Anyone made an ultra light 12"F4 newt for eq mount?

[Flame Nebula]

Hi

Thinking about scopes on eq mounts, got me thinking. 

In principle, it should be possible to make one with a weight less than 14kg(wt of relatively light VX12). I'm not thinking of trying to do this, but wondered if any of you guys have ever seen such a scope on an equatorial. It occurs to me, that some kind of lightweight truss design would cut out a lot of the weight?

Thanks 

Mark 

[dweller25]

I think truss designs are slightly heavier than solid tubes for the same mirror size.

Edited April 2 by dweller25

[Flame Nebula]

19 minutes ago, dweller25 said:

I think truss designs are slightly heavier than solid tubes for the same mirror size.

Hi

I'm just opening this up to thinking outside the box. What about magnesium aluminium alloy - very light but much stronger than aluminum and high resistance to bending. 

Obviously, one would need to see if these were commercially available, but if they were, one could imagine a significant weight saving. 

Not the sort of thing that would be commercially made, but if someone with skill could get them and create the truss with them, it might work. 

[saac]

StellaLyra 12 inch using carbon fibre tubes comes in at 24kg. That is reported as the tube weight, I wonder if it includes the mirror and mirror cell as well though?

https://www.firstlightoptics.com/stellalyra-telescopes/stellalyra-12-f12-m-lrc-classical-cassegrain-carbon-truss-telescope-ota.html

Jim 

[Flame Nebula]

8 minutes ago, saac said:

StellaLyra 12 inch using carbon fibre tubes comes in at 24kg. That is reported as the tube weight, I wonder if it includes the mirror and mirror cell as well though?

https://www.firstlightoptics.com/stellalyra-telescopes/stellalyra-12-f12-m-lrc-classical-cassegrain-carbon-truss-telescope-ota.html

Jim 

Hi, 

The design would need to beat the 14kg aluminium OTA for the VX12. 😬

It would be tough, but not impossible. I'm sure a magnesium-aluminium alloy truss design would work to get weight down even lower. It would certainly cool quickly! 😊

Maybe even a wooden frame would work, if the right type of wood? 

Thanks 

Mark 

Edited April 2 by Flame Nebula

[Peter Drew]

To make any headway with this proposition you would have to consider an ultra-lightweight primary mirror.      🙂

[Flame Nebula]

Looking on Internet, I can see lots of homemade truss designs that look like they might be lighter, but all are dobsonian designs. Now, if it was possible to connect any of them to a losmandy plate.... 

[Flame Nebula]

1 minute ago, Peter Drew said:

To make any headway with this proposition you would have to consider an ultra-lightweight primary mirror.      🙂

Hi Peter

Anyone make these? 

[John]

Orion Optics primary mirrors tend to be thinner than most, and therefore lighter.

One of those honeycomb or strut back type designs is needed to lighten further I guess. Skywatcher use  something like that on their 14 inch and upwards dobs I seem to recall.

 

[Peter Drew]

Google Mel Bartels for further insight.       🙂

[Flame Nebula]

Apparently ts optics sell a 12" mirror at only 6.3kg. Can we go lighter? 

[Flame Nebula]

4 minutes ago, Peter Drew said:

Google Mel Bartels for further insight.       🙂

Mmm, so he's shown it is possible to get 12" mirrors down to around 3kg, maybe less? Based on the 16" 3.5 kg one. 

So, that's our mirror sorted. 😁😁

[Flame Nebula]

14 minutes ago, John said:

Orion Optics primary mirrors tend to be thinner than most, and therefore lighter.

One of those honeycomb or strut back type designs is needed to lighten further I guess. Skywatcher use  something like that on their 14 inch and upwards dobs I seem to recall.

 

Hi John, 

I wonder if OO would be prepared to make a bespoke 12" that could get below 10kg (for the right price... 😂) and be capable of equatorial mounting. 

They are already down to 14 kg with their VX12, so I'm sure they could. Perhaps an ultra thin steel tube, or magnesium alloy tube, or honeycomb. 

 

Edited April 2 by Flame Nebula

[John]

4 minutes ago, Flame Nebula said:

Hi John, 

I wonder if OO would be prepared to make a bespoke 12" that could get below 10kg (for the right price... 😂) and be capable of equatorial mounting. 

