Sometimes (rarely) I see that the noise model during 3D refinment that is flat (left below)
I have seen this on 3 of around >150 data sets or so. These examples images above are both for sub 3A unbinned data sets.
For one case the raw movies were redone and particles reimported and the noise variance returned to ascending as a function of resolution similar to what is seen right above.
I was curious as to 1) why this is, 2) how might one overcome these issues when they arise and 3) any further or deeper insights anyone might have.