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My 6" achro bino weighs exactly 15kg. A grob estimation is: Your Triplet has one more lens element vs an doublet, wich add about 50% to the weight of the lens assemby, add to this further 13% "160mm = about 13% more area and weight, assumed same thicknes of the glas"
Aluminum tubes of 150mm diam, 650mm length and 3mm thick is about 2.2 kg x 2 = 4.4kg wich would be the max you could save in weight but add to this the weight of the CF tubes.
Then comes the hardware you need atacking the tubes with each other!
I think you'll end well over 15Kg for the instrument alone. A good and stable forkmount will at add further 10-15kg then comes the tripod!
Nevertheless it will be an awesome binoscope!

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That sounds like quite a wonderful bino-scope, I'd expect some amazing to phenominal views with it! Good to try for lowest possible weight, it will be interesting to see when all is done.

In my wildest imaginings I've thought about someday getinng another 160ed and making a bino - but for now it remains wild imaginings. I'd love to know how this turns out and what the views are like.

Best of luck with the project

[edit] doing the money math, that is an extremely reasonable way to get ~200mm equivelant apo! hmmm never thought about it that way, but 200mm Apo's are way over double the cost of 2 160's...]

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I never heard about a gain of 40% in lightgathering/throughput on a bino scope vs cyclop mode, but I have heard and read of a gain of about 40% in detecting low contrast planetary features over monokular mode. Thats a huge difrence in performance!

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- binocular viewing can give breathtaking views
- 160 mm binocular corresponds to approximately 200 mm monocular, so it is already a deep sky telescope
- 160 mm is probably the biggest aperture which can be build as a reasonable light-weight telescope that can be easily transported and mounted in a few minutes

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read carefully the first post...

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- binocular viewing can give breathtaking views
- 160 mm binocular corresponds to approximately 200 mm monocular, so it is already a deep sky telescope
- 160 mm is probably the biggest aperture which can be build as a reasonable light-weight telescope that can be easily transported and mounted in a few minutes

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You're assuming that's true. I don't believe that's true at all. Quoting it doesn't make it true.

It's not cummulative. You can divide the light but you can't add them. If you add the beams you're back to a single eyepiece. The 200 will be brighter and have more resolution. How does that correspond "approximately" to a "200 mm"? Based on what I'd like to know?

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That sounds like quite a wonderful bino-scope, I'd expect some amazing to phenominal views with it! Good to try for lowest possible weight, it will be interesting to see when all is done.

In my wildest imaginings I've thought about someday getinng another 160ed and making a bino - but for now it remains wild imaginings. I'd love to know how this turns out and what the views are like.

Best of luck with the project

[edit] doing the money math, that is an extremely reasonable way to get ~200mm equivelant apo! hmmm never thought about it that way, but 200mm Apo's are way over double the cost of 2 160's...]

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I don't understand why 2 x 160mm ~ 1 x 200mm. Each 160 goes into one eye and I don't think it's cummulative. You still only have the resolution of one. You will have some constrast gain and probably a reduction in the 'floater' nuisance.

The combined light-gathering is actually closer to a 9". So you would have the brightness of a bino on a 9" but the resolution of the 160. Bino on a 9" you also have the resolution of a 9".


The brain (my brain) doesn't make things half as bright when I close one eye. That's not where a gain is. I can understand the novelty of it and if it's something somebody really wants, well then... great.

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First of all you need to calculate based on Binocular Summation, not on the sum of all the aperture, and certainly not on the summation factor times the diameter of the aperture. The concept of Binocular Summation is well documented and extensive discussion can be found in either the Binocular forum or the Binoviewer forum. Look in the Best Of threads links or the Resources links.

Binocular summation shows that when using two apertures delivering light to two receptors (the two eyes), the summation effect is sqrt of 2 ( the two eyes) times the area of light delivered from one aperture to one eye. So your effective aperture is sqrt of 160x160x1.414 = 190mm. Still not to shabby, but the combined light gathering is more like 7.5", not 9".

Binocular Limiting magnitude has been tested extensively and compared to monocular LM and found to follow the sqrt 2 summation factor. You can see approx 0.4 magnitude deeper when using same aperture thru two eyes. Numerous tests by numerous individuals using a variety of instruments shows results ranging from 0.2mag to 0.4mag gain.

Resolution using two eyes will be improved over that of one eye. This is almost certainly a result of greater signal to noise and two receptors where one is canceling out noise seen in the other. I have found after many tests on resolution targets and stellar sources, a gain of not much more than 10-15% in resolution. So, when using binocular vision, resolution will not be based on the 160mm single aperture, but will be improved, although not by the factor of sqrt2. The binocular vision resolution will be similar to that of a 180mm scope (+/-) used in mono. However, the ultimate resolution, resolution at the Rayleigh Limit, wil not be greater than can be achieved with the same size scope.

