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Equipment Discussions >> Binoculars

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Mr. Bill
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Reged: 02/09/05

Loc: Northeastern Cal
Re: best binocular for viewing milky way new [Re: PowellAstro]
      #6042228 - 08/23/13 04:55 PM

Quote:

They are very nice and I am sure the views are very good. I am interested in this is the only reason for the questions. Do, you get any rotational error, if the two large 2" diags are not swung the same amount together?




no....if everything's square and parallel which is tweeked and locked in during initial setup. This is where careful attention is required during construction.

Small corrections in collimation is easily achieved by a slight adjustment with 5/32 hex wrench to 3.1 inch mirror's holder 3 point wobble plate. Takes about 10 seconds if necessary at the beginning of observing session.

Components are quite robust in holding alignment and often don't require any tweeking from session to session.


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Rich V.
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Reged: 01/02/05

Loc: Lake Tahoe area, Nevada, USA
Re: best binocular for viewing milky way new [Re: Mr. Bill]
      #6042267 - 08/23/13 05:16 PM

What's nice about this three mirror design is that the last two mirrors (2" diag + 1-1/4" diag) mimic a rhomb prism. This allows the "turrets" to rotate independently for easy IPD adjustment without creating any error. The mirrors must be locked into a rigid assy so that they remain parallel to each other at all times, of course.

This is really no different than the rotation of the optical axes of a standard binocular around the hinge axis when setting IPD.

Rich


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PowellAstro
scholastic sledgehammer
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Reged: 10/14/09

Loc: Tennessee
Re: best binocular for viewing milky way new [Re: Rich V.]
      #6042289 - 08/23/13 05:30 PM

I have two nice SN-6 Tubes that show very sharp images @ 150-200x with single eyepieces. They are F/5 scopes. The OTAs are 7" OD. They already have the secondary mirrors as they are designed for WF. So, if I build a mount to connect the two OTAs and add the two 2" diags and two 1.25" Diags, they should work? Small Collimation errors, if all else is aligned as it should be, could then be done by the secondary of these two OTAs. They are 152mm - F/5, 752mm FL. What are your thoughts?

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Rich V.
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Re: best binocular for viewing milky way new [Re: PowellAstro]
      #6042349 - 08/23/13 06:15 PM

Quote:

I have two nice SN-6 Tubes >>> So, if I build a mount to connect the two OTAs and add the two 2" diags and two 1.25" Diags, they should work?




You'd have to ray trace the idea first. An f5 light cone is tough to get through the extra optical path without significant vignette. This is made worse by the Newtonian design that usually doesn't have the additional back focus to accommodate the extra optical train. You may also have to consider just where you're putting your head/body as you move the binoscope in altitude. The refractor design makes this a lot easier.

Bill's design was made more effective by using the f5.5 objectives rather than f5. IIRC, Bill ray traced f5 vs. f5.5 and the longer ratio definitely worked best regarding vignette in this instance.

Rich


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PowellAstro
scholastic sledgehammer
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Reged: 10/14/09

Loc: Tennessee
Re: best binocular for viewing milky way new [Re: Rich V.]
      #6042407 - 08/23/13 08:10 PM

Has any one measured the back focus through the 2" and the 1.25" combo. I have to add about 75mm extension tubes now to reach focus. The scopes were built for full frame astrophotography and the extension is required to view with an eyepiece. I know easy viewing would be limited to a small portion of the sky but the high power view and lack of CA would be nice. The secondaries are 2.14" now.

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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: best binocular for viewing milky way new [Re: PowellAstro]
      #6042834 - 08/24/13 01:40 AM

On using a pair of SN-6's for a bino... Look into this.

A pair of Amici prisms mounted to point rearward allow to look in the same direction the instruments point (like having 'bazookas' mounted on each shoulder), provide an even count on reflections so that the image is is not mirror-reversed, and provide an upright image, too! Furthermore, the optical path length through glass moves the focus a bit farther back, thus providing some extra room to install stuff. You might even be able to use 2" format Amicis, which would provide big fields.


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PowellAstro
scholastic sledgehammer
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Reged: 10/14/09

Loc: Tennessee
Re: best binocular for viewing milky way new [Re: GlennLeDrew]
      #6042849 - 08/24/13 01:57 AM

Where could I purchase or get hold of the Amici Prisms? The two inch and 1.25 diags would fit right on the unit with no other work or making of parts. Do these Amici Prisms come with a way to attach them or would that have to be made?

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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: best binocular for viewing milky way new [Re: PowellAstro]
      #6042870 - 08/24/13 02:47 AM

Amicis made into 90 degree diagonals are readily available all over the place. They would fit right in. For the 1.25" size, which can be had for about $30-40 apeice (I think) you may be able to keep the current focusers. For the bigger 2" size, a shorter focuser *may* be required.

With the current focuser racked fully in, how far past its lip does the focus lie?


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PowellAstro
scholastic sledgehammer
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Reged: 10/14/09

Loc: Tennessee
Re: best binocular for viewing milky way new [Re: GlennLeDrew]
      #6043324 - 08/24/13 10:38 AM

About 75mm out. I had already replaced them with 2 Inch low profile GSO dual speed 10:1 units.

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GlennLeDrew
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Re: best binocular for viewing milky way new [Re: PowellAstro]
      #6043365 - 08/24/13 10:57 AM

That 75mm of back focus will certainly accommodate a 1.25" Amici diagonal. The question now becomes, is there room for head clearance? Your ears require to not press against the tubes while you look straight ahead , with BOTH eyes through two eyepieces. I stress this last because, when checking out things with just a single scope, one can all too easily rotate the head a little so that the ear clears, and not be fully aware of doing it.

