Should I get binoviewers?

[Kronos831]

Hello, it’s been a while, I ve been studying for my English proficiency exam and haven’t been able to do much observing. Aside from catching glimpses of Jupiter and Saturn here and there, it’s been a quiet summer. Now that we’re drifting into winter, it’s time I made some upgrades to My equipment, as here in Greece, we have a tradition of knocking on people s doors on Christmas Eve, singing the carols and be given money and candy in return.Every year I grab my violin and stay from day to night playing get enough to upgrade my collection 😁 , lucky me . Primarily , I will be getting a 14mm Explore Scientific 82° eyepiece and the Skywatcher heritage 130p to help me observe in remote locations. The last addition I am considering to buy is a pair of binoviewers. I am very excited about this concept as i find using only one of my eyes during planetary and sometimes nebula observation rather uncomfortable. I am planning to using this on my 8” Skywatcher dob, and maybe the heritage 130p.When I buy the heritage I will get the 2 stock eyepieces I got with my dob , so I will have 2 sets of eyepieces ready to go, then I will buy a second 8mm bst starguider  for these rare clear nights and maybe in the future another 14mm explore scientific. The question is, will they work with my eyepieces or my telescope? What will I need besides a Barlow and which binoviewers should I get?

[mikeDnight]

If you haven't already tried using a binoviewer I'd suggest doing so at an astronomy club before buying one. Not everyone gets along with them!

Personally I love them and would suggest you buy a cheap model, which are generally optically and mechanically very good. A 2X Delux Skywatcher barlow is excellent and will allow you to screw just the barlow lens element directly into your binoviewer, or use the full length barlow for a little more amplification. Don't waste money on expensive high end eyepieces for bino viewing. A good plossl or orthoscopic pair will deliver stunning lunar and planetary views that will equal the very best single planetary eyepieces in performance. Binoviewers are ok on brighter deep sky objects but generally they are best for moon and planets, where as deep sky is often better observed using a single quality wide field eyepiece.

[joe aguiar]

i only use mine for moon and planets

remember the binoviwer splits the light into two cones to give each eye light, unlike re binos that have a scope for each eye. So the aperture is spilt in half so if u have a 6" sct its like viewing from a 3" scope.

iam not sure i heard of people using it for dso because of this and most dso are dim to begin from

last i kinda find it so i dont use it much

joejaguar

[Whistlin Bob]

I think people's experiences vary- I can only relate mine which has had good and bad about it.

I bought some William's Optics Binoviewers second hand and in excellent condition through this forum- they came with a 1.6x and a 2x barlow and 2x 20mm Ultra Wide Angle eyepieces. So lets get the bad out of the way:

- Unless adjusted correctly for the distance between my eyes it's quite hard to form a single image. This makes it hard to share views with people you may be observing with.

- Because of the UWA eyepieces and where you put your head when you're looking through both eyes they're quite susceptible to reflections- I need a hood when I use them.

- I use them with an 8" (same as yours) and a 14" dob- I can only achieve focus with 1 of the barlows in the 8" and both of them in the 14", so it's always quite a high magnification exercise when I use them.

- In cold weather they're very susceptible to misting over.

And the good? Only one thing:

- The view on bright targets with 2 eyes in good conditions is absolutely stunning. Fabulous contrast and detail, and an illusion of three dimensions. I've read a lot about "spacewalk" eyepieces- that's exactly how I'd describe the BV's on open clusters and globulars- completely immersive. The moon is stunning, rendering enormous detail and making you feel like you're actually there. I've not had a really great planetary view through them, but that's more about the low altitude of the planets in the UK this year. I've a tingling excitement for when the planets are a little higher. 

I've had to learn what conditions to use them in to avoid disappointment. But when those conditions are met it's just a fabulous experience and extremely enjoyable. I don't regret their purchase for one second. 

Oh- and I've had to Velcro a weight onto the bottom end of the telescope to keep it in balance...

 

[Kronos831]

Thanks for the advice! I will definitely try to get in touch with my local astronomy club. However, which model should I get?

(Preferably models from First light optics (FLO) )

[mikeDnight]

I bought a revelation binoviewer around ten or twelve years ago which cost me £99. It has performed admirably alongside much more expensive, and supposedly superior models, and I have no desire to "upgrade".

Also, with the moon and planets through my 100mm apo, the binoviewer, 2X SW Delux barlow and paired cheap 16.8mm orthoscopics or plossl's out perform any and every high end single eyepiece that's ever been in side by side comparison. It's truly jaw dropping!

[joe aguiar]

mine is an antares bino viewer i think that cost 199 cdn

joejaguar

[Whistlin Bob]

@mikeDnight I don't how true it is, but I've been told that the internals of most  binoviewers are more or less identical. I'm not sure how true this is, but it would certainly explain how yours perform so well. 

If the OP wants to maximise budget at FLO I wouldn't be scared to order the OVL ones they stock, although I've no experience of them.

