12" Binocular Telescope - under construction

[Omaroo]

Our astro society (Macarthur) had Mark Suchting of Deep Sky Optics as its guest speaker tonight. He gave a great talk on the theory and practice of binocular telescope design and use.

As a real bonus he also brought along Paul Shoppis' set of 12" binos (which use Marks optics) that I originally fell in love with at Lostock this year and again at SPSP. Thanks Mark for driving all the way south to show people what a great viewing experience can be had through a set.

Anyway - as an added surprise he brought my two new matched f/5's that he had just completed!! They are true sparklers, and I can't wait to start to build the binos now that the core components are ready to go :thumbsup: Once again - thanks Mark!!!

I'll keep this thread going as I go through each process. Keep coming back for more as I progress.

Here are our two new babies:

Cheers
Chris

[iceman]

Fantastic Chris, shiny new mirrors! They look great.

I look forward to following your progress!

[h0ughy]

top stuff, so whats your next step

[Omaroo]

Thanks Mike! I'll be sure to post it all here. The IIS star party at Lostock is where I was bitten by the binobug as you know. Can't wait to start designing the hardware now - materials, mirror cells, electro-mechanical collimation systems, rotating cages, etc, etc, etc.......

Dave - I guess that there is a fair whack of theory to be applied first to come up with the appropriate dimensions of everything. Based on these I'll make a decision on what materials I'll use - nice wooden components or lots of aluminium & carbon fibre. I'll start to order accessories such as 3-vane curved spiders, focusers, truss joints, etc, etc now.

The journey begins! :D

[skies2clear]

Wonderfull stuff Chris!

Those 2 mirrors give us a double adrenaline rush. Let us know how you progress through this project,

Clear skies,
Nick

[Satchmo]

It's always great to see/hear peoples reaction when they lock the view in and after about a second the binocular processing kicks in. Seeing the detail in TUC 47 or the Tarantula pop out of from what seems like urban haze is a breathtaking thing.

For all the debate about equivelent `monocular' aperture, I think the important part is just to have two discrete optical trains, with good eyepieces. The brain does the rest! Consideration of portability and ease of setup are bigger than how much aperture. Perhaps in this case Size Doesn't Matter ?.
Macarthur AS crowd got a laugh when I described Paul Shopis as the Howard Hughes of binoscopes. So many people have looked through his scope but never met him :)

[Omaroo]

Hey mark - your PM box is full.... I've been trying to reply but the system says that you're chokkers...:whistle:

Cheers
chris

[Ric]

Great looking mirrors Chris, what you intending to build sounds fascinating.

I'm looking forward to following your progress as it all comes together.

cheers

[Omaroo]

Step 1: Mirror protection and transport.

Given that these mirrors will not form part of the permanent structure of the scope, and will be inserted before each viewing session and removed after, they need to be protected in transport. There are several thousand dollars-worth of glass here - so I want them safe.

I've built the first of two boxes which will stack and be locked together for transport. The bottom has a raised section which will hold the mirror up off the bottom. There is good room at each corner to be able to curl your fingers underneath to safely grip and lift the mirror out. I'll be covering the interior in felt - which will close the gaps down the side and protect the sides. The wood I used is 2cm-thick solid jarrah - nice and solid and very pretty. Brass screws finish it off.

I intend to make an elasticised soft acid-free "swimming cap" to cover the mirrors to protect them from dust and being accidentally touched.

Cheers
Chris

[Orion]

It's going to be great to see this come to life!:thumbsup:

[Omaroo]

Thanks Ed - just as I enjoy your own story!

There can't be anything better than building one yourself, and I can't wait to get stuck in. :thumbsup:

On another thought... I'll see if I can incorporate a filtered peltier-cooled airstream into the boxes somehow. I can get this going in the morning and have their core temps down to ambient before I go out!

Cheers
Chris

[Orion]

An peltier-cooled airstream sounds good. Interesting.

[mrsnipey]

Ooooh, so jealous. Enjoy.

[Garyh]

What a great project to start!
she`l be alot of work but boy you shall be rewarded with such magic views.

