@geehalel thank you SO MUCH for your work. Indeed, having a driver available to track correctly to be able to plate solve as a quick sync technique would be amazing. Let me know whenever there is something to test. All my very best and again, thank you. Federico
@geehalel: regarding your question of the field rotation axis: I guess as long as the axis of the mount and the guide scope are parallel, the center of the rotation axis should be the center of the sensor, i.e. the distance between mount axis and guide scope axis is far too small to cause any parallax as the points projected on the sensor are at infinity. Things should become more complicated, once both axes are not (perfectly) aligned: in the extreme case of the guide scope axis being perpendicular to the mount axis, there is no more rotation, only translation. In between there should be a mix between rotation and translation, i.e. the center of rotation is moved away from the center of the sensor. My understanding is, that the deviation introduced by such misalignment is what is coined "cone error". Maybe you find some hints in the logic regarding cone error correction to model this; there should also be some literature where this is being described / worked out.
Does this makes sense ?
on second thought: as long as both axes are not perfectly aligned, the center of rotation moves rapidly away from the center of the sensor: let´s assume we have a 1.5 degree fov with our guide scope. If the alignment error between mount and guide scope axis is more than 0.75 degrees, the center of rotation is already off the sensor. I think you can calculate the center of rotation by calculating the fov of your guide scope / sensor combination and substract the deviation angle of the scope axis and mount axis in degrees. How many pixels this equates to, you can derive from the fov calculation. The direction of the deviation should be the opposite of the axis deviation in relation to the sensor orientation.
This is without guarantee. Just my understanding.
on a third thought: I probably should have rather asked you, what you are aiming at. With my hints above, I was in "equatorial mode". In Alt-Az there is no rotational axis of the rig itself. If you want to derotate the exposures made on an alt-az mount, I think the way to go is by star pattern alignment, i.e. agnostic of any mechanical rotation calculation.