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Say no more field rotations for the Seestar S50

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#1 kaicyung

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Posted 24 December 2023 - 12:11 AM

Seestar, say goodbye to field rotations.

 

Attached below are captured tonight under nearly full moon. No cropping nor special processing were performed. Just either raw output or simple signal boost to highlight the underlying noise.

No internal modifications to the Seestar.

 

Happy holidays.

 

Kai

Attached Thumbnails

  • 1703393987523~2.jpg
  • 1703389129502~2.jpg

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#2 tarbat

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Posted 24 December 2023 - 06:56 AM

So how?  Did you mount the Seestar on an EQ wedge and set your location to 90°N?



#3 Psion

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Posted 24 December 2023 - 07:02 AM

The EQ wedge cannot work in principle. Seestar made some corrections, then you just need a lot of signal from the background and you can't see the rotation of the field of view.



#4 tarbat

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Posted 24 December 2023 - 07:07 AM

Why not?  Try it.  Mount the Seestar on an EQ wedge, polar aligned, turn off location services for the Seestar app and tell it that you're located at 90°N.

 

The EQ wedge cannot work in principle.



#5 Psion

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Posted 24 December 2023 - 07:23 AM

This is not how the principle of goto and alignment of the mount works. In addition, if you do not keep the Seestar level with the horizon, the application will not allow further work.



#6 GadgetX

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Posted 24 December 2023 - 07:32 AM

So how?  Did you mount the Seestar on an EQ wedge and set your location to 90°N?

Question of the day.  Not even a hint...

 

M



#7 kaicyung

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Posted 24 December 2023 - 08:39 AM

Happy holidays.

I want to follow up on what turned out to be a controversial post I wrote on Facebook last night on my attempt to eliminate field rotation noise from the Seestar output, and I am repeating it here.

 

Before I begin, let me profess that the Seestar is a fantastic smart telescope that enables anyone to enjoy the fun and beauty of astrophotography. If you like its simplicity as I do, and want to keep it that way, then read no further. Among the many AP rigs that I own, I seem to return to the S50 time and time again because it is so simple and the result is so satisfying.

 

I like to explore what is possible with such a portable and inexpensive system, in which it is becoming a gateway to the more involved world of  astrophotography and astrophysics. This is for my own enjoyment, and is not meant to force others to do the same.

 

I also enjoy tremendously what I thought was the most collaborative, generous and supportive group. People who do astrophotography are not in it for fame or money, for there is none in neither account.

I also am the type of person who likes challenges, where the exploration and discovery journey is more fun than the destination. So if I seem to leave you hanging and not itemize every step of my processes, it is because I thought there will be some of you who like to dig into this a little more and figure it out him/herself.

 

To summarize what I figured out last night, I found out the Seestar S50 is capable of running in the equatorial mode, with the existing software and hardware,  with no hacking that violates in any manner. I imaged the Horsehead Nebula for 140 minutes, collected a total of 546 frames. There is no field rotation in sequence, as evidenced by the video clip I produced via PixInsight:

 

https://photos.app.g...qdtF5PAFUY2HgY6

 

The result image, with simple background subtraction and stretching ( the edge noise is due to my quick and dirty polar alignment)

 

https://photos.app.g...5k2r5XEQ9gB3ULA

 

I used an old wedge that I had before, and verified its general use over 2 regions of the night sky (Capella and Horsehead).

 

There are some limitations imposed by the existing ZWO software, but they are trivial to fix.

 

There are some strain to the body of S50, as it need to be tilted the way any equatorially mounted system demands. However, I believe the integrity of the unit is sound and I won't hesitate to run the rig overnight.

 

I can give more details in a later post, but I want to let those who want to figure it out to try their hands on it first.

 

Again,

 

Happy Holidays.

 

Kai


Edited by kaicyung, 24 December 2023 - 09:24 AM.

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#8 Robert_E_630

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Posted 25 December 2023 - 02:03 PM

pics of equatorial wedge or it didnt happen



#9 kaicyung

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Posted 25 December 2023 - 04:31 PM

pics of equatorial wedge or it didnt happen

One better... a video to explain the setup...

