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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

What means always for resetting guiding calibration

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Why are so many calibrations needed?

The correction for declination should be able to be calculated.
The correction for pier side can be determined by doing calibrations on both sides of the pier and once the effect of a pier side change has been determined this can be applied to future calibrations. It should be no more than reversing the Ra correction direction, the Dec correction direction, or both.

Even for a portable set up all that should be needed is a calibration at the start of the evening to determine the camera rotation.
4 years 4 months ago #46098

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I agree, in theory. However, in practice guiding often breaks down after switching to another target. I think that might have to do at least partly with changes in weight distribution, inherent frictions in the mount and cable drag. Those parameters cannot be calculated. Recalibrating in that case restores guiding accuracy.

I also don't know how difficult your solution would be to implement given the current code. Wolfgang would be able to weigh in on that.

In the end I don't care one way or the other, as long as guiding works reliably, reproducibly and accurately and there is a way to fix it, short of rebooting everything, if it goes awry.
Last edit: 4 years 4 months ago by Jose Corazon.
4 years 4 months ago #46099

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Why should I re-calibrate once declination has changed? As far as I understand it, during calibration the orientation of the camera is being detected. Unless the camera has moved there shouldn't be any reason to do it again, no?

Whoops! Your messages were posted while I was typing mine.
Last edit: 4 years 4 months ago by Alfred.
4 years 4 months ago #46100

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Just a small clarification: my question was, what is expected if the option was selected and not whether this behaviour should be mandatory.

I personally have very good experience in the combination of EKOS and PHD2 and never had problems with calibrations once calculated. I even re-use calibrations over several nights as long as I am sure that I did not rotate the camera and changed the scope.

But there are several out there that need such re-calibrations. And for those, I would like to set the option such that it makes most sense for them.
4 years 4 months ago #46104

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Hello folks,
I implemented option 2 - which was quite easy. You can test it here .

Thanks for your quick response!

Wolfgang
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4 years 4 months ago #46114

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You're right, back to the task at hand. My thoughts:

1) "What is expected"? Well, "always" is pretty clear. The normal expectation would be 3.
2) Would that be reasonable and helpful though? No. I agree with Wouter and Jo, 1+2 would be the proper solution. And "always" should be changed to something that doesn't raise wrong expectations. But then,
3) since I would never use this option, don't pay much attention to my opinion.

P.S.: "2 only" is good enough! IMO it doesn't make sense to put that much effort into implementing something that I deem a negligible detail.
Last edit: 4 years 4 months ago by Alfred.
4 years 4 months ago #46115

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With all due respect, it is not a negligible detail if your imaging is dependent upon the scheduler. I agree, if you sit next to your scope, or rather are awake to control the flip and can manually erase the calibration and restart it if necessary, then this becomes a negligible detail. But for those of us who are putting the scope out in the backyard and letting it acquire images fully automatically, it really is an essential feature.

Thanks Wolfgang for putting in the effort! Will test as soon as there is a clear night again.

Jo
Last edit: 4 years 4 months ago by Jose Corazon.
4 years 4 months ago #46121

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Point taken, Jo! It was just a negligible comment from some guy who does neither use the scheduler nor re-calibrate at all, thus doesn't have a clue! :-)

Out of curiosity... if you scheduled a movement in declination once the meridian has been crossed, let's say by pointing the scope to a nearby star and immediately returning to the object, wouldn't that achieve the same?
4 years 4 months ago #46123

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Ahhh..., Alfred, thanks for bringing that up!

That is precisely the difference between imaging from the middle of Frankfurt and the middle of Dallas....

...well, not really...

But in good old American, I would say 'that's a klutz!'

Which loosely translated into German means something like '' ' ne Kruecke hoch 3".

Here at Indi, we strive for PERFECTION!

Nothing less will do.

That's why nitpickers like me are tolerated here.

I wonder for how much longer...

:-)

Anyway, it really will help a lot if you are using the scheduler to fully automate your imaging sessions. That is my main objective here.

Herzliche Gruesse und nimm's mir nicht uebel,

:-)

Joachim
Last edit: 4 years 4 months ago by Jose Corazon.
4 years 4 months ago #46124

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Sorry, I have to admit that I ended up with option 3, i.e. each slew clears the calibration. This is more or less one line of code.

Implementing 1 and 2 turned out to be more complicated, since there are several ways in KStars to slew to a new target and not all are handled the same way.

But during my tests it seems that option 3 isn't that bad, since in a typical workflow slew --> align --> guide it does not matter whether you clear only once or additionally during alignment, since no new calibration has taken place.

OK for you or are there situations where this could be disturbing?
-- Wolfgang
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4 years 4 months ago #46125

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That sounds like a great solution to me Wolfgang. One question: would this be affected by dithering? I am not sure how this is implemented but if no slew is involved and only pulses to the mount to offset it then I guess this is a great solution since it covers cases 1 and 2 as well.

FYI I only use the internal guider, not PHD2. Unfortunately the weather here in Spain is very bad at the moment so I am afraid there is no way for me to test this, sorry.


Wouter
4 years 4 months ago #46126

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Hi Wolgang, everyone
Does this affect those of us who guide only with PHD2 in any way?
Here's hoping negative!
Cheers and clear skies to all.
4 years 4 months ago #46127

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