A few Binoviewing Questions - what to expect and getting the best out of using them?

[Fozzie]

Hi all,

I’m intrigued by, and have decided to have a go with some, Binoviewers in my two fracs.  Hopefully I will be taking delivery of the WO package with 2x20mm Ep’s and a 1.6x “barlow” this week.

Obviously the pit falls of inwards travel are well documented, I think I maybe ok with just the 1.6x Barlow, but I also have a 2.5x revelation Barlow and 2x ES telextender..

As memory serves me most of my EP’s in the 2”diagonal come to focus around 3.5” (scale on the draw tube) so I’m hopeful that I may not even need a Barlow but in anticipation do any of our more experienced Binoviewer’s for see a problem with the above equipment. (and no I’m not cutting my scopes down either!)

Will probably be used on moon and planets in all essence.

One thing that concerns me is eye relief, I’m hoping if all goes well to be using the SLV.. will the use of a Barlow, push out eye relief beyond the 20mm after the Binoviewer has had its way with the light path?

This really is a bit of a punt, as you can probably tell, and I have no idea what to expect (or what I’m really doing!). 

Any advice on getting the best out of these would be greatly appreciated.

Ta

Fozzie

[Saganite]

Hi Fozzie,

The only way I am able to use the WO binoviewers on my ED100, is by removing the diagonal and inserting the bino directly into the focus tube. I believe it can be achieved but for some while I have been quite happy using them in the Lightbridge, so have not bothered to investigate further. I do know that a kit can be purchased from an Astro supplier in the USA, Seibert Optics, that will solve the problem. 

[F15Rules]

Hi Fozzie,

I wish you well with your binoviewing experiment..BV's tend to be a bit of a "Marmite" piece of kit - people seem to really love them or can't get on with them.

I'm one who really likes them - on the right targets. IMO BV's are great for Lunar, Planetary (probably solar, never tried that), double stars, globulars/tighter clusters and some nebulae such as M42.

I have found though that the only way to get truly satisfying performance in a refractor is to shorten the tube to avoid the use of an OCS or barlow. This is a step too far for many, I know, and I note you state you don't want to do that, but for refractors I really don't see the problem, apart from the practicalities/effort to have a one-off modification to the scope.

I had my 5" D&G F15 shortened byabout 130mm by Moonraker as part of a total tube refurbishment. Ok, I had to be without the tube for a couple of weeks, but boy, when I got it back it was worth it. I could use my longer focal length eyepieces at native focal length (important to me in a long FL scope as BV's don't work so well with very high barlowed magnifications, I've heard it said that around 12mm is about as short a focal length as should be used ideally), so for example a pair of 32mm plossls used at native length deliver a nice x59 in my D&G, whereas if I had to use a 1.6x barlow the mag shoots up to x95 - not nearly so good for wider fields.

But I can still (and do) use the scope in cyclops mode simply by using extension tubes of good quality, such as WO, which have compression rings and twin large retaining screws to keep everything nice and tightly in place. Also, having a 360 degree rotatable focuser really helps, and a good 2" focuser (mine is a Moonlite) to take the weight of a loaded BV, which can be considerable.

I think that binoviewing is often found to be less satisfying because people are put off by the higher magnifications that have to be used without enough infocus and the inertia/resistance against shortening a scope tube, which is seen variously as vandalism or too much effort...if done properly it is neither, it is simply a valid, worthwhile modification to equipment that enables the scope to deliver amazing views with ultimate comfort.

I think that scope manufacturers could help greatly by offering their OTAs of a shorter length (as Takahashi do), with extensions supplied to allow cyclops viewing, as a default manufacturing feature.

I know many people say they "don't get on with Binoviewers", and for some that is probably true, and to do with their eyes - but I really think that for many others, they expect top drawer results immediately, without preparing their scopes properly to accept Binoviewers.

