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5 hours ago, Alan64 said:

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

No. I’m just making an observation that halving the area of a circle doesn’t half the diameter. 

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4 hours ago, Rob Sellent said:

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

- - - -

Some more interesting links on bino summation and the such here

My 60mm b1200 lunt focuses ok with 1.6x GPC, can’t comment on the moonlight 

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Mike puts it perfectly, imv.  Using binos on, say, a 10 inch scope absolutely does not reduce its performance to that of a 5 inch.  The resolution of a 10 inch aperture is retained. Of course, the light is split but the information it carries is integrated by the observer and the resulting image is significantly more detailed with, to my eye, only minimal loss of perceived image brightness. With lunar and planetary, as well as brighter nebulae, globs and open clusters, the latter consideration is simply not an issue.   

Having to use a Barlow ahead of the viewer is no real disadvantage.  It means, among other things, that generally more comfortable longer focal length eyepieces can be used. I think that Roland Christen recommended not going below 10mm - the advice is widely cited. I’ve not found any advantage either in apparent fields of view wider than about 60*.  Though they’re much touted as bino friendly, I personally didn’t like the 17mm Morpheus to bino that much - though I like it a lot in mono and keep one.   My ‘favourite’ bino pair are probably 18mm Tak LEs with a 2x Powermate ahead; I’ve also had great planetary views with 11 and 8mm TV Plössls and a 1.7 (>1.5x) Baader GPC.  For wide field viewing I’m happy with mono.

I think you just have to give it a go!  No need to break the bank, there are some good values out there, new and s/h and you can always sell on if you don’t like it. Until you try, you’ll always be wondering ... 🤔

 

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I tried binos on my 10" f4.7 dob - and loved them for the moon + planets!  I really felt they were better than mono (for me) on that scope. Mine are Baader Maxbrights, a 2.6x GPC, and I use a pair of 15mm TV plossls.

 

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well for those that don't like what I said on my first post there is a quote"

The main disadvantage to using a binoviewer is the reduced light.  Stargazing is all about light-gathering.  Observers put a lot of effort and money into big telescopes and high-transmission coatings, and high-reflectivity mirrors, trying to squeeze every possible photon out of an instrument.  A binoviewer then splits the incoming light and reduces the brightness by 50%. 

and there are a ton of threads u can look up that can argue my point, it did go on to say the brain once merges the image may seem to brighten that view but that's the brain tricking us as we are now seeing it in stero view instead of a single view, that's doesn't mean the image IS brighter BUT seems brighter.

I guess like we see upside down but our brains straighten the view and we see the correct right side up.

I guess you can try it and see if you like it, models like skywatcher/ Antares and  orions are pretty cheap at about $199 or try to find a used pair. I find I like viewing without my binos even tho I have a pair but once in a blue moon I do use it on planets /moon only

joejaguar

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Sorry Joe, whatever others may think or say, my view of the moon or planets does not dim by 50% when using a binoviewer as compared to a single eyepiece view at the same magnification. Neither does a mono view appear twice as bright. Even brighter DSO's such as M42 and M13 appear quite spectacular through my cheap binoviewer and nowhere near 50% dimmer than a single eyepiece view. Infact the only reason I don't use my binoviewer more often for DSO viewing is down to positional comfort rather than any dimming of the image.

I do acknowledge there is some light loss, but it is truly minimal and not even close to 50%. I am pretty sensitive to very subtle differences in contrast, definition and brightness, so if my brain is deluding me, then it's doing a spectacular job!

Edited by mikeDnight
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I didn't write that, theres tons of that online if one choose to look. I also heard this in mag like sky and telescope and astronomy mags many years ago, of course I cant say which issue or month as I don't get those mags anymore since most people have gone the age of the digital paper now.

some agree some disagree your free to feel your way, I personally don't think dobs are best first scope BUt most people do so all is subjective I guess

joejaguar

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also bear in mind you said moon bright planets, i mean you can view those item with a 50mm or 60mm scope since they are so close and bright. Its also hard to measure brightest ourselves, for instance the eye cant tell the difference in a 9% or less roughly, even 30% light gathering power from a 5" to a 4" scope is not a huge difference cause the light is spread over the circumference. there is a difference its abit bighter but its not massive brighter, so 50% brighter is not a huge difference.

look at the moon with a 4" refractor sure its bright look at it with a 5" refractor is it brighter sure can most people tell the difference and by how much I don't think so

joejaguar

Edited by joe aguiar

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And there is the problem of unequal light splitting which does vary among brands. Even the best aren’t 50;50 on each side.  Some of the poorer ones are only 60:40 though which might explain why some people find certain brands just don’t work well for them. I wonder if how well some peoples eyes compensate for brightness differences side to side affects their perception of overall brightness? 🤔

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3 hours ago, joe aguiar said:

A binoviewer then splits the incoming light and reduces the brightness by 50%.

