I checked carefully last night PA with SC and IPolar and did some tests.
IPolar mounted inside Cem25P with no adapter. Calibrate more times, checked in every RA mount position (and obviously while i was rotating RA it slightly changed PA precision), changed gain up to 7X (at gain 0 just polar star can be seen).
SC: did a multi polar alignment routine. I checked PA from east to west through 15° step: as always happened, PA on east side is quite different from west side at about >1'...
I carefully polar aligned with SC (excellent: <30") in one position: IPolar way out of alignment (red circle outside of the edges of red cross).
I carefully polar aligned with IPolar (the red circle perfectly matched the red cross): SC says more or less 2.5-3' PA misalignemnt...
Who says the truth?
I took some 2 min shots with the above 2 different PA methods: the shots taken after PA with SC are little little slightly elongated than those one taken with IPolar (but only when viewed at 100%)..
I have this idea: IPolar is mounted inside the RA axis, while SC did a PA with main scope and camera. So IPolar seems to be more solid and united with the mount: so it should be better to indicate the right PA than SC.
Any idea or tests?