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Binoviewers, Plossls & stating the obvious?


russ.will

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With an SCT and a short frac in the stable, it's hard to ignore the ebullient praise heaped on binoviewers by those who have them, especially for planetary, lunar and solar viewing. I'd just like to check I've got my info correct, as I fancy having a dabble using Plossls.

Binoviewers are magnification neutral, ie they don't add any of their own?

The SCT should have plenty of in-focus to cope with the added optical path length (100mm?) of a binoviewer.

I note the various 'glass path correctors' of differing magnifications. Is this just another way of saying 'Barlow nose-piece' or are they something different? I assume I'll need one for the frac, but is there an easy way to predict which?

I see much fuss about clear aperture. As I only intend to use Plossls at this stage and a 25mm Plossl has a 21.2mm field stop and even the cheapest BV seems to manage 20.something mm, is this really an issue?

There seems to be two levels. Your Denkmiers, Baader MkV, Zeiss, etc at the top end. The bottom seems to be clones in the shape of SW, Celestron, TS etc. Just above are Baader Maxbright and Williams Optics jobs, at least in price. Is this one rung up from the bottom actually worth it?

Cheers,

Russell

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Hi Russell, I can only vouch for the WO set with the included 20mm EP's and the 1.6 Barlow - on Jupiter in comparison to a 12mm mono EP against a pair of Baader zooms in the bino - the 12mm mono was just a little brighter, but with the 11" aperture, the nominal drop in brightness was a bonus just edging out the glare, using the 12mm WO EP's with the 1.6 Barlow giving around a focal length of 12.5mm worked very well - not too bothered about the FOV as the tracking took this up on the scope - colours and even contrast were more than enhanced in 2 eye mode, as you say - not a problem with focus in the SCT, there's talk of extended light paths with the 2" diagonal - this increases the focal length - not a problem for planetary - the Baader's are a little big when trying to get close in - the supplied EP's were very comfortable to use and a pleasure for extended sessions on Jupiter.

Had a go at a few DSO's - I have a lot of light pollution - so not really the best test - this is where the marginal light loss as opposed to mono view will be sacrificed, but on Jupiter - well worth the money for this alone - but I think the favourable location of Jupiter this past 2 oppositions just added to the wonderful views.

Paul.

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Hi Russell.

I've had chance to use the TeleVue binoviewer which costs in the region of £1000. Its a great binoviewer, yet as I didnt have £1000 to spend on one, I chose to opt for the cheaper end viewer. Mine is a revelation costing in the region of £90, a much safer option if you're just wanting to try them out. I can tell you they are excellent value.

When using a SCT you won't need a Barlow but for most refractors you probably would. Mine has a standard 2X Barlow screwed to the nose piece. Some Barlows unscrew from the main Barlow body and can be screwed directly onto the binoviewer. Not only does this allow focus to be attained, it also allows the use of longer focal length eyepieces, making viewing more comfortable. Plossl's and orthos work fine.

Even on small apertures such as an equinox 80ED the use of the binoviewer greatly increases the performance of the telescope on the moon and planets. I bought an ED80 only a few weeks ago, placed my binoviewer into it and aimed it at Jupiter. The view astounded me! Five belts, NEB,SEB, NTB, STB, SSTB and also the equatorial band, enhanced by two subtle festoons decending from the southern edge of the NEB. The corresponding zones were equally obvious. The GRS hollow was easy to see and the RS itself showed a variation in the colour across its tiny surface. Closing one eye, the finer detail disappeared.

The moon was stunning and in 3D.

I have a nice collection of excellent Pentax XW's, great for the planets. The binoviewer with a couple of cheap 16.8mm orthos beat them.

Obviously a 3" scope is limited in respect to light grasp, but greatly enhanced as a planetary instrument with the use of a binoviewer. In my larger refractor even the brighter DSOs seem to benefit with the use of two eyes.

Mike

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Hi Russel, as stated with most things you have to use a barlow or seriously modify your scope to gain focus . On a SCT though you have loads of focus . I have the WO make but can imagine most providing the exact same performance. For bright objects the advantage of two eyes I found staggering, my little 35mm Lunt provides fantastic 3d like views . In my SCT on planets and the moon ... Well seeing is believing. So far I have only ever needed to use the provided 20mm plossls and my two 25mm TV's . I have not attempted to use them on any dim dso yet , thats mainly because once I start skimming the surface of the moon with them thats where I stay .