Contrast is said to follow the sqrt 2 form, but anyone that finds a realistic way to actually test that, please let me know. Same instrument (one eye vs two) on a variety of Sb objects is probably not a good test due to the variation in core vs extended total brightness from one object to another. Probably the best way is a variety of instrument sizes on the same surface brightness extended object. Even at that, it would be quite subjective.

You would need an 9" scope with binoviewers to get the same effective light gathering and image brightness (at same power) as this setup. The scope with binoviewers would have much better 9" stellar resolution.

With all that, you've gotta like the views thru a pair of 160mm binoculars.

edz

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.....
Resolution using two eyes will be improved over that of one eye. This is almost certainly a result of greater signal to noise and two receptors where one is canceling out noise seen in the other. I have found after many tests on resolution targets and stellar sources, a gain of not much more than 10-15% in resolution. So, when using binocular vision, resolution will not be based on the 160mm single aperture, but will be improved, although not by the factor of sqrt2. The binocular vision resolution will be similar to that of a 180mm scope (+/-) used in mono. However, the ultimate resolution, resolution at the Rayleigh Limit, wil not be greater than can be achieved with the same size scope.

....
You would need an 9" scope with binoviewers to get the same effective light gathering and image brightness (at same power) as this setup. The scope with binoviewers would have much better 9" stellar resolution.
...

edz

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Resolution using two eyes will be improved over that of one eye. This is almost certainly a result of greater signal to noise and two receptors where one is canceling out noise seen in the other. I have found after many tests on resolution targets and stellar sources, a gain of not much more than 10-15% in resolution. So, when using binocular vision, resolution will not be based on the 160mm single aperture, but will be improved, although not by the factor of sqrt2. The binocular vision resolution will be similar to that of a 180mm scope (+/-) used in mono. However, the ultimate resolution, resolution at the Rayleigh Limit, wil not be greater than can be achieved with the same size scope.

....
You would need an 9" scope with binoviewers to get the same effective light gathering and image brightness (at same power) as this setup. The scope with binoviewers would have much better 9" stellar resolution.
...

edz

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Ed,

your statement that in practice you gain 10-15 % in resolution with a bino was new to me, so I can expect that a 160 mm bino is almost equivalent to 180 mm mono for moon and planetary observation while for deep sky objects I can expect approximately 200 mm (compared to a Newton telescope, for a refractor it is somewhat smaller, 192 mm).
Both sounds very nice.

To my mind the most interesting point is, however, that binocular telescopes give a more natural and impressive view of the sky. That's why I am trying to construct a rather large but still portable bino.

Thomas

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That also caught my eye.

Ed, are you saying that a 160mm bino can resolve closer double stars?

Isn't what you're saying a contradiction? A gain of 10-15% but the same Rayleigh limit. Where is the gain?

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Signal theory....

The signal to noise ratio (contrast)of extended objects is equal to...

The square root of the sum of the number of detectors, or sq rt of 1+1=2 or 1.414. In other words, the contrast of two eyed observing is equal to 41% more than one eyed for the same apertures.

That sounds good to me. Surface area is either squared or square root?

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All of the results are based on test charts? What about the question of double stars?

I find it interesting that the result is non linear, i.e., the binocular has an advantage at less than highest resolution which it gives up at higher powers. That is unexpected.

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P.S.Where are you going to buy the lenses ??

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For instance it takes 25x to see 5 arcsec, 40x to see 3 arcsec and 60x to see 2 arcsec. Then as you approach the resolution limits of the scope the plotted slope climbs rapidly. It takes perhaps 100x to see 1.75 arcsec, 150x to see 1.5arcsec, 200x to see 1.4arcsec. Then, no matter how much power you use you cannot see any better than 1.4 arcsec.

edz

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For instance it takes 25x to see 5 arcsec, 40x to see 3 arcsec and 60x to see 2 arcsec. Then as you approach the resolution limits of the scope the plotted slope climbs rapidly. It takes perhaps 100x to see 1.75 arcsec, 150x to see 1.5arcsec, 200x to see 1.4arcsec. Then, no matter how much power you use you cannot see any better than 1.4 arcsec.

edz

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Ed, I'm obviousely not understanding something here in your nomenclature. I am totally confused when you say:

"Then, no matter how much power you use you cannot see any better than 1.4 arcsec."

There is probably an explanation somewhere but I have split .5" doubles, I have seen Encke's Division. Both double and line are much finer than 1.4 Arcsec.

Thank you in advance for your explanation.

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I believe EDZ's 1.4 arc-sec was just an example!

Resolving power is determined by dawes limit (RP=4.41/D) wich is based on nearly equal bright point sources on a black background.

Planetary features are extended objects, (dark subjects on a brighter background) hence Dawes limit can be exceeded by as much as a factor 14.

