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I'd like to know more about bino viewers.

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#1 Szumi

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Posted 18 September 2021 - 03:14 PM

I have two scopes, a C8 Edge and a Stellarview 80mm.  I have a Baader MKVI 8-24 eyepiece and I'd need another one.

 

Would a binoviewer work with both scopes? 

 

Which binoviewers should I consider? 

 

Is a binoviewer best on an alt az mount or will a eq mount work?  I can configure my ieq45pro for alt az.

 

Anything you can tell me about binoviewers that I likely don't know would be welcome information.

 

Thanks,

 

Szumi


Edited by Szumi, 18 September 2021 - 03:15 PM.

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#2 paul hart

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Posted 18 September 2021 - 03:42 PM

Hi Szumi

 

I have an old pair of Burgess binoviewers which work very well with both my Stellarvue 80 mm refractor as well as a 127 Orion Maksutov. Maks/SCT's do not need an adapter because there's enough range to allow for getting focus. I use a 1.9x OCA with the refractor, but you can also use a 2x barlow.  What I like best about BV'ers is I'm much more relaxed when viewing. I've also used it with my dob on dso's with an OCA. There's a slight loss of light but unless observing very faint objects I barely notice it. Binoviewers shine on the moon and planets where I see more detail with less eye fatigue. I see a little bit of 3-D effect on globular clusters. 


Edited by paul hart, 18 September 2021 - 03:52 PM.


#3 Bob4BVM

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Posted 18 September 2021 - 03:43 PM

Lots of resources and reviews  and experienced advice on the BVer forum here on CN !

CS
Bob



#4 ngc7319_20

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Posted 18 September 2021 - 03:45 PM

I have two scopes, a C8 Edge and a Stellarview 80mm.  I have a Baader MKVI 8-24 eyepiece and I'd need another one.

 

Would a binoviewer work with both scopes? 

 

Which binoviewers should I consider? 

 

Is a binoviewer best on an alt az mount or will a eq mount work?  I can configure my ieq45pro for alt az.

 

Anything you can tell me about binoviewers that I likely don't know would be welcome information.

 

Thanks,

 

Szumi

The C8 Edge will probably be easier, since SCTs have lots of back focus.  Whether it works on the Stellarvue 80 is unclear. Typically a binoviewer will need 5 inches of back focus (unless you add some Barlow-like device).

 

Various Barlow-like devices can be used to fix back focus issues, though they generally increase the power / magnification.  This might be ok for planets, but maybe not if you are trying for wide views.

 

Which bino?  I don't have enough experience to tell you.  I like Zeiss / Baader and Denkmeier, but these can be fiddley to make focus, etc.  There are many good brands.  TeleVue is one of the easier ones to use, owing to their 2x BinoView lens that eliminates many back focus issues (though it doubles the power).  Baader and Denkmeier also have various add-on lenses to help make focus, though they tend to need real-time adjustment, etc.

 

Alt-Az mount is easier, since orientation (up direction) is fixed and makes the bino more stable mechanically.  With an EQ mount you will often need to rotate the bino -- sometimes it will try to rotate on its own -- and sometimes it will flip down and try to dump out the eyepieces.



#5 spereira

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Posted 18 September 2021 - 04:00 PM

Moving to Binoviewers.

 

smp



#6 Spikey131

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Posted 18 September 2021 - 04:12 PM

I have a C8, two binoviewers (Baader Maxbright and WO) and pairs of Baader Zooms as well as TV 24 and 19 Panoptics.  They all work well together.  I need to use the zooms without any eye guards to fit my face.  The Televues are more comfortable.

I also use them with a TV 76, but for this I need the Baader Zeiss prism and a 1.25x GPC to achieve focus.  What you will need with the Stellarview, I don’t know.

 

I used the with tracking and non-tracking mounts and they work fine.



#7 kroum

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Posted 18 September 2021 - 10:24 PM

I’m my opinion, the major advantage of binoviewers vs. mono viewing, is the reduction in fatigue.  When you can have both eyes open, you can relax and concentrate on the view itself, rather than being distracted by the “noise” coming from your closed eye.

 

to further this, I think you should maximize your viewing comfort when binoviewing.  Meaning, comfortable eye relief eyepieces, and a tracking mount so that you can *JUST* look.

