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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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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
The following user(s) said Thank You: Jose Corazon
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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No worries, alles gut! Using the scheduler doesn't make sense yet in my case as most of the time I drive 100km to a dark place where there is nothing else to do other than to watch my equipment taking pictures. Things like aiming at a new target, re-focusing and such are very welcome things to do. This might change once I have a bed or proper internet connection though.

I would *assume* that re-calibrating after *every* slew during a scheduler session would not increase the total number of re-calibrations very much (compared to the 1+2 solution), if at all.
4 years 4 months ago #46130

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The intent is that this only comes into play when the box "Always reset guide calibration" is selected. There were cases where this did not happen, although the box was ticked and that would result in the following exposure sequence showing star trails.
So as long as you do not tick that box, nothing should change for you. If you tick the box, recalibration would occur every time the mount slews.

I also need to come back to Wouter's point, though: Would dithering trigger recalibration then, i.e. is dithering handled by the mount the same way slewing is? Intuitively I would say not, because dithering only involves guide pulses, which happen all the time during guiding anyway, so of that were to trigger recalibration, it would effectively start an endless loop. But I want to make sure that this does not become an unintended consequence.

Thanks so much, Wolfgang, for restoring this option.
4 years 4 months ago #46133

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I'd second the question what happens for people using PHD2. Does that setting have any influence? Does EKOS send any info to PHD2 regarding a flip of coordinates?

Also, what about people with a mount that doesn't report pier side? How do you detect a flip there?
4 years 4 months ago #46135

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AFAIK Ekos doesn't need to send any mount information to PHD2 because it will read it from the camera and mount specified in PHD. That covers the pier side, declination, guide focal length, guide camera and pixel size. It should have all it needs to be able to do a good calibration and allow for changes in pier side and declination so it shouldn't need to keep doing calibrations. The Ekos guide controller can force addional calibrations but they may not be needed.

I'm not sure how PHD handles a pier side change on a mount driver that doesn't report the pier side. The way I'd resolve that is get a driver that does report the pier side, even if I had to write it myself. Reading the PHD help could give an answer, there are a number of ways that they could implement this. At worst redoing the calibration after every slew.

Dither is handled by the guide application offseting the guide star position and using the normal guide commands to drive the guide star to the new position. My guide system has a pixel size of 1.68 arc seconds so a 2 pixel dither will need a little under 0.5 seconds of guiding at 50% rate. For PHD Ekos will send a dither command at a time of it's choosing and will then wait until it's guide accuracy criteria have been reached.
4 years 4 months ago #46137

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Yes, meridian flip worked nicely with my (eqmod-driven) GP-DX. The CEM60 driver doesn't work in that respect, because there's no pir side info. Not because the driver doesn't relay that info, but because you cannot get it from the mount. It just doesn't report that info :( Therefore I asked if there's any communication implemented to actually signal PHD2 to flip the calibration. But I think the is none.
4 years 4 months ago #46139

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Hi
I think it important that whatever change which is made to the EKOS guider, leaves the PHD2 behaviour exactly as it is.
Thanks.
4 years 4 months ago #46140

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