 

 

 

https://www.facebook...mibextid=Nif5oz

 

 

 

You will see a pretty robust discussion there. If you don't use Facebook, the video can be found here:

 

 

 

https://photos.app.g...h8mcYZcbm2pses6

 

 

 

Merry Christmas.



#10 kaicyung

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Posted 25 December 2023 - 06:14 PM

Thank you, I'm not very convinced. You can see the rotation of the field of view in the your final image. The total exposure of the stacked images is 91 minutes, and the image is very noise and poor quality. Here is my photo of 69 minutes of exposure in AZ mode. I hope ZWO will do a mosaic after the New Year, and this will be resolved.

I intentionally left the image as unprocessed as possible to show the underlying SNR. Only background gradient was removed and applied a simple stretch. The edge noise is typical of EQ mount based integrated light frame, caused by imperfect polar alignment ( a rough 5 seconds polar alignment ) and S50's aggressive dithering algorithm.

The acquisition time is actually 140 minutes, with close to full moon. It averaged out to be around 4 frames per second. Getting the best quality data was not my aim that first night.

Edited by kaicyung, 25 December 2023 - 07:38 PM.

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#11 tarbat

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Posted 26 December 2023 - 04:32 AM

Why would you turn off the altitude gear? With the ALT-AZ Seestar mounted on an EQ wedge, all you're really doing is fooling the Seestar into thinking it's located at the north (or south) pole, where there is no field rotation on an ALT-AZ mount. It's still operating as an ALT-AZ mount, but once tracking an object the ALT gear should hardly move at all, depending how accurate your polar alignment was.

 

I think you need to turn off the Altitude gear, so set the location as the North Pole.



#12 thomasd1776

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Posted 26 December 2023 - 08:44 AM

Happy holidays.

I want to follow up on what turned out to be a controversial post I wrote on Facebook last night on my attempt to eliminate field rotation noise from the Seestar output, and I am repeating it here.

 

Before I begin, let me profess that the Seestar is a fantastic smart telescope that enables anyone to enjoy the fun and beauty of astrophotography. If you like its simplicity as I do, and want to keep it that way, then read no further. Among the many AP rigs that I own, I seem to return to the S50 time and time again because it is so simple and the result is so satisfying.

 

I like to explore what is possible with such a portable and inexpensive system, in which it is becoming a gateway to the more involved world of  astrophotography and astrophysics. This is for my own enjoyment, and is not meant to force others to do the same.

 

I also enjoy tremendously what I thought was the most collaborative, generous and supportive group. People who do astrophotography are not in it for fame or money, for there is none in neither account.

I also am the type of person who likes challenges, where the exploration and discovery journey is more fun than the destination. So if I seem to leave you hanging and not itemize every step of my processes, it is because I thought there will be some of you who like to dig into this a little more and figure it out him/herself.

 

To summarize what I figured out last night, I found out the Seestar S50 is capable of running in the equatorial mode, with the existing software and hardware,  with no hacking that violates in any manner. I imaged the Horsehead Nebula for 140 minutes, collected a total of 546 frames. There is no field rotation in sequence, as evidenced by the video clip I produced via PixInsight:

 

https://photos.app.g...qdtF5PAFUY2HgY6

 

The result image, with simple background subtraction and stretching ( the edge noise is due to my quick and dirty polar alignment)

 

https://photos.app.g...5k2r5XEQ9gB3ULA

 

I used an old wedge that I had before, and verified its general use over 2 regions of the night sky (Capella and Horsehead).

 

There are some limitations imposed by the existing ZWO software, but they are trivial to fix.

 

There are some strain to the body of S50, as it need to be tilted the way any equatorially mounted system demands. However, I believe the integrity of the unit is sound and I won't hesitate to run the rig overnight.

 

I can give more details in a later post, but I want to let those who want to figure it out to try their hands on it first.

 

Again,

 

Happy Holidays.

 

Kai

Thank you for posting this, especially in the face of so much negativity. I saw your post on Facebook and It is perplexing to me as to why something like this would be controversial, but indeed it is. In my opinion, that type of behavior stiffles creativity. I respect it when people push things to the limit and explore new possibilities. It seems like you have done what many said on Facebook was not possible.

