New binoscope project, 150mm refractor

[keith5700]

After living with my 400mm binoscope for years, I’ve decided to build something a bit more practical.

I just want to drag something out of the shed, have a look around for half an hour, and then push it back in.

So I’ve decided on a 150mm refractor bino. It’s still a binoscope, I’ve tried using just one eye but find it horrible.

I’m going for the under and over design, so there’s only one optical flat in each side.

I like to over complicate things, so I’m making all the variables, eyewidth, diopter and focus, move by servos. This means I can store the settings for swapping users, or eyepieces.

The most difficult bit is that to alter the eyewidth I need to move the eyepiece holder and the objective lens together, but I’ve solved it by having a driveshaft between the 2 and some 90 degree bevel gears.

Hopefully all will become clearer as I progress, but here’s my basic layout.

[keith5700]

I won’t bore everyone by showing how I made every single part, but this is a typical part.

Loads of hogging out on the lathe, over to the milling machine, finish off by hand, in the anodising tank, into the dyeing tank, then seal the dye in.

[keith5700]

And after a couple of weeks this is how far I’ve got

[Mr H in Yorkshire]

Seriously impressed and coincidentally planning something similar with a pair of 6" f/5 objectives I got years ago from Surplus Shed but with a double mirror bino arrangement. I thought I'd make mine focus from moving the objectives which (at least in my naive head) slightly simplifies the design.  Good luck with completion work.

[keith5700]

1 hour ago, Mr H in Yorkshire said:

Seriously impressed and coincidentally planning something similar with a pair of 6" f/5 objectives I got years ago from Surplus Shed but with a double mirror bino arrangement. I thought I'd make mine focus from moving the objectives which (at least in my naive head) slightly simplifies the design.  Good luck with completion work.

Thanks. My main focus will be by moving both objectives together with one servo motor. The diopter adjustment will be with a second small servo which will move one objective forwards, and the other one backwards, in equal amounts.

Then there’s the third motor moving one eyepiece holder and objective left or right, for the eye width. The other eyepiece remains in a fixed position at all times.

[Mr H in Yorkshire]

Hi Keith, slow to get back to you - busy helping son put up a greenhouse.

I did wonder why the pairs of shafts looked like they would slide in the circular housings, now I know. May I ask, if you are able to move the objectives at all, why not one servo each side and do the focus for each eye directly, which is what I had at the back of my mind when I said 'simplifies the design'. I might be selfish and not even provide IPD, I will think about that. I can't quite work out from looking at the pictures, how your IPD adjustment will work. I can see the lower lightpath opening in the circular plate is somewhat slotted, will the objective motion be within that substantial bracket at the objective end? The one thing I can't avoid is provision of collimation to achieve strain free binocular image fusion. I am thinking to have a 'base' (part of the overall housing) on which sit two trays, one with lateral adjustment, the other with vertical adjustment, both hinging from the eyepiece plane. How will you provide collimation between the two light paths?

My overall project is make a more substantial version of my motorised binochair, I am particularly pleased with the success of the 4-bar linkage between chair and binos, and mount it all on a small trailer. Here's a picture that shows the general idea.

 

[markse68]

You make really beautiful things Keith 👍 Hopefully this works out and you get to use it more than that other beautiful scope you made. 

(I have that same hoover too- they’re great  )

[keith5700]

Thanks Mark. Yes, Nilfisk vacuum, best thing ever!

MrH, hopefully latest pics are a bit clearer. The mitre gear turns an M10 threaded and keywayed shaft, which moves the objective sideways. A shaft runs through the 3” ally tube and will turn a similar setup for the eyepiece holder that side.

The main focus gearmotor/ballscrew will push the objective that side, and the other objective will be also connected to this, but with the little servo in between. This servo will turn some sort of thread so this objective can move slightly relative to the other one. This will give the diopter setting.

So, these will be the 3 variable settings.

I haven’t thought too much about the initial collimation, but from my previous binoscopes, it will centre around getting the shafts which everything slides on to be perfectly parallel, or coaxial, to the theoretical centreline of the scope.

last time I used a long water tube level, and a laser, which datums off the sliding bars, and projects on a target at the other end of the shed. I’ll know more when I think about it properly.

im just waiting for my belts and pulleys to turn up, so I can try the mechanisms.

[Mr H in Yorkshire]

Thanks for the explanation, and yes the photos clarify things considerably. The engineering is looking svelte, that's definitely the right word. At a guess what do you reckon the finished weight will be?

[Chriske]

You're going to enjoy this big bino. Observing with these large binos has many advantages. Simply said, you see much more compared to a 'singles scope'. I've built a few binos myself...😉

To me, as a mechanical engineer, there's a high drooling factor involved in what you construct...👍

[keith5700]

MrH, everything in the photo comes to 5kg. The lenses weigh 5kg together. I was hoping to keep below 15kg total but with the lenses being heavier than anticipated I think it will be a bit more.

Chriske, this is my 4th binoscope.  I have a 400mm reflector bino I tried to sell, but no interest. I’ve stripped it and am trying to sell the parts. I just want something a bit quicker to drag out of the shed and setup these days. Using just one eye for viewing gives me a right headache after 10 minutes or so, even if I keep the other eye open.

