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Equipment Discussions >> Refractors

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ThomasM
sage


Reged: 04/19/09

A 160 mm f/6.5 binocular telescope
      #3720212 - 04/02/10 07:14 AM

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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roadi
Pooh-Bah
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Reged: 08/18/07

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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3720409 - 04/02/10 10:20 AM

Not to take away your excitement, but I think you are rather optimistic about the weight, not only the instrument alone, but also total with mount!

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!

Edited by roadi (04/02/10 10:25 AM)


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ThomasM
sage


Reged: 04/19/09

Re: A 160 mm f/6.5 binocular telescope new [Re: roadi]
      #3720574 - 04/02/10 11:34 AM

Quote:


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!




Rodi,

I hope too that it will be an awsome binoscope and I easily understand your scepticism about the weight.

Now doubt, it will be difficult to get below 20 kg including mount and tripod.

How do can it work?

- the lenses, are really light- at least for this size- only 3,5 kg each. With air spaced triplets it seems impossible, but oil spaced can be thinner because all three elecments are in direct contact.

- the carbon tubes are only 0.5 kg each, they are already delivered

- the two tubes are almost in direct contact fixed only by a few light but stable aluminum pieces in between

- the two mirror systems adds another 2 kg, so instrument alone will be below 13 kg

- I will not use a fork mount, the mount will be similar to that of big binos, like Kowa Highlander or the Fujinon 150mm bino (see http://www.intercon-spacetec.de/produkte/neuheiten/produkt/monti_kowa_highlander/), but more stable
It will be mounted on a carbon tripod (3kg), which also exists already

All in all, drawings for the construction are almost finished and I hope that everything works out as planed.

Thomas


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Ziggy943
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Reged: 08/11/06

Loc: Utah
Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3720635 - 04/02/10 12:06 PM

I am wondering who is the source for the lenses. What are you expecting the cost to be?

Being bino's I take it that this is intended as a visual Deep-Sky instrument. I guess I have to ask WHY?????


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GShaffer
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Reged: 02/28/09

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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3720810 - 04/02/10 01:24 PM

Given what I have seen and heard here I believe the only good answer is "why not?"

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CounterWeight
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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3720834 - 04/02/10 01:33 PM

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...]

Edited by CounterWeight (04/02/10 01:41 PM)


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roadi
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Reged: 08/18/07

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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3720861 - 04/02/10 01:41 PM

Thomas,
Thats an exciting project you are going into! It will almost be a GrabN Go giant bino, surprisingly lightweight!

Hope it all works out for you and hope to hear more about it!

By the way, where do you get these EMS? any homepage?


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ThomasM
sage


Reged: 04/19/09

Re: A 160 mm f/6.5 binocular telescope new [Re: roadi]
      #3721120 - 04/02/10 03:56 PM

Thanks to all for the best wishes for the project,

Rodi,

the EMS erecting mirror system will be manufactured in Japan:

http://www.page.sannet.ne.jp/mazmoto/index-e.htm

they are available with different options in different size, the 2 inch version can provide a large field of view, however, depending on the f-number of the telescope large mirrors may be needed.

I choose the 2" inch version since I will get wide field views which is at least equivalent to that of the huge 150 mm Fujinon bino, while also wide ultra field eyepiece can be used for deep sky viewing and planetary observation up to 250 x magnification.

Thomas


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dscarpa
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Reged: 03/15/08

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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3721129 - 04/02/10 04:02 PM

It would be a incredible lunar planetary-scope! I'd be happy with half of it. David

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roadi
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Reged: 08/18/07

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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3721138 - 04/02/10 04:06 PM

Thanks for the link Thomas

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Ziggy943
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Reged: 08/11/06

Loc: Utah
Re: A 160 mm f/6.5 binocular telescope new [Re: CounterWeight]
      #3721170 - 04/02/10 04:28 PM

Quote:

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...]




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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CounterWeight
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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3721320 - 04/02/10 05:58 PM

A few things come to mind, esp compared to a conventional binoviewer. I had a Denk BV'er for a while. Folks seem to like them, I did, but sold them all the same. So 2-eyed viewing - I think that's what this project / idea is about? There is some differce in the light throughput to each eye in a conventional binoviewer on a mono scope vs. that of an actual binoscope, right? I've no idea what formula Thomas used for the eq apeture - but if it's so, then great. An interesting variant would be to collimate both tubes into one eyepiece view?