 

I myself am interested in trying the Seestar in an equatorial setup but I remain concerned about strain on the gears and such. A lot of comments have been made on this issue, but I am not sure anyone knows anything other than that the Seestar has plastic gearing and was not designed to be in an eq setup. I have seen some photos of the internal components, but they have not given much insight into the design of the azimuth axis. I would be interested in knowing more about the Seestar's azimuth axis design.


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#13 kaicyung

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Posted 26 December 2023 - 10:54 AM

Thank you for posting this, especially in the face of so much negativity. I saw your post on Facebook and It is perplexing to me as to why something like this would be controversial, but indeed it is. In my opinion, that type of behavior stiffles creativity. I respect it when people push things to the limit and explore new possibilities. It seems like you have done what many said on Facebook was not possible.

 

I myself am interested in trying the Seestar in an equatorial setup but I remain concerned about strain on the gears and such. A lot of comments have been made on this issue, but I am not sure anyone knows anything other than that the Seestar has plastic gearing and was not designed to be in an eq setup. I have seen some photos of the internal components, but they have not given much insight into the design of the azimuth axis. I would be interested in knowing more about the Seestar's azimuth axis design.

Thank you for your comforting comments. I was quite shocked with some of the tones. Not the concerns about the stress, which I understand and appreciate, but from some who professed their expertise yet doubted what seemed to be a relatively simple mod. I am far from being an expert, so please be kind and enlighten me.

 

Seestar actually has electronic sensors to detect stalls in its motors, and I confirmed it in my earlier journey when I accidentally try to shut it down with my dew shield still attached. All is well.

 

I am actually in deep contact with a fellow modder who took apart the unit. He reported back on the mechanical integrity of the base motor and it's supporting infrastructure as follow:

 

The internal photos in the files of the group are pretty good at showing every component.  I don't think it is going to be a problem. The plastic gears might wear more quickly, but I'd expect it to last many hundreds of hours.  As light as it is, I don't think it would be a problem.  As for support, I have not closely examined the mating surfaces, but it's meant to be taken places and that requires a certain robustness in the design.


Edited by kaicyung, 26 December 2023 - 11:45 AM.

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#14 kaicyung

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Posted 26 December 2023 - 11:02 AM

Why would you turn off the altitude gear? With the ALT-AZ Seestar mounted on an EQ wedge, all you're really doing is fooling the Seestar into thinking it's located at the north (or south) pole, where there is no field rotation on an ALT-AZ mount. It's still operating as an ALT-AZ mount, but once tracking an object the ALT gear should hardly move at all, depending how accurate your polar alignment was.

I really don't know how this mis-information was deduced or formulated. My mod is just a simple change in the same spirit as mounts like the Az-GTI and many others. A perfectly polar aligned and mechanically perfect equatorial mount will never need to move the ALT gear once it has centered on the target of interest.


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#15 afeld38

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Posted 26 December 2023 - 12:25 PM

Hi Kai,

I am interested in trying this on my Seestar. However, it is not clear to me how you polar align. Usually the telescope is at a fixed home position, and you adjust the wedge to achieve polar alignment. With your modification, the finder scope is mounted on the telescope arm. What is the "home position" in the set up? Do you simply set the wedge to your latitude?

Thanks,

Alan



#16 jprideaux

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Posted 26 December 2023 - 12:25 PM

I'm following this discussion but I probably won't spend a lot of time investigating myself until all the steps to successfully make it work are shared.  

 

I do have a few questions.

  1. Will it be possible to make it work without any software changes by ZWO?
  2. Will it be possible to make it work without opening the chassis and making a DIY change to the internal hardware and/or circuit board.
  3. If making it work includes faking out the software to make it "think" the device is located at a different latitude on the planet (like the North Pole), will the GOTO still work if the software is faked out like that when you are not actually at that location?
  4. If there are concerns about strain on the motors and gears, has anyone tried to not do a polar alignment but the same strategy to only align the system perhaps half-way to the North axis?  Like splitting the difference between where you are an the North Pole?  Would that work? Would there be any benefit for reducing field rotation in doing that?   


