Binoviewers vs. Binoscopes

[@ishanr8697]

I have the Skywatcher Flextube 305 mm, with a Mitotoyo microscope binoviewer converted for astronomical use. There are tradeoffs, but I can get good views from 60x up to 450x magnification with 1.25 inch eyepieces. All in, I paid around $3500 for the set-up, including go-to. For my budget, I think this is impossible to beat. A 500mm x2 binoscope in a low light pollution area is the dream, but for now, it's just a dream.

[@astronomydrawings]

Well, at least you can easily carry yours up a mountaintop. With my binos that would be a bit more difficult... 🤣 Cheers and best of luck with your setup! Clear skies!

[@ishanr8697]

@@astronomydrawings I struggle to carry mine up 5 flights of stairs, don't think I'll be climbing mountains with it any time soon!

[@MyAstronomyNights]

Brilliant! A question I have been thinking about for a while now, thanks for another great video 😁

[@astronomydrawings]

Thank you very much! 😆

[@atheosmonde]

The most fascinating thing about this, is this gentlemans english accent.

[@astronomydrawings]

Hahaha... Thank you, though I'm far from a native speaker. 😉

[@peters4040]

Great video. A rare look into these niche parts of the astronomy hobby. Here are a few details that I might add. 1) Binoviewers that do not merge at higher power might need to be sent in for collimation. 2) Binoviewers are better for skies that have some light pollution. The reduced brightness is far less noticeable since a reduction in brightness also reduces the skyglow. That having been said, I use a binoviewer but would have a binoscope if I could afford it and had a way to transport it. I find my binoviewer much more enjoyable than a single eyed view in my light-polluted backyard using my 10" dob. Once again I envy your equipment. - Pete

[@astronomydrawings]

Thank you for the comments! Well, you can only collimate a binoviewer so much and the bigger the binoviewer, the more small errors become apparent with high-power eyepieces. IMHO I also don't think that binoviewers would have an advantage over binoscopes under light-polluted skies because if you lose more light also your object becomes dimmer. Anyway, we astronomy enthusiasts tend to favour the equipment we have, and rightfully so. 😆 I fully concur with your conclusion and I too have observed exclusively with binoviewers in the past because I preferred observing with both eyes, even if it meant some (or even significant) light loss. Envy? Wait until you want to move my bino to a dark sky... 🤣 Cheers and clear skies to you!

[@mbaddah]

Thank you Peter for taking the time to explain these differences :) I currently own a 14.5" dobsonian and have shorter truss poles for my WO Binoviewer to reach focus. Tbh other than the moon and planets, views of DSO were too dim for my liking. I have been considering a Binoscope for some time but the unfortunate reality is that i'd never transport it to dark skies. I'm now thinking about upgrading my BV to something like a Baader MaxBright or Zeiss with better eyepieces and just accepting the compromise. I also purchased a pair of 100mm binoculars which are fantastic minus the neck pain :) So will upgrade these to 120/150mm APM binoculars for my true bino fix. I look forward to more of your videos, thanks!

[@astronomydrawings]

Thank you for your kind comments, Mohammed. 😊 Yes, every telescope setup is a compromise and where you win at light gathering power you will lose elsewhere, e.g. transportability. If you need to go to a dark site for your observations, a big binoscope's a bad idea so in your case that Maxbright or Denk II with power switch will probably give you a lot more satisfaction. And those 120/150mm binoculars would be a great add-on too. I'd be wondering which of both (binos or Dob+binoviewer) you'd use the most. 🤣 Cheers!

[@mbaddah]

@@astronomydrawings Thanks for the suggestions. I suspect those binoculars will be quite close to the dob+bv, i'll let you know if i ever do a comparison :D

[@marcorossi7739]

Ottimo video, Peter! Molto chiaro ed esplicativo, bravo!

[@astronomydrawings]

Grazie mille, Marco! 😆

[@streamrealfun]

thanks, Peter. Im into binoscopes since 2014. Complete gamechanger. Now I use 80mm APO, 120 ED and 300mm Binodob... last one is a hassle and not often in the field, as you mention might happen, but: a daydream at night, such wonderful DSO sessions! Highly recommend this type of visual astronomy

[@astronomydrawings]

Unfortunately binodobsons are too difficult to make and it's almost impossible to make a profit out of them. I heard that also JMI has stopped producing them, so that was the last commercial producer. Also Mr. Otte who built mine has stopped. It's a pity because, as you said from your own experience, there's no comparison... Enjoy your great setup! My compliments!