 

Binoviewers take some fiddling to set up and focus properly, they also aren’t well suited for low power wide field views, which are another couple of reasons why a tracking mount compliments the experience.  If you have to constantly nudge the scope, or re-find the object while you’re fiddling with focus and eye placement, you’re not concentrating on the viewing experience.


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#8 jprideaux

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Posted 19 September 2021 - 07:51 AM

All good advice above.  To elaborate some...

 

OCA - optical corrector assembly - basically a barlow with perhaps an additional corrective feature.

It's main job is the barlow effect that moves the focal point out farther to help make-up for the light-path needed in the binoviewer. It screws into the binoviewer itself.    Note that the farther the barlow is away from the eyepiece, the more the magnification.  Sometimes people will screw it into the 1.25" diagonal before the binoviewer if the OCA that they happen to have is not quite high-power enough to get the job done if screwed into their binoviewer.  OCAs come in various powers.  For example 1.3x, 1.6x, 2.0x, 2.3x, and more.

 

Most of the BV designs (except the linear version) need an extra 100mm (or so) of light-path that need to somehow be made-up for. For example, if you are at infinity focus with a particular eyepiece without the binoviewer and then use that same eyepiece with the binoviewer, you will need to rack the focus in around 100mm.   That won't be possible with many scopes.  Using an OCA with an eyepiece without a binoviewer will require you to move your focus position out.  For example, with my refractor, I need to add an extension tube when using a OCA without a binoviewer.  When doing this, when I add the length of the extension tube to the focus travel left for my focuser, if the sum exceeds 100 mm I can then remove the extension tube and use a binoviewer (with the OCA) and get infinity focus. 

 

There are also special diagonals in which some binoviewers can directly screw into to save a bit in light path which can let you get away with using a lower-power OCA to reach focus.  Some people with DOBs also move their primary mirror up a bit for this same reason.

 

Scopes that focus by moving the mirror (like the C8) typically have a much greater focus range and you may not need any OCA to reach focus.  The only down-side is that with moving the mirror, you may not be working at F10 anymore and you may be loosing a bit of aperture and the center obstruction becoming a bit more in percentage.  Most people simply don't worry about that.

 

Some binoviewers also have "switching" options to easily move various different OCA into play for different magnifications.

 

The linear binoviewer is a special case.  It's design has two transfer lens in play which makes the total light-path  actually zero for the binoviewer - therefore it can be used with any scope that you can otherwise reach focus without a binoviewer.  It does have a few drawbacks - otherwise everyone would simply be using them.  They are a bit more complicated with more air-glass interfaces and are more prone to internal reflections.  They split the pupil for each eyepiece which has some strange effects when used for terrestrial viewing with how out-of-focus things look.  The design has an internal field-stop of 17.4mm which will make any eyepiece used also be limited to a 17.4 field-stop.  The complexity of the design also means that you need to have your eyes just in the right place for the image complexity to work - so eye placement is less forgiving than for conventional binoviewers.

 

I personally have both the Williams Optics (WO) BV with the supplied 1.6x OCA and 20mm eyepieces as well as the Orion Linear BV for which I bought the Baader 18mm orthoscopic eyepieces due to the field-stops being a good match.  I also bought the Celestron 10mm Ultima wide eyepieces for when I want to use either BV with more high-power.   I typically use my WO BV for high power (since I have to use the OCA with it) and the Linear BV for lower power.  I can even use a .66 reducer with the Linear BV for even lower power.  The linear is more finicky with getting the eye-position just right but I enjoy using it.  I also enjoy using the WO BV for higher power.  

 

Viewing comfort is HUGE for any visual observation and also important when using BVs.  Most visual astronomers find viewing more comfortable with Alt-Az mounts. 

 

Some people do like using two zoom eyepieces with BVs. Some other people prefer using single-FL eyepieces with BVs.  It is really up to individual preference.

 

Others are big fans of the BVs with OCA switching capability.

 

Since you are using 2 eyepieces, the width of the eyepieces matter for your inter-pupil distance as well as your face geometry.  Some people have issues with really fat eyepieces and prefer to avoid them.  You would have to find out if two Baader MKVI 8-24 used together causes you any issues in comfort.  