Last week a buddy and I viewed the double cluster through my D&G with a WO BV such as you have bought, but with no barlow, and a pair of old style Tal 25mm "plossls" (the old ones are more like Erfles), with around a 60 deg field of view. So we viewed the clusters at x59 and could fit most of both comfortably into the field of view. The view was spellbinding. We also tried a pair of ES 24mm 68s. Here, my buddy had problems with the IPD, whereas I managed fine, and the view was even better. The supplied WO 20mm 60s are very good and, at native maginification rather than the effective 12.5mm focal length that the x1.6 barlow will deliver, they give very satisfying low-medium power views. Again, a pair of native 12-14mm eps will deliver amazing lunar and planetary views also, with no barlow.

Just my 2p's worth

Good luck whichever way you go, and do persevere, it is worth it!  

Dave

[Fozzie]

Hi Dave,

Many thanks for that greatly detailed response, really appreciate the time spent in writing it..

I think experiment is the correct word, did a lot of research over the weekend on the who, what’s, when’s and why’s of binoviewing and managed to get a second hand set, so if the experiment fails, at least I should be able to move on with a nominal loss.

Very keen to make it work though, it’s the moon that I really want to try this on, more than anything.

I think the WL wedge already has too much in focus that the only true way is to cut the tubes, which, (and I say this knowing the great work done on your D&G thanks to the post after it had been moonrakered) still sounds like a step I can’t bring myself to take.

I think the supplied Crayford and R&P on the two altair fracs I have are man enough for the job, the R&P on the 72mm is a fantastic unit in comparison to the Crayford on the 4” and they have a lot of focus range compared with a celestron 102 omni I used to have.  

I essence it’s not the wider views I’m after, it’s the (presumed enhanced) detail & contrast you get from both eyes on the Luna surface, so turning the 20mm’s in to a 12.5mm will get close to 100x in my F11 (and if it works with WL, then 35x on the sun in the 72mm) Both more than workable on those targets, if not a bit short of what I would like on the moon, hence the 2x and 2.5x extender/barlow reference.

Fingers crossed, I can gain enough out of the light path, I’ve also got a 1.25” diagonal which also helps in that sense (I think)…

A nice pair of 15mm or 12mm SLV's would be the tonic, if I can get some focus..

Thanks again for the informative response..

Regards

Steve

[Fozzie]

Hi Fozzie,

 I do know that a kit can be purchased from an Astro supplier in the USA, Seibert Optics, that will solve the problem. 

Thanks Steve

I came across these whilst researching over the weekend... those path correctors will cost about as much as I have paid for the BV's I rekon..  Maybe I need a rainy day before going down that path.. (by rainy day I mean obviously not tomorrow, or Wednesday or Thursday..... or Friday, or any day next week.......................!)

ta

Steve

[F15Rules]

Hi again Fozzie,

If Lunar is your main target you should be fine with the barlow. The Starwave is a great scope (I had the Lyra version which Fondofchips has used for the past couple of years) and the focuser should take the BV no problem.

The views of the Moon are indeed magnificent. A first quarter Lunar at any magnification through your WO's will transfix you. A small tip, I found, from my use of binoculars, that opening up the binoviewer wider than you need it to be, then slowly pulling each side "in" until you get a really nice, single merged image as you do in binoculars really helps you get the optimum viewing focus and comfort.

Do let us know how you get on!

Dave

[Fozzie]

That's great Dave, much appreciate the input..

Will let you know how I get on with these...

Thanks

Fozzie

[Mark at Beaufort]

I can't add much to the excellent post of Dave (F15Rules). I have used binoviewers for several years on my 4" Astro Tech APO frac and focus just stops before it hits the buffers. I use a 1.6X Barlow but I have also found that this Baader takes it out further - http://www.firstlightoptics.com/baader-planetarium/baader-classic-q-225x-barlow.html. Unfortunately with the 2.25x the mag becomes too great.

Over the years I have experimented with several EPs and the best focal length was 17mm with the 1.6X barlow with the scope having a FL of 709mm. I did buy some William Optics 12.5mm planetary EPs which although very good gave too much magnification because of the barlow.

I use my binoviewers for Lunar and Planetary. However, putting them into a Lunt Herschel Wedge/Continuum Filters simply blows you away viewing the Sun.