[@streamrealfun]

@@astronomydrawings thanks, a shame, no one does it no more! Had to ask so many people and wait 18 months for my custum made 300mm Binodob... john Dobson would do commercial Binodobs nowadays... and call them SBS: Sidewalk BinoScopes... enjoy your supernice bino-beauty!

[@BoogalyTheGreat]

I love the idea of viewing with both eyes! And I love the idea of objects appearing more 3-D. I’m leaning towards a binoscope, in the form of giant binoculars. Thanks for the vid, very helpful.

[@karylhogan5758]

Same

[@astronomydrawings]

Thank you very much!!! 😊

[@uhohDavinci]

Planetary views through that Binoscope must be spectacular! I hope I can build something like that one day.. Doesnt need to be mobile. A real "observatory" class setup.. Fantastic work.

[@astronomydrawings]

Thank you very much! Yes, planets (on a good night with excellent seeing) are almost like photographs. Be careful with building a binoscope because there are many pitfalls, especially it has to be very stable and rigid, otherwise you'll have difficulties merging the images.

[@Ko6pa]

What a remarkable video ! Such an important and easy to understand information, thanks a lot 👍👍

[@astronomydrawings]

Thank you very much for your kind words! I'm really happy that you found my video useful. 😊

[@Ko6pa]

@@astronomydrawings You are welcome 🤝 Two eyes vs one was also great 🔥

[@RSTI191]

You have provided one most informative Astronomical equipment videos I have seen You Tube. Explanation and graphics were spot on. It all boils down to what you want as far as view and pleasure. I have a 25" Obsession, an Astro Physics 155 EDF (mostly solar) and APM 150 Binoculars. Each has their own job/use/function. I use a binoviewer with both 25" and 155 EDF.. Thought smaller aperture, I find the most pleasing view is with the 150 binoculars. I live in Bortle 3 sky The 16" JMI binocular telescope sounds promising and excellent compromise between light gathering ability and a pleasurable view. Can't say thanks enough for the post...

[@astronomydrawings]

I can't thank you enough for your kind words. Well, the 16" binoscope may be a serious competitor for your 25" Obsession, but it will be more complicated to set up and use. Personally I've never been overly impressed by binoviewers and for some strange reason they never offer the same experience as true binoculars or binoscopes. But all of this is personal and it's not just about observing experience but also about sacrifice. As I said, I'll never transport my binoscope anywhere anymore... Cheers!

[@RSTI191]

@@astronomydrawings You are very welcome. I can only use my lowest power E/P's with the binoviewer on the 25" for planets. It's not just only a binoviewer I have use the lens portion of an Astro Physics barcon barlow to do it. Hence power is 2x. It may be great for planets, but doesn't work for deep sky unless someone figures out a way top make 60mm 2" E/P's small enough for interocular with the B/viewer. I would assume once the RB-16 is setup there isn't much to other than some minor collimation adjustments?? I think you mentioned you are in Australia. I'm in California with family in Melbourne. Thnx again..

[@RSTI191]

Well my friend, it appears you have yourself a very rare toy. I spoke with Jim Burr today, he's 84, retired not manufacturing them anymore. He did mention your setup in the land Down Under.

[@astronomydrawings]

@@RSTI191 If you have to use a 2x Barlow with your binoviewer then obviously you're having problems using it on faint and/or large objects. The more expensive binoviewers come with very good OCAs, some even 2" to avoid vignetting, and add only 1.2x power. Still it isn't the same as a binoscope because there still is significant light loss and you can forget 2" eyepieces, unless you're using the 2" Siebert model. So i take it that you've ordered the 16" JMI binos? Actually I would be very interested to hear how they hold up against your 25" Obsession. Theoretically the 16" binos should give you a little bit less light, but with binos you can never tell. I had the opportunity to compare my 18" binos to a 27" Ariete Dob, and it was hard to tell a difference, even though both were f/5. The binoscope offers much lower power and hence you're able to fit very large objects in the FOV, plus with both eyes the FOV seems significantly larger as well, so perhaps this illusion compensated the fact that (theoretically) the 27" captured more light? Your experience could be invaluable for other astronomy enthusiasts out there! Oh, and BTW, I'm in Italy... 😀

[@RSTI191]

What part of Italy are you from?

