Although I'm satisfied (despite the fringe) with outbreaks of a partially visible moon with a cheap 500mm lens:
1/100 iso 100 f /?
I can not understand why the IQ is very diminished when the same thing is done with a moon that is almost totally visible:
1/80 iso 100 f /?
I guess that totally visible is much brighter and when I try to compensate the situation by changing the aperture, this effect appears.
Is there an obvious explanation or do I just spoil the approach every time?