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John

Binoviewer Performance Questions

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I'm quite keen on trying out binoviewing again so I've been reading up as much as I can on the various options available and on tips for getting the best from them.

I came across this interesting report on planetary observing with refractors using 4 types of eyepiece with around 5mm of focal length. Also thrown into the mix are a pair of William Optics binoviewers to see what impact they had when used on the same targets with the same scopes and eyepieces:

http://www.wlcastleman.com/equip/reviews/5mm_EP/5mm_ep.html

Towards the end of the report this question and conclusion caught my eye:

"Does use of a binoviewer provide improved planetary viewing to monocular viewing?

  • Yes, binocular viewing allows detection of subtler surface detail and color due to the benefits of binocular vision. However, binocular viewers decrease light transmission, increase light scatter and lower contrast and color saturation. While there are beneficial planetary viewing results with binoviewers, benefits are greatest with a high performance refractor and are of minimal benefit with an entry level refractor."

Not having much experience of using binoviewers myself I thought I'd ask observers on here whether their experiences agree with the above, or differ from it ?.

I guess higher quality binoviewers would mitigate the negatives identified but to what extent ?

To what extent does the use of both eyes overcome the negative impacts that are suggested by this reviewer, assming that they exist to some degree even if perhaps over emphasised by the reviewer ?.

Was the reviewer pushing things too far by using 5mm eyepieces with a relatively inexpensive binoviewer ?

I realise that I'm eventually going to have to "bite the bullet" and find out for myself but I'm interested in reading others experiences prior to dipping my own toe.

Thanks :icon_biggrin:

 

 

 

Edited by John

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There is a noticeable dimming to the views but being able to use two eyes over one seems to compensate for this. I only had the WO bino set for a couple of days before I sold them on so I didn't have extensive experience with them. Although there was a load of faffing reaching focus, both the days and nights were clear and I did get to spend a fair amount of time viewing the moon, sun in Ha and WL and a couple favourite DSO's. I felt viewing dso's with the binos actually showed improved contrast especially on M42. Again WL views were improved but due to the loss of light in the already aperture restrained LS60 Ha views really suffered most notably proms.

Moments of poor seeing seemed far more tolerable using two eyes over one and because of this I felt the magnification could be pushed that little bit more. I have read mention by many that they feel the views become almost 3D but personally I didn't feel this is the case. I admit there did seem to be some depth to the WL views on the sun due to the increased contrast / detail on the surface granulation but I'm not sure I felt this was the case on the moon where most note to noticing it. On the moon I often went from viewing with one eye to using two just to see if using two eye's made any difference but other than being far more comfortable and natural there really didn't seem to be any more depth than could be seen with a single eye.

Overall I would thoroughly recommend bino viewers to anyone with pockets deep enough to fund doubling up on eyepieces. It is worth bearing in mind that there is a lot of faffing to start with as you find what extensions, barlows, gpc or tube chops will be required. You also need a fairly substantial focuser and reasonably sturdy mount. Each double ep change will be followed by getting your left and right eye to work in unison but other than that I'm sure as with anything if you do it often enough you get used to it. 

 

Moonshane has recently got up and running with his binos and would probably offer you better insight as he may have now had chance to try them with his ED120

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Hello John. As you probably are aware I have gone into binoviewing with the 120ed apo. The Binoviewers I use are the TS ones. I think the first thing IMO in this hobby usually the more you pay the better quality of view. This in my experience is usually the case but not always. But the rate of return of views you get also IMO diminish compared to the cost factor. To simplify just because you spend 4times the amount on a product compared to another,do not expect 4times better views(I am sure a man of your experience knows that already)