[Mr H in Yorkshire]

I'm not surprised about the weight, my pair of Jaegers achromats weigh just over 4kg, a friend 'smuggled' them over in his ski gear, saved a fortune in duties. For the benefit of HMRC, I made that up.  What make are your objectives. Sorry if I keep pushing you for info that you are probably going to post at some time.

Bino viewing is definitely the best way to reduce vision defects, I am differently long sighted and astigmatic in each eye, if I look with either eye alone everything is mediocre, but with both eyes something magic happens, what the brain does by way of image enhancement is truly amazing.  

I'm truly surprised there were no takers for the bino reflector, not even a club. I have drooled over pictures of it myself, but realistically the Yorkshire skies would keep it in the garage.

Edited October 18, 2023 by Mr H in Yorkshire

[keith5700]

Latest pics. Hope the telescope is visible amongst all the crap. Thought I’d photograph it before all the black anodising and painting. The RH eyepiece is static, the LH one does the sliding for the eyewidth. The complicated bit is keeping the LH objective in line with the eyepiece. So the bevel gears turn a shaft which goes to the front lens, which goes through another bevel gear set, which moves the objective.

Dont mind saying though, I screwed up a little. When the eyepiece moves right the objective moves left! Didn’t think about that. Just need a left hand thread M12 tap and die to sort that out.

The over complicated mirror holders are so that when setting these, any movement in either plane won’t alter the centreline position, ie. the rotation and pivot centre will always be exactly in the centre of the mirror. It’s a lot more work, but pays off when it comes to collimation time.

 

Edited October 26, 2023 by keith5700

[Mr H in Yorkshire]

That is a tour de force of astro engineering. I won't ask any questions, because I'm sure all will be revealed. Well one question: are you logging your hours?

[Peter Drew]

Whilst I'm in complete awe of the design and expertise of the engineering I have to say that my approach to the construction of binoscopes is at the other end of the spectrum.  Applying the "KISS" principle It takes me around 2 weeks to make a similar aperture model yet still retains simple IPD adjustment, focusing and almost instant  user collimation.  The main downside to all  these binoscopes of 150mm and upwards is the weight.       🙂

[Albir phil]

2 minutes ago, Peter Drew said:

Whilst I'm in complete awe of the design and expertise of the engineering I have to say that my approach to the construction of binoscopes is at the other end of the spectrum.  Applying the "KISS" principle It takes me around 2 weeks to make a similar aperture model yet still retains simple IPD adjustment, focusing and almost instant  user collimation.  The main downside to all  these binoscopes of 150mm and upwards is the weight.       🙂

Yeah keep it simple,I seem to remember a company in the USA who made 8-10inch reflecting Binos with electric motors on the eye spacing ,don't think they caught on much though.Cant remember who it was that made them, your's are much less complicated as I remember Peter 👍

[Peter Drew]

JMI  (Jim's Mobile).  Sadly, Jim is no longer with us.    🤩

[Albir phil]

11 minutes ago, Peter Drew said:

JMI  (Jim's Mobile).  Sadly, Jim is no longer with us.    🤩

Ah yes are they not trading now, I've still got the cad drawings for those I made, never got the time to pursue it much more than one unit😀

[Mr H in Yorkshire]

On 26/10/2023 at 19:56, Peter Drew said:

JMI  (Jim's Mobile).  Sadly, Jim is no longer with us

JMI Not with us, as in up there with the stars or just retired?

[Peter Drew]

Sadly, the former.

[windjammer]

Lovely work !

[Mr H in Yorkshire]

Really looking forward to the next instalment. No pressure. 😀

[keith5700]

Update time.

It’s still a complex project, but that’s what my hobby is. After years of keeping things simple at work, it’s nice to get home and do some unrestricted engineering.

I might scrap the focus motor idea though. It works ok, but then there’s some subsequent creeping of the motor, because the 10 turn pot isn’t accurate enough. A stepper motor upgrade may be the way for the future.

I’m using toothed belt drives for both axes. I’ve used them hundreds of times at work and home, and this one works fine, as in almost imperceptible play and flex, because the free lengths are very short.

im trying to borrow a set of rollers to roll the ally sheet to make the main tube, but no luck yet.

Need to start drawing up the Az drive next. This will be similar to the Alt drive, but the clutch system will need a rethink, so the lever is out of the way.

Edited December 22, 2023 by keith5700

[Mr H in Yorkshire]

Looking excellent (and expensive).

[Mr H in Yorkshire]

I see you have a control box of sorts but is that just for focus and IPD? Are you considering GOTO or 'drive to' as I call it (the motorised equiv of push to') using encoders. I have encoders (from astro-gadgets, a Ukrainian company) on my binochair and they are great, they work with Stellarium or Skysafari? I'm still working through my binoscope project but my 'engineering' is so rough compared with yours I'm actually sufficiently embarrassed that I've gone back and cleaned up some really rough bits. I can't help it, I once did a personality exam and it turned out I was an extreme pragmatist/analyst type, it's the pragmatist bit that allows me to get away with scruffy work, but I have always admired the patience shown by real engineers.