[@RefreshingViews]

Hi Peter, love the set up, love your skies, and love your drawings. I'll throw in the new-ish linear binoviewers that have a built in corrector so you can treat it like an eyepiece despite the longer length. I am using it to good effect in my C11 and 90mm Megrez with zoom eyepieces. As you say, equipment is all about a trade off with infinite variables of budget, portability and observing choices. Although you focussed on deep sky observing, I know a few observers who only use binoviewers for solar system viewing where a bit of light loss does not matter and we want high power views from the corrector. Of course, a binoscope won't provide extra resolution (albeit at a brighter image). Keep up the videos - and let us know when you are open for a star party!

[@astronomydrawings]

Thank you for your kind comments! Of course, it all boils down to personal preference, portability etc. As you highlighted, a binoviewer can do wonders on the planets and bright star clusters and you can easily take it with you to your perfect observation spot. I'm sure that you love it with your C11, also because you don't actually need a corrector. Thank you once more!

[@tadassiksnius3402]

Very informative video! Weather here in uk has been miserable for quite some time, but that didn't get rid of the need to try binoviewing. Subscribed and best of luck

[@astronomydrawings]

Thank you very much for your lovely comment and for subscribing of course. Hopefully you'll also like my next videos. Cheers and... if the weather's miserable in the UK, you're always welcome here in Italy. 😊

[@tadassiksnius3402]

@@astronomydrawings thank you :) We've been considering a little property in Sardinia after first holiday there. Best wishes. Your futures next door neighbour 😀

[@TJK-ko9wn]

Thanks for the video! I've always wanted to see a comparison like this. One thing to note though, is that the corrector protruding into the optical path, is not blocking the entire outer portion of the mirror, but just a relatively tiny area on one side. However, the amount of light coming from the scope is being divided in two by the binoviewer. So fainter objects will appear dimmer for that reason, more so than the corrector is blocking 50% of the light path. This will not be as noticeable on bright objects, as our brains working with both eyes will more than compensate for the difference.

[@astronomydrawings]

Thank you for the lovely compliment! 😊It depends on the corrector... Some are longer than others while some might actually fit the entire light cone. You are right about the beam splitter and the light loss (plus increased power) cannot be compensated by using both eyes. Hence objects, especially faint nebulae and galaxies, will always look dimmer, even with a 2" binoviewer.

[@TimK-1971]

@@astronomydrawings Something of an anomaly that I've notice, is that when I use my 20x80 Celestron binoculars to look at the moon, and switch over to looking through my 8" SCT (with only one eye) at 50x. Perceptually, they seem to be the same size. I suspect that our brain can perceive more than double the information with two eyes (@ 20x) than we can with one eye (@ 50x). What are you thoughts on this?

[@astronomydrawings]

@@TimK-1971 When using both eyes it looks like everything gets bigger... the FOV and the object. To me personally the difference is significant whereas others don't see a big difference in size. I suppose it's personal, how our brain processes the data of both eyes. Haven't you noticed the same with binoviewers?

[@TimK-1971]

@@astronomydrawings I've never had a chance to look through binoviewers. I have 4 pairs of binoculars though, and love each one of them. Someday I really hope to get to see the moon with binoviewers, and compare them to my 20x80's. Do binoviewers reveal 3D views of objects like the moon? Seeing the craters at decent magnification in true stereo vision is jaw dropping for me, more so than with just one eye through a telescope. I love sharing it with anyone walking by, just to see their reaction. Thanks for responding!