As for the Binoviewers the closest comparison I can do to binoviewing v Cyclops was between the televues 8mm plossl and the Pentax 7xw. I tried both these on the lunar and Saturn. And IMO the best views came from the Cyclops 7XW . Was this because the TS Binoviewers were holding back the plossl ? . I don't think so as IMO when the 8mm televues plossl has been used in Cyclops and the Pentax 7XW I have had the cleanest sharpest views through the Pentax 7XW of Saturn ever and this includes the televues 8mm in Cyclops . But with Binoviewers I think it comes down to the quality of eyepieces you use and Binoviewers and telescope. There is no point in using Baader Binoviewers no 4/5 with baader Zeiss diagonal and some xo Pentax  with a mid quality refractor. As  Imo think that to say what I have said before and that your scope is only as good as the weakest link in the optical chain. Also using 5mm eyepieces i would of thought is really pushing a binoviewing set up? And even if you have a quality 4inch frac then single xo 5mm eyepiece in Cyclops may be possible on a good night seeing but I would of thought in this high power set up to enable the scope eyepiece to provide the best then maybe the William optics Binoviewers where not quite up to the same quality and a better results may be obtained by a better quality Binoviewers like the Baader mm 4/5 ?

In my opinion John even though the Pentax XW in Cyclops to date has given  me the best views of Saturn and lunar. Binoviewing with two eye's is more relaxed and allows you to see things differently and still in nice sharp detail. Now if I had the 120ed apo with Baader Zeiss diagonal and Baader MK 4/5 Binoviewers and two pentax 7XW then this would be a class one set up, and IMO would more than likely be better than my single Pentax 7XW Cyclops experience and probably give me a new best view of Saturn☺   

I hope the above is some help

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32 minutes ago, John said:

I'm quite keen on trying out binoviewing again so I've been reading up as much as I can on the various options available and on tips for getting the best from them.

I came across this interesting report on planetary observing with refractors using 4 types of eyepiece with around 5mm of focal length. Also thrown into the mix are a pair of William Optics binoviewers to see what impact they had when used on the same targets with the same scopes and eyepieces:

http://www.wlcastleman.com/equip/reviews/5mm_EP/5mm_ep.html

Towards the end of the report this question and conclusion caught my eye:

"Does use of a binoviewer provide improved planetary viewing to monocular viewing?

  • Yes, binocular viewing allows detection of subtler surface detail and color due to the benefits of binocular vision. However, binocular viewers decrease light transmission, increase light scatter and lower contrast and color saturation. While there are beneficial planetary viewing results with binoviewers, benefits are greatest with a high performance refractor and are of minimal benefit with an entry level refractor."

Not having much experience of using binoviewers myself I thought I'd ask observers on here whether their experiences agree with the above, or differ from it ?.

I guess higher quality binoviewers would mitigate the negatives identified but to what extent ?

To what extent does the use of both eyes overcome the negative impacts that are suggested by this reviewer, assming that they exist to some degree even if perhaps over emphasised by the reviewer ?.

Was the reviewer pushing things too far by using 5mm eyepieces with a relatively inexpensive binoviewer ?

I realise that I'm eventually going to have to "bite the bullet" and find out for myself but I'm interested in reading others experiences prior to dipping my own toe.

Thanks :icon_biggrin:

 

 

 

Hi John,

I've used a cheap end revelation binoviewer for about 7 years and really love it. It was my friend paulastro who talked me into buying it in the first place, and after trying his several times, i took the plunge. I really like high end eyepieces for mono viewing, Pentax XW's being among my favourites. When my bv arrived Paul loaned me a cheap pair of 16.8mm Kson orthoscopics. Last year after observing through my scope he demanded them back as they were simply stunning performers on the moon and planets. 

Not everyone gets along with binoviewers but I love them for solar system viewing, as they reveal detail more easily than the mono view. Even the Kson ortho's at £60 each give as sharp a view as any mono XW when used in the binoviewer. Interestingly, Paul has had several high end  binoviewers pass through his hands over the years, and is of the opinion that there isn't enough improvement in image quality to warrant the price hike. The biggest drawback for me is that I now have to choose friends based on eye separation. :icon_eek:

Mike

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I've been using a WO bino on and off for a while predominantly with a 102mm Sky-Watcher Skymax. Personally, I wouldn't recommend using individual eyepieces of less than around 15mm.

