152mm f/5.9 Binoscope

[Chriske]

Hi,

Does anyone know a good source to buy a 150mm achromat, airspaced.

I already found this one, is not to expensive.

Thanks

[John]

These people in the UK sell Istar achromatic objective lenses:

https://www.peak2valleyinstruments.co.uk/page_2238911.html

 

[Chriske]

Thanks John, but I don't think these people are selling in my budget range...😳

[John]

You could try a "wanted" advert in the UK Astro Buy & Sell website on on our classifieds section. You never know what might be out there !

 

Edited January 17, 2021 by John

[Chriske]

I could do that John , but there's an additional problem.
A need in fact two of these lenses. And on top of that they need to have exactly the same focal length.
Now you surely know what I'm planning to do with these lenses...😉

[Peter Drew]

I presume you are planning a binocular?  I have built several using Skywatcher 150mm F8 and F5 objectives and never had a problem with mismatched focal lengths.   🙂

[Chriske]

Nice...!!!
Thanks Peter...!...

[Chriske]

Yet again as always, I plan to add a IPD unit starting from 55 to 70mm

[Chriske]

1 hour ago, Peter Drew said:

I have built several using Skywatcher 150mm F8 and F5 objectives and never had a problem with mismatched focal lengths.   🙂

Do you have pictures of these bino's..?

[Peter Drew]

1 hour ago, Chriske said:

Do you have pictures of these bino's..?

Not to hand but there should be some somewhere on SGL or Cloudy nights.        🙂

 

[John]

7 minutes ago, Peter Drew said:

Not to hand but there should be some somewhere on SGL or Cloudy nights.        🙂

 

Here are some

 

[Rusted]

Unused 150mm f/8 achromats are taking up cupboard space all over the world.
They sound like fun until you need to limbo dance just to get under the eyepiece.
You need a very tall pier and solid mount to make the most of them.
They are very nose heavy and most tripods lack the masculinity to cope.

I'd second making an appeal for donors.

[Chriske]

Why not use a star diagonal Rusted, so no need to a Limbo...😁

[Rusted]

44 minutes ago, Chriske said:

Why not use a star diagonal Rusted, so no need to a Limbo...😁

Lying on your front, to look into a star diagonal, a few centimetres above the ground, is considered the sign of a beginner.
Not to mention the dewing of one's meter long [self isolation] beard from repeated contact with the wet grass.
Limboing on your back and looking straight upwards is the approved way for serious amateur astronomers. 

EDIT: Owners of such large refractors should probably invest in a mechanics "creeper" trolley:

Silverline 783171 40-inch Mechanic's Creeper: Amazon.co.uk: Car & Motorbike

 

Edited January 18, 2021 by Rusted

[Chriske]

It has begun...

To do : IPD-unit and focusers

[Chriske]

[Chriske]

Still at it...
First-mirror cells 'installed'.
Don't know yet what I'll use to move the eyepiece housing(red). I have three options LMUU bearings, Iglidur bearings, or just plain PLA bearings. As  the eyepiece housing do not move to often and not very fast at all, I think LMUU bearings are overkill. These housings will be riding on 2x 8mm brass rods.

The eyepieces are at its widest position in the drawing, so for observers with 76mm IPD. The closest the IPD can get is 54mm, that will cover most of the kids eyes.

[Chriske]

Second mirror installed, next the focusing-part.

[Chriske]

Needed to redraw it all, in the past I ordered sec/thir. mirrors a bit to small....🥴
So I ordered two new -larger- mirror sets.  Meaning I now have a spare mirrorset to make me another binoscope in the futur...😝
Due to Brexit didn't know what to expect, so this I ordered  a new mirror-sets in Germany instead of OO.  Sorry guys...🥴

Started printing the first parts today.

[Chriske]

Still at it, almost all parts printed.
The red central knob is to set IPD
Blue parts contains a right/left nut.
Brass rods are there to guide the units during IPD adjustments. Maybe I'll add some linear bearings(like LMUU), don't know yet. Friction between rods and PLA might be just fine..
Brown part is just an aid to collimate the second mirrors(yellow is a small dummy mirror, to check collimation from the outside).
Green is a laserbeam

Need to start drawing the focusers now, last parts... Probably Helix-type, but guided by ball bearings instead of threads.

 

[Chriske]

Still at it, all parts printed, busy assembling.

 

These have to hold on a bit longer, black paint still wet...

 

This is a dummy to test all the actions before I proceeded making the final two units.
These units serve as focuser and IPD adjuster at the same time. And on top of it contains the secondary(last) mirror.

[markse68]

Awesome!

Mark

[Chriske]

PID setscrews(left and right handed thread) and its holder.

[Rusted]

Blimey! Does Elon know you've borrowed his alien technology?  

[F15Rules]

Full respect to your design and engineering skills!👍

They look very solid..and heavy🏋️!!

What do you plan to mount them on?

Dave