 

With whatever BV you get, spend some time working with it (a few days) before drawing any final decisions about whether it is for you.  I almost sent my Linear back after a day because I was not yet used to its peculiarities.  But after working with it a few more days, I learned how to use it and now really enjoy it.  I also was initially frustrated with the Williams Optics BV since I could not reach focus with my refractors even with the supplied 1.6x OCA.  Then I learned that I could screw the 1.6x OCA into 1.25" diagonal to make it an effective 2.2x OCA and reach focus.  I could alternatively have purchased the WO 2.0 OCA and that would have also worked with my refractor.

 

I personally greatly prefer using two eyes for all my visual observation!


Edited by jprideaux, 19 September 2021 - 07:53 AM.

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#9 dustyc

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Posted 19 September 2021 - 07:02 PM

The Linear bino doesn't dim the view like the beam splitter types. Handy when you're teasing out faint fuzzies. 



#10 Escape Pod

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Posted 20 September 2021 - 12:18 PM

Wandering into this topic with the same fundamental questions as the OP. As such, your detailed response was especially  helpful, jprideaux.
 

I like the idea of viewing planets and especially the moon through the binoview. But I am especially interested in doing more widefield nebula and other DSO viewing. I recently ordered an APM 24mm that I plan to use with my 80ED frac for widefield targets like the North American Nebula and Milky Way panning across Albireo etc… .

 

I gather from your post that  the linear binoviewer like the one by Orion is the way to go here for a short tube frac because they don’t require a Barlow.  But are binoviewers the right way to go here? How would you compare the experience of a short tube refractor like the ED80 to a dedicated set of binoculars?

 

 

 

All good advice above.  To elaborate some...

 

OCA - optical corrector assembly - basically a barlow with perhaps an additional corrective feature.

It's main job is the barlow effect that moves the focal point out farther to help make-up for the light-path needed in the binoviewer. It screws into the binoviewer itself.    Note that the farther the barlow is away from the eyepiece, the more the magnification.  Sometimes people will screw it into the 1.25" diagonal before the binoviewer if the OCA that they happen to have is not quite high-power enough to get the job done if screwed into their binoviewer.  OCAs come in various powers.  For example 1.3x, 1.6x, 2.0x, 2.3x, and more.

 

Most of the BV designs (except the linear version) need an extra 100mm (or so) of light-path that need to somehow be made-up for. For example, if you are at infinity focus with a particular eyepiece without the binoviewer and then use that same eyepiece with the binoviewer, you will need to rack the focus in around 100mm.   That won't be possible with many scopes.  Using an OCA with an eyepiece without a binoviewer will require you to move your focus position out.  For example, with my refractor, I need to add an extension tube when using a OCA without a binoviewer.  When doing this, when I add the length of the extension tube to the focus travel left for my focuser, if the sum exceeds 100 mm I can then remove the extension tube and use a binoviewer (with the OCA) and get infinity focus. 

 

There are also special diagonals in which some binoviewers can directly screw into to save a bit in light path which can let you get away with using a lower-power OCA to reach focus.  Some people with DOBs also move their primary mirror up a bit for this same reason.

 

Scopes that focus by moving the mirror (like the C8) typically have a much greater focus range and you may not need any OCA to reach focus.  The only down-side is that with moving the mirror, you may not be working at F10 anymore and you may be loosing a bit of aperture and the center obstruction becoming a bit more in percentage.  Most people simply don't worry about that.

 

Some binoviewers also have "switching" options to easily move various different OCA into play for different magnifications.

 

The linear binoviewer is a special case.  It's design has two transfer lens in play which makes the total light-path  actually zero for the binoviewer - therefore it can be used with any scope that you can otherwise reach focus without a binoviewer.  It does have a few drawbacks - otherwise everyone would simply be using them.  They are a bit more complicated with more air-glass interfaces and are more prone to internal reflections.  They split the pupil for each eyepiece which has some strange effects when used for terrestrial viewing with how out-of-focus things look.  The design has an internal field-stop of 17.4mm which will make any eyepiece used also be limited to a 17.4 field-stop.  The complexity of the design also means that you need to have your eyes just in the right place for the image complexity to work - so eye placement is less forgiving than for conventional binoviewers.