Bino GPC 2point6 (1).jpg

As the smaller the f/l the more difficult it seems to be to combine the images. I now have pairs of 15mm, 18mm, 25mm and 32mm eyepieces. I use three GPC's of 1.6x, 2x and 2.6x to achieve focal lengths shorter than 15mm. I have a pair of TeleVue 15mm Plossls which work well as the eye lens size and eye relief is just about tolerable. I think the pair of Hutech 25mm ortho's are the easiest to achieve combined images. I even sometimes use a pair of 25mm Sky-Watcher MA's as they are light, have smooth draw tubes and comparatively large field stops. I also have a pair of TeleVue Panoptics but found them rather heavy to handle with one hand and prefer my 18mm BCO pair.

WO bino Baader 32mm.jpg

The eyeguard extenders on the 32mm BCO's are very useful with the bino.

Edited by Mak the Night
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Hi again John,

I'd just like to add that I use a X2 Barlow screwed to the nosepiece of the binoviewer to reach focus and reach a magnification high enough to attain a reasonable image scale.

Mike

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Wow !!!

Top notch rapid responses there folks - really appreciated :hello2:

Can't think of any other forum where I'd get such interesting and thoughtful replies in such a short space of time :icon_biggrin:

Can I ask suplementary question ? - what about double stars ?. I enjoy observing them and I wonder if binoviewing would enhance that experience as well ?

Thanks again.

 

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Just some of my experience th

On ‎2016‎-‎10‎-‎18 at 20:12, John said:

"Does use of a binoviewer provide improved planetary viewing to monocular viewing?

  • Yes, binocular viewing allows detection of subtler surface detail and color due to the benefits of binocular vision. However, binocular viewers decrease light transmission, increase light scatter and lower contrast and color saturation. While there are beneficial planetary viewing results with binoviewers, benefits are greatest with a high performance refractor and are of minimal benefit with an entry level refractor."

Not having much experience of using binoviewers myself I thought I'd ask observers on here whether their experiences agree with the above, or differ from it ?.

I guess higher quality binoviewers would mitigate the negatives identified but to what extent ?

To what extent does the use of both eyes overcome the negative impacts that are suggested by this reviewer, assming that they exist to some degree even if perhaps over emphasised by the reviewer ?.

Was the reviewer pushing things too far by using 5mm eyepieces with a relatively inexpensive binoviewer ?

I've only had maxbright, so no experience with any high-end binoviewers, here's some of my thoughts anyway:smiley:

1. Decrease light transmission: this should be the direct result when the light is splitted in two., you'll only get some 71% of light into each eye compare to cyclops, so it should be dimmer.

2. Increase light scatter: no my experience, scatter is noticeable less compare to cyclops. If I compare my oy orthos in bino to cyclops, the difference  is more than 18 BCO compare to an low-end multi-lens EPs.

3. Constrast: I've use binoviewer mostly on Moon and Jupiter, and a few bright Messiers, constast was better to my eyes According to what I've read, the signal to noise ratio is better when viewing in both eyes, since the brain filters out the weaker signal (i.e. noise in one eye).

4. 5mm eyepieces are pushing well over limit to what I've understand, one reason is that our eyes will be very sensitive to slightest misscollimation in the binoviver, it's much better to use OCS or barlow to reach higher power. Another reason is mentioned here by Glenn that image diminution is significant when exit pupil is well below 2mm.

Edited by YKSE
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Hi John

I'll report in more detail tomorrow when I have more time but am loving mine so far.

My overriding view is that after the small amount of extra effort setting up it's wonderfully relaxing compared with cyclops. Only really tried moon and Ha but impressive so far.