I cant imagine paying a fortune would gain much performance with what you will be doing with them.

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Russel, what I've understand is like this:

1. The magnification of binoviewer is scope and binoviewer dependant. For frac or newt, it doesn't change magnification; while for SCT or Mak with moving mirror, it adds more mag. The increase of mag depends on the added total length binoviewer comparing to using stock 1.25" diagonal.

2. Added optical path is >110mm (Baader maxbright with T2 connect is the shortest).

3. GPC is not exactly as a barlow according to Baader's maxbright instruction, it corrects chromatic aberration too. For a frac, 1.6x or 1.7x is safer bet than 1.25x, IMHO.

4. The issue will be slight vignetting when you use a pair of EP with 21.2 field stop in a binoviewer with 20mm free aperture. I have no experience of that, and my wild guess is the vignetting should be very mild, since I've read that some didn't even notice vignetting of 24mm Pan (27mm FS) in a maxbright (23mm free aperture).

5. I'm sure the best ones have their advantages(utilizing max FOV of 1.25" EPs, some scopes can be binoviewing all the time etc), I got mine when the local shop was closeing down, so quite good price, can't complain. :smiley:

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i am currently using Denk 2(26mm prisms) with or without powerswitch and awaiting on delivery of Zeiss with 30mm prisms.

I disagree on statement that you will have to heavily modify your refractor to accomdate binoviewers.You can simply use a barlow to reach focus with binoviewers and with that combo planetary views will be stunning.My denks came with a OCS what screws infront of diagonal and with this combo you can reach focus on ANY refractor.Obviously native focus will require drastic approach by shortening the OTA to gain that extra inward focus.On refractors binoviewers do not magnify anything in native and your 20mm plossl will be 20mm plossl.A lot of binoviewers use plossls,including myself,i use Erfles,These simple and cheap eye pieces provide excellent quality of image and are compact,as such,if you have issues of fitting your nose in between larger eye pieces,what normally is the case,plossls will work perfectly.Same goes for orthoscopic eye pieces,these provide beautiful quality images and again are relatively cheap and light.

Baaders glasspass correctors are not only correcting aberration but also act as barlow.

In SCT binoviewers will magnify,i think minimum you can achieve was x1.25 but you will never have them in native focal length as in refractors.

As for quality of binoviewers,well,majority of them come from the same factory in China and are only branded differently depending on what company they go to.

WO,Celestron,Skywatcher,etc are great starter sets,but limited to planetary only due to small prisms.Baader maxbrights are a good step up,where televue,denks,denk2 and Baaders mark V are top tier with 26-28mm prisms,good quality coatings and will give you the ability to use lower power eye pieces with wider angle without the issue of vignetting,what means you can use your binos also for DSO`s.

For both telescopes,a prism diagonal is strongly recommended to shorten the light pass.

Its a whole new experience with binoviewers and if you really enjoy them,it can open doors to something interesting and new.Binoviewers did that to me and i am hooked on them now.Much more relaxed view and that half magnitude loss is really worth it. 

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Russell,

If you go down the path of the Binoviewer don't do it my way. I spent ages trying to find 2, 24mm Panoptics which I did in the end. I decided to go 24mm with the SC having an extra meter over yours. Then when I was in England last on a buying trip forgot to buy the Binoviewer. Now I have moved on to other things like being a member, though not paid up, of the secret Dob Mob.

What I would ask is if you decide on something that doesn't cost a packet, can you write it up and I may still have a dabble in that area.

Alan

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Hi Russell.

There is something else to consider as respects magnification. If you screw a Barlow to the nose of a bino viewer it doesn't simply double the magnification. The increased distance between Barlow and field lens of your eyepiece increases the amplification of the Barlow. You can measure the exit pupil produced by the bino/eyepiece combination to calculate the magnification accurately. This needs to be a precise measurement to obtain an accurate magnification. Or, if you're lazy like me, simply compare image scale of the bino view compared to the image scale of a single high power eyepiece. You can get a fairly good idea of the magnification this way, though it won't be totally accurate.

Mike

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Thanks chaps - Some great input there.

I'm still not quite sure what makes a GPC that different from a Barlow/Smyth lens, but no matter.

