New Newtonian Telescope From China

Topic starter

Jul 7, 2025

I have finished all my tests on this Clearsky Alpha 200mm F/4 Newtonian reflector. The redesigned structure for supporting the secondary mirror is stable and easy to adjust.
Clearsky offers two options for purchasing this telescope, you can either get a kit and install Skywatcher primary mirror & secondary mirror, or buy the kit with Clearsky's quartz mirror preinstalled. I myself got the Skywatcher version.
I don't know if they have any plans to sell this telescope outside China yet, but you may leave a comment if you are interested.
Sample image was taken with Touptek Skyeye62ac camera and Clearsky St17 mount

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Stephen Shen

Topic starter

Jul 7, 2025

The model I'm using is not the final version. Final version that they sell on the market has shorter dew shield

Vandewattyne

Jul 7, 2025

Do you have a link with more details?

Stephen Shen

Topic starter

Jul 7, 2025

Vandewattyne:
Do you have a link with more details?

They don't have a webpage for this product yet, so if you are interested, I might answer your questions

John Stone

Jul 7, 2025

What coma corrected did you use that can illuminate a full-frame chip with an 70mm secondary mirror?

does it screw to the focuser draw tube?

What is the back-focus distance? Is there room for a rotator? 65mm ( 55mm + 10mm needed for the wanderer Astro mini V2 m54)

is the tube strong enough to avoid flex and hold collimation at any orientation?

is the focuser EAF compatible?

can I get a. 250mm and 300mm version?

what strehl ratio is specced for their mirror?

what is the size/spec on their secondary mirror?

what is the cost? How can I order?

Christian Andres

Jul 7, 2025

This looks like an interesting design for a 8" newtonian. I guess the tube serves only as a light shroud for the truss design? I would be interested to see the primary cell and the secondary holder.

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Stephen Shen

Topic starter

Jul 7, 2025

Christian Andres:
This looks like an interesting design for a 8" newtonian. I guess the tube serves only as a light shroud for the truss design? I would be interested to see the primary cell and the secondary holder.

Yes you can actually just remove the tube, and that makes the system more wind-resistant

Stephen Shen

Topic starter

Jul 7, 2025

John Stone:
What coma corrected did you use that can illuminate a full-frame chip with an 70mm secondary mirror?

does it screw to the focuser draw tube?

What is the back-focus distance? Is there room for a rotator? 65mm ( 55mm + 10mm needed for the wanderer Astro mini V2 m54)

is the tube strong enough to avoid flex and hold collimation at any orientation?

is the focuser EAF compatible?

can I get a. 250mm and 300mm version?

what strehl ratio is specced for their mirror?

what is the size/spec on their secondary mirror?

what is the cost? How can I order?

I use sharpstar 2-inch 1x mpcc for full-frame imaging, this mpcc is not locked by screwing into the focuser
The back-focus distance is 55mm, I am not sure if it is CAA compatible (since I don't have a wanderer CAA yet)
The tube only functions as a shield for blocking light, the entire structure is steady. Based on my test, the telescope remains stable after meridian flip.
Yes the focuser is EAF compatible, currently I am using a Touptek EAF on this telescope. I have plans to upgrade to an Oasis EAF but it seems that I would need an adapter for Oasis focusers
They do have a 10 inch version already in production, and I think they are working on 12-inch version
I don't know specs of their own mirrors，I have asked the manufacturer and hopefully I can get answers tomorrow.
For now, they haven't launched the product overseas, so I don't know how you guys could purchase. I can help you contact the manufacturer, though.

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Dan Watt

Jul 7, 2025

Can you share any images of the primary mirror cell and secondary spider? I'm curious how their cell designs differ from the rather poor designs available from most of the mass manufacturers.

Can you share any single subs? These stars are pretty rough looking but it could be artifacts from processing.

Joey Conenna

Jul 7, 2025

From the diffraction spikes it looks like the spider vanes are not colinear. Is the spider CNC machined?

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andrea tasselli

Frequent contributor

Jul 7, 2025

I wouldn't say so. Mayhap there is a slight cone error and the scope flipped during the imaging run. To judge that you need a single frame.

Joey Conenna

Jul 7, 2025

You're right, with those three sticks holding up everything it is very possible.

Reza Mohammadi

Jul 7, 2025

Stephen Shen:
Sample image was taken with Touptek Skyeye62ac camera and Clearsky St17 mount

I know this guy. let me ask more info.

Stephen Shen

Topic starter

Jul 8, 2025

Dan Watt:
Can you share any images of the primary mirror cell and secondary spider? I'm curious how their cell designs differ from the rather poor designs available from most of the mass manufacturers.

Can you share any single subs? These stars are pretty rough looking but it could be artifacts from processing.

I accidentally dropped screws on the primary mirror, resulting in some scratches. I think that's where these spikes come from

Stephen Shen

Topic starter

Jul 8, 2025

Dan Watt:
Can you share any images of the primary mirror cell and secondary spider? I'm curious how their cell designs differ from the rather poor designs available from most of the mass manufacturers.

Can you share any single subs? These stars are pretty rough looking but it could be artifacts from processing.

Stephen Shen

Topic starter

Jul 8, 2025

John Stone:
What coma corrected did you use that can illuminate a full-frame chip with an 70mm secondary mirror?

does it screw to the focuser draw tube?

What is the back-focus distance? Is there room for a rotator? 65mm ( 55mm + 10mm needed for the wanderer Astro mini V2 m54)

is the tube strong enough to avoid flex and hold collimation at any orientation?

is the focuser EAF compatible?

can I get a. 250mm and 300mm version?

what strehl ratio is specced for their mirror?

what is the size/spec on their secondary mirror?

what is the cost? How can I order?