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John, I'd have to disagree with Dudes 1" aperture loss theory for the following reasons. If there was a drop in lightgrasp that equated to a 1" drop in aperture then the 13.2 magnitude star situated close to the periphery of the ring nebula would be undetectable, where as in reality it is very easily seen in a 4" with binoviewer. And of course a 4" will retain its resolution capabilities irrespective of its eye end configuration. 

Mike.

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Some good reports here John, I too have already questioned the possibilities with my vendor, but not in any rush just yet.

The mention of light reduction is without doubt due to the image being shared/spread over two occulars. Quite often if something is shared or split, the end result is often less than 100% of the original, and by how much is probably down to the users own perception? Your larger aperture may mitigate some of this light loss.

Maybe time to bite that bullet, it's the only way to discover for yourself if this option favours your eyes/needs, as you know full well, what suits one user does not favour the other, but the reports here are favourable. 

 

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4 minutes ago, Charic said:

...Maybe time to bite that bullet, it's the only way to discover for yourself if this option favours your eyes/needs ....

 

I have a feeling that you are right Charic :icon_biggrin:

 

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John I am not a serious star splitter but I do love using the binos for this use. Basically everything YKSE stated I find to be the case- there is less perceived scatter to me using binos than mono. Splits seem easier-but- how you get to the mag needed also matters quite a bit. Anything that makes merging harder such as low FL eyepieces can detract performance and everyone has their own limit. Many use an OCS/GPC  type of set up and I also use a "powerswitch" to have roughly 1.3,2.3 and 3x with my dobs and similar for my fracs- very handy.

So, yes a properly assembled bino system will enhance star splitting and provide a very low scatter and jet black background platform to observe from.

As a side note...the weight of a bino set up can adversely effect the collimation of some scopes ie my VX10 which can soften the views. My 15" and my refractors are unscathed by this fortunately.

Gerry

PS there are ways to overcome the collimation issue...

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I have a little more time now John, so here’s my initial feedback as a complete binoviewer (BV) newbie. The key challenge as intimated above is establishing what you need to do / use to get to focus point for particular magnifications. The first time you get to focus is a big yippee moment!


There are various ways the reach the focus point of course and I have used a few already. The key problem is inadequate in-focus as the BVs use up in the case of my Maxbrights (BMs - which I’d strongly recommend – see below for reasons) is 110mm. Not many scopes have this much spare capacity in the focus range.


One reason for recommending the BMs is that I know you have a Baader Zeiss t2 diagonal. The BMs can screw directly to the t2 male connection on the diagonal, saving around 30mm of in focus on top of the 30mm or so you saved with the diagonal vs. a standard mirror unit. Furthermore, Baader glasspath compensators (GPCs – which I’d also recommend) have a 34mm thread and can be screwed into the male t2 on the diagonal prior to the BMs being screwed on.
You do though still need to shorten the light path by 110mm for the BVs given that the diagonal savings don’t reduce this, just help with overall light path length.The reason for the GPCs is to shorten the light path so that you can reach focus but they also, like a barlow, effectively increase the focal length of the scope. The savings off the 110mm are as follows:


1.25” Glasspath Compensators:
1.25x, focus gain: approx. 20 mm
1.7x, focus gain: approx. 35 mm
2.6x, focus gain: approx. 65 mm
2” Newtonian 
1.7x, focus gain approx. 80mm


Whilst not cheap they are very flexible and allow the BVs to be used in most scopes.


In my PST mod, I found that with the standard 1.25” nose for the BMs I could not reach focus with the 1.7x GPC and my (only pair so far of eyepieces) 18mm BCOs (effectively 10.5mm focal length so 95x). I was close though and arranged for 6mm to be trimmed off the end of the nose. I lost the filter thread but can now focus. The views were very nice and full disk which surprised me!  This matter was complicated by the critical placement of the etalon at focus point – 200mm so I cannot shorten the tube further and any reductions need to be behind the etalon in the system. I therefore also decided to buy a Baader t2 (non zeiss) diagonal specifically for the PST mod as it will (possibly/hopefully) allow me to use the BVs with no GPC allowing me to reduce to 55x which should provide a brighter view I think.


