binoscope DIY with 70mm Travelscopes

[silv]

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.

[silv]

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?

[ZeroID]

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.

[silv]

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 (http://www.cloudynights.com/topic/438786-curious-about-an-inexpensive-refractor-binoscope/) 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 :D

And I think you pushed me in the right direction. Cheers.

[Satchmo]

http://www.bigbinoculars.com/70bt45.htm

[dannat]

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.

[silv]

Oberwerk :D

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.

[silv]

OMG, delivery today! :party:

[silv]

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...

[silv]

Or I keep the one, do away with the diagonal and immerse myself handheld and one-eyed into the diamond studded black velvet cloththththththth

[dannat]

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

[silv]

surely nice binos but that is 900€, Daniel.

[silv]

2 70mm Travelscopes are 140€, 2 60mm are 100€. helluva difference in my pocket.

[julianh72]

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.

[silv]

you're probably right. But :D

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.

[julianh72]

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

[Satchmo]

'Binoviewers' have a narrow field field and basically suck on deep sky objects.

[silv]

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.

[silv]

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 (http://www.ebay.de/itm/BST-Starguider-Binoviewer-with-3x-1-85x-Barlow-32mm-Pl-eyepieces-/162175381703?hash=item25c267f0c7:g: JRAAAOSwIgNXuJDN). 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?

[Wavytone]

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.

[Kunama]

Where is the fun or the challenge in that :question:

[silv]

yes, where's the fun or challenge? :)
I own a nice enough cheap bino.
What I would like is to have exchangeable eyepieces and filter threads to battle the light pollution outside my window.

no answer yet re the diameter of the 60mm tubes.

But I found the adapter that would be working with my mirror lens to morph into a telescope
http://www.baader-planetarium.com/en/baader-zenith-prism-diagonal-t-290-°-with-32mm-prism--(t-2-part-14).html
I'm lucky to have a T2 lens, apparently. Because other bayonets have an even shorter focal path.
For those lenses like Canon EF and such there are "lens2scope"-adapters which don't fit 1.25" eyepieces but come with extra 10 and 20mm ones.

If it turns out that the 60mm scopes are also too wide I'll get that adapter and check whether there's anybody in my city who has a binoviewer and lets me test it in my lenscope.

[silv]

and in the meantime I'll close my eyes and imagine Jupiter through a 79mm Mak bino.

Regarding the FoV I found a calculator which is very naughty because acc to this Jupiter will only be a whiteblue pinhead with a 6mm plossl.

Would you think I can fit a barlow somewhere in that adapter?

Ah, it doesn't have to be the planets, though. Any walk among the stars will be grand.

[silv]

did you know that pink bunnies do play golf?

[silv]

that's the Crap Nebula as captured by my crappy zoom lens at 150mm and cropped. 3x15 seconds on a broken, also crappy EQ5 and 3 darks.
Fun in 2012.

[Wavytone]

Well, I have messed with camera lenses before - at one point I had a 600mm f8 mirror lens mated to an Edmund RKE 28mm as a finder, and a Russian MTO 1000mm f10 similarly set up. Both had T rings to suit 42mm screw mounts.

The snag with both of these - and your camera lenses - is that the back focus distance is so short you'll find very few 1.25" eyepieces will reach focus by the time you have managed to get an eyepiece adapter on. With a star diagonal, very few eyepieces will fit.

The second problem is that old-school camera lenses are not diffraction-limited -not even close - the result being that at high magnification, looking at bright stars or planets is going to be rather disappointing.

Have fun...

[silv]

but those are all mere assumptions, aren't they?

And in their intention simply demotivating.

So no factual knowledge plus demotivation.

hm.

[silv]

The distance from lens end/T2-male-thread to getting focus at the end of a 20cm Plossl is roughly 8cm. With my lens.

And if it needed a longer light path there are focal correctors - by the way usually sold - or at least offered - with binoviewers, anyway. A bit like barlows.

If needed - I would probably be okay with 1.7.
That puts my "Mak" still in a very favourable fastness over "normal" Mak scopes.

No reply from Celestron-Germany yet.

[silv]

never got a reply from Celestron-Germany. How odd... they're the same people as Baader here and Baader actually showed nice customer service in the past. Ah well. Who cares when Amazon has free returns on every order.