#17 kaicyung

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Posted 26 December 2023 - 01:11 PM

Hi Kai,

I am interested in trying this on my Seestar. However, it is not clear to me how you polar align. Usually the telescope is at a fixed home position, and you adjust the wedge to achieve polar alignment. With your modification, the finder scope is mounted on the telescope arm. What is the "home position" in the set up? Do you simply set the wedge to your latitude?

Thanks,

Alan

The home position is with the lens arm fully pointing up if the base was on the ground, no different than a normal EQ mounted scope where the front is facing close to Polaris. You will get a warning that S50 will not let you point directly up as the internal software still thinks it is in Alt-Az mode, but it will be close enough for you to do rough polar alignment for now. 5-10 seconds exposures are very forgiving for such rough alignments. This is mainly a software limitations and and should be quickly remedied via a software change in this EQ mode.

 

Good luck and let me know if I can help.


Edited by kaicyung, 26 December 2023 - 01:12 PM.


#18 kaicyung

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Posted 26 December 2023 - 01:19 PM

 

I'm following this discussion but I probably won't spend a lot of time investigating myself until all the steps to successfully make it work are shared.  

 

I do have a few questions.

  1. Will it be possible to make it work without any software changes by ZWO?
  2. Will it be possible to make it work without opening the chassis and making a DIY change to the internal hardware and/or circuit board.
  3. If making it work includes faking out the software to make it "think" the device is located at a different latitude on the planet (like the North Pole), will the GOTO still work if the software is faked out like that when you are not actually at that location?
  4. If there are concerns about strain on the motors and gears, has anyone tried to not do a polar alignment but the same strategy to only align the system perhaps half-way to the North axis?  Like splitting the difference between where you are an the North Pole?  Would that work? Would there be any benefit for reducing field rotation in doing that?   

 

I did not do any software or hardware modifications! Just adding the edge and arranged the proper orientation.

 

This mode is enabled by my changes because Seestar's latest software and firmware now uses 3 point calibration routine to determine it's orientation as a first choice, with leveling as a fall back. 

 

As I commented above, the modder that I have been in contact with who pry open the unit gave his assessment to the mechanical and structural integrity of the unit. We will investigate further on this as I fully understand people's concerns on this one. For me, after.trying it out over 2 nights, I am at peace and can sleep during the acquisition session. The optical arm is light and the moment of inertia is small. The base of the unit seems well built and sturdy.

 

Again, proceed with your own judgement.

 

There's so much inquiries into this setup that I should probably have a followup video describing the operation and theory behind it. I thought it was pretty obvious.


Edited by kaicyung, 26 December 2023 - 01:21 PM.


#19 tarbat

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Posted 26 December 2023 - 01:25 PM

You will get a warning that S50 will not let you point directly up as the internal software still thinks it is in Alt-Az mode, but it will be close enough for you to do rough polar alignment for now.

Have you tried using Sky Safari to control the Seestar to get it to go beyond the limit imposed by the internal software?  In Sky Safari, connect to the Seestar over WiFi, defined as an Alt-Az goto Meade LX200 Classic.



#20 jprideaux

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Posted 26 December 2023 - 01:30 PM

I did not do any software or hardware modifications! Just adding the edge and arranged the proper orientation.

 

This mode is enabled by my changes because Seestar's latest software and firmware now uses 3 point calibration routine to determine it's orientation as a first choice, with leveling as a fall back. 

 

As I commented above, the modder that I have been in contact with who pry open the unit gave his assessment to the mechanical and structural integrity of the unit. We will investigate further on this as I fully understand people's concerns on this one. For me, after.trying it out over 2 nights, I am at peace and can sleep during the acquisition session. The optical arm is light and the moment of inertia is small. The base of the unit seems well built and sturdy.

 

Again, proceed with your own judgement.

 

There's so much inquiries into this setup that I should probably have a followup video describing the operation and theory behind it. I thought it was pretty obvious.