I managed to get focus in my 12” dob without the paracorr and with the GPC and my single 24mm Panoptic but only with the 2.6x GPC so 173x and a bit too much mag really. A bit more testing to do on this I think but I am buying a pair of 25mm plossls which will reduce this to 124x which might be just OK.


With my 120mm ed I find that I can readily focus on the moon with the 1.7x GPC inserted in the t2 part of the diagonal at (I think) a magnification of around 100x. The views were simply stunning. I tried with the 2.6x GPC (not sure but the placement made it about 180x I think). This was good but getting towards the limit I think both in terms of eye placement and seeing for the night. I cannot focus on the sun currently with my 1.25” Lunt wedge unless I use the 2.6x GPC. At 130x this seems a bit much for the seeing on the day I tried. Again I hope the 25mm plossls will help with this. It’s possible that in the future I will buy a 2” Baader wedge and this will almost certainly require the tube to be cut by perhaps 100mm or so. I’d not really have a problem doing this as it’s a scope I’ll be keeping.


Overall, I feel that even if the detail visible is the same as cyclops vieweing, the additional effort and cost is justified for me in terms of the comfort of viewing. The two eye view just feels so much more comfortable and relaxed and even if I have to stick with cheap plossls for a long time, I am confident that I’ll still be happy. Whilst initially I anticipated using one or a couple of pairs of eyepieces and a number of GPCs, I am starting to conclude that more eyepieces and no GPC or a single one might be the better option as it’s easier to change two eyepieces than removal and insertion of a GPC, especially in the dark.


One thing that has net been a real problem has been merging the view with two eyes. It seems a bit harder with higher magnification, presumably with the smaller exit pupils and finding the right inter pupillary distance. 
On the whole, I’d definitely recommend BVs based on my experience so far but you need a ‘can do’ approach to challenges to get to where you’ll need to be to start enjoing them.


At this point, I envisage ending up with a pair of 25mm plossls on top of my current 18mm BCOs and possibly eventually another 24mm Panoptic to match my current one, a pair of 19mm Panoptics and maybe also a further 11mm Delite to match my current one. I’d then possibly sell the 18mm BCOs and the 25mm plossl. I am still in a state of flux though and will take my time before making expensive purchases like the above. Another Baader Zeiss t2 prism would be on my hit list too for general night time use. 


It’s never cheap to make the switch but I feel that it can be cheaper than you think and as cheap you you let it become.

Sorry, I waffled on a bit but thought my musings might be of some use :icon_biggrin:

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I've been a huge fan of binoviewing ever since trying a unit many years ago. I currently have 5 ranging from cheap to expensive and apart from less field vignetting of the more expensive models I find little difference in performance on the objects I use them for, lunar, planetary and solar. My setup in regular use is a revelation unit with cheapo SW 2x Barlow lens removed from its body and screwed on to the front of the binoviewer, the eyepieces are a pair of Celestron 32mm Plossls. Hardly an expensive approach!. It's worth bearing in mind that standard Barlow lenses increase their magnification effect depending on their distance from the eyepiece. The light path through a binoviewer is quite long so a 2x Barlow will provide nearly 4x, I would say that it is better to increase magnification with a Barlow than to use shorter focus eyepieces. Overall, I find the reported benefits of binoviewing well outweigh any negatives.

I'm currently on my last day of a visit to Tenerife where I've been enjoying binoviewer views at over 100x on my 80mm PST mod and up to 800x on lunar detail with a Celestron 8se. The good seing here helps!   :icon_biggrin:

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More excellent feedback - thanks so much for going to the trouble :smiley:

I'm not envisaging a wholesale switch to binoviewing (unless I'm really blown away by it) so I expect I'll get something relatively low cost to test the water and have as an option for certain targets.