8-inch version costs USD 1499 (with sky-watcher mirrors), quartz mirror version would cost USD 2299. 8-inch version uses 70mm secondary mirror.
10-inch version version costs USD 2499, which uses 80mm secondary mirror. There is a variant that is optimized for full-frame imaging, and it would be USD 2899 USD. The variant uses a larger focuser and 90mm secondary mirror.
Estimated price for 12-inch version would be USD 3599.
As for the CAA issue, a friend of mine which also uses the same telescope in Australia uses wanderer CAA in the way shown in the picture attached.
You may contact the manufacturer:
[email]sky.freedom@126.com[/email]

Jordan Morley

Jul 8, 2025

Looks very heavy

Stephen Shen

Topic starter

Jul 9, 2025

Jordan Morley:
Looks very heavy

Indeed! Although they used a lot of carbon fiber, but it is still over 10kg

Wei-Hao Wang

Jul 9, 2025

Ouch. If an 8 inch weighs more than 10kg, then I can't imagine how heavy a 12 inch is going to be. (I am interested in a 12" Newt.)

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andrea tasselli

Frequent contributor

Jul 9, 2025

A standard CF-tubed 8" Newt with rings and plate (and standard 2" focuser) weighs between 7 and 8 kilos. This one looks more like an exercise in design rather than practicality.

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Dan Watt

Jul 9, 2025

andrea tasselli:
A standard CF-tubed 8" Newt with rings and plate (and standard 2" focuser) weighs between 7 and 8 kilos. This one looks more like an exercise in design rather than practicality.

Yeah a quick count shows 50+ individual parts instead of a single monolithic tube. And on top of that there IS a CF tube in the middle as a shroud so it's not like they lack the ability to make CF tubes. If this was a 16" or larger scope, sure but for an 8' this is a crazy amount of extra junk.

MaksPower

Jul 9, 2025 · Edited: Jul 10, 2025

The designer clealy isn't a mechanical engineer. the whole structure from the top to the ground should be assessed for flexure to identify the weak points and deal with those, and avoid over-building where it’s unnecessary.

The tripod and three sticks it is perched on are the first issue.

And CF tube is stiffer than the truss - keep the rings and delete the rest of the truss. Newtonians do need the tube to keep stray light out.

The designer of this is unaware of the real purpose of a Serrurier truss - on large telescopes it allows the top and bottom ends to sag (which is inevitable on a large observatory scope) on either side of the connection to the Dec axis, whilst relying on the geometry of two parallelograms to maintain the collimation of the top and bottom.

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Jed Hu

Jul 10, 2025

MaksPower:
The designer clealy isn't a mechanical engineer. the whole structure from the top to the ground should be assessed for flexure to identify the weak points and deal with those, and avoid over-building where it’s unnecessary.

The tripod and three sticks it is perched on are the first issue.

And CF tube is stiffer than the truss - keep the rings and delete the rest of the truss. Newtonians do need the tube to keep stray light out.

The designer of this is unaware of the real purpose of a Serrurier truss - on large telescopes it allows the top and bottom ends to sag (which is inevitable on a large observatory scope) on either side of the connection to the Dec axis, whilst relying on the geometry of two parallelograms to maintain the collimation of the top and bottom.

Hey, man, the tripod and three connecting rods you mentioned are Stephen's own equipment. He was probably using them temporarily mounted on the equatorial mount for shooting. This has nothing to do with the design of the telescope; it's purely the user's own doing. This is my own equipment, and we usually use it this way.

Jed Hu

Jul 10, 2025

Dan Watt:
Can you share any images of the primary mirror cell and secondary spider? I'm curious how their cell designs differ from the rather poor designs available from most of the mass manufacturers.

Can you share any single subs? These stars are pretty rough looking but it could be artifacts from processing.

Hello! I'm the designer of this telescope. Mr. Stephen was our product's very first user. We have discussed the cause of the split star spikes in the photos he took and ultimately identified the issue. The reason was that during imaging, after the meridian flip, the rotation angle of his camera changed slightly. This slight change wasn't further adjusted during the image stacking process. This is entirely avoidable minor oversight; it is absolutely not caused by the telescope's design or manufacturing precision. The vast majority of components in our telescopes are CNC machined, achieving very high precision. Furthermore, we employ a fundamentally different collimation (optical axis adjustment) structure compared to all other Newtonian reflector telescopes on the market, specifically to ensure stability during imaging. I have sample photos taken with the same model and structural images of the primary mirror cell you mentioned available.
If you have any other questions about this telescope, feel free to ask me directly. Thank you for your reply.

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MaksPower

Jul 11, 2025 · Edited: Jul 11, 2025

Sure the quality of the machining of the parts is evident, but you haven't used Finite Element Analysis (FEA) to work out where you needed strength, and where you didn't. It's quite obvious just looking at it.

If FEA had been used I would expect you would find your truss serves no mechanical purpose and could have been omitted, making it lighter, many fewer parts, lower cost, and quicker to assemble.

The difference is this:

When you're building a one-off for yourself you don't really care much about the material cost, or your time. Once you have something that works well, you stop. I've "been there done that" many times in my telescope-making days.

But if you are aspiring to build a product that will go into volume production, this is where the product has to be optimized - fewer parts, less weight, less labour, and lower input cost. If this is done well it's quite usual for the result to be better quality, lighter and lower cost than the first prototype you started with. This is what I run in my day job in a large engineering enterprise.

If it is done poorly (Meade and Synta being examples) the product will forever be compromised.

PS like the mirror cell, except that I would not use springs - I always opt for push-pull screws (two smaller M4 screws pushing either side of an M5 bolt pulling). That way collimation stays put, forever.

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Interested?