Cassini division has an angelar width of no more than 0.5 arc sec, but is easily seen in a 2.5" aperture scope.

Alpo studies of an elusive Martian NPC rift, called the "Rima Tenuis" suggest that this feature has a width on the order of 0.1 arc-second and has been regularly observed with 8" apertures!

This is ofcause from a 20+ year old book "Observing and Photographing the Solarsystem"

Edited by roadi (04/05/10 07:38 PM)

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This is just a plan, but may be you find it interesting. For almost two years I am thinking to construct a quite large binocular telescope. Presently I use a 2x115 mm bino, which is very nice, but for deep sky observing the aperture is just at the limit what is needed, e.g. to show spiral structure in the largest galaxies (M51, M33)

- So why a 160 mm f/6.5 binocular?

- binocular viewing can give breathtaking views
- 160 mm binocular corresponds to approximately 200 mm monocular, so it is already a deep sky telescope
- 160 mm is probably the biggest aperture which can be build as a reasonable light-weight telescope that can be easily transported and mounted in a few minutes

So the key idea of the project is getting a maximum of optical performance with a lightweight telescope

Here are the characteristics of my planed 160 mm f/6.5 binocular telescope

- two 160 mm apochromatic oil spaced triplet lenses, focal length 1050 mm giving up 2,5 degree field of view
- lightweight carbon tubes
- erecting mirror system (EMS) for 2” eyepieces with 97 per cent total transmission
- estimated weight of the bino 12-13 kg ( both tubes), with mount and tripod less than 20 kg


I hope to get it finished until the end of the year


Thomas

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Just a quick update, the first of the two apo lenses is finished
after aspherization the strehl is 0.992 at 532 nm

Thomas

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This is just a plan, but may be you find it interesting. For almost two years I am thinking to construct a quite large binocular telescope.....Thomas

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I saw a bino made from two Astro-Physics refractors (130mm or so I believe?) at Stellafane about 7 or 8 years ago. The owner had it pointed at the radio towers on Mt. Ascutney during the daytime (a target about 15 miles away). It provided a good view. A few friends looked thru it at night and were really impressed.

Also a number of years ago I saw offered in one of Don Yeier’s auctions a bino made from two Brandt 8-inch doublets installed side-by-side in a 20-inch sonatube. It had double focusers with four diagonals at the tail end and simple alt bearings in the middle. The mount was not offered. No one bid the reserve, so the thing went back to the owner. I’ve never heard of this scope again. I should have bid...

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This is just a plan, but may be you find it interesting. For almost two years I am thinking to construct a quite large binocular telescope. Presently I use a 2x115 mm bino, which is very nice, but for deep sky observing the aperture is just at the limit what is needed, e.g. to show spiral structure in the largest galaxies (M51, M33)

- So why a 160 mm f/6.5 binocular?

- binocular viewing can give breathtaking views
- 160 mm binocular corresponds to approximately 200 mm monocular, so it is already a deep sky telescope
- 160 mm is probably the biggest aperture which can be build as a reasonable light-weight telescope that can be easily transported and mounted in a few minutes

So the key idea of the project is getting a maximum of optical performance with a lightweight telescope

Here are the characteristics of my planed 160 mm f/6.5 binocular telescope

- two 160 mm apochromatic oil spaced triplet lenses, focal length 1050 mm giving up 2,5 degree field of view
- lightweight carbon tubes
- erecting mirror system (EMS) for 2” eyepieces with 97 per cent total transmission
- estimated weight of the bino 12-13 kg ( both tubes), with mount and tripod less than 20 kg


I hope to get it finished until the end of the year


Thomas

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Lovely looking stuff! It's re-firing my enthusisam to finalize the design for my own 120mm f/5 project. I'm quite impressed with your estimate on the final mass. I wouldn't be surprised if my bino, in spite of its 40mm smaller aperture, weighs fully as much as yours!

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As you are in the process of constructing a large 160 mm binoscope, perhaps you may like to have a look at a completed 203 mm binoscope and a 250 mm binoscope now in the process of construction wholly by an amateur astronomer in Macau in the Far East.

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there's a German company called BINOPTIC which manufactures high-quality Bino-scopes and uses LZOS APO lenses ( web page )

Here's a picture of two 175mm LZOS APOs coupled to a Bino-scope

Regards,

Ralph

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there's a German company called BINOPTIC which manufactures high-quality Bino-scopes and uses LZOS APO lenses ( web page )

Here's a picture of two 175mm LZOS APOs coupled to a Bino-scope

Regards,

Ralph

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Oh my

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there's a German company called BINOPTIC which manufactures high-quality Bino-scopes and uses LZOS APO lenses ( web page )

Here's a picture of two 175mm LZOS APOs coupled to a Bino-scope

Regards,

Ralph

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Oh my

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Ziggy,

so you own this extremely nice instrument? Can you please tell us something about the performance, how does M51 look like or other spiral galaxies?

many thanks in advance

Thomas

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there's a German company called BINOPTIC which manufactures high-quality Bino-scopes and uses LZOS APO lenses ( web page )

Here's a picture of two 175mm LZOS APOs coupled to a Bino-scope

Regards,

Ralph

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Oh my

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Ziggy,

so you own this extremely nice instrument? Can you please tell us something about the performance, how does M51 look like or other spiral galaxies?

many thanks in advance

Thomas

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I don't own one. It was an expression of awe. A WOW moment. It looks like an awesome instrument to own.