They are already down to 14 kg with their VX12, so I'm sure they could 

 

In the past OO have been prepared to undertake bespoke requests. No sure what their position is now though.

It's not just the cost though, you might have to be rather patient to get the instrument as well 😉

[John]

One idea would be to go along to a show such as the International Astronomy Show where lots of vendors and some manufacturers gather under one roof. You could broach your ideas with a number of people at the same time, to test the water 🙂

Vendors – UK Astro Show

 

[saac]

Some related discussion here:

Jim

 

[Flame Nebula]

2 minutes ago, John said:

One idea would be to go along to a show such as the International Astronomy Show where lots of vendors and some manufacturers gather under one roof. You could broach your ideas with a number of people at the same time, to test the water 🙂

Vendors – UK Astro Show

 

Thanks John, 

Certainly a good idea. 

Interesting, if you go on CN and type Great Attractor, there's a photo of a homemade 12" equatorial mounted, looks a very interesting design. I'm not showing the image, in case I fall foul of copyright! 🤔

Various discussions on it, and our own Peter Drew gets a mention. 

[JTEC]

Mark, may I pass on to you a fable that has been of value to me over the years when making choices in a multifarious field?  Long ago I was playing around with big cameras, the sort where you put a cloth over your head to view the image on a ground-glass screen, amusing myself doing landscapes.  I fancied that I needed another lens and went into a store that sold high end photo kit.  Behind the counter stood a pasty youth with - sign of the times - plentiful gel on his hair. This could be a waste of time, I thought.  ‘I’m looking for another lens’, I said, ‘but I’m not sure which one to go for.’ ‘Well sir’, replied the pasty one, ‘it depends entirely on what you want to achieve.’  I  draw on his unexpectedly wise words to this day and always when buying a lens, an eyepiece, etc - the choices in our hobby are vast and so are the lures and temptations.

Reading your posts - and please don’t take this the wrong way - I feel that you still need to clarify and simplify.  Exactly what is it you want to achieve?  Planetary imaging?  DSO imaging?  Wide-field or other? General visual observing?  All of the above? To quote another even more ancient proverb: no one type of scope is best for everything and all have limitations.
 
Opinions differ as to what scope for what.  The best steer, imv, is to look at what the best practitioners are using.  I know that fine planetary images are being produced with Newtonians but Damien Peach, by common consent the best planetary imager in the world, has always used SCTs.  Fabulous wide-field images are being produced with small refractors - and, having done lots of it, imv, that’s the best place to start with this kind of imaging - the longer focal length stuff is more demanding in every respect. However, a small or even a middle sized refractor is not the best choice for planetary or lunar imaging because, at the sizes we can afford, such a scope won’t have the aperture to resolve the available detail and, usually, the image scale will be too small. For general visual, a small refractor (which I think you already have) for wide field views plus a medium sized (8-12”) Dob.  Having owned big Newts and several EQ6 mounts, I think a big Newtonian OTA on one would be a bit of a handful, not just to manhandle but, more importantly, to get to perform optimally - too much to wobble about. Not impossible to achieve, but requiring a heck of a lot of attention to detail and offering lots of things to frustrate and go wrong. 

Please heed the words of Confucius from the camera store … 🙂  

Good luck!

 

 

 

 

 

Edited April 2 by JTEC

[Flame Nebula]

32 minutes ago, JTEC said:

Mark, may I pass on to you a fable that has been of value to me over the years when making choices in a multifarious field?  Long ago I was playing around with big cameras, the sort where you put a cloth over your head to view the image on a ground-glass screen, amusing myself doing landscapes.  I fancied that I needed another lens and went into a store that sold high end photo kit.  Behind the counter stood a pasty youth with - sign of the times - plentiful gel on his hair. This could be a waste of time, I thought.  ‘I’m looking for another lens’, I said, ‘but I’m not sure which one to go for.’ ‘Well sir’, replied the pasty one, ‘it depends entirely on what you want to achieve.’  I  draw on his unexpectedly wise words to this day and always when buying a lens, an eyepiece, etc - the choices in our hobby are vast and so are the lures and temptations.

