dithering with ASiairPlus

[pmrid (Peter)]

I ran multiple sessions on the same target last night NGC5139. As an experiment, I wanted to see what might be causing blue halos on brighter stars by using no filter then a ZWO IRCut filter. I was doing 3 minute subs for all. At the end, I had some time before moonrise so for the hell of it, I decided to run some subs of M83. But I decided to run 10 minute subs instead of 3.

Dithering remained set at 1 pixel every 3 subs.

Trouble was, ASiair kept dithering at 3 minute intervals instead of 10. Most subs of M83 were ruined.

Just a note of caution for those who dither.

[ronson]

Hi Peter,

Sorry to hear you are having issues with the dithering. I use AA+ and dither regularly. Haven't had any issues, nor have I read someone having similar issue on CN or Stargazers Lounge, unless it’s a very new one. AA will wait until the image acquisition is completed, then dither, then wait for the tracking/guiding to settle and start the next image. If your AA starts dithering while still taking the image, then something is wrong.

FYI I use 5 pixels dithering to account for the guide scope to main scope imaging px resolution ratio and usually dither after each image.

Restarting and resetting to factory defaults might be some steps to try and solve the issues. If it's a bug and you can reproduce it, please let ZWO support know, so they can investigate and fix it.

[pmrid (Peter)]

I am red-faced this morning after a night trying to figure this out. It looks like it was not dithering out of sequence that was the source of the problem. It was me. I had not tightened up the reducer on the scope so it was susceptible to a small wobble. Mea culpa.