M51 would no doubt look like a little fuzzy with a bit of a swirl and another littler fuzzy to one side.

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Wow!, let the serious work begin. Thanks for keeping this thread updated

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Bigger is better , here a pictures of a pair 203 mm F/9 Apo Bino :-)

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Bigger is better , here a pictures of a pair 203 mm F/9 Apo Bino :-)

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Markus:

Umm, tell the guy in the photo he's looking thru the wrong end.

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Meanwhile I have put the two apo lenses, the carbon tubes , the EMS mirror system and 36 mm Hyperion aspheric eyepieces provisorily togehter.


Thomas

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Meanwhile I have put the two apo lenses, the carbon tubes , the EMS mirror system and 36 mm Hyperion aspheric eyepieces provisorily togehter.


Thomas

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Wow. With these two EPs can your eyes accommodate the interocular distance ? I assume the eyepieces are in 2" mode.

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David,

the Hyperion Aspheric 36 mm are indeed in 2" mode, their diameter is 57 mm and they are very comfortable to look through. The bino refractor allows also using even larger eypieces, such as two TV Ehtos 17 mm which are 2" with 63 mm diameter. Their focal plane is quite unusual, you need 10mmm inward focus. So far I could test them only at day, I find them quite comfortable when using winged eyeguards, you don't see any field stop.

best regards

Thomas

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you don't see any field stop.

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Bigger is better , here a pictures of a pair 203 mm F/9 Apo Bino :-)

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Then I'd have to say your eyes are not quite properly placed at the eye point. I use a pair of 13mm Ethoi, and always see the field stop circles framing the view, both during the day and at night.

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you don't see any field stop.

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Then I'd have to say your eyes are not quite properly placed at the eye point. I use a pair of 13mm Ethoi, and always see the field stop circles framing the view, both during the day and at night.

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Glenn,
I think this rather varies from person to person. There are plenty of people, myself included , who do not see the field-stop surrounding the FOV in a 13 Ethos.

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Ralph, What's the weight of the 175mm apo-bino-giant?

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Congratulations on getting it nearly done! How was collimation process? Look forward to reading your next posts about it, hope your weather allows ample sky time

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Congratulations ...now we need some observing reports of what this bino can do!

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No, we don't
I have a pretty good idea of what this bino can do and don't want to hear about it


Now to be fair:

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Congratulations ...now we need some observing reports of what this bino can do!

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Now to be fair:

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Hopefully the whether will become better, at the moment most of the time we have a mixture of snow and rain. I had already a change to do some initial tests under a dark sky seeing the double cluster in Perseus and M33. I would say breathtaking, and I was very happy to see clearly spiral structure in M33. I hope that I can present more impressions soon.

best regards

Thomas

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Awesome! Really amazing that your handcrafted 160mm APO is even lighter than a commercially available 100mm achro.

Thomas, are you now selling your 2x115 mm bino for a friendly price?

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your weight number must be without objectives.... Fuji 150 achros weigh 40 lbs and thats a straight through achro....Vixen 125mm achros weight 10.9 KG so......

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Have you noticed any field rotation difference between the left and right EMS 2-mirror erectors?

Because the focus is via changing the intermirror spacing, there must be some mechanical tolerance to allow that motion. Peter Abrahams mentioned , in the thread in the ATM forum about the monster Macau binocular by Luciano Jorge Ricci, that he noticed field rotation "lean" in other specimens with 2-mirror erectors ,( probably EMS?).

A unitary 2-mirror "prism", with no changes of the intermirror spacing, would avoid such possible "lean" problems, because the 90 deg angle between the mirrors can be more closely controlled and locked. The interpupillary spacing could be 2:1 lateral motion of one eyepiece and its "prism", ff. the WW II Zeiss 12 x 60 and 25x100, etc.

Such 2:1 motion , on one side of the binocular only, need not be linked . One could lock/unlock the eyepiece and its mirror pair for IPD adjustment. A reversed binoviewer, without eyepieces, would serve as a handheld comparator to check for lateral parallelism of the two lines of sight (lateral "collimation", lateral "alignment")

Elimination of perceptible lean, with virtual, phantom rooflines ,does not require the precise control( within a few arc seconds) needed for elimination of double images in a prism with a real,materially existing roof edge,

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