Heck, I encourage experimentation, asking questions, trying stuff out... when nobody can be physically damaged. It isn't knowledge until you actually do it. Like what Reimann did with Euclid, or Bell with 'relativity', or me with respect to "very hot" hot sauce(I was almost damaged by that experiment), or that daredevil whose famous last words were "watch this! (termianlly damaged)" The more knowledge in the pool the better, even if it 'dont try that-


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roadi
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Reged: 08/18/07

Loc: GGS
Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3721408 - 04/02/10 06:55 PM

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!

Edited by roadi (04/02/10 06:56 PM)


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Ziggy943
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Reged: 08/11/06

Loc: Utah
Re: A 160 mm f/6.5 binocular telescope new [Re: roadi]
      #3721500 - 04/02/10 07:56 PM

Quote:

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!





Where did you get those numbers? I don't see them here anywhere.


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CounterWeight
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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3721732 - 04/02/10 10:06 PM

read carefully the first post...
Quote:



- 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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Ziggy943
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Reged: 08/11/06

Loc: Utah
Re: A 160 mm f/6.5 binocular telescope new [Re: CounterWeight]
      #3721858 - 04/02/10 11:49 PM

Quote:

read carefully the first post...
Quote:



- 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











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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ThomasM
sage


Reged: 04/19/09

Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3722069 - 04/03/10 04:37 AM

Ziggy,

the statement that a 160 mm binoscope correspond to aprroximately 200 mm mono holds only for low contrast objects, such as most deep sky objects. Your right, the light does not add, but if you look with two eyes, the noise is reduced and weaker objects become visible.
The gain is a factor 1.4 in area, more precisely square root of 2, which is almost equivalent with a factor 1.2 in diameter.
More details are given in the book 'binoclular astronomy',

here is link,

http://www.amazon.de/gp/reader/1846283086/ref=sib_dp_pt#reader-page

page 3

The angular resolution will certainly not increase, but even for planetary viewing often more details can be seen, since finer contrast steps are becoming distinguishable. Furthermore, true binoviewing helps if the seeing is not optimal. However, for plantetary viewing I would not dare to give a factor how you actually gain over viewing with a single scope.


Thomas


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roadi
Pooh-Bah
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Reged: 08/18/07

Loc: GGS
Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3722103 - 04/03/10 05:46 AM

Ziggy943,
About the contrast gain of 40%, I have my reference from the book "Observing and Photographing the Solar system" author: Thomas A Dobbins, Donald C Parker and Charles F Capen.

I havn't done actual measuring my self, "don't know how" but relating to my own findings viewing planets both monocular and binocular, I have no reason to doubt that claim! I can make out subtible details on the planets wich I can't monocular.
If the contrast gain in percentage is correct and you want to take advantage of the binomode, then you'll need 226mm aperture to equal a 160mm binoscope in lightgrasp. On the resolution part you are correct. Besides those wich Thomas allready mensioned, you have the advantages using 2" EP's in the binoscope wich you can't take full advantage of in most binoviewers if widest possible field is desired.

Thomas,
Interesting book, I'll have to read it!


Edited by roadi (04/03/10 06:03 AM)


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EdZ
Professor EdZ
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Reged: 02/15/02

Loc: Cumberland, R I , USA42N71.4W
Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3722190 - 04/03/10 07:57 AM

Quote:

Quote:

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...]




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.




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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Mr. Bill
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Re: A 160 mm f/6.5 binocular telescope new [Re: EdZ]
      #3723045 - 04/03/10 06:11 PM

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.



Edited by Mr. Bill (04/03/10 06:26 PM)


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ThomasM
sage


Reged: 04/19/09

Re: A 160 mm f/6.5 binocular telescope new [Re: EdZ]
      #3724016 - 04/04/10 10:49 AM

Quote:


.....
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




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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zdravko
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3724071 - 04/04/10 11:31 AM

Thomas congratulations on 160 F/6,5 APO bino scope project.
I own a 120mm F/5 achro bino scope and a 150mm F/6 achro and a smaller 76mm F/6 APO are in progress.So I'm familiar with views through a binoscope.I can confirm all the theory what had been said about contrast and resolution gain.
But for me the purpose of a large bino sope is is observing the wide field skies with both eyes.And such an instrument can also go from very low to very high powers with diferent eyepices.And no long focus big refractor can do that, even if it has a few precent better resolution.And 2,5 degres of 160mm APO view will be a dream comme true for you.
I just hope you can do it cheaper than to buy a FUJI 150mm apo binocular.
Just dont forget to post somme pictures as the project progresses.