Just a thought? could you actually turn your lovely mirror boxes into a mirror cell as well? like just slide the whole mirror box into the base of your bino scope with your cooling built in to the boxes as well. Have rails under them with collimation bolts etc...never have to take out the mirrors out of the boxes..
That just cmae to me while looking at those lovely boxes..lol
cheers

[Omaroo]

What a great thought Gary. Make them in to removable "cells" or "mirror cartridges" which means less handling of the glass itself - along with cooling systems in place, etc, etc.

Hmmm..... the rocker box assembly could then be made "skelatenous" and exist merely to hold these assemblies - as well as allow the image-merge adjustment by moving each box as a whole. Collimation adjustment would be set up as per usual via the mirror cell itself.

Hmm....... weight might be a factor, but I'll definitely give it thought!

Gary - thanks and cheers!
Chris

[Lee]

Love the jarrah Chris - nice timber to work with.... but $$$'y

[Omaroo]

Thanks Lee... yup it's exxy but a wonderful wood. I'm lucky that I have a few planks of it lying around from a neighbours building project a while ago. :thumbsup:

[Omaroo]

Focusers -

I bought (or more accurately, Jenny bought for me) two Bintel 10:1 Low Profile Newtonian focusers for the project. They have 37mm travel so should be nice. They're a tiny but heavy but are good value.

I've reversed one of the focuser shaft assemblies so that the slow focusing knobs are symmetrically presented for the user. The great thing is that as you turn both the same way, the tubes rack in and out in the same direction on either side :) Nice!

If you want to see how good Bintel have priced these focusers for us Aussies - check out this site: http://www.telescope-service.com/ATM/focusers.html#TSFOCNCs We get them for $149, they are selling them from this German site for 219EUR, or AU$350!!!!

[Omaroo]

Rocker Box -

Having given some consideration to the separate mirror box concept I've decided that we might look again at that when I build "MkII". For the moment I'm going for the tried and true design.

The box will be very short. The combined weight of two mirrors and the jarrah is quite a bit - so having short sides might help with balance. anyway - I like the idea of the mirrors being up higher - they're more accessible and easier to place and remove.

Two long rails are 755mm inside edge to edge, two short are 420mm. Height will be 130mm (nice and short). Aluminium rail will form frame under the sides which will hold the two separate mirror cell assemblies. Edges are rebated so that the finish is nice and neat. Jeez this jarrah wood is tough - it's like steel to cut. Stainless screws will hold it together - and the edges of the frame will be either tigged or bolted.

[Orion]

Looking good. Jarrah is tough but the finish of the wood is all worth it.

[Satchmo]

Pauls 12" Bino spider close up.

[Omaroo]

Thanks Mark

I guess that there is a spherical depression in the top of the actual secondary holder that the centre bolt mates with? Any idea of the gap between the top and bottom sections?

I've got this shot of it from another angle but it tends not to shed any light on its construction...

Cheers
Chris

[Satchmo]

The threaded nylon rod passes through the spider hub and threads into the secondary holder, so the 3 cap screws threaded through the hub can bear against back of the holder. The gap would be a few mm, as all thats required is enough clearance for some adjustment tilt of the sec holder.

[Omaroo]

Mark - so that main threaded rod flexes to a degree, right?

[Satchmo]

Yep, and in the process makes adjusting the tilt via the three knobs a joy, as they are always essentially `spring-loaded'. This is the secret to success behind the Protostar spiders.

[Omaroo]

Good one :) - I'll build my own then.

Anyone know of a source of threaded delrin rod?

[erick]

Interesting idea, I haven't liked my secondary collimation mechanism and want to get into it to see how I can improve it. But why delrin, Chris, wouldn't that be too rigid?

[Omaroo]

I think that it depends on the gauge of the rod Eric. I've used delrin in many projects in the past and have always found that it machines better than nylon. Nylon would be absolutely fine here, don't get me wrong.

[erick]

Thanks. :)

[Satchmo]

No the rod is just Nylon, most big hardwares sell Nylon bolts .

The Hub is actually some kind of dense polypropylene..I said Delrin because I could spell it easier, but in hindsite wasn't a good idea :)

I think Cut to Size plastics in Chatswood can sell an offcut of suitable plastics , but I don't see any reason why the hexaganol hub couldn't justt be lamination of 2X 12mm ply ?