Dithering issues

[Joeistotalycool]

I was reviewing my data I captured last night on M106 and the tiff produced has lots of vertical bands through it. I think it was because I had RA only dithering enabled, but I just want to make sure. I was using a canon 1200d (modded), 10min RGB subs. PHD2, Dither scale of 3 on random mode, With the RA only box checked 

[wimvb]

Was your camera RA-aligned (long edge aligned with RA direction)? Dithering in one direction only will create walking noise in that direction. Your image looks like that. Even if the dithering is randomly moving the mount along the RA axis, adding the subs will still create the pattern. Simply because addition can be done in any order, so your subs might just as well be ordered to show a steady RA drift.

Carefull calibration can reduce the pattern.

http://pixinsight.com.ar/en/info/processing-examples/19/crux-southern-cross.html