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Old 02-10-2016, 04:48 PM
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silv (Annette)
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binoscope DIY with 70mm Travelscopes

Hey People

Would this work?

2 Celestron 70/400 Travelscopes,
10 and 20mm EP, finder and diagonal included,
Arca Swiss mounting plate with 2 1/4" screws, either 140 or 200mm?
Rollei C5i-II camera tripod, supports 10kg

I saw plenty of DIY machined binoscopes on the web but with much bigger aperture, hence also require elaborate diagonal fabrications.

I assume mounting the scopes perfectly parallel on that plate should be really easy because they'll have to sit really close together to enable that stereo viewing through the diagonals.

What do you think?

Annette

I'll add my reasoning for binoscopes in the post below.
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Old 02-10-2016, 05:12 PM
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The other day, I looked through my old NZ$25 Optical Valley 7x50.
Out of the open window into the western sky. I was amazed how many stars I was able to see in the black satin - beyond that ever present light pollution in my Rostock suburb.

More stars than a 20 second tracked exposure with a 500/6.3 camera lens was able to see.

And the bino viewing experience is so much more direct and breathtaking...
with a surprising apparent blackness of the sky, illogically caused by that darn light pollution...

It was just beautiful.
And lately, while looking at nebula photos here on IIS, I noticed that I am beginning to prefer b/w versions over colour because my head can discern details better if it's not distracted by pink billowing clouds.
So the other day I thought, "Mhmm, with all this light pollution all around me and my changing preference for b/w, maybe binos are my way to go?"

[The next day, I read up on why LP is conquered by binos.]

Them 7x50 were quite shaky handheld so I grabbed my tripod, legs drawn all in, placed it on my belly while sitting in the comfy chair and imagined looking through those binos, now.
Yup, would work. Just need one of them iron sticks to mount the bino on the ball head.

But then… you know… 7x50 … really pretty experience but very limited.
With that comfy chair/tripod solution out of my window, I could easily handle bigger glasses…
And if I manage to cycle to the beach some nights… without that chair… I’d need diagonals to be comfy while viewing … or some other tricky mount that costs €250 or more…
Also… binos usually don’t come with filter threads … and I’d really like to try out the North American Nebula through binos with a UHC filter…

I remembered Clive Milne and his 16” or 20” newtonian bino scope.
Why not try a really small one? Say 70mm refractor which come with diagonals for comfortable viewing and can hold filters?

That’s my reasoning. I feel reasonably smart, now, too.
Because I couldn’t find pictures of DIY 70mm binoscopes on the web, only the big ones which aren’t portable at all and require much more DIY and material.

So what do you think?
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Old 02-10-2016, 05:57 PM
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Try it and see. If you can find a couple of suitable scopes cheap enough it just might be a starter. I nearly picked up two 6" F 5 mirrors and diags with a view to building one but finances weren't quite ready. It really comes down to whether you can align the EPs for your eyes.
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Old 02-10-2016, 11:16 PM
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ah, you're right. Hadn't given that much thought at all.

Distance between my pupils is exactly 7cm.
That's not going to work with 2 70mm scopes side by side. Not without special diagonals, that is.

60mm have a better chance to work, straight out of the box.
Pity. 60mm is not much more light than my 7x50 binos.

But your comment got me googling again (my primary hobby is googling)
and I found good stuff on cloudynights.

Asymmetric tube construction
And a thread that is exactly about my 70mm idea.
Very good.

I knew there'd be something I'd have to consider before purchasing anything.
I'm just not that smart as I would like to think

And I think you pushed me in the right direction. Cheers.
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Old 05-10-2016, 09:51 AM
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http://www.bigbinoculars.com/70bt45.htm
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Old 05-10-2016, 11:30 AM
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mark's suggestion can be had for less at telescope express also, if you want to build your own maybe start with a 100mm bino, if not try the 70's. the germans take VAT off when buying too.
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Old 05-10-2016, 05:49 PM
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Oberwerk

yup, I ordered 2 Celestron Travelscopes 70/400, hoping my interpupilary distance can be tricked somehow.
They'll arrive tomorrow.
Cloud forecast is horrible which is, of course, to be expected after an astro purchase.

If the tubes turn out too fat to accommodate my 7cm IPD on the side-by-side mounting plate, I'll return them and get the 60mm instead.
Unless of course I come across some other hurdles...

I'll update the thread soon.
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Old 05-10-2016, 06:36 PM
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OMG, delivery today!
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Old 06-10-2016, 02:14 AM
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to align them straight out of the box on the simple mounting plate, an IPD of >= 8cm is required.

Possibly part of my testing problems atm are due to mis-collimation of one or both setups.
When I focus them separately, though mounted side-by-side, and then step back to look at how the scopes are aligned, they are not in the same hight.
I assume, that's due to collimation - maybe due to inadequate diligence on my part.

Until I'm sure that those issues are mostly out of the way, I can not yet say whether or not I'll keep them.

A hacksaw is needed to get the scopes closer together for 7cm IPD.
3 places: the front features a useless, fat bead all around the tube = 2.5mm.
Hacking that off in a tiny place on both tubes would gain 0.5cm.
Afterwards, another 1-2mm could be gained by hacking off the lower finder mounting screw.
And then there are the 2 inner focuser knobs of the R&P. I should think it's safe to hack them off, too.

Daylight views are crisp with 20mm EP. Haven't unpacked the other 2 nor the barlow.

The focuser and focuser housing are plastic, partially coated with look-like-metal-paint.
It's working fine and smooth using an EP.