[@astronomydrawings]

@@TimK-1971 It's not possible to see any real 3D on astronomical objects because they're simply too far away. That being said, many people do experience a sort of "3D feel" when using binoviewers or a binoscope. This is merely an optical illusion, probably caused by chromostereopsis (slightly different chromatic aberrations in both eyepieces) so it's most notable on the Moon, planets and rich star clusters. Personally I find this effect much more pronounced in binoculars or binoscopes compared to binoviewers (which have never really satisfied me). In any case, there's simply no comparison to observing with both eyes, as you suggested. 😊

[@mikepaul6688]

Great video of such a niche area of amateur astronomy. Something that appears to be even rarer and more complicated would be a Schmitt-cassegrain binoscope. They seem like they would be a really nice fit for a binoscope though, due to the placement of the eye-pieces and the smaller size.

[@astronomydrawings]

There actually are some SCT binoscopes around, but they are limited in size, probably 8" or so at most. The problem is that their light goes out at the rear, at the centre of the telescope, and that this exit hole is 2" at most. Therefore, if you have to redirect this light towards the centre of two (bulky) SCTs in order to use them as a binoscope, you'll get some significant vignetting.

[@dirttrack1123]

I'm thinking 2 4se's saddled

[@douginorlando6260]

I remember reading a research paper that found a 20% improvement in seeing with binocular over monocular. The measurement of “seeing” was in terms of how much faster the observer would notice subtleties of the image.

[@astronomydrawings]

Hello Doug! Was this a medical test or a test done in dark conditions? Because if this were true, an 18" binoscope would make no visible difference at the eyepieces over an 18" monocular scope, whereas I can guarantee that the difference is significant. 😉

[@douginorlando6260]

Astronomy Drawings ... as I recall, it was not a measurement of ability to detect or not detect an image feature at very low light levels. It was more about picking out a feature in a cluttered scene. The brightness & contrast of all observations was set identical whether seeing through one eye or through both. There may be more measurements and findings about detecting JND (just Noticeable difference) in a dark image with no time limit but I don’t remember. I really liked the video and subscribed. The technical insight reminds me of Huygen optics KZbin channel.

[@astronomydrawings]

@@douginorlando6260 There's a study (don't remember the name from the top of my head but I mentioned it in my other video) that showed that summation depends on the complexity of the task with simple detection showing a much higher summation than pattern recognition. Perhaps you'd be interested: kzbin.info/www/bejne/Y6vIfKSan7KJqrM In the end, I'm not a scientist and surely won't pretend to have all the answers. They're just my impressions after having observed with this binoscope for 6 years and in the end the numbers don't really matter. I'm very happy that I can discuss this with you and especially that you like and even subscribed to my channel. Thank you very much! 😊

[@normaalewoon6740]

Actually, there's another solution that goes even further: night vision goggles. They may be as expensive as a big dob, but they offer several advantages: 1) more sensitive to light than your eye, adding at least a few magnitudes (depending on the quality). For example, a 16 inch dobson would get as powerful as a 1 meter one. This easily justifies a €7000 purchase for a high quality night vision tube 2) a 21 mm front lens, allowing for much lower magnifications and even more surface brightness on large, dim objects 3) sensitive from red to infrared, so you can see in h-alpha 4) usable on large telescopes as well as small ones, or without a telescope and just a 1x magnification You can use a binoscope and two monocular night vision devices (pvs-14), but you probably won't. The seeing advantage would apply to background noise in the nv tubes (similar to noise in crt monitors), which is a rather small improvement for a high cost. A binoviewer design (pvs-7) doesn't cost more than a monoviewer, so that's probably the best. Some people use a single monoviewer though, which sounds like a waste of potential to me The disadvantages are the 40 degree field of view, the limited lifetime and the many lenses in the light path, which will lead to distortions and vignetting. Night vision can be used in prime focus, but this will make it harder to watch with 1x magnification Personally, I prefer to do something totally else: simulating what I want to see. With a fast graphics card, I can render 3d nebulae, galaxies and even exoplanets in real time and explore them from nearby. Space engine is a 3d space simulator for this. I've also made some 3d nebulae in unreal engine myself. I still go out to watch space in reality, but my pc makes up for the disappointing parts of the hobby and can do lots of other cool things as well, just on my desk. When I go out, I use an 8 inch cassegrain with a binoviewer most of the time. I'm planning to build a 12.5" dob

[@astronomydrawings]