I briefly tried a pair of binoviewers a while back (Revelation I think ?). I had a few good moments with them and the 12" dob but that was the only scope that I could readilly get them to come to focus with. Having changed the focuser on that scope I've probably scuppered that now because it's set up for cyclops mode. I guess I could re-install the focuser (Moonlite) without the spacers in place and use an extension tube when cyclops observing but I'd prefer not to do that at the moment.

I also had some difficulty merging images and I'm not sure that I even really managed it but I did not keep the last binoviwers for very long - I confess that I got rather frustrated with them :undecided:

The binoviewer would not come to focus, even with the supplied barlow-type element, with my ED120 or Vixen ED102SS and I'm not keen to take a saw to either of those.

My two most recent acquisitions, the Takahashi FC-100DL and TMB LZOS 130 F/9 seem to be much more "bino friendly" scopes.

With the Tak I have around 80mm of focus travel / extenders that I could use to get the binoviewer to focus plus I have the Baader T2 Zeiss prism with 1.25" click lock which has a quite short light path. I may need to use a barlow-type element but maybe not ?. I'd prefer only to use these things when I want to up the magnfication if possible. MikeDnight uses the F/7.4 version of this scope with a BV - I wonder if he is using a barlow element or not ?

The TMB LZOS 130 has a built in extendable section between the scope tube and the Feathertouch focuser which allows the whole focuser to be moved inwards or outwards around 120mm. For cyclops observing I have the extension in it's outermost position. This is the most "bino friendly" scope I think and also the 130mm aperture will support binoviewing better from what I've now learned.

So I have 2 scopes to use BV's with I think. I can do white light solar with the 1.25" Lunt Herschel wedge and the Tak I guess - or would the weight of the BV + EP's be to much for the poor Herschel wedge ?. I would need to either put the polararizing / continum filter on the nosepiece of the BV or get another so I can have one on each eyepiece barrel I suppose ?

So much to think about ! :icon_biggrin:

Thanks again for all your feedback :hello2:

 

 

 

 

 

Edited by John

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13 hours ago, Dude_with_the_tube said:

Once again i will NOT agree with the concept that binoviewing is expensive or for people with deep pockets.Thats a wrong statement.you can get a WO for 100 s/h,as for eye pieces,you dont need Pentax or Naglers,a simple plossl,erfle will perform brilliantly,however,my absolute favorites in binoviewers are orthos.They provide no scatter,clear neutral colour image, a pair of 25mm and a pair of 12mm will set you back for lets say 200 quid,thats what a cost of one Pentax XW or TV Delos/Nagler? Would you say that is expensive? Tv Ethos costs far more than that!

£200 is a lot of money to many a person myself included. That's just short of a weeks wage and after paying bills and putting food on the table I'd be looking at 2-3 maybe even 4 weeks to buy a couple pairs of eyepieces which I may mention would be no where near the quality of the Pentax or delos. It has been mentioned in at least one other thread that some members recommend astro kit of £200 -£500 like it's nothing when their are cheaper (albeit maybe not as good) kit available. I admit it easy to forget just how much astro kit is when everything else in this game is so expensive and I'm not immune to forgetting this either as I recently recommended an ED120 to someone like £600 used was nothing. Not once did I stop to think how demanding this might be on the persons day to day life to save for.

If there is one thing I learnt about bino viewers while reading up on them is that they are not all created equal. The top end BV's have better prisms which are key to reducing the light loss as prisms are generally not 100% efficient at passing light so the better quality they are the less dimming one should experience. Also the top end BV's have larger prisms so allow for a better FOV. IE: you are less likely to experience vignetting in a 32mm plossl as you would in a budget pair of WO's. Which given you are going to use longer focal length eyepieces due to GPC or barlows to reach focus can make a big difference. So the long term BV experience is going to require a substantial investment if your going to get the best from your expensive telescopes. My guess is the larger prisms and so aperture of the high end BV's also allow for further reduction in light loss

It is also worth considering that in the case of John he isn't going to want to have 3 cases full of ethos & pentax sitting idle while he bino views through a pair of SW MA eyepieces. Yes the views do seem more contrasty and far more comfortable with detail seemingly easier to pick out but 1) you are loosing light due to the prisms, splitting the light path, GPC or barlows adding extra glass to the mix 2) more often than not going from using premium glass wide field eyepiece in Cyclops to using plossl or reduced fov ortho in BV's. It is not like you can improve on this much as you are restricted to the eyepiece being slim allowing you to use both eyes.