 

Thanks.  So with the recent change to first try a 3-star alignments, does it not need to know (for this step) the actual GPS coordinates for where the telescope is located so there is no user "faking out" needed (like manually entering different GPS coordinates)?  So is it just a matter of devising a way to do a near polar alignment and any changes you made were just to facilitate that near-polar pointing and then the existing software successfully oriented itself to the sky as long as the 3-star step passed and it did not have to fall-back to the alternative orientation step that is reliant on it being level?



#21 kaicyung

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Posted 26 December 2023 - 01:51 PM

Have you tried using Sky Safari to control the Seestar to get it to go beyond the limit imposed by the internal software?  In Sky Safari, connect to the Seestar over WiFi, defined as an Alt-Az goto Meade LX200 Classic.

I don't use sky safari. Instead, I was going to use Nina and configure it to control Seestar via its LX200 protocol. Have not started yet but I don't foresee much issues. I am actually more excited to see if Nina can treat it like a true EQ mount and performs its own 3 point polar alignment. It really all depends how much Seestar 's firmware implemented the LX200 protocol.

 

Anyone wants to give it a shot first?


Edited by kaicyung, 26 December 2023 - 02:22 PM.

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#22 kaicyung

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Posted 26 December 2023 - 01:52 PM

Thanks.  So with the recent change to first try a 3-star alignments, does it not need to know (for this step) the actual GPS coordinates for where the telescope is located so there is no user "faking out" needed (like manually entering different GPS coordinates)?  So is it just a matter of devising a way to do a near polar alignment and any changes you made were just to facilitate that near-polar pointing and then the existing software successfully oriented itself to the sky as long as the 3-star step passed and it did not have to fall-back to the alternative orientation step that is reliant on it being level?

Bingo!


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#23 smiller

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Posted 30 December 2023 - 12:19 PM

Wow, amazing result!!   
 

Obviously ZWO didn’t design the SeeStar to do this, so I expect risk of additional stress due to the scope’s weight now pushing on the Az drive system at an angle instead of straight down.

 

I think the big implication is, like the Dwarf II and classic SCTs that can use a wedge, ZWO could design a future SeeStar to ensure it is robust operating at an angle and support this with SW/FW to be a normal and automatic operating mode.

 

Also note that for targets high in the sky where field rotation is the worst, field rotation drops dramatically even with modest tilts of the telescope away from Zenith.  So even if ZWO in the future (or current ZWO users today doing what kaicyung is doing) only tilt by a more modest 15-20 degrees with less risk to the scope, you can reduce field rotation significantly.   However, you may want to wait until many people are doing this regularly and demonstrating no long term issues with the scope.

 

I do this with my huge Alt/Az Goto 12” Dobsonian which is clearly not meant to be on a wedge!  I just put it on a piece of plywood that is propped up about 7-10 degrees away from the target, tell the controller I’m 7-10 degrees more North (for southerly targets) or more South (for northerly targets) and the two star alignment works perfectly, the system is fooled that I’m operating at a different latitude on the planet and it finds and tracks targets as normal, yet field rotation is reduced.  I limit it to about 10 degrees for fear of stressing the system, plus a Dob will literally just tip over if I try it more.

 

 It’s simple math: Tilting the scope is exactly the same thing as operating the scope at a different location on the planet.

 

Very interesting to see people taking advantage of this.  Perhaps ZWO will find a way to support something Iike this officially… either now with a more modest tilt, or with a future product.   It’s a zero (or very low) cost way to eliminate field rotation.


Edited by smiller, 30 December 2023 - 06:40 PM.

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#24 kaicyung

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Posted 30 December 2023 - 02:01 PM

Thanks. This series of posts in Facebook got me realized how much misunderstanding there are around this smart telescope. I decided to start a YouTube channel specifically to discuss the finer points of Seestar. First 2 videos are uploaded and I expect many more short and concise clips to follow:

 

https://youtu.be/4L_tbcIbDZw


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#25 kaicyung

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Posted 31 December 2023 - 10:20 PM

I will be giving a talk at TAIC on this and other topics. Please join me:

 

https://youtube.com/...o?feature=share

 

Happy New Year.

 

Kai


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