Edited November 9, 2019 by Whistlin Bob

[Stu]

3 hours ago, Whistlin Bob said:

If the OP wants to maximise budget at FLO I wouldn't be scared to order the OVL ones they stock, although I've no experience of them.

They look exactly the same as the TS ones I have which are excellent value and perform very well.

Just a note, binoviewers dont 'turn a 6" scope into a 3" one'. Yes, the light is halved to each eye but the resolution is preserved and your brain does some very clever stuff combining the image. I really enjoy mine for high power lunar and solar viewing where they help combat floaters and provide very relaxed observing and fantastic detail when seeing allows.

[mikeDnight]

Exactly what Stu says!

Whatever jiggery pokery goes on in the binoviewer the brain puts back together again flawlessly. In fact I'd say there's a significant gain in the ease with which observable detail reveals itself, as both retina's are deciphering the information in the image rather than just one. So in a sense, by using a binoviewer, you are increasing the potential power of a telescope, not reducing it. 

[John]

I've tried binoviewers a few times and currently have a set of the William Optics ones on loan from FLO.

I've not really taken to them to be honest. I get nicely merged images and the view of the moon (for example) looks nice with both eyes but I've not felt them to be something essential in my toolkit.

Maybe I'll become converted someday ?. Or possibly not.

[JTEC]

They add a new dimension to lunar and planetary observing, as many have said. Don’t assume though that they’re no good on DSOs!  M42 is utterly spectacular and indescribably immersive.  Brighter DSOs like M27 are also enhanced, as are globs and open clusters. You’ll never look back. 

It helps that expensive widefield eyepieces are not required. My preference is for orthos and Televue plossls down to about 8mm.  I once tried a pair of 13mm Ethoses (not both mine!) and while the view was spectacular it was also quite confusing. 

People sometimes report that they can’t get the hang of binoviewers.  I’m convinced that this has nothing to do with any special skill - imv, if you can use binoculars you can use a binoviewer.  Problems arise I think when the bino isn’t accurately collimated, interpupil distance isn’t spot on and exact differential focusing can’t be achieved; also, if eyepieces can’t be orthogonally seated and held truly on axis when rotated to achieve focus. These are constructional issues to do with the particular bino being used and nothing to do, imo, with any mysterious binoviewing skill being required. In fact, once the set up is good, binoviewing is wonderfully relaxing, floaters are less obtrusive and, thanks to whatever the brain does in terms of combining the data from two eyes, you see more. 

I should add that my experience has been with refractors and a C11; never tried them with a Newt.

Edited November 9, 2019 by JTEC

[Rob Sellent]

I've recently purchased an unbranded set of binoviewers to work out whether they should be part of my tool kit or not. As far as I can gather they look like Kunming's generic binoviewers which can be found in the likes of TS Optics, Orion, Omegon and William Optics which I believe are all internally identical. That is, all prisms and correcting glass are 25mm in diameter whilst the clear aperture on each eyepeice side is around 20-21mm.

With a few sessions under my belt I can only repeat the general consensus herein. Most objects or starfields appear very immersive, almost three dimensional in appearance. With both eyes working subtle detail becomes a tad more apparent, comfort is slightly augmented and there is a reduction of floaters at higher magnifications.

Obvious downsides include added weight and possible balancing issues, doubling up on eyepieces and a slight dimming of the object. In my case, I've purchased another zoom so as not to buy any more eyepieces and restrict myself to observing brighter objects. Other downsides is the necessary increase in magnification required to reach focus (typically you need to use a glass path corrector (GPS) or Barlow) and to avoid using eyepieces whose field stop is larger than the clear aperture of the binoviewer. This means low power and/or wide field observing is very difficult to achieve with most binoviewers.

Needless to say, I think you ought to purchase your binoviewers secondhand. My own came with a pair of decent 20mm eyepieces, 1.6x GPS and nice case for under €150. If you decide they're not for you, I feel you could easily move them on without losing out.

Finally, is it worth it? This is a very subjective call. Like @John, I feel they're not essential to observing. However, like all the others in this thread, I do feel they add a lovely dimension to observing and have certainly increased my enjoyment and viewing experience at a relatively low cost.

 

[Geoff Lister]

In addition to giving "depth" to planets, nebulae and the Moon; at my advancing years, I have floaters in my eyes, and I find that these are much less obvious when the image is in both eyes.

Geoff

[Stu]

Regarding the comments from @Johnand @JTEC it took me a number of years and about 4 pairs of binoviewers before I found a setup that worked for me. I have had 6 pairs in total I think, perhaps more!

The best pair I have are Baader Mark IV which only have a single set screw for the eyepiece holders but the tolerance is very tight and the collimation is excellent. Equally I have had a couple of pairs of the Kunming ones and have found these excellent too. The self centring eyepieces holders and dipotre adjustment helps to keep everything aligned and balanced focus achieved.