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


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Ziggy943
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Loc: Utah
Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3725057 - 04/04/10 09:18 PM

Quote:

Quote:


.....
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




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




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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EdZ
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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3725118 - 04/04/10 10:00 PM

The measured gain was recorded with dozens of instruments using USAF charts, but I could not record any more gain at the Rayleigh limit. If a resolution reading is taken with one eye at (say for instance using a 100mm scope or binocular) 4 arcsec is observed, than again taken with two eyes, the reading could be reduced, without increasing power, to 3.8 or 3.7 arcsec. However, once the power was raised up to about 1mm to .75mm exit pupil, at which point readings reached the Rayleigh limit, no further gain could be realized by observing with two eyes.

So my comment states, as long as you are observing below the Rayleigh limit, you can reailze some 10%-15% resolution gain by using two eyes without increasing power. But, as you approach the Rayleigh limit, the scope simply cannot resolve any better than that, regardless of using two eyes or one.

The resolution gain is realized when there is some room for improvement and when using two eyes gives the benefit of signal/noise.

edz


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Ziggy943
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Re: A 160 mm f/6.5 binocular telescope new [Re: EdZ]
      #3725233 - 04/04/10 11:10 PM

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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CounterWeight
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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3725292 - 04/04/10 11:45 PM

I remember going over a lot of this in the BV forum a while back, but more with respect to light loss per eye in a conventional BV on a single OTA. Then what the brain does re-assembling the information.

My thought was that binoscoping, is not going to get you resoultion of more apeture, more like turning up the 'image brightness' - for the eyes/brain - of what the apeture will get you. (somewhat like turning up music volume on an amplifier, it can't improve on the original recording just give more of the subtle) hard to make a good analogy as most folks listen to music with both ears.

Ziggy, you have the AP-900 mount - you could easily do a TEC160ED bino-scope with that, you're 2/3 the way there... ?


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john 127
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Re: A 160 mm f/6.5 binocular telescope new [Re: Mr. Bill]
      #3725378 - 04/05/10 12:43 AM

Quote:

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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EdZ
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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3725577 - 04/05/10 06:35 AM

Quote:

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.




If you read the history of the tests I done, you will find double star examples in the results.

In a plot of the results of magnification vs resolution, you will see that the resolution/magnification relation also is non-linear. For all resolution up to near let's say 2 arcseconds of the scope limit, the apparent resolution (equal to magnification times arcseconds) is nearly a constant slope plot set by the limits of your eye. 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.

This is exactly the same non-linear pattern.
Resolution plotted

Also note the references in the discussion on Binocular vision. Eye tests typically show that people gain one line on the Snellen chart when using two eyes over one eye.

edz


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Re: A 160 mm f/6.5 binocular telescope new [Re: zdravko]
      #3726791 - 04/05/10 05:42 PM

Quote:


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





thanks for the good wihses to the project,

I am planing to get the lenses for GPU optical, hopefully it works out.

Thomas


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Re: A 160 mm f/6.5 binocular telescope new [Re: EdZ]
      #3726840 - 04/05/10 06:06 PM

Quote:

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




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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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3726958 - 04/05/10 07:17 PM

Ziggy,
Ed was using an example for some particular aperture, not making a blanket statement applying to all apertures.


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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3726985 - 04/05/10 07:32 PM

Quote:

Quote:

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




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.




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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Re: A 160 mm f/6.5 binocular telescope new [Re: roadi]
      #3727385 - 04/05/10 11:31 PM

Thanks guys, I feel better now. No, I didn't catch the linking of the example to the 80mm scope. I thought I was going a little nuts.

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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #3727537 - 04/06/10 01:17 AM

I've been reading about the JMI binoscopes, the APM offerings, and of course the binoscope company that always advertises on AMart... The fellow I sold my TOA 130s to was making a Tak/TOA 130 binoscope. Have asked in a thread on the BV forum here.

I think whatever the context, folks like 2 eyed viewing, and there's some merit to the persuit. I decided - if I ever go that way again - that I'll go with a true binoscope of some sort over a BV'er on a single OTA. To each their own, but I'm almost afraid to look through a 130mm or larger widefield refractor binoscope.