[Fozzie]

Mark, now thats interesting, the Baader classic Q barlow has a 1.3x option if fitted directly to the EP... would I be daft to assume this could be substituted with the 1.6x of the BV's, installed in the nose, and do the same job but with less magnification...? if so, that's an interesting option, all provided it moves the focus point out enough to gain focus.

Hmmmmm

ta

Fozzie

[Fozzie]

Over the years I have experimented with several EPs and the best focal length was 17mm with the 1.6X barlow with the scope having a FL of 709mm. I did buy some William Optics 12.5mm planetary EPs which although very good gave too much magnification because of the barlow.

I use my binoviewers for Lunar and Planetary. However, putting them into a Lunt Herschel Wedge/Continuum Filters simply blows you away viewing the Sun.

Hopefully if I can get them to work in the Wedge, this is what I will see....!

Just on the 12.5mm EP's, im assuming the magnification was amplified not just by the Barlow element but by the increased light path of the BV (think I read that happens somewhere?!)  Did you ever manage to figure out what additional factoring the BV added..

I say this because 12.5/1.6 = 7.8 for the revised EP FL then in to the 709mm FL doesn't give a huge magnification.. or am I missing something obvious?

Thanks

Steve

[Mark at Beaufort]

Steve I remember that Andrew did a review of magnification and binoviewers - here is the link - http://stargazerslounge.com/topic/62314-magnification-factor-in-barlows-and-binoviewers/?hl=binoviewers+and+magnification#entry614885

In theory my Frac - 709mm x 1.6x divide by 12.5mm should be about 90x but it was far higher than that. I can't remember the comparison now but it felt like 150x. On the Sun I now use my 25mm Plossls with the 1.6x barlow and the Sun fills the FOV. So if you take the logic that the Sun is half of a degree with an eyepiece of 52 degree this would be similar to a 8mm EP in cyclops. See attached diagram.

Hopefully, I am not talking rubbish.

[Fozzie]

Hi Mark, 

No I was anticipating that the light path of the BV's adds to the magnification, based on Andrews postings (if I've understood then to be correct) the usual Diagonal-1.6x-BV-EP gives around a 3x magnification, turning the supplied 20mm into a rough 6.5mm FL EP.  around 172x in my F11...

If the 1.6x goes in front of the diagonal, it's even longer on the focal length so even higher magnification..

Here's a throw out question, what if you had two 1.6x nose pieces and screwed them in to the Ep's would the extra travel through the BV still give a larger magnification or would this reduce the impact some what nearer to the true 1.6x of the barlow....?

Just a thought?! (EDIT Although reading through Andrews postings again, he does actually comment in this vain, gives the lowest magnification, nearer the native of the barlow...)

Thanks

Steve

Mind = Blown BTW!

[Space Hopper]

Hi Fozzie,

I'm sure you'll love the views through your binoviewer.

Wait to you see the moon and Jupiter......

There's no doubt its an expensive area of the hobby, but from a visual perspective, its completely changed the hobby for me.

The best thing about it is the ease and comfort you'll feel at the eyepiece.

Using both eyes is so much better, and so much more natural.

You can relax when observing, spend more time at the eyepiece, no squinting etc.

Of course with refractors its all about the back focus issue,

I use a William optics FLT132 refractor, which being optimised for imaging, makes it perfect for binoviewing.

I can use my MK V bino with no amplification (no barlow, gpc, ocs etc) and still have plently of infocus left.

I can even add a Herschel wedge into the mix and STILL focus natively.

I love using low powers and high powers. With the 24 Pans i'm working at 38x mag. With the 13 Naglers & 2.6x gpc i'm unto 185x

On a good night Jupiter looks stunning, as does the moon.

I've always used Baader systems, and am pretty clued up with them.

Great system, with lots of options.

Another good resource is the Binoviewer forum over on CN.

Let us know how you get on with them Fozzie !  

[Fozzie]

Thanks TB

I had been looking at the baader systems, 365 astro seem to have a fair selection of options including COS/GPC's..  Maybe if it works out for me I might well look at investing.

