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Question Adjusting torque on the Linear

  • Guillaume
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23 Jun 2020 09:18 - 05 Aug 2020 06:27 #330 by Guillaume
Dear,

I'd like to know who to determine the best torque value.
I was perfectly running with a small T150 and 70% torque (about 8kg).
Now I have a T250 and about 16kg. Well balanced, the mount does not have any issue pointing in any directions but my guiding is not so good (I may have a lot of things to improve).
I'm guiding with an OAG at 1000mm focal lengh.
I was asking myself :
- Does the torque need to be increased ?
- Does tracking adjustment will help me ? (didn't find explanation about how to chose de value)
Last edit: 05 Aug 2020 06:27 by Guillaume.

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  • Stefano82
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24 Jun 2020 11:44 #331 by Stefano82
Replied by Stefano82 on topic Adjusting torque on the Linear
Dear Guillaume

Increasing the Torque value beyond the limit indicated at page 32 of the StarGo User Manual, doesn’t improve the tracking and may stress the motors, so this operation it is not suggested.

If a good balancing has been performed, check the focal length ratio between the main telescope and the guide telescope.

In order to achieve a good tracking, the guide telescope focal length should not be too short compared to the main telescope focal length.

Please, to better understand how to help you improve the tracking, let us know your main telescope focal length.

If the mount is well balanced and the focal length between the two scopes have the proper ratio, the tracking adjust may help you. You can find the explanation of this tool at page 28 of the StarGo User Manual, it could be also helpful to read the following topic:

www.avalon-instruments.com/forum/welcome...-tracking-adjust#189

Feel free to ask for any further information

Kind regards

Stefano
Avalon Instruments Team

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  • Guillaume
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25 Jun 2020 08:04 #335 by Guillaume
Replied by Guillaume on topic Adjusting torque on the Linear
Dear Stefano,

Thanks for the reply.
I guide with an OAG so focal lenght equal imaging focal: 1000mm.
My sampling is a bit more precise en guiding because I use a 2.9um/pix sensor for guiding and a 3.8um/pix for imaging.

I'll carefully read the manual. Thanks.

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25 Jun 2020 21:49 #336 by ken.self
Replied by ken.self on topic Adjusting torque on the Linear
When you say your guiding is not good, can you be more specific?

-- Ken
Avalon M-Uno; GSO RC8; ASI1600; Optec focuser; Aaeon UP/Ubuntu/INDI

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  • Guillaume
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05 Aug 2020 06:25 #355 by Guillaume
Replied by Guillaume on topic Adjusting torque on the Linear
My guiding is between 0.6" and 1" RMS with large peaks sometimes 2" away.
This was not an issue with my old setup which had 1.38"/pix sampling but is an issue now with my new setup which has 0.7"/pix sampling.

It may be related to the OAG which has a substantial higher definition now compared to before and may be way more sensitive to seeing.

Someone had good result with zfilter algo inside PHD2 (the only time I tried was catastrophic so I went back to lowpass2.

Note: I use the parameters recommended by Avalon with an OAG 1000mm focal length.

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07 Aug 2020 09:32 #366 by Michel
Replied by Michel on topic Adjusting torque on the Linear

Guillaume wrote: My guiding is between 0.6" and 1" RMS with large peaks sometimes 2" away.
This was not an issue with my old setup which had 1.38"/pix sampling but is an issue now with my new setup which has 0.7"/pix sampling.

It may be related to the OAG which has a substantial higher definition now compared to before and may be way more sensitive to seeing.

Someone had good result with zfilter algo inside PHD2 (the only time I tried was catastrophic so I went back to lowpass2.

Note: I use the parameters recommended by Avalon with an OAG 1000mm focal length.


I have a similar setup but my focal length is 1500mm and my scale is 0.5. While i never got it stable at 0.5, and usually it is between 0.5 and 1 when it comes to guiding, i never had a problem with the stars being round. My guide camera has a 2.9um pixel size, but i use bin 2x2 in phd2, and I use the subframe option (i noticed that even if i set it to 1.5s exposure time, it takes longer to come in).

On the avalon I use 0.2 for both dec and ra, and the rest similar to Avalon's recommendation of phd2. Although sometimes I set the dec minmo higher, to reduce the unnecessary corrections. I also set in the stargo the RA compensation (forgot the exact name) to -50, which I found best for my setup. Let the auto thing run for a bit and find your value.

That being said, poor seeing or wind can impact my guiding a lot. I end up tuning the parameters in phd2 slightly and I got it under control most of the times.

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