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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3805715 - 05/14/10 03:15 PM

Quote:

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




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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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #3806019 - 05/14/10 06:18 PM

Quote:

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




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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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4083380 - 09/30/10 03:31 PM Attachment (119 downloads)

Quote:

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




Meanwhile the key components arrived, the two 160 mm oil spaced triplet apo lenses, the EMS mirrors and the carbon tubes (not shown on the pictures). The total weight is less 10 kg, so a bino with less than 12 kg seems to be within reach.

I will keep you informed on the progress

Thomas

Edited by ThomasM (09/30/10 03:59 PM)


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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4085816 - 10/01/10 01:44 PM

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!

I'm eager to follow your progress. Perhaps you could drop a line to the gang in the Binocular forum, in case there are folk there who don't frequent this one. This would be of immense interest to all us non-Cyclopeans!


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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4086741 - 10/01/10 09:49 PM

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. Unfortunately the link is in Chinese but pictures therein illustrate the process of manufacturing very clearly. Except the lens, he made everything himself.
http://forum.hkas.org.hk/viewthread.php?tid=1018&extra=page%3D2

K W TONG
C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST


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Re: A 160 mm f/6.5 binocular telescope new [Re: TONGKW]
      #4087099 - 10/02/10 03:07 AM

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

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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4087217 - 10/02/10 06:57 AM Attachment (133 downloads)

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

Edited by dothead (10/03/10 02:25 PM)


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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: GlennLeDrew]
      #4089366 - 10/03/10 10:22 AM

Quote:

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!






A 120 mm Bino is already a very nice telescope, especially if you can you use wide field eyepieces. I got aware of your 11x50 bino combined with to 13 mm Ethos and I am very eager to combine Ethos eyepieces with my big bino once it is finished.


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Re: A 160 mm f/6.5 binocular telescope new [Re: TONGKW]
      #4089427 - 10/03/10 10:50 AM

Quote:

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.




thanks for the link, I was already aware of these big binos, since there is also a thread here at CN, but without all these nice pictures. Especially the 250 mm bino will have impressive light collection, on the other hand the chromatic abberation of achromatic f/5.5 lenses of this size is presumably quite substantial.

Thomas


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Re: A 160 mm f/6.5 binocular telescope new [Re: dothead]
      #4089458 - 10/03/10 11:06 AM

Quote:

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





Ralph

if fully agree, BINOPOTIC binos are very nice, I own already a 115 f/7 bino. The 175 mm f/8 bino is an impressive instrument. I am hoping to achieve nearly the same light collection power with the 160 mm apochromatic bino thanks very high transmission (oil spaced triplet apo lens, only two 99 per cent high reflective mirrors instead of three 96 per cent in the BINOPTIC). If I really get the the total weight down to 12 kg, it will be a very portable instrument, almost grab and go. On the ohter hand, the resolution of the 175 mm binoptic is off course slightly higher.

Thomas


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Re: A 160 mm f/6.5 binocular telescope new [Re: dothead]
      #4089592 - 10/03/10 12:11 PM

Quote:

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




Oh my


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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: Ziggy943]
      #4089681 - 10/03/10 12:59 PM

Quote:

Quote:

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




Oh my




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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dothead
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4089855 - 10/03/10 02:23 PM

oh me - oh my

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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4090203 - 10/03/10 05:17 PM

Quote:

Quote:

Quote:

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




Oh my




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




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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Re: A 160 mm f/6.5 binocular telescope new [Re: CounterWeight]
      #4148333 - 10/28/10 03:17 PM Attachment (120 downloads)

Quote:

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




This is another update on the 160 mm bino presently under construction.


Meanwhile I have put the two apo lenses, the carbon tubes , the EMS mirror system and 36 mm Hyperion aspheric eyepieces provisorily togehter. As you can see it is a strange combination of nice pieces and 'trash' like plywood and tape. Anyhow, I need to put all the stuff together in order to figure out the final length of the adapter connecting the EMS mirrors and the carbon tubes. Hopefully, more later soon.

Thomas

Edited by ThomasM (10/28/10 03:19 PM)


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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4148448 - 10/28/10 04:03 PM

Looking good!

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Re: A 160 mm f/6.5 binocular telescope new [Re: pcad]
      #4557289 - 05/02/11 02:29 PM Attachment (98 downloads)

Here is the next update. Yesterday I could connect the two 160 mm telescopes and make the optical axis parallel. A tree in a few hundred meter distance looked very detailed and contrasty at 65x magnification.