Well, this is a discussion that's already been going on from some time, i.e. what's "real" visual observing and what's "cheating". I know several people who're using night vision devices or who don't want to go out in the cold anymore and who enjoy the views of their telescope on their TV. Yes, you see much more etc. etc. but is this still the "real deal"? Soon there will be CCD sensors that will let you see just as much as the best photographs. Personally I prefer to see less but to see things as they really appear to my eyes, even if I have to suffer the cold but... with the feeling of immersion that only a binoscope can offer. 😊

[@normaalewoon6740]

@@astronomydrawings yeah that's understandable. I would also love to have a binoscope, but they are quite impractical as you mentioned, especially when you live in a city. For the most part though, I don't care too much about the viewing method, as long as I can have some fun and see something cool. Simulating is what I do the most, because it's far more practical than anything else and just as immersive

[@abumoslemtamer7331]

Thank you !

[@johnstewart579]

Thank you for this video

[@CamilleTELLIER-u4j]

A votre avis, est-il possible de fabriquer un binoscope avec deux instruments du type célestron 8 ou 11 pouces ? c'est-à-dire dont l'oculaire sort par le fond du tube et non sur le côté comme le Newton ou le Dobson ?

[@astronomydrawings]

Je sais qu'il y a des personnes qui l'ont fait avec deux SCT de 8". 11" me semble difficile parce que les télescopes sont trop gros et faut des tubes trop longs pour arriver au point d'observation ("vignetting"... perte de lumière).

[@CamilleTELLIER-u4j]

@@astronomydrawings Merci. J'espère y parvenir aussi, sans toutefois être sûr d'obtenir une image deux fois plus lumineuse et précise.

[@kambizeqbal33]

Phenomenal video, Thank you very much💯💯💯👊

[@astronomydrawings]

Thank you very much!!! 😆

[@kevinmccarthy8746]

WOW, Super interesting.

[@deltacx1059]

1:11 this is total coincidence but my homemade refractor can actually do it. I didnt have the focus area with enough confidence to rix the focuser in place so my scope actually has a sliding tube to adjust where the focuser itself starts. I use the scope for visual and astrophotography so that feature does come in handy.

[@cannibalholocaust3015]

I’m currently making a 66mm refractor binocular telescope setup. Hunters in the US have begun doing this with spotting scopes (look up Adams adapters for an idea). I was going to use 82mm scopes but couldn’t find a matching pair at reasonable money. I wanted to know how two 66mm scopes will compete against a Singular 95 or 115mm refractor using Binoviewers. Is it as simple as 66x2 = 132mm total aperture therefore in theory better than 115mm refractor? I’m guessing not, as nothing is ever simple 😂

[@astronomydrawings]

No, you need to compare aperture, not diameter. A 66mm bino has 2x34.19cm2 aperture = 68.38cm2. A 115mm mono has 103.82cm2 of aperture, which is about 50% more, a quite visible difference. The 115mm also has superior resolution. But... the binos have a smaller exit pupil, allowing for lower power and so the two would offer a completely different experience. The 66mm binos would behave like a good 66mm pair of binoculars with the possibility of higher power. Excellent for cruising the Milky Way and retaining the joy and immersion of obser6with both eyes. The 115mm would rather be an excellent planetary scope (supposing it's an APO) but with a binoviewer it would suffer from significant light loss. It all depends on the binoviewer and the object in question, but I expect it would still slightly outperform the 66mm if the binoviewer is of high quality and with sufficient aperture. Still, no binoviewer can match the "feeling" of a binoscope, nor can it take 22mm Naglers, for example.

[@c.guibbs1238]

Thanks for that very explanatory video ! If my understanding is good, there won't be a significant discrepancy between a 100mm pair of binos and a binoviewer mounted on a 6" telescope, as some of the light is lost. Perhaps on bright objects, such as Planets, nonetheless...

[@astronomydrawings]

I'd expect 100mm binos to outperform a 6" scope with binoviewer. That being said, 100mm binoscopes are usually designed for low-power observing, though I've tried a pair of 100mm APO refractors mounted together as a binoscope and they were stunning. I don't have to tell you what Saturn looked like, I suppose... 🤣

[@stuartcoffee9799]

wow gives me something to think about!!!! i libe in pineville mo. im amlimited to what the sevensisisters? the moon... don thinkiam far enpough north. like say indiana .... my next place of resisi...... it was relaxing to hear someone speek science...momis 88 and doesnt understand, most peeps here dont understand either... or care...verry enlightening... tahnks stuart coffee..