The bit that's missing from this sentence is that, allowing for whatever losses there are in the binoviewer, the total amount of light is delivered to both eyes so it is all used.

Just to show that this is not as simple as it sounds, just close one eye. Does everything suddenly reduce in brightness by 50%? The answer is no, proving that the brain's processing and interpretation of the signals from your eyes is a huge part of what you perceive.

My view is that some threshold objects may be lost to the few percent losses within the binoviewer, but the brightness certainly does not reduce as has been implied.

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I don't think that's a fair comparision its more like if u have water draing into 2 pipes the flow is half compared to all th water going down 1 drain is more of a comparion to opening one eye. remember in the binoviwer the beam is splitinto 2 beams. in regular binos theres a barrel of the same size to each eye.

so I wouldn't comparing opening 1 eye to both splitting the beam

joejaguar

Edited by joe aguiar

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23 minutes ago, joe aguiar said:

I don't think that's a fair comparision its more like if u have water draing into 2 pipes the flow is half compared to all th water going down 1 drain is more of a comparion to opening one eye. remember in the binoviwer the beam is splitinto 2 beams. in regular binos theres a barrel of the same size to each eye.

so I wouldn't comparing opening 1 eye to both splitting the beam

joejaguar

My point was that cutting 50% of the light by closing one eye does not reduce the brightness of your perceived image, showing that your brain is heavily involved in the perceived image. The total amount of light recieved into the brain is the same vs mono viewing.

Quite happy to agree to disagree. I shall carry on enjoying my binoviewers :)

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What has not been pointed out is that the response of the eye to light intensity is not linear. In fact you have to double or halve the light in order to even notice the difference, so while technically a binoviewer halves the light to your eye, as far as the eye/brain is concerned the drop in brightness is only "1". This is the exact same reduction in brightness as changing from a 14mm to a 10mm eyepiece, for example, and I don't think there are many people advocating only ever using one length of eyepiece. For lunar and planetary observation where the objects are very bright to begin with, a small drop of light is not going to be an issue anyway. 

In addition, there are the advantages of binocular summation. From wikipedia: 

Quote

By combining the information received in each eye, binocular summation can improve visual acuity, contrast sensitivity, flicker perception, and brightness perception.

 

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Yes, and I personally believe that the brain's image processing gain is the big benefit, outweighing light loss (which doesn't bother me at the mag I run at on my 10") on bright targets. For me, I find reading something / seeing at distance is easier with both eyes, compared to closing one.

I dont use binoviewers on DSOs (for several reasons).

My absolute best planetary views have been mono in my 15" (the binos dont focus in that scope).  BUT for a quick faster cool down look, the 10" comes out and the binos go in ;)

 

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Binoviewers are clearly a Marmite subject on here !  🤓

I've had two pairs and can only echo most of the comments so far.

It depends so much on each individual's eyesight and it's crucial that they are well collimated and that the interpupillary adjustment is set perfectly, not just "ok". If either of these are the slightest bit off, then the brain starts to compensate for them, re-aligning the two images, resulting in eyestrain and headaches.

It's bad enough with daytime terrestrial viewing, but nighttime stars and planets are much more reluctant to fuse back together in one's brain.

Whenever I look through any Bins I always draw my eyes back from the eyepieces to separate the images and see if any horizontal objects are aligned vertically.   It's surprising how often they're not, even with brand new pairs.

I've had two pairs of Binoviewers,  my first were Astro BC&F and my current ones are BST Starguiders, (apparently the same as Acturus).

The BC&F were fine, but the nose piece had no provision for a short integrated Barlow, so I had to use a conventional Barlow, which extended them out quite a long way, hanging of the scope's focuser.  The Starguiders came with a plain nosepiece and two interchangeable integrated Barlows, which enable infinity focus on any of my scopes without increasing the physical length. They also have self-centering eyepiece clamps, rather than thumbscrews, which also helps to retain collimation.