If you do decide to go the route of BV's John whether try b4u buy or other wise it may be worth considering a nice 1.25" diagonal. I found that greatly improved the ability to reach focus over a larger 2" diagonal.

Edited by spaceboy
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2 hours ago, John said:

 

My two most recent acquisitions, the Takahashi FC-100DL and TMB LZOS 130 F/9 seem to be much more "bino friendly" scopes.

With the Tak I have around 80mm of focus travel / extenders that I could use to get the binoviewer to focus plus I have the Baader T2 Zeiss prism with 1.25" click lock which has a quite short light path. I may need to use a barlow-type element but maybe not ?. I'd prefer only to use these things when I want to up the magnfication if possible. MikeDnight uses the F/7.4 version of this scope with a BV - I wonder if he is using a barlow element or not ?

 

 

 

 

 

 

Hi John,

Attached are a couple of images showing my cheap bingo set-up. I do use a X2 Barlow that I unscrewed from its original body. It screws directly into the nose of the binoviewer, as without it I couldn't reach focus. Despite the extra length added to the nose of the binoviewer and the fact that, as I use a prism, full insertion isnt possible, the Tak prism holds the BV perfectly well. Rotating the eyepiece holders merges the images, so once youve merged the images, note where the locking screws are and youll be able to easily maintain a merged image. You might also be able to see that ive slightly retracted one of the orthos by about 1.5mm. This was done so that the retracted eyepiece was as sharply focused as the fully inserted one. I've used this set-up for so long now that I can easily readjust it to suit me if another observer alters it.

Mike

 

2016-10-19 13.03.18.jpg

2016-10-19 13.04.37.jpg

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I wouldn't underestimate the 25mm Sky-Watcher MA's for an inexpensive bino pair.

25mm.jpg

There are a number of reasons I'd recommend them, although I will say that I don't use them in combination with a GPC and have a pair of 25mm Hutech ortho's for that.

AH 25mm.jpg

1/ The 25mm Sky-Watcher MA's are comparatively cheap; just under £16 a piece on Amazon at the moment.

2/ They have pretty decent quality lenses that have quite adequate coatings making them eminently useable for an inexpensive reversed Kellner (a bit of CA notwithstanding).

3/ Being a reversed Kellner they have relatively big field stops (25mm?) and a generous field of view which is appreciated more in a binoviewer than when they are used individually. In fact, I actually prefer these to the 20mm WO SWAN's that came with my WO bino!

4/ The plastic upper barrels contribute to the low weight of the eyepieces. This can be a factor in a bino and can help keep the overall weight down. Although the downside is they probably have poor flocking.

5/ The smooth aluminium draw tubes are light and have no tapers. Having no safety undercuts facilitates easier insertion and extraction from bino dioptres with brass compression rings. WO supply SWAN eyepieces with their bino which have tapered draw tubes. The irony is that WO bino's have compression rings and tapered draw tubes can permanently deform compression rings.

6/ The SW MA's have generous eye lenses (15-18mm?) which significantly aid image merging (see comparison with Hutech 25mm orthoscopic above).

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2 hours ago, John said:

More excellent feedback - thanks so much for going to the trouble :smiley:

I'm not envisaging a wholesale switch to binoviewing (unless I'm really blown away by it) so I expect I'll get something relatively low cost to test the water and have as an option for certain targets.                                     

The binoviewer would not come to focus, even with the supplied barlow-type element, with my ED120 or Vixen ED102SS and I'm not keen to take a saw to either of those.