I take note of the non-necessity for premium EPs. To put it another way, the incremental improvement provided by opening both your eyes, is way in excess of that provided by jumping to excessively expensive glass. I was going to run with Plossls/Erfles anyway, so that's good to know.

I was, off the back of comments here and read elsewhere, prepared to accept the Baader was worth the outlay. I was also warming to the idea of a prism diagonal, so I was settled the Baader Maxbright Binoviewer, as it seemed the neatest and most robust way of incorporating the two.

Then they discontinued it:icon_eek:

That's complicated things.

Russell

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Some great advice here..

I don't doubt that TV Pans will deliver stunning views, but for the cost of pair of Pans you could buy 3 or 4 pairs of well performing EPs..the slower your scope the better modest cost EPs will perform.

If you have an SCT I'm guessing it will be F10 or slower, in which case plossls will be just fine. I use Baader Classic orthos and Tal plossls and am very happy with their performance in my Maxbrights and F15 refractor (shortened to eliminate the need for a Barlow or OCS.

If you doubt the effectiveness of binoviewers, take a pair of binoculars, close one eye and observe stars for 3 minutes...then open your eye and observe for 30 seconds. Nuff said!

Dave

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good thing about binoviewers is they ability to use wide range of eye pieces.All depends on your finances really.If you are feeling generous,then pairs if 24mm panoptics are the top of the tops,but come at cost,also some people might struggle with inter pupilary distance what means you will not be able to get your nose between the eye pieces,alternatives are Ex Sc 24mm 68 deg or stripped maxvisions, another common pair is 20mm pairs,a lot of peeps use 16;13 and 9mm Nalgler pairs for planetary due to these being quite compact but again its the costs of naglers,Meade 5000 18mm uwa is another common pair.Still,i think best value for money is the simple plossls in likes of TV or ANY other good quality plossls,Baader classics or geniune orthos or again ANY other brand of orthos you can get your hands on.Edmund optics 28mm RKEs will give you really unique experience and true 3D image.

Good reading material is the section about Binoviewers in Cloudy Nights.

And lastly,binoviewing doesnt necesseraly has to be expensive.you can pick up lets say a WO binoviewer for 100quid,add a pair of plossls for 20 quid(even GSO plossls will work!) and you are off :)

it is the same as with single eye pieces,you buy,try and move on.

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There's been some great feedback on here, plus the reading suggested elsewhere. Unusually for me, I've decided discretion is the better part of valour at this point and I'm going to stay well within my budgetary limits. As such, I bought a second hand TS Binoviewer plus 1.6x nosepiece off ENS Optical. I bought my LX200R from Steve and it's an absolute peach, so I trust him and know returns won't be an issue if something should prove to be up.

I also asked if he had anything in his Aladdin's cave, in the way of Plossls to match any of the ones I've been amassing for a 20mm EP shoot out I was thinking of doing. He didn't, but he's sending me a pair of the WO 20mm EPs (SWANs?) that normally bundle with their BV, on approval to play with. How very nice of him. I believe the 20mm SWANs are an Erfle, meaning 5 elements, 70deg FOV and 17mm of ER. This means the same FOV as a 25mm Plossl, but at a higher magnification and with a bigger AFOV, plus it's as much as you can fit in a 1.25" format. They should be a reasonable place to start, IF I'm not overly offended by the edges....

Going forward; I'd worked out that the minimum (due to the FL of the SCT) focal length I would need is 15mm. Also, as the frac will likely need the 1.6x nosepiece it will effectively be working at F9.6, so I have no real need or interest in premium glass anyway. Indeed, there is plenty to suggest in other threads, that the 'corrections' premium glass enjoys, actually militates against them in daylight and these will be used for white light solar.

So, for the 15mm end, I was eyeballing the GSO Superview 15mm, another Erfle. Any thoughts? Seems a little short for an Erfle, to my mind.

Russell

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Well, for some reason I found myself clicking 'Buy' on a pair of BST Starguider 15mm. I seem to recall using BSTs in my Lunt Wedge when I first got it and don't recall any kidney beaning issues, so they're okay for daylight use, whilst being small and cheap enough for binoviewer use. If I'm wrong, I'll find out soon enough.