Here you see the binocular telescope inside the bag which is obviously not yet finished. The telescope is almost 1 m long, total weight presently approximately 11.5 kg, but a few parts (dew shields) are missing).

best regards

Thomas

Edited by ThomasM (05/02/11 02:31 PM)


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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4557417 - 05/02/11 03:39 PM

wow, looks like it's going to be a fantastic instrument! It's definitely going to be way brighter than a single 160mm refractor w/ a Mark V binoviewer. It would probably take an 8 or 9 inch refractor w/ Mark V to match the brightness of this scope.

And 2 inch eyepieces, very nice. Two Pentax XW 40mm's would give you 26x!!!


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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4557428 - 05/02/11 03:45 PM

Awesome looking instrument with the carbon fiber tubes! First light may be in near future? looking forward to it, especialy on the galaxies

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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4557456 - 05/02/11 03:58 PM

That would be my dream setup

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Re: A 160 mm f/6.5 binocular telescope new [Re: GlenM]
      #4558191 - 05/02/11 11:32 PM

Thomas, beautiful work, and thanks a lot for keeping the updates coming on this amazing project.

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203 mm F/9 Apo Bino new [Re: CounterWeight]
      #4558946 - 05/03/11 12:06 PM Attachment (96 downloads)

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

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Re: 203 mm F/9 Apo Bino new [Re: APM M.Ludes]
      #4559344 - 05/03/11 03:13 PM

Quote:

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




Markus:

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


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Re: 203 mm F/9 Apo Bino new [Re: Jeff B]
      #4559479 - 05/03/11 04:02 PM

LOL

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Re: 203 mm F/9 Apo Bino new [Re: APM M.Ludes]
      #4560761 - 05/04/11 07:44 AM

thats Matthias , he always do it this way, bigger eyepiece lens at this side :-)

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Re: 203 mm F/9 Apo Bino new [Re: Jeff B]
      #4560773 - 05/04/11 07:57 AM

Quote:

Quote:

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




Markus:

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







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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4561052 - 05/04/11 11:06 AM

Quote:




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


Thomas




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


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Re: A 160 mm f/6.5 binocular telescope new [Re: davidpitre]
      #4561611 - 05/04/11 04:01 PM

Quote:

Quote:




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


Thomas




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




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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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4562043 - 05/04/11 07:39 PM

Quote:

you don't see any field stop.




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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Re: 203 mm F/9 Apo Bino new [Re: APM M.Ludes]
      #4562230 - 05/04/11 09:19 PM

Quote:

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




Markus:

Ok now that you've plopped that picture out there and I've given my usual smart-*BLEEP* remark, I have to ask the screamingly obvious question: Just how well does the big bino-scope work?

Jeff


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Re: 203 mm F/9 Apo Bino new [Re: Jeff B]
      #4563090 - 05/05/11 10:30 AM

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

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Re: A 160 mm f/6.5 binocular telescope new [Re: GlennLeDrew]
      #4563996 - 05/05/11 06:37 PM

Quote:



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.





Glenn,

that's interesting, I agree the eye placement with Ethos eyepieces in a bino is more critical than for example with the Hyperion aspheric. Do you always see the fields stop as a sharp ring?

Actually, I was quite some time undecided whether Ethos eyepieces fit to a large bino since correct eye placement is certainly an issue. On the other hand, I expect breath taking views on M31 or M33 under dark sky with two 100 degree eyepieces.

More later when the bino is finished and I can report on first light under the stars.

best regards


Thomas


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Re: A 160 mm f/6.5 binocular telescope new [Re: GlennLeDrew]
      #4564009 - 05/05/11 06:45 PM

Quote:

Quote:

you don't see any field stop.




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.




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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ThomasM
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Re: 203 mm F/9 Apo Bino new [Re: PhilCo126]
      #4565459 - 05/06/11 02:09 PM

Quote:

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




as far as I know the 175 mm binocular telescope built by the German company Binoptic weights 40 kg or so.

The 160 mm bino I am presently building will finally weight only 12 kg, at least I hope that. But I should add that this is a somewhat unfair comparison because the 175 mm bino was constructed seveal years ago on the basis of commercial apos, while I was trying to push the weight to the lowest possible limit using carbon fiber and special light weight designe.

Any how, I think that 150-160 mm is the limit for a such a telescope if it should be easy to transport it under a really dark sky.

