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Daft question. probably.


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Ok so I am getting started with guided imaging, trying to get all my gear dialled in and get up to speed with N.I.N.A ready for when the nights really start to draw in. I have had some problems with PHD, sorted now hopefully, but this question did pop into my mind the other day./

When you are using a guide scope and PHD does that correct the mount tracking or replace the mount tracking, ie do you rely only on the pulses from PHD or do you run the mounts tracking as well?

I feel like this is a dumb question and the answer is that the guiding just improves on the mount and corrects any errors but, I figured I would ask it anyway. be gentle!

Ed.

 

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1 hour ago, irtuk said:

Ok so I am getting started with guided imaging, trying to get all my gear dialled in and get up to speed with N.I.N.A ready for when the nights really start to draw in. I have had some problems with PHD, sorted now hopefully, but this question did pop into my mind the other day./

When you are using a guide scope and PHD does that correct the mount tracking or replace the mount tracking, ie do you rely only on the pulses from PHD or do you run the mounts tracking as well?

I feel like this is a dumb question and the answer is that the guiding just improves on the mount and corrects any errors but, I figured I would ask it anyway. be gentle!

Ed.

 

There are no stupid questions!

Phd2 sends corrections to improve the mount's tracking.

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When I look at the source code for my Linux INDI driver.  I see the tracking sending adjustments to the mount.  When guiding is enabled, a correction received from the guiding software is added to or subtracted from each tracking adjustment.  The total adjustment (corrected) is then sent to the mount.  I have not seen the ASCOM code, but given that my comparison of the PHD2 graphs for ASCOM and INDI are virtually identical, I'd say ASCOM does the same thing. 

I did a night of Windows software control with ASCOM when I bought my iOptron mount to verify that the Linux INDI driver for the mount gave the same result as the iOptron-provided ASCOM driver.  Overall, both drivers were more or less the same, with the exception of how the Meridian Flip was performed.  But, I set it up so the mount firmware performed the flip and told the driver software to mind its own business, so differences between INDI and ASCOM didn't apply for the only difference I was able to find.

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21 hours ago, irtuk said:

Ok so I am getting started with guided imaging, trying to get all my gear dialled in and get up to speed with N.I.N.A ready for when the nights really start to draw in. I have had some problems with PHD, sorted now hopefully, but this question did pop into my mind the other day./

When you are using a guide scope and PHD does that correct the mount tracking or replace the mount tracking, ie do you rely only on the pulses from PHD or do you run the mounts tracking as well?

I feel like this is a dumb question and the answer is that the guiding just improves on the mount and corrects any errors but, I figured I would ask it anyway. be gentle!

Ed.

 

 

No such thing as a dumb question Ed,

Hopefully Jon's post above hasn't confused you... (did me :) , very in depth reply !)

PHD2 doesn't control the mount directly.  In an imaging set up the mount control is typically done via EQMOD or GSServer on windows, or Ekos on Linux. These applications receive the co-ordinates of the target  from whatever planetarium application you use to position the scope on that target, and then it begins to track it at sidereal rate.  Now in an ideal world there would be no backlash in a mounts drive system, and polar alignment would be precise with no errors, and the scope would be perfectly aligned with the mount without any cone error.  But in reality these things creep in and can affect the end results when imaging. PHD basically monitors the effects of these errors and corrects for them by effectively giving the mount a small nudge in which ever direction is required to compensate for the error and keep the mount on as near perfectly track as possible.  It does this by sending the small corrections to the application that controls the mount (eg EQMOD) which then applies the correction by sending instructions to speed up or slow down the tracking rate, or moves the DEC axis accordingly.

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2 hours ago, malc-c said:

Ekos on Linux

You mention EQMOD on Windows and EKOS on Linux as if they were the same thing!

If you use EQMOD in Windows, you'll use EQMOD on Linux.

Let's hope this hasn't removed the simplicity of the answer to the (I think excellent) question:

On 19/09/2021 at 15:20, irtuk said:

do you run the mounts tracking as well?

Yes.

Cheers and HTH.

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1 hour ago, alacant said:

You mention EQMOD on Windows and EKOS on Linux as if they were the same thing!

If you use EQMOD in Windows, you'll use EQMOD on Linux.

Let's hope this hasn't removed the simplicity of the answer to the (I think excellent) question:

 

You know some people can't win... If I had left out any reference to Linux you would have jumped on me for suggesting Windows was the ONLY platform. !!!  

If you read the EQASCOM prerequisites http://eq-mod.sourceforge.net/prerequisites.html it states "A PC running windows" - It makes no reference to frigging LINUX.... so why would I suggest otherwise. 

I get the feeling that you have something personal towards my postings and take some pride in always trying to "correct" things....

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4 minutes ago, malc-c said:

I get the feeling that you have something personal towards my postings and take some pride in always trying to "correct" things....

I had to use the ignore function, certainly helps 👍🏼😎

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1 minute ago, alacant said:

 Just trying to avoid any confusion for any future readers of the thread:)

Cheers

What by saying EQMOD is linux based when the prerequisites page makes no reference to such things.... that leads to confusion ! 

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Gents, let’s keep this cool, calm and courteous please, and remember the CoC for language etc.

All we are trying to do is help the OP, not prove points to each other.

Many thanks,

Stu

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