[@astronomydrawings]

Thank you! I'm just trying to give an unbiased view and offer an in-depth analysis of both options so the viewers can make their own choice. I'm glad that you appreciate that.

[@anthonyhaynes8738]

What about the linear binvieeers from oroon

[@astronomydrawings]

Interesting question... I haven't tried it yet, but looking at the specs I can already tell you this... It doesn't go as deep into the focuser as the OCA of an ordinary binoviewer and therefore it won't lose any light there. However... it has an aperture of only 17.3mm, which means that using eyepieces with a bigger field stop would be pointless. This means high power or small FOV only. Plus, it adds a lot of glass in front of the eyepieces and even though it's expensive glass it will make you lose some light, on top of the reflections that some people have reported. In short: perfect for planets and the Moon, but I'm not having high hopes for DSOs. To conclude, the choice remains the same: - An (e.g.) 18" monoscope with binoviewer, which therefore loses some light and which is limited to 1.25" eyepieces with a field stop up to 17mm only Or - A 12" binoscope with no light loss or eyepiece compromise and which will hence seriously outperform the 18" with binoviewer (or provide an incomparable experience of immersion against an 18" without binoviewer). My 2pc... 😊

[@deltacx1059]

0:18 wish i inew what that was like in general. 0:43 in no other hobby have i heard someone be so relaxed when naming a price like that.

[@LEGOBubuS]

😊❤🎉

[@likbezpapuasov4888]

Why direct view not a CCD?

[@astronomydrawings]

IMHO, seeing things with your own eyes, even when they're much fainter than what you see on photographs, is a much more satisfying experience. 😊

[@deepskywim]

Thanks for the nice overview. However, a binoscope is way to expensive for me. But I have never enjoyed the view through one of course...

[@astronomydrawings]

As I hinted, a binoscope needn't be that expensive. Take a look here... 😊kzbin.info/www/bejne/d4LMhqyla7ulq8k

[@joetuktyyuktuk8635]

"Can reduce your telescope down to a mere 12-14" scope..." Quietly drags my 11" Schmidt-Cassegrain out of the room...

[@astronomydrawings]

Well, even though an SCT doesn't require a corrector, the binoviewer will definitely make you lose some light, reducing your 11" to perhaps a 9".

[@MagicAccent]

*Cries in 4"*

[@chattywalrus8485]

The starscapes you can see through that masterpiece at direct observation would be enough to get a suicider out of bed on doomsday! I wouldn't mind an upcoming Chicxulub 2.0 if I'd get to spend my final nights asteroid gazing with that baby! Sorry, it's the news these days, but you get my point.

[@astronomydrawings]

I do. 😊 Many thanks for the compliment. 😆

[@chattywalrus8485]

@@astronomydrawings I'm not financially or in terms of stargazing skills ready for a binoscope, but I thought I'd give a binoviewer a try for some planetary observations after I watched your video.🤩

[@astronomydrawings]

@@chattywalrus8485 I'm sure that you'll be very pleased with it. Even my cheap binoviewer's given me years of thrills. 😊

[@chattywalrus8485]

💗

[@chattywalrus8485]

@@astronomydrawingsJust played with the binoviewer looking at the Moon for a short while, before clouds came in; actually a very short while; didn't even get to use both my pairs of eyepieces. Panicked twice: first when I had to roll the focuser all the way in one direction and then almost all the way back, then when I really struggled to overlap the images from the two eyepieces; I couldn't do that with my glasses on; it took nearing my eyes to the eyepieces and fiddling with the binoviewer's focusers to get the 3D view, which was not too bad, not too bad at all. I'll try it with a path corrector, too; is that supposed to also ease the alignment of the images through the two eyepieces?