Im not as interested in using the bino's at the moment for DSO, I usually use the Newt for this anyway, and from a dark site, which the opportunity to get out seems to get less and less..  So im more than happy with Luna and plants at the moment.

I think the options as I currently see them are, in order of preference, in the aim of achieving focus

• Do absolutely nothing and all will come to native focus because im lucky (Yeah Right!)
• Standard kit supplied with WO BV i.e. Diagonal - 1.6x - BV - 20mm EPs EP = 168x mag (approx.)
• Adjsut the Barlow/corrector with the baader classic nose piece i.e.  Diagonal - 1.3 - BV - 20mm EP's = 138x mag (approx)
• Buy a second 1.6x Barlow/corrector and use in EP's i.e. Diagonal - BV - 1.6x - 20mm Ep's = 90x-100x mag (hopfully and defo approx.)

If non of the above work out or provide too much mag

• Buy a cheap second hand EVO90, Strip it, cut it, paint it (sounds like an interesting "get me away form the kids" project) to see how native focus suits me
• obtain quote for cutting down scope(s) from moonraker
• obtain quote for Seibert OPC
• Decide if I want to go ahead with either..

Eitherway, it's going to be really interesting!

Thanks for all the advice so far!

Fozzie

[Dude_with_the_tube]

i binoview 100% of my observation time now and few things to mention.

You need to remember that binoviewer with its prisms etc will reduce the brightness as such i wouldnt suggest to use them in refractor less then 4".I think the best candidate would be a Skywatcher 100ED you can pick one up for 250-280quid second hand.However,your 4" Starwave will work perfectly too if you dont want to invest into new scope.

Also to fight with the inward focus issue,i would strongly suggest to get a prism diagonal as that will reduce the light pass.

But my best advise:

Is there a possibility for you to actually try binoviewing with some friends who have it already before you actually go out and splash you cash on something?This would really help you to decide if this is for you or not.Reason for that:If you really like it and think it is the way forward,and your Starwave doesnt come into focus with supplied barlow,i would strongly suggest to cut the tube and dont be afraid of it as it is a straight forward and simple surgery to do.by doing so you will do yourself a massive favor as being able to have bino in native opens a lot of possibilities.Firstly you have the freedom of using different eye pieces and play with magnifications by adding/removing barlow or powermates,and secondary you will be not stuck on high magnifications only due to inward focus issues.

And lastly,binoviewing is not that expensive as everyone thinks.Yes it can be complicated,but once mastered it is simple and enjoyable way of observation.

Also remember,you do NOT need expensive eye pieces for binoviewing.Simple pair of cheap plossls will work perfectly.I binoview with pairs of orthos and erfles and found them to be simply outstanding.Only use pairs starting from 16mm and up to 35mm to have good eye relief,for higher magnifications i use 2x and 4x powermates.

[Fozzie]

Thanks Dude,

Would have loved to give it a go first, John (telescope40) had some at ingleton, unfortunately the clouds and rain had other ideas..  I've bought second hand, they are currently at the post office waiting on collection, so I'm very committed at this stage.

As I say this is more an experiment at the moment, just to see if I can get on with them, before I seriously invest in shortening tubes or BV's with a larger clear aperture to take wider lower powered EP's. 

As I say my main focus on these is the moon and hopefully, if the 1.6x works, solar with the 72mm.

I'm actually seeing the seibert optics OCS as a good option at the moment, with a 1.25x corrector you can use in a newt or frac as it covers both options for BV use..

Im not adverse to cutting the tube down if I like it and invest in a better BV set up bu, I will defo experiment first with an second hand scope, like an evo 90.. I can get our machinist at work to cut it down so cost free..  before I go throwing any significant money at it or sending my F11 to be reduced!

A smaller 90mm evo would make a great grab and go job too.

Thanks for the tips everyone.

Fozzie

[Telescope40]

Hi Fozzie.  Reading this with interest.  Pity U never got a go with my Celestron BV unit due to the 10/10 clouds at Ingleton.  Typical.     Optimistic you will be won over  and then join  the "BV pack".    

I'll come back to this thread for an update  very soon.

John

[Fozzie]

They're here!

Let the clouds lift then the fun begins!