5: Update, a tips how to see that there is a polar align error
that has been a mystery for me. When I use CdC to lock on an object, I lock and center CdC to M13 in this example.
CdC is setup to report back coordinates from EQMOD. After a while the telescope pointing starts to drift away.
Patrick who develop CdC (Skychart) give me an explanation why it behave like this.
It's because of bad polar align.
PHD guide the telescope to keep it centered on the object but because of bad polar align it doesn't follow
the RA and DEC coordinates and that's the coordinates it reports to CdC.
We get an drift as in the image below.
This is how it could look, after about one hour and an error of polar align of about 10' or more.
The inner circle is telescope pointing, and as you see the M13 is not anymore centered in the
telescope (but it's centered in the camera because of auto guiding).
That's an indication that you maybe have to improve your polar align.
Thanks Patrick for this explanation! Maybe obvious for others but not to me until now.