Do we have quantitative testing or theory to base these frequencies on?
To use Jon's example of stacking 100 frames and dithering every 2, that will give 50 dither positions, which to my mind is certainly more than adequate to spot a statistical outlier. I would have thought far fewer (perhaps 20) would also be more than enough, ie dithering every 5, however this isnt based on anything empirical, just a feeling for how many samples it should take to establish what is an outlier.
Of course if theres no real penalty to dithering (Quick) then makes sense to do it a lot and I would support that.
I would have thought a rule of thumb like 50 dither positions throughout the stack would be a better way of stating the required frequency, as sub exposure times and number vary greatly between projects and individuals.
EDIT: of course, what I have been neglecting above, is that this is done millions of times for every image, so while 20 might work a lot of the time, there will still be many pixels in the stack where flukes occur and having a much better range of samples will help, so in fact 50 does sound like a much more sensible number than 20.
Edited by happylimpet, 15 August 2019 - 05:50 AM.