***********

While I have by now figured out plan B to perfection (the binoviewer thingy with my existing 500/6.3 mirror lens),
today, I will receive two (used) 60mm Travelscopes to give plan A the last test.

I feel a little bit of joy, even. Pre-Joy or what do you call it? Anticipation.

The €90 I can totally justify. I estimate another ~€10 to get them securely fastened in an aligned position on the tripod.
Might even be sturdy enough to be transportable and not lose alignment.

If that works well I'll get a month supply of daily contact lenses for €20 to compensate for my eye's diopter difference.

And thus will have Xx60 binoculars with exchangeable eyepieces, filter threads and diopter compensation for €120 instead of €800.

:prey:

[jeelan]

How about using the objectives from a 60 or 70mm travelscope to create your own Binoscope?

Provided you calculated the focal length correctly, a 45* fixed mirror and 2 star diagonals, or three star diagonal joined correctly would give you an adjustable IPD that is independent of the distance between the objective barrels...

Below is a drawing from Cloudynights - one of the members made a "binobox"....

cheers
Jeelan

[silv]

oh! thank you for your suggestion!
I am going to find the original thread and try to understand what a bino box does.

I am stuck regarding alignment and fastening of the 2x 60 Travelscopes.
Alignment and getting 2 congruent images forming 1 image in my brain DOES work. And it really DOES look awesome!
That's the good news.
A damper on these news: I was unable to manually hold the scopes in that position long enough to look for any flaws which might still pop up.

The bad news is that I need some form of clamp to hold them together with rings for 1 scope that work like in a finder scope: with these little bolts for alignment, you know?
Off the shelf there are NO finder scope rings with a max outer diameter of below 70mm, my IDP.
Let alone a clamp to hold them together.
Celestron's famous lack of QA also produced 2 scopes with slightly different locations for their mounting plate. ... go figure...
So at least 1 scope would have to get 100% support from the holding-mechansim.

[silv]

Sounds like a project for 3D modelling and printing, right.
3D printing with ABS because that is probably hard enough.
The most dubious part here would be the adjustment screws or rather the holes in the brackets and their threads.
3D printing is not good for fine threads.
And they would degrade over time, anyway.
A nut would have to be placed into the holes to guarantee firm threading for off-the-shelf bolts.

But: if I don't print it myself - who is going to insert the nut immediately after printing when the ABS is still warm enough and will snug tightly around the inserted nut?

Also I don't find a plan on thingiverse for such a clamp.
So I'd have to make one myself- and that means I'd have to really invest time and energy to get to know a 3D modelling software package.
Not a small feat, either, even though I'm good with computer stuff.

I've sent a PM to Meru (member of the forum who started to 3D print and offer prints in the Sales section) about this but he's no longer an active member.

I found a site where you can post a "Looking for-ad " for a 3D plan and print you need. A willing designer with a printer then picks up the ad and works with you on the project to the finish line.

But you have to include a price in the text and I have no idea what that should cost. I don't want to be unfair in the payment - but I can't afford much, either.
€100 is out of the question. I'd bee too close to the binoviewer setup cost with my 500/6.3 mirror lens that the 60mm bino would no longer be an advantage over that. (Or so I think. But what do I know...)

Just yesterday I decided to throw away my yearning for the stars and seriously think up a whole different hobby that would give me satisfaction and fun.

And now I'll have to - just have to - read up on the bino box thingy... :D

[silv]

Could be a hit in the bino community, though, if the clamp ever sees the light of day.
Don't you think?

Buy 2 Travelscopes for 90€, get a clamp printed for, I dunno, 50€, put it on your average camera tripod with maybe a fluid head - and off you go, traveling through the stars... with filter threads and adjustable magnification, too.
(And a packet of contact lenses if you have a diopter difference like I do.)

[silv]

bino box - ah!
yes, I came across the concept in my months-long research.
I discarded it as unfeasible for my non-existent DIY skills and tools.

So that's ticked off, too, now. Good.

I can go and look for a different hobby, now. And send back the 60mm scopes to AMazon.
Thank god for free returns here in Germany!

[petertinkerer]

Rather a late reply to your original post, but I think this is what you had in mind. The Celestron travel scope 70 objectives work well, even up to 60X with 3X barlows and the 20mm included eye pieces.

Peter