In general I have found that linger focal length eyepieces work better, and personally prefer to Barlow these than use natively shorter focal lengths, it just seems to work better. I have a lovely pair of Zeiss ex microscope orthos with low scatter, excellent transmission and good eye relief which I won't ever part with.

I mainly use mine on my Tak, which has enough in focus to allow them to work natively, but I do generally prefer a single wide angle eyepiece for low power still. I persevered because of floaters in my observing eye which affects my lunar, solar and planetary observing, particularly with a 4" scope where exit pupils are small. It has taken a long time, involving quite an element of brain training I think, but I now solely binoview for solar and lunar, and often for planetary. It is well worth persevering.

[tooth_dr]

I use binoviewers for h-alpha solar viewing, and it’s pretty awesome. The biggest advantage for me is public outreach - people naturally take to using two eyes versus one. When there is only one EP there is some reluctance to try it out, but with BVs they dive straight in and feel more comfortable. There is a bit of adjustment but the narrowest setting even suits down to 3-4 year olds too. 

Edited November 10, 2019 by tooth_dr

[Alan64]

19 hours ago, joe aguiar said:

i only use mine for moon and planets

remember the binoviwer splits the light into two cones to give each eye light, unlike re binos that have a scope for each eye. So the aperture is spilt in half so if u have a 6" sct its like viewing from a 3" scope.

iam not sure i heard of people using it for dso because of this and most dso are dim to begin from

last i kinda find it so i dont use it much

joejaguar

Regarding resolution per inch of aperture, would you get that of a 6" for each eye, or that of a 3" still?

[tooth_dr]

6 minutes ago, Alan64 said:

Regarding resolution per inch of aperture, would you get that of a 6" for each eye, or that of a 3" still?

Is it light gathering that is halved? So like comparing 6” with 4.25” rather than 3”?

Edited November 10, 2019 by tooth_dr

[Alan64]

7 minutes ago, tooth_dr said:

And without being too pedantic if light gathering is halved wouldn’t that mean comparing 6” with 4.25”?

Are you saying that the resolution per eye would receive that of a 4.25"?

[John]

22 minutes ago, tooth_dr said:

Is it light gathering that is halved? So like comparing 6” with 4.25” rather than 3”?

I started a thread on this a few years back on this topic. It might be of interest:

 

[Rob Sellent]

35 minutes ago, tooth_dr said:

I use binoviewers for h-alpha solar viewing, and it’s pretty awesome

Just out of interest, how do you get focus? I've got a Lunt 60mm B1200 Tilt tuned with Moonlite. Using a 1.6x glass corrector I can't reach focus. Do you think a 2.6x glass corrector might get there?

- - - -

Some more interesting links on bino summation and the such here

[johninderby]

One point that I rarely see raised when discussing binoviewers or binoculars is that they aren’t suitable for everyone. In some people using them causes eye strain and they just aren’t comfortable to use. This has nothing to do with colimation etc but simply that some people have issues with vision convergence. Particularily if they have different levels of vision in each eye. One person may rave about how great binoviewing is while the next may find them worse than single eye viewing. 

Best thing is to try a few different ones to see if they suit you. 

Edited November 10, 2019 by johninderby

[Stu]

28 minutes ago, Alan64 said:

Are you saying that the resolution per eye would receive that of a 4.25"?

Each eye gets full aperture in terms of resolution (assuming no internal vignetting due to undersized prisms). Regarding brightness, it is a more complex issue but your brain has some clever mechanisms it uses when combining images, so don't think you end up with an image half as bright. You don't.

[Highburymark]

I have a pair of the OVL binoviewers (£150-ish new in the UK) as well as Baader MkV. Use them for solar ha with a Lunt LS60 and lunar with my refractors. Would happily recommend the OVL - great value

[mikeDnight]

3 hours ago, Alan64 said:

Are you saying that the resolution per eye would receive that of a 4.25"?

I don't go along with the often stated claim that the light grasp is halved. If you use a 6" telescope you will still get the full resolution of a 6" aperture, but with the added advantage of doubling your sensitivity to fine detail (the resolution remains that of a 6"), as you're using both your retinas. Neither is the light grasp halved! You will get the same light grasp of a 6" scope as light grasp is determined by the aperture. The binoviewer will divide the light recieved by the aperture and there will be some minimal light loss due to reflection on the prism surface, though anti reflection coatings greatly reduce such reflections. The light that enters the prism leaves the prism, that is why prism diagonals are so highly rated. On leaving the prisms the combined light is recieved by both retinas and the brain receives all the light from the combined light paths. So you are essentially using the full aperture of a 6" with the exception of very minimal loss at the prism. I use a 100mm refractor and objects like the Orion nebula, M13, M27 lose none of their wow factor, and are certainly not equal to a 2" or 3" aperture but still retain the full punch of the 4" apo.