I also have a pair of Revelation 20x88t right angle prism binoculars which have a screw adjustment IPD control which enables them to be set perfectly.

astro bcf.jpg

revelation 20x88t.jpg

starguider.jpg

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On 09/11/2019 at 17:45, mikeDnight said:

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

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

IMG_0653.JPG.fabbdbdbf74127383f5477d39d5a4d57.JPG

When I have tried binoviewing (I've  tried 3 binoviewers so far) I have found a few difficulties. I'm still keen to find something that works for me but here are the challenges..

1. Collimation was always out but my guess is this could be due to wonky eyes or not trying hard enough to get used to them and not due to badly collimated binoviewers - the jury is still out on this.

2. Balance and vibes  - having more weight hanging further out makes these things more challenging.

3. More stuff to set up eats into observing time - most of my sessions are short.

4. Holding the binoviewers out sideways so I can have a natural viewing angle. 

On point 4 how do you manage to point those binoviewers out to the side without gravity pulling them down. Nothing I had was strong enough to hold them sideways so I always had to point them straight up.

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2 minutes ago, Paz said:

On point 4 how do you manage to point those binoviewers out to the side without gravity pulling them down. Nothing I had was strong enough to hold them sideways so I always had to point them straight up.

Looks like Mike has a standard Tak focuser, with a compression ring fitting presumably. I have a Feathertouch on mine and it will hold the binoviewers in a similar way, just tighten it up enough.

One important thing, make sure the weight is tending to tighten the barrel thread up rather than undoing it, if that makes sense. If you put the binoviewer on the wrong side then the barrel can suddenly unscrew, leaving the whole lot pointing at the ground and at risk of falling out. This happened to me once, luckily the diagonal had a click lock fitting which was done up tightly so nothing dropped out.

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35 minutes ago, Stu said:

Looks like Mike has a standard Tak focuser, with a compression ring fitting presumably. I have a Feathertouch on mine and it will hold the binoviewers in a similar way, just tighten it up enough.

One important thing, make sure the weight is tending to tighten the barrel thread up rather than undoing it, if that makes sense. If you put the binoviewer on the wrong side then the barrel can suddenly unscrew, leaving the whole lot pointing at the ground and at risk of falling out. This happened to me once, luckily the diagonal had a click lock fitting which was done up tightly so nothing dropped out.

That must tighten up well - and that little tak prism did well to hold all that together without exploding!

I know what you mean about the thread direction on the diagonal barrel, I've had the odd occasion where an eyepiece swung down for this reason and you watch for a moment wondering if it is going to drop out before having the presence of mind to grab everything!

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3 hours ago, Paz said:

When I have tried binoviewing (I've  tried 3 binoviewers so far) I have found a few difficulties. I'm still keen to find something that works for me but here are the challenges..

1. Collimation was always out but my guess is this could be due to wonky eyes or not trying hard enough to get used to them and not due to badly collimated binoviewers - the jury is still out on this.

2. Balance and vibes  - having more weight hanging further out makes these things more challenging.

3. More stuff to set up eats into observing time - most of my sessions are short.

4. Holding the binoviewers out sideways so I can have a natural viewing angle. 

On point 4 how do you manage to point those binoviewers out to the side without gravity pulling them down. Nothing I had was strong enough to hold them sideways so I always had to point them straight up.

Hi Paz,

Using the Tak 1.25" back can be problematic, in that the compression ring needs to be overtightened to prevent the binoviewer from gradually slipping under its own weight.  To overcome the problem I use a Skywatcher 2" to 1.25" low profile adapter in a Takahashi 2" back. It is a brilliant little device that grips the diagonal like a vice, and also allows me to rotate the back end without unscrewing anything. By releasing one of the two locking screws I can move the angle of the binoviewer with ease.

The collimation issue you mentioned could simply be the locking screws on the binoviewer pushing the eyepieces slightly off axis. With my binoviewer for example, if I put the locking screws on the outside edge of the eyepiece holders the image will never merge. But if the screws are screwed into the holes between the eyepiece holders, the images merge perfectly. This may be due to less than perfect engineering. Also, I never focus rotating the diopter adjustment. Instead I've wound the diopters close to their inward setting, then after focusing the scope I retract one of the eyepieces until both images are perfectly focused, then lock the retracted eyepiece in position (its only about a millimetre difference). It sounds complex but its really quite simple. Once you've found your perfect setting its probably wise not to allow others to adjust the diopters, as this will throw the whole thing out and it can take a while to re-set it to your own preference. 