I also was also checking out available in-travel on the ED80 and it was looking dodgy with the sizable ES 2" Diagonal I have. I've often considered that a decent 1.25" diagonal would be a handy one-time purchase, but couldn't convince myself to click on a Baader/Zeiss Prism, or Televue Everbright, etc. So I settled for a Revelation Quartz 99% Dielectric. I figure you have to spend a LOT more before you'll better one of those.

I suspect that binoviewing is not like getting a new EP, in so far as you aren't going to have to spend nights and nights looking at faint fuzzies and stars at, or just beyond, the edge of field to tell a difference. I'll post up my initial impressions straight away. :)

Russell

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BST`s should work perfectly fine Russ.

There is only one concern i have about your set up .Thats that 2" diagonal.it could be the case that this will prove not suitable due to longer light pass.I had issues when i started binoviewing and i used WO 2" dielectric and image was very soft and mushy and sort of also dimm.And the cause of this was my diagonal.Once i changed out to a prism,all was spot on.it might be only me so dont take this as granted and i hope your set up works out fantastic.Looking forward to your first light and impressions :) 

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Hello all. Bit late to this thread.  Can only re interate whats already been said. 

Just one question if I may, probably aimed at "The Dude" -  with reference to the use of a prism diagonal rahter than a mirror type.  Never come across this info.  Any prism type diagonals in particular you might suggest, for use when  planetary binoviewing. 

Thx in adavnce    John

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Well, for some reason I found myself clicking 'Buy' on a pair of BST Starguider 15mm. I seem to recall using BSTs in my Lunt Wedge when I first got it and don't recall any kidney beaning issues, so they're okay for daylight use, whilst being small and cheap enough for binoviewer use. If I'm wrong, I'll find out soon enough.

I also was also checking out available in-travel on the ED80 and it was looking dodgy with the sizable ES 2" Diagonal I have. I've often considered that a decent 1.25" diagonal would be a handy one-time purchase, but couldn't convince myself to click on a Baader/Zeiss Prism, or Televue Everbright, etc. So I settled for a Revelation Quartz 99% Dielectric. I figure you have to spend a LOT more before you'll better one of those.

I suspect that binoviewing is not like getting a new EP, in so far as you aren't going to have to spend nights and nights looking at faint fuzzies and stars at, or just beyond, the edge of field to tell a difference. I'll post up my initial impressions straight away. :)

Russell

I'm pretty much a total convert to binoviewers now and most of my recent astro spends have been on eyepiece pairs and Baader bits and bobs, the problem is you can get great planetary views quite cheaply but then the bug bites and you want wider views and things start getting expensive.

Regarding the discontinued Maxbrights, I think i read somewhere that Baader are bringing out a new version, so hopefully they'll have bigger prisms and bridge the gap somewhat between the generic chinese ones and the high end ones.

I use a Baader (non zeiss) T2 prism with both my Maxbright and WO binoviewers, I have an adapter that allows me to screw the WO's to the T2 prism directly and this actually gives a slightly shorter light path than the maxbright T2 combo, 5mm shorter if I remember correctly.

The biggest problem with using a regular type diagonal is that the eyepiece holder alone could be 30mm long, the T2 prism only adds 37mm of optical length.

james.

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John,

baader prisms will work perfectly fine.Doesnt necessarily has to be 2" one.I went for 2 " as my binoviewer had 2 " accessories and also at that point i was still thinking of using the scope in cyclops mode too.(well never actually happened lol). I got my 2" zeiss prism for 190quid from astro shop in polsky land when they where having some sort of sale :D

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I think i read somewhere that Baader are bringing out a new version, so hopefully they'll have bigger prisms and bridge the gap somewhat between the generic chinese ones and the high end ones.

No issue with that statement - The Baader website clearly states that the Maxbright Binoviewer is no longer available and that an improved version will be forthcoming. Unfortunately, it's also quite clear that there is no time frame for the arrival of the replacement.

This is good, because the fact a newer Baader BV is imminent, means all of the Maxbrights are now worth less than their owners think! #keepinganeyeonUKABS

Given that at this point, all I have done is read about BVs, there are only a couple of things I'd ask of a new Baader BV:

1. 25mm clear opening - Be honest, it's enough.

2. Click Stop EP holders. Got a 2" one and love it.

I'd be interested to hear what current BV owners (of any ilk) would ask for, but keeping it within the realms of sub £200 wish list. Let's be realistic.....

Russell

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