Focussing with the Sony NEX5-N, ~480g, connected to the T2 thread in the focuser via a ~5cm long T2-Adapter:
the focuser is dancing until locked into place. For windstill env. and short exposures okay-ish.
The photos are much brighter and more contrasty than with my multi-brand 500/6.3 mirror lens. But purple fringing almost throughout the whole FOV.

Back-Focus on infinity was not possible during daylight. At the end of the barrel, I could not count the leaves on ~2km distant trees.
Might be pointing towards mis-collimation, right?
I've seen beautiful M42 photos taken with this scope so it should be possible.
As soon as this stormy low has passed, I'll try a nighttime test.

At night is where my 500/6.3 lens shines for some reason. Stars are pinpoint...
If the nighttime test on infinity with the TS is successful, I might just keep at least 1. Because.

So... miscollimation?
Should I attempt that and afterwards, hack the superfluous parts off?

Should I send them back and order the TS 60mm?

Would I like what I see through a 20x60 binoscope?

Keeping the 70s without the confidence that I can make them work for me, is too expensive a gamble...
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Old 06-10-2016, 02:20 AM
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Or I keep the one, do away with the diagonal and immerse myself handheld and one-eyed into the diamond studded black velvet cloththththththth
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Old 06-10-2016, 06:42 AM
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hacking at them introduces dust & moisture if you don't have a good solution to seal back up -it if were me id be returning them & grabbing the TS 70mm 45 deg bino [previously the 90 deg version had about 10% clipping resulting in light loss]

holding a telescope hand held at anything over 10x is quite difficult
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Old 06-10-2016, 08:37 AM
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surely nice binos but that is 900€, Daniel.
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Old 06-10-2016, 08:43 AM
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2 70mm Travelscopes are 140€, 2 60mm are 100€. helluva difference in my pocket.
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Old 06-10-2016, 02:45 PM
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There's a simple reason that all binoculars bigger than about 50 mm aperture use some variant of the "old-fashioned" Porro prisms, rather than the more compact "straight through" roof prism design - it is necessary to have a "bent" light path to get the eyepieces closer together than the diameter of the objectives and housings.

Not wanting to rain on your parade - but why not buy a pair of astro-binoculars (15x70, 20x80 or similar)?

Or fit a bino-viewer onto a single refractor OTA, if you want the ability to vary the magnification?

It seems to me that either of these options would be a simpler means of achieving large-aperture binocular viewing.
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Old 06-10-2016, 03:19 PM
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you're probably right. But

simpler means means 900€ and my means don't allow for that expenditure.

For the price of the Travelscope binoscopes I could get a readymade 15x70 which wouldn't fulfil my shopping list at all:

45* diagonal for comfortable viewing.
exchangeable EP.
Filter thread to be able to see stuff even under heavy LP.
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Old 06-10-2016, 03:49 PM
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Quote:
Originally Posted by silv View Post
you're probably right. But

simpler means means 900€ and my means don't allow for that expenditure.

For the price of the Travelscope binoscopes I could get a readymade 15x70 which wouldn't fulfil my shopping list at all:

45* diagonal for comfortable viewing.
exchangeable EP.
Filter thread to be able to see stuff even under heavy LP.
I would think that a bino-viewer on a conventional single OTA would tick all of those boxes - and you wouldn't be limited to "only" 70 mm aperture
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Old 06-10-2016, 04:05 PM
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Quote:
Originally Posted by julianh72 View Post
I would think that a bino-viewer on a conventional single OTA would tick all of those boxes - and you wouldn't be limited to "only" 70 mm aperture
'Binoviewers' have a narrow field field and basically suck on deep sky objects.
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Old 06-10-2016, 04:37 PM
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that's what I read, as well, when I first checked out the binoviewers. and they're expensive, too.

If I "hack away" the 3 protruding outer(!) parts, I could almost get them to 7cm IPD. Almost. I wish I were bigger headed.
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Old 15-10-2016, 07:37 PM
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Not a single starry night since opening the thread. ...

I've sent back the 70mm Scopes.

Now I'm pursuing 2 paths.

* One is still a binoscope, now with 2 60mm Travelscopes.
I've emailed Celestron Germany (Baader) for the exact max tube diameter.

If that diameter is less than 7cm it would fit my IPD.
Then I'd order 2 at Amazon (thank GOD for free returns in Germany!)
and test whether I can mount them parallel and stable! enough to work as binoviewer.

* The second path is now the binoviewer.

Baader's Maxbright would be first choice if a 2nd hand comes up of the now discontinued model.
My 2nd choice would be the Arcturus because I found 1 really okay review about it on the web. And it's totally cheap: 165€ new here in ebay.de, sold as "BST Starguider Binoviewer. Comes with Barlow 3x and 1.5x.
No EP.

The advantage of a binoviewer for me is the diopter thingy.
I need that because my eye diopter difference is 2.5.
Don't know whether this particular requirement can be fulfilled by my crude binoscope setup. Possibly only by sacrificing the true 2-eye-perception?

If binoviewer then a scope is necessary. Somehow I am fixated on a Mak design with bigger aperture than my mirror lens 500/6.3. That one has a ~79mm aperture.
Except for 2 Mak models in the 80-90mm range, all seem to have a focal ratio of 13 or thereabouts.
That must be very dim indeed... especially with a binoviewer...
The 2 faster Maks, Omegon Mightymak 90 and Kasai Pico-8, have f/11 - still very dim ...

But there is still my Samyang / Walimex / Bower 500/6.3 ....

How about I adapt that lens to be my scope for a binoviewer?
At least temporarily?
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Old 17-10-2016, 07:38 AM
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Hate to say this but it seems to me you're determined to make life hard for yourself and waste your money in the process ... why not just buy a pair of cheap 70mm binoculars... they will work better and cost less than any of the options you're pursuing.
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