[@BeadsByAria]

The statement about a Barlo decreasing Coma by making the telescope slower, i.e. increasing the focal ratio, is absolutely incorrect. Coma obtains at the focal plane. A Barlow simply increases the magnification that is in effect observing the image at that focal plane. So to give a concrete example: a 20 mm eyepiece with a two power Barlow will give the same magnification as a 10 mm eyepiece. Assuming the same apparent field of view, the amount of coma visible will be exactly the same. So, to make this even more clear with another example. Suppose you’re using an F4 Newtonian. And suppose you use a 20 mm eyepiece with a 2 power Barlow. Now imagine a second Newtonian with the same aperture but now operating at F8. And now use the identical 20 mm eyepiece but no Barlow. Both scopes will give the same magnification and the same apparent and actual field of view. But the view in the F4 Newtonian will still exhibit 8 times as much coma. Note that coma varies as the cube of the focal ratio. Moreover, the F4 Newtonian using a 20 mm eyepiece and a 2x Barlow will show just as much coma as it would using a 10 mm eyepiece with no Barlow. But with respect to aberrations, there is one advantage of a Barlow. By providing an eyepiece, with a less steep light cone, the eyepiece own inherent aberrations will be minimized. But this has nothing to do with the aberrations of the primary optic. Joseph Cannavo

[@astronomydrawings]

A Barlow does reduce coma because it reduces field curvature as the focal ratio of the total optical system is increased. If what you're saying were true, an SCT would be an f/2 scope instead of f/10 with all the coma that such a mirror would exhibit. Instead, the hyperbolic secondary mirror increases the focal ratio, flattens the field curvature and coma is greatly reduced. For the same reason, "Barlowed Newtonians" are sold as f/10 systems instead of f/5 and they exhibit less coma than a standard f/5. The Barlow is also an essential internal element of high-quality eyepieces as it reduces not only astigmatism but also coma. The difference between a Nagler and a classic Erfle is not just lens quality but most of all that a Nagler has an internal Barlow.

[@lucesextranas942]

È un design molto attraente per quelli di noi che amiamo l'astronomia visuale ma è molto difficile da trovare. Ha i suoi svantaggi: volume e peso, prezzo elevato... ma soprattutto è praticamente inesistente sul mercato. Non so nemmeno se riuscirò mai a provarne uno, figuriamoci a acquistarlo. Un vero peccato.

[@astronomydrawings]

Beh, il prezzo è relativo come ho spiegato nel video e un binoscopio non deve costare più di un monoscopio con +/- le stesse prestazioni, senza contare la torretta binoculare. Però, in effetti, ha i suoi svantaggi e meglio avere un posto fisso. Se un giorno passi a Canossa saresti sempre il benvenuto al nostro osservatorio se vuoi provare il mio. 😊

[@lucesextranas942]

@@astronomydrawings Sarebbe un piacere conoscerti, Peter. Vivendo in Spagna non è facile per me, ma non escludo di fare un tour astronomico in futuro, nel quale una visita a Canossa sarebbe d'obbligo. ;-) Gazie! Per ora, navigando in rete, praticamente nessuno produce binoscopi Dobson. Una domanda fuori tema: dato che sono uno studente italiano e un appassionato di astronomia... ci sono forum interessanti di astronomia visuale su internet? In italiano, intendo dire. Grazie!

[@astronomydrawings]

@@lucesextranas942 In effetti, nessun produttore commerciale offre binoscopi tranne ancora la JMI che ne offre un 16". Anche Arie Otte che ha costruito il mio ha smesso perché troppe preoccupazioni per pochi guadagni (e spesso clienti impossibili). Costruire un binoscopio è un'avventura e non sai mai dove finirà. Un errore di un mm può essere fatale e la rigidità dev'essere al massimo. Anche col mio devo aggiustare l'allineamento dei due "tubi" ogni volta che giro verso un altro oggetto. Per la tua domanda dei forum, consiglio fortemente forum.astrofili.org, di cui sono stato membro dal 2006, anche se gli ultimi anni non sono più molto attivo.

[@lucesextranas942]

@@astronomydrawings Graze mile, Peter!

[@dannyserge9982]

Si un professionnel n'accepte pas de réaliser un instrument pareil, alors ce n'est sûrement pas moi qui vais me lancer là-dedans.

[@astronomydrawings]

Les producteurs professionnels ne construisent pas des binoscopes parce que c'est trop compliqué et ils ne réalisent pas de profit. Mais je peux t'assurer, tous qui ont essayé mon binoscope ne pouvaient plus lâcher les oculaires.