Reading your posts - and please don’t take this the wrong way - I feel that you still need to clarify and simplify.  Exactly what is it you want to achieve?  Planetary imaging?  DSO imaging?  Wide-field or other? General visual observing?  All of the above? To quote another even more ancient proverb: no one type of scope is best for everything and all have limitations.
 
Opinions differ as to what scope for what.  The best steer, imv, is to look at what the best practitioners are using.  I know that fine planetary images are being produced with Newtonians but Damien Peach, by common consent the best planetary imager in the world, has always used SCTs.  Fabulous wide-field images are being produced with small refractors - and, having done lots of it, imv, that’s the best place to start with this kind of imaging - the longer focal length stuff is more demanding in every respect. However, a small or even a middle sized refractor is not the best choice for planetary or lunar imaging because, at the sizes we can afford, such a scope won’t have the aperture to resolve the available detail and, usually, the image scale will be too small. For general visual, a small refractor (which I think you already have) for wide field views plus a medium sized (8-12”) Dob.  Having owned big Newts and several EQ6 mounts, I think a big Newtonian OTA on one would be a bit of a handful, not just to manhandle but, more importantly, to get to perform optimally - too much to wobble about. Not impossible to achieve, but requiring a heck of a lot of attention to detail and offering lots of things to frustrate and go wrong. 

Please heed the words of Confucius from the camera store … 🙂  

Good luck!

 

 

 

 

 

Thanks JTEC, 👍

I think I've made my decision to go with an 8" newt (200pds) on AZEQ6. But, I was curious about the possibility of very light newtonian designs that could be easier to man handle. 

But going back to clarify my interests. I would say planetary and doubles. But I'd like to both dso and planetary AP. Visual too! 

I've actually been very pleasantly surprised at how good some images of Mars and Jupiter in particular are, taken by some imagers on astrobin. So, for £500 for a 200pds,plus outlay on accessories, it would be a good start. The beauty of this approach, is I am confident I can also use the scope for nice visual observations and dso AP too. If I'm really not happy with my planetary images, then I need to work out, is because I am failing somewhere in my skill set, or is it because I need more aperture. Where I might struggle with the 8" newt, is trying to match C9.25 /C11 images of Saturn's rings(although, ironically they may be a bit difficult to image by the time I get my scope later in year😉) 

But, if I do decide that my skillset is not the issue, and I need more aperture, maybe then is the time to jump to a C9.25 or C11. 

Fortunately there are a few Confucius-like people on this forum, who have steered me on a wiser path. 😊

A long time ago, I knew someone who was only 24 years old. He bought himself an 8.75" dobsonian. He remembers that the most wonderful thing he saw was that the moons of jupiter looked like discs! But, alas when he tried to zoom to high mags, he found he couldn't cope with the nudge nudge or kept moving the scope the wrong way. In the end, the scope didn't get used. That 24 Yr old swore that the next big scope he got would have to track. 

Time moved on 35 years (where's it go!?), and now we have goto tracking dobs😊, and heavyweight Az-eq6 mounts🙂. 

So, the time is near. I've not been able to afford/justify some nice kit previously (various reasons), but I've built up my funds. The hopefully soon, I'll get to sit and stare at jupiter and its moons in an 8 incher again, and relax. 

Anyway, if anyone is still awake and reached the end of my post, well done! 🤣🤣

Edited April 2 by Flame Nebula

[ONIKKINEN]

Hubble optics also makes fairly light mirrors, on their site some 12" primary mirrors are quoted at 4kg.

[Flame Nebula]

51 minutes ago, John said:

In the past OO have been prepared to undertake bespoke requests. No sure what their position is now though.

It's not just the cost though, you might have to be rather patient to get the instrument as well 😉

Thanks John 

Especially when I tell them I'd like gold plated magnesium alloy truss designed equatorial mounted, newt, total weight 9 kg, delivery in 4 weeks please. 🤣🤣🤣

[Flame Nebula]

2 minutes ago, ONIKKINEN said:

Hubble optics also makes fairly light mirrors, on their site some 12" primary mirrors are quoted at 4kg.

Hi, when I started reading your post, I thought you were going to point me towards the hubble space telescope 🤣

But, thanks for the info 👍