 

I personally have both the Williams Optics (WO) BV with the supplied 1.6x OCA and 20mm eyepieces as well as the Orion Linear BV for which I bought the Baader 18mm orthoscopic eyepieces due to the field-stops being a good match.  I also bought the Celestron 10mm Ultima wide eyepieces for when I want to use either BV with more high-power.   I typically use my WO BV for high power (since I have to use the OCA with it) and the Linear BV for lower power.  I can even use a .66 reducer with the Linear BV for even lower power.  The linear is more finicky with getting the eye-position just right but I enjoy using it.  I also enjoy using the WO BV for higher power.  

 

Viewing comfort is HUGE for any visual observation and also important when using BVs.  Most visual astronomers find viewing more comfortable with Alt-Az mounts. 

 

Some people do like using two zoom eyepieces with BVs. Some other people prefer using single-FL eyepieces with BVs.  It is really up to individual preference.

 

Others are big fans of the BVs with OCA switching capability.

 

Since you are using 2 eyepieces, the width of the eyepieces matter for your inter-pupil distance as well as your face geometry.  Some people have issues with really fat eyepieces and prefer to avoid them.  You would have to find out if two Baader MKVI 8-24 used together causes you any issues in comfort.  

 

With whatever BV you get, spend some time working with it (a few days) before drawing any final decisions about whether it is for you.  I almost sent my Linear back after a day because I was not yet used to its peculiarities.  But after working with it a few more days, I learned how to use it and now really enjoy it.  I also was initially frustrated with the Williams Optics BV since I could not reach focus with my refractors even with the supplied 1.6x OCA.  Then I learned that I could screw the 1.6x OCA into 1.25" diagonal to make it an effective 2.2x OCA and reach focus.  I could alternatively have purchased the WO 2.0 OCA and that would have also worked with my refractor.

 

I personally greatly prefer using two eyes for all my visual observation!



#11 ngc7319_20

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Posted 20 September 2021 - 12:53 PM

The Linear bino doesn't dim the view like the beam splitter types. Handy when you're teasing out faint fuzzies. 

I think this is not true.  While there is no beam splitter prism, each eye only gets light from half the aperture.  So in that sense, yes the image is dimmed.


Edited by ngc7319_20, 20 September 2021 - 12:56 PM.

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#12 kroum

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Posted 20 September 2021 - 01:02 PM

Wandering into this topic with the same fundamental questions as the OP. As such, your detailed response was especially  helpful, jprideaux.
 

I like the idea of viewing planets and especially the moon through the binoview. But I am especially interested in doing more widefield nebula and other DSO viewing. I recently ordered an APM 24mm that I plan to use with my 80ED frac for widefield targets like the North American Nebula and Milky Way panning across Albireo etc… .

 

I gather from your post that  the linear binoviewer like the one by Orion is the way to go here for a short tube frac because they don’t require a Barlow.  But are binoviewers the right way to go here? How would you compare the experience of a short tube refractor like the ED80 to a dedicated set of binoculars?

I know this isn’t directed toward me, but I think I can also answer…

The liner binoviewer would be suited to the 80mm ED refractor because you are guaranteed to be able to focus without having to use a optical path corrector, or to shorten the tube of your refractor, however the linear binoviewer has a reduced clear aperture compared to the prism types. I think it’s 16-17mm -ish, compared to 22mm for the cheap Chinese bvers and 27mm for the premium bvers like the Baader and denkmeyers.

 

You will get significant vignetting if you try to use a 24mm super wide angle eyepiece like the 24mm APM UFF with the liner binoviewer since it has a field stop larger than the clear aperture of the binoviewer.  You could probably use the 18mm APM though.

 

So, the linear binoviewers and the prims binoviewers are kind of half dozen of one and 6 of the other as far as low power wide fields of view go… what you gain by not using an optical path corrector, you lose on the reduced clear aperture…


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#13 Escape Pod

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Posted 20 September 2021 - 01:08 PM

I know this isn’t directed toward me, but I think I can also answer…

The liner binoviewer would be suited to the 80mm ED refractor because you are guaranteed to be able to focus without having to use a optical path corrector, or to shorten the tube of your refractor, however the linear binoviewer has a reduced clear aperture compared to the prism types. I think it’s 16-17mm -ish, compared to 22mm for the cheap Chinese bvers and 27mm for the premium bvers like the Baader and denkmeyers.

 

You will get significant vignetting if you try to use a 24mm super wide angle eyepiece like the 24mm APM UFF with the liner binoviewer since it has a field stop larger than the clear aperture of the binoviewer.  You could probably use the 18mm APM though.