Oh, the little Tak prism is as tough as old boot. Mine has taken a real hammering over the years and is still going strong. ☺

IMG_3424.thumb.JPG.4e69fec2d9e942d97bb50ae5b60d1dcb.JPGIMG_3426.thumb.JPG.182d62ad6494fe841fa9050b4fd596e5.JPG

Edited by mikeDnight
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I'm a little biased here as i've been a binocular and bino-viewing enthusiast for a good few years now.

I've always believed theres no better way to observe.

I always think "why would anyone want to observe with one eye when you have two ?" What do you do with your other eye while monoviewing with the other ? Keep it closed ? Keep it open ? Cover it over. This just leads to squinting through your observing eye.

When you listen to music through a pair of headphones they generally sound better and feel more comfortable in stereo don't they ??  They do to me.  I apply the same principles to visual observing.

I've never yet seen a mono view through any telescope compare with a two eyed view, on any object, and i've looked through a whole host of different scopes and eyepieces in the last 20 years or so.

Even with something like a 21mm Ethos, one of the worlds finest widefields, while the views have been spectacular in some cases, i still prefer a two eyed view through my personal favourite 24mm Panoptics. 

I can quite happily observe something like Saturn or Jupiter for 10-20 mins continuously, in complete comfort, waiting for that extra steady bit of seeing to come along.

I can't do that mono-viewing. It would get far too uncomfortable.

But thats just my own £0.02p on the subject, and i appreciate that others don't necessarily agree with me.

 

If i had to recommend a system, i would go with Baader Planetarium. The Mk 2 Maxbrite (or a used Mk1) is reasonably priced and best of all, they supply a whole host of excellent prisms and diagonals,

all with a T2 format so excellent compatibility and as short a lightpath as you can get. The William Optics are nice as well, but don't have the T2 compatibility.

Another more expensive option is the Denkmeiers where you have a 'Powerswitch' to give you 3 different magnifications with just the one set of eyepieces.

Theres alot to be said for Powerswitches. Less fiddling around, and more time observing for one.....

 

 

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Why observe with one eye? In my case I just find it more comfortable and easier. But as I have said before some people just don’t get on with binoviewers and I’m one of those that doesn’t. Bins during the day I can manage but at night just don’t like them at all as they give me eyestrain and a headache and find they don’t improve the view one little bit so why bother. 

But if binoviewers work for you why not use them. 

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14 minutes ago, johninderby said:

Why observe with one eye? In my case I just find it more comfortable and easier. But as I have said before some people just don’t get on with binoviewers and I’m one of those that doesn’t. Bins during the day I can manage but at night just don’t like them at all as they give me eyestrain and a headache and find they don’t improve the view one little bit so why bother. 

But if binoviewers work for you why not use them. 

I'm just the same John.

I have tried them (various brands) a number of times over the years and with a number of different scopes but just didn't feel comfortable or relaxed when using them. I've now realised that they won't add anything to the hobby for me (apart from a little frustration) so I won't keep on trying them.

I do urge others to try binoviewers though - they clearly do provide much observing enjoyment and satisfaction to many :smiley:

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An important thing to note is that when you go down the route of bino-viewing you have an optimised set up to begin with.

Most (not all )refractors won't come to focus without some form of amplification.

A Newtonian won't focus at all without it.  

This amplification means having a longer focal length which = more magnification + a slightly dimmer view and that higher power is at the mercy of poor seeing conditions.

 

You have to be really careful with any sort of Catadioptric. Focusing is not the issue here, but if you have too long a lightpath (read visual back and 2" diagonal, then binoviewer and eyepieces) ) your scope

will then lose aperture as you end up racking the primary way too far in to try and focus it. This in turn increases the focal length (sometimes by quite a bit) , makes the secondary

obstruction as a percentage much larger and also introduces spherical aberation in to the mix, which all results in a dim, over magnified and poor contrast view.

 

A lot of observers are naturally disappointed by these sorts of issues, and blame the binoviewers, look at the outlay, the views and say binoviewing is not for them.

Its not a fault with the binoviewer at all ; and a bit of forward planning can make the difference between liking them or quitting on them all together which i think is a shame,

because once everything is optimised the views are so much better, and then the full benefits to two eyed viewing can be really enjoyed.

 

 

 

 

 

 

 

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