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Jeff,
For dithering to be effective in reducing fixed pattern noise , the movement of each frame should generally be in a random or spiral pattern of pixels up to a certain amount , usually calculated from a ratio and multiplier between the image scale between your imaging camera and guide camera ( generally movement of frames are not in a direct horizontal or vertical pattern )
I don’t know if you can successfully dither without a software designed program as the dither function and movement is not guess work , there are sophisticated algorithms involved to enable it to be effective.
Just remember guiding can be “wild” or poor one night and fantastic the next
My guiding numbers on Saturday night were 0.65 to 0.75 arc sec total and last night were 1.15 to 1.35 arc sec total ( huge difference) same set up and both nights clear , no cloud
If your using PHD2 guiding ,I recommend you post your guide logs to the forum so they can be analysed.As your probably aware when guiding goes a bit haywire it can be attributed to -
Periodic error ( mechanical )
Mount Balance
Cable snags
Wind
Cloud
Atmospheric turbulence
Humidity and Dew
Altitude
Flexure
Guiding set up and parameters
Vibration
And so on ......
Not an easy fix but can be evaluated in time
Cheers
Martin
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