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PowellAstro
scholastic sledgehammer
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Reged: 10/14/09

Loc: Tennessee
Re: best binocular for viewing milky way new [Re: GlennLeDrew]
      #6043387 - 08/24/13 11:12 AM

If I use the 2 and 1.25 diags, they are on top and not between the tubes. I will have to find some info and specs on the different Amici units and see how they could work. I don't have any idea yet what the setup using them would look like.

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GlennLeDrew
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Re: best binocular for viewing milky way new [Re: PowellAstro]
      #6043547 - 08/24/13 12:43 PM

No other diagonals required. Just the Amici diagonal inserted directly into the focuser, turned so it points directly backward, away from the object in view.

For the clearest picture in words, the full optical train is thus: Schmidt corrector, primary mirror, secondary mirror, Amici prism diagonal, eyepiece.

If this were a single scope, in use it would look exactly like you were resting a bazooka on your shoulder, aiming it at your target. The view would be upright and correct, just like a handheld bino. How cool is that?


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ThomasM
sage


Reged: 04/19/09

Re: best binocular for viewing milky way new [Re: GlennLeDrew]
      #6043562 - 08/24/13 12:52 PM

Quote:

In the ultra-wide AFoV department, I do use 13mm Ethos eyepieces (100 degree) on my home-made right-angle bino, yielding:
12.7X50, 7.7 degrees
20.8X60, 4.7 degrees

If I obtained the 17mm Ethoi:
9.7X50, 10 degrees (but field curvature would be worse)
15.9X60, 6.2 degrees.





Yes, your homemade UWA binocular looks very impressive, I looked already several times in your gallery.

On the other hand, I think I will go for a commerical binocular, in my case it paid off to built a large binosocpe, but going to such exercise twice is too much for me, at least presently.

After all the comments, I will probably purchaise a Zeiss Dialyt 7x42, it seems to me a good compromise between magnification, aperture, edge sharpness and field of view (8.5 degree FOV).

Thomas


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PowellAstro
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Reged: 10/14/09

Loc: Tennessee
Re: best binocular for viewing milky way new [Re: ThomasM]
      #6043879 - 08/24/13 04:22 PM

@ GlennLeDrew

I see how to get the right eye angles and focus with the 2 and 1.25 inch diags. I don't see how to get these angles with just one diag added to each scope. With the 2 and 1.25 diags the focus would move the eyepieces toward you and away from your eyes, just like a center focus bino. With just the Amici diags, the focus would move up and down not back and forth. I am missing something in what you have said.


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GlennLeDrew
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Re: best binocular for viewing milky way new [Re: PowellAstro]
      #6044165 - 08/24/13 08:10 PM

In the scheme I'm outlining it's required to have the main tubes change spacing if an adjustable IPD is desired. Otherwise for a fixed IPD (yours) the two OTAs can be fixed in place (less the small adjustment at, say, the rear end of one for collimation tweaking).

The focusing would be done by sliding the eyepiece in and out of the diagonal. Space permitting, a compact helical focuser could be attached to each Amici diagonal.


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PowellAstro
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Reged: 10/14/09

Loc: Tennessee
Re: best binocular for viewing milky way new [Re: GlennLeDrew]
      #6044372 - 08/24/13 11:02 PM

ok, cool. Now I see the setup. Thanks.

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GlennLeDrew
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Re: best binocular for viewing milky way new [Re: GlennLeDrew]
      #6044452 - 08/25/13 12:12 AM

I was less precise than I should have been, and so just to be clear...

The compact helical focuser would be placed between prism diagonal and eyepiece, this being smoother than sliding the eyepiece in and out.

But nothing compels the installation of such focusers, at least initially.


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ThomasM
sage


Reged: 04/19/09

Re: best binocular for viewing milky way new [Re: Erik Bakker]
      #6052545 - 08/29/13 01:16 PM

Quote:

Kenny,

Some of your past endorsements for your 7x42 Dialyts contributed to me embarking on the same route. Absolutely wonderful experience cruising the Milky Way with my Zeiss FL 7x42's. Tried to find a nice pair of the Dialyt version but did not succeed, so settled on the new Victory FL's after a few months. Delightful binos. Such an involving, bright relaxing view. Unsurpassed for the MilkyWay!




Today my Zeiss Dialyt 7x42 arrived, I got it second hand from Ireland. It is really a very nice binocular, the daylight test was very promising and now I am waiting for a dark nigth. I think it will perfectly complement my 160 mm binoscope.

Thanks a lot for all the helpful comments!

Thomas


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Erik Bakker
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Re: best binocular for viewing milky way new [Re: ThomasM]
      #6052762 - 08/29/13 03:06 PM

Congratulations on a great find Thomas. The Zeiss 7x42's are wonderful, be it the Dialyt or the Victory. The large exit pupil is very demanding on our own pupils, so most people should expect less than pinpoint stars at night. Give yourself some time to get to know your 7x42's with their special qualities and character, you will be richly rewarded!

Of course, you will have to supply some pictures


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Stacy
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Reged: 09/15/02

Loc: Seattle, WA
Re: best binocular for viewing milky way new [Re: ThomasM]
      #6052778 - 08/29/13 03:14 PM

Quote:

Today my Zeiss Dialyt 7x42 arrived, I got it second hand from Ireland. It is really a very nice binocular, the daylight test was very promising and now I am waiting for a dark nigth. I think it will perfectly complement my 160 mm binoscope.

Thanks a lot for all the helpful comments!

Thomas




Woot!

Nothing better than finding a good used bino!


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