Thomas


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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: GlennLeDrew]
      #4988836 - 12/28/11 05:23 PM Attachment (83 downloads)

My binocular telescope is (almost finished), it took quite a while. Here are some pictures, total weight of the bino (without finder and eyepieces) 11.8 kg.

best regards

Thomas

Edited by ThomasM (12/28/11 05:26 PM)


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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4988880 - 12/28/11 05:44 PM Attachment (79 downloads)

another picture

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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4988883 - 12/28/11 05:46 PM Attachment (75 downloads)

and another picture....

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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4988891 - 12/28/11 05:50 PM Attachment (62 downloads)

and a third picture

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CounterWeight
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4988900 - 12/28/11 05:55 PM

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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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: CounterWeight]
      #4991370 - 12/30/11 01:45 AM

Quote:

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




Jim,

thanks for your best wishes. Exact collimation can be easily achieved with the two adjustment knobs in the EMS mirror systems:

http://www.page.sannet.ne.jp/mazmoto/manual-e.htm


it works very well, I can use even quite heavy eyepieces, such as the Ethos 17 mm ( 750 g)

best regards

Thomas

p.s. I had already some hours under a dark sky, Jupiter at 210x was very nice, M33 at 85X shows very detailed spiral structure

Edited by ThomasM (12/30/11 10:20 AM)


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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4991689 - 12/30/11 09:37 AM

Thank you Thomas, that link didn't work for me but I have his site bookmarked from other persuits. Am really impressed that you kept the weight down so well using triplet objectives. One question I want to ask is have you just looked though one side in 'cyclops' mode and then back to both eyes on same obeject, how do you describe the apparent difference? I am living vicariously through your posts on this so please use superlatives liberally? Thanks



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Re: A 160 mm f/6.5 binocular telescope new [Re: CounterWeight]
      #4991968 - 12/30/11 11:49 AM

Congratulations on getting this project done...now we need some observing reports of what this bino can do!

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Re: A 160 mm f/6.5 binocular telescope new [Re: t.r.]
      #4992259 - 12/30/11 02:13 PM

Quote:

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




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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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: CounterWeight]
      #4992546 - 12/30/11 05:12 PM

Jim,

today for I few minutes I could see the moon between the clouds. At 55x it was really impressive, I prefer low power and maximum contrast. For the moon you don't need such a big bino, what counts - at least for me - is contrast, seeing the crescent and the ash grey part surrounded by the dark sky.

best regards

Thomas


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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: Erik Bakker]
      #4992552 - 12/30/11 05:19 PM

Quote:

Quote:

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




..


Now to be fair:





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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gatorengineer
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4993022 - 12/30/11 10:06 PM

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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Re: A 160 mm f/6.5 binocular telescope new [Re: gatorengineer]
      #4993053 - 12/30/11 10:27 PM

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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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: JKoelman]
      #4993659 - 12/31/11 10:00 AM

Quote:

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?




Johannes,

yes, I will now sell my 2X 115 mm bino, it is a nice instrument.
Indeed, it was difficult to get the weight of the 160 mm bino down to 11.8 kg, most import are the oilspaced lenses which are only 3.5kg each.

best regards

Thomas


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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: gatorengineer]
      #4993671 - 12/31/11 10:05 AM Attachment (47 downloads)

Quote:

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......




Actually, it is the total weight of the bino (without eypieces and finder telescope), the combination of carbon tubes and light weight lenses allow that, the bino on a bathroom scales


Thomas


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junomike
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #4994462 - 12/31/11 04:27 PM

Thomas, Without prying, can you give us a rough estimate as to the cost of such a project?

Mike


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Gordon Rayner
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Re: A 160 mm f/6.5 binocular telescope new [Re: ThomasM]
      #5670631 - 02/09/13 12:18 PM

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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ThomasM
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Re: A 160 mm f/6.5 binocular telescope new [Re: Gordon Rayner]
      #5670792 - 02/09/13 01:40 PM

Quote:

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,




Actually, I a am not sure wheter I understand your point.

So you mean adapting the interpupillar separtation by varying the distance between the two mirrors of the EMS erecting system will result in field rotation? In other words the horizontal lines visible with two eyes will be slightly tilted?

It this was the question, I can only state that I algined the binocular telescope such that for me it is fine, other people who had looked through it have not complained so far, but it may be that they haven't noticed.

Does this answer at least part of your questions?



Thomas


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