Hey there!

This is a recap of last nights session with KStars.
It also was my first night with the Moravian G2 8300 color cam.

So for the beginning: Everything (almost) worked like a charm
It´s just... the results are... useless...

So what i did is was a session on the wizard-nebula.
From the beginning i started to solve both cams (guiding cam ASI 120 and the G2) in park position to make sure "they know where they are" AND to test Platesolving.
I knew it worked great outdoors, but since i found out that its a difference to run on mac remotely or to work on my linux notebook direct, it was the first time i was trying to solve on the mac. No problems, solved in seconds. Thats mostly because i now wrote to the main scope 1100mm instead of 1000mm like in the Tipps i got here in the forum. Thanx for that.
After that i went to capella for focusing, solved in the second iteration, great! Thats really fun!
Then i went for the wizard nebula, solved on third iteration, GREAT too, because i rember solving action taking minutes before
Set up guiding,dithering, cooling main cam, start when -10° is received just EVERYTHING was working flawless.
The guiding graph did not exceed 1arcsec, thought that looks good for me...

BUT: As you see, none of the pictures is usable, because of lines instead of stars....

And i consider that the problem of the guiding has something to do with dithering... Because almost EVERY Dither-iteration endet with a dithering-error.
You can see that on the screenshots. I took lots of screenshots because i thought its running so flawless, something must be wrong

I have all the stuff attached, and also the logfile for that session. Had to cut out the second half of the log, because it was too big for the forum with 33mb...

As you can see on the last picture, the stars became more and more out of control the later it got.

So please guys, tell me what the fault could be. Any suggestion will help!

cheers
Niki

I can feel your pain. Were you able to relate which crunched captured frame corresponds to which section of the log?

-Eric

Oh its not as bad Eric

I dic not take the time to exactly control which picture corresponds to which part of the log. I know that the first pic is the best and that its getting worse, the longer it takes. I thought maybe some of you guys have a fast idea by checking the screenshots. If not so, i‘m going check that more accurate. But would it help?


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Fast idea: do it again without dithering

-Eric

I will. The thing is that i can not see what was wrong with dithering...


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Neither do I. Dithering should have zero impact while capturing, hence my question about relating captured frames and log sections (to see whether there is overlap).
If your guiding is perfect *during each whole capture*, then you might (might) have a big flexture issue, or you might have a big difference between your CCD resolutions that makes guiding inefficient, but all this sounds unlikely. Last frame is even either tracking off or tripod hit... My opinion is that we should better apprehend the problem if guiding is constant, and to guide permanently, you need to remove dithering from the equation.

-Eric

So that is what i‘ll do next session.




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Well, you had quite a few dithering failures. Does tracking continues but autoguiding stops? re-acquire? re-aquire on a hot pixel - use darks. I guess I would sit with it and watch how it handles each frame (shorter ones) and dithering. not sure if settling is required in options. I think it automatically settles the dither before taking the next pic - maybe measure the amount of time to offload the image to disk and set this time in the settle option.

How would i know if autoguiding stops and tracking continous? And why should tracking NOT continou? What does re-acquire mean? My english is not so good, sorry?

What is interesting maybe is, that the egg-form of the stars always points in the same direction. And in the bginning, i recognized that the "guiding marks" where all left of the center.

Those are good questions, that's why I say you'd have to watch the progress while imaging. Maybe the logs will say but watching its behaviour and checking is very helpful. I actually found a problem when I heard the scope making weird noises - not in the logs -lol. When it says dithering failed, then I imagine its no longer guiding or it has to re-aquire the guide star - i.e. find a new guide star and start tracking it. If you do not use darks with your guide cam, its easy for the guider to lock on to a hot pixel and you will have no guiding.

Also, look for possibility of guiding being interfered by the image download which can take a lot of time, causing the guider to stall for a while, maybe even lose the guide star.

OK. Good points you are talking bout.

Especially the camera download time could be the key, since it was the first time i used the g2 cam.
And what i know bout it now is that it takes some time to get the pictures from the cam.
Last time i was using guiding via kstars, it was my dslr. there is not such a long download-time.

I´ll definetly have a look on that.

Atm testruns with guiding, without dithering. Funny that, on an object very deep near horizon in the south, my guiding hits run out of the cross to the right. Same setup working good on cassiopaia region. How come? Suggestions? Weighting problems? I even had a failure when calibrating...

Taking testshots atm on hpersei

Cheers, Niki


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