap Revelation Binoviewer with a 2X barlow on its nose, and 16.8mm Kson ortho's, the view of the Moon through my Tak FC100DC made a superlative 5mm TMB Super Monocentric look second rate. You'll be hammering nails through those Naglers and using them as door stops. Seriously! lol.gif

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#4 havasman


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Posted 26 March 2024 - 10:43 AM

If you're talking about outreach targeting inexperienced observers, I would never use binoviewers. They're way too tweeky and most 1st time observers find it hard enough just to hold the exit pupil in cyclops mode at medium-low magnifications. Also, resetting the independent eye focus for each user would be a daunting task. Way too much trouble with too many failure modes for newb users unlikely to see or appreciate the advanced, incremental gains BV's can offer. Even cyclops focusing can be very difficult for a newb.


If you insist, I find Vixen SLV's very easy to use in my Denkmeier's with their long ER and twist-up eye cups. The 20mm or 15mm are easiest. TAO 32mm are excellent, especially with the Denk's power switch, and offer LER but lack twist-up eye cups and it can be hard for inexperienced users to hold their eye in place. They'd likely smudge the eye lens with eyelashes or foreheads.


I share my scopes' views often but never via BV. I will have guests for 4/8's totality and will have binoculars with and w/o WL filters on parallelogram mount but the Ha scope will be cyclops.

Edited by havasman, 26 March 2024 - 01:11 PM.

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