 

So, the linear binoviewers and the prims binoviewers are kind of half dozen of one and 6 of the other as far as low power wide fields of view go… what you gain by not using an optical path corrector, you lose on the reduced clear aperture…

Goodness. Field Stop. Didn’t know I didn’t know about that. I think you just answered my question. Googling 15x70 Barska Binoculars :)


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#14 kroum

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Posted 20 September 2021 - 01:28 PM

Goodness. Field Stop. Didn’t know I didn’t know about that. I think you just answered my question. Googling 15x70 Barska Binoculars smile.gif

Having owned a pair of 15x70 binoculars before, they are great for the Milky Way and general browsing around the stars, but they are quite a different experience from binoviewing through a telescope.

 

15x70 used hand-held are a recipe for a lot of neck and upper back strain very quickly.  If you’re sitting and can prop your elbows on the arm rests, that’s a lot better.  If you have them on a tripod, that’s also good, but you’ll be craning your neck to look at anything much higher than the horizon.  A parallelogram mount and a reclining chair is probably a very good combo, but for viewing comfort and ergonomics, binoviewers on a telescope can only be beat by 90 degree bino-scope probably.


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#15 Escape Pod

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Posted 20 September 2021 - 02:04 PM

Sounds like there's no avoiding getting my head around field stops. :)

 

Do traditional, prism-style binoviewers have similar issues with wide eyepieces? If not, I'm thinking I could still achieve some good fun exploring the moon and smaller DSOs like m42 through my 150mm Frac. 

 

Are virtually all refractors limited in terms of back focus? I know my SW 80ED f7.5 has some extra focus travel ability for astrophotography....

 

 

Having owned a pair of 15x70 binoculars before, they are great for the Milky Way and general browsing around the stars, but they are quite a different experience from binoviewing through a telescope.

 

15x70 used hand-held are a recipe for a lot of neck and upper back strain very quickly.  If you’re sitting and can prop your elbows on the arm rests, that’s a lot better.  If you have them on a tripod, that’s also good, but you’ll be craning your neck to look at anything much higher than the horizon.  A parallelogram mount and a reclining chair is probably a very good combo, but for viewing comfort and ergonomics, binoviewers on a telescope can only be beat by 90 degree bino-scope probably.



#16 dustyc

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Posted 20 September 2021 - 02:38 PM

I think this is not true.  While there is no beam splitter prism, each eye only gets light from half the aperture.  So in that sense, yes the image is dimmed.

The linear splits the pupil into 2 halves, each getting the full amount. The exit pupil is a half moon shape. 

There is no polarization effect either. 



#17 kroum

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Posted 20 September 2021 - 02:48 PM

The linear splits the pupil into 2 halves, each getting the full amount. The exit pupil is a half moon shape. 

There is no polarization effect either. 

So you mean that your left eye sees the left half of the image and your right eye sees the right half of the image?



#18 jprideaux

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Posted 20 September 2021 - 07:34 PM

So you mean that your left eye sees the left half of the image and your right eye sees the right half of the image?

Each eye only sees half the image if you back your eyes up an inch or two from the eyepiece but as you bring your eyes into position, each eye sees the entire image.  

 

I think the "each eye sees full light intensity" only applies under very special circumstances like if your pupil dilation is fairly small and that full-intensity half pupil completely covers your pupil.  

 

Anyway, if your goal is to see the Milky Way low-power with as large a FOV as possible, the best optical device is binoculars.  Yes for ergonomics with larger apertures, a binocular telescope with angled viewing would be most comfortable unless you want to lay in a lawn-chair and use a parallelogram mount.  For higher powers like for planets or seeing craters close-up on the moon, it is better to use a telescope and binoviewer.   

Those that love refractors (like me) like to try to use our binoviewers with as low power as possible and try all sorts of tricks to either not need a OCA or as week of one as possible.  But most of us agree that we do like using our binoviewers once we figure out focus and get things dialed in!  Going high power is fairly easy with binoviewers and the extra light-path (for the designs that have the extra light-path) then works to your advantage.


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#19 Szumi

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Posted 21 September 2021 - 03:57 PM

I thank you all for the replies, there is enough information in them for me to start me on my way looking into this way of viewing. 

 

Szumi




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