My two most recent acquisitions, the Takahashi FC-100DL and TMB LZOS 130 F/9 seem to be much more "bino friendly" scopes.

                     

 

 

 

 

 

 

Hi John. Don't you fancy taking a bit off the scope to help with reaching focus if needed? I can lend you a nice big sharp hacksaw if required or an angle grinder if you wish to speed things up a bit?. 

I know some people do chop their scopes?. But when I first read about this fix I just looked at my poor 120apo open mouthed. There was no way I was even going near the scope with a saw ,never mind chopping it?. So early on in my binoviewing introduction I had decided binoviewing was supposed to be an add on to the Cyclops experience and not to take over from Cyclops. So I made the decision if the TS Binoviewers did not work with my existing kit then I certainly was not going to chop my beloved expensive scope(in my eyes anyway even though it was purchased used). Therefore luckily the TS Binoviewers will reach focus in straight through set up without any real problem. And when it came to the diagonal set up (which is more comfortable, especially in targets higher up in the sky) they did not reach focus initially, but I did have a used televues 1.8 barlow when put in the optical chain did allow me to reach focus☺. So I think I have been relatively lucky compared to some to get there optical path to focus . But if I was going to have to buy this that and the other to get the Binoviewers to work in my scope then I would not of carried on binoviewing. The only real expensive I have had apart from the second hand Binoviewers themselves was eyepieces. Originally got some used sw plossl to get me going to make sure I could reach focus, to make sure the images merged and that I liked the binoviewing experience. When I did find binoviewing a positive add on to the Cyclops experience then I started to pair up some existing eyepiece, the televues plossl pairs were purchase second hand. And I also managed to pair up my existing 18mm BGO , which I never thought I would do as these are getting very hard to find ,but give amazing views IMO. So the entire add on kit (not including my original kit) cost under £300.  This includes second hand Binoviewers , and to double up existing eyepiece in  televues 32mm ,  televue 8mm,   sw plossl 25mm and 10mm and 18mm BGO. I think this represents pretty good value for money considering the added image experience binoviewing gives especially in the refractor.

I hope the above helps☺

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The point I was trying to make is you start a thread 'what eyepiece shall I buy to get the best from my scope?' and the reply more often than not will be pentax or televue at £100's of pounds. Ask the same question for binoviewers and that goes totally out of the window to the point even a £15 SW MA is considered "OK".

The reason why I let my BV's go after only 2 days was because I felt BV's represented a single eyepiece similar to a zoom for example. After spending a fortune on ES eyepieces for wide field views etc I had no intension to use BV's with plossl night after night and using my ES would not pay off due to the stopped down aperture of the WO BV's along with possible eye position problems. 

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Just to be clear, I am not proposing chopping anything off with a saw, rather getting an engineer to cut off a section with a lathe and make a connecting adapter to allow it to be returned to standard if required.

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Yes, but the point I was trying to make is that unless you spend a great deal of money on a large prism bino the whole bino experience is going to have some limitations. It is a fundamentally unrealistic comparison to make with expensive wide angle eyepieces and an inexpensive bino which only allows a 66° FOV at best.

The analogy just doesn't make sense. A relatively inexpensive bino gives a stereo viewing experience that has both advantages and disadvantages to wide angle mono viewing.

Subjunctive replies to hypothetical threads notwithstanding, the experience I had with the £16 SW MA used as a bino pair felt very different to using them singly. I have other bino pairs that I use more, but they are all suited to a small prism bino and the 42 - 50° FOV is ample enough.

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Bino-viewers, just  like 3D when viewing the Moon!........Who knows?
I'm not sure there is a full Moon this Christmas day as there was last Year, but if Flo were able to loan John a pair of Bino Viewers for evaluation purposes! as he has done many times in the past, testing  oculars ?  then a positive feedback may improve sales prior to Christmas,  looking for that  Moon shot!..........its a win win for Flo & John......he he he he!:happy9:

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