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ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia

Bino-viewers for birding scopes? Why isn't everyone using them? (1 Viewer)

Aotus

Well-known member
United States
I just recently acquired my first scope after a long period of hesitation because, in part, I know that I hate using one eye to take pictures through a view finder on a camera and I suspected that I would have no fun trying to watch birds that way. Well, so far, I have mixed feelings about the one eye experience with my new scope, but then I find out about "bino-viewers" for telescopes and I am completely shocked that I hadn't heard of them before. I know that there aren't a lot of scopes that can be made to take non-proprietary eyepieces, but among those that can, why isn't this 'mod' standard practice? I genuinely want to know because I expect I will be doing some heavy forum research over the next week to fit some binoviewers to my Nikon Monarch scope.

Thanks for any insights, and, if you have tried a scope with bino viewers and/or know of a configuration that works well I would love to read (and see?) all about it.
 

Aotus

Well-known member
United States
i may have posted too quickly... my enthusiasm is receiving the cold water treatment as I search more about it. Damn. Would still love to know if there has been any developments, aside from the Swaro BTX ($$$$), that are worth looking into.
 

jring

Well-known member
Hi,

you will generally not have enough infocus to use an astro binoviewer on a spotting scope. Plus they always loose light due to splitting the beam and good quality ones are not cheap.

Joachim
 

wllmspd

Well-known member
Most Astro binoviewers come with “glass path correctors”, essentially a 2x lens that removes much of the infocus issue. However you are now limited to views at the higher end what you’d want to use which is not ideal.
There is a new type of binoviewer that might avoid this issue the “linear binoviewer”… ORION LINEAR BINOVIOEWER - mini-review - Binoviewers - Cloudy Nights not come across many people using it yet:
Orion even sell an 80mm spotter with them installed… Orion 80mm Semi-Apo Binocular Spotting Scope | Astronomy Technology Today

Another option is a binoscope from someone like APM, Oberwerk or Explore scientific. With angled eyepieces and mounted to a tripod it’s essentially two spotters connected together, though even when made of a light metal they are not a light option. However you get to use pretty much any astro eyepieces, so no magnification restrictions and really wide fields are available. My 70mm are about 4.5kg which is fine for a stroll round a bird reserve, but I’d probably not want to lug it up any big hills. Takes up backpack space, especially as you need to factor in pairs of eyepieces (I am not a zoom fan). Views are very immersive and good for relaxing long distance viewing.

Peter
 

jring

Well-known member
Most Astro binoviewers come with “glass path correctors”, essentially a 2x lens that removes much of the infocus issue.

That should say "most binoviewers can be equipped with a glass path corrector as an extra accesory". And yes, it will push your magnification up into areas where the image might be too dark after the beam splitting.

The new "linear binoviewer" trades a narrower true field of view for more brightness and no magnification - the unobstructed field stop diameter is 17.3mm, you can probably get away with a mm or two more with a bit of vignetting...
If you aim for 30x with a 60 deg afov, that should be fine... but forget about super wide field low mag views...

Joachim
 

wllmspd

Well-known member
Binoscopes have moderate f-ratios and some have smaller prisms that others which can both limit the field stop diameter and hence widest apparent field. I work around 30x with mine and 76degree AFOV.

Peter
 

DRodrigues

Well-known member
Aotus,
Have a look at cr-binobirding
The linear binoviewer aren't easy to use with spotting scopes since these "erect" the image, so result in a up-side and horizontally inverted image when used directly with spotting scopes...:cry:
 
ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia

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