Forgive my understanding on this but I thought I would share my experience I have with centering. I have celestron CGEM-DX mount and use a 8" SCT.. May camera is a ATIK 8300 OSC. My image scale is 0.69 pixels. The best centering I can ever get is 78 pixels. Typically it takes around 8 maybe 9 tries to get there. Usually I tell the mount, via hand controller, to move to my target before starting my sequence. From there I let SGPro do the rest. What I see is that my first center is always low 80 pixels off. Then for each centering attempt it just seems to bounce around between 80 and like 95 pixels. Finally after maybe 8 or 9 attempts it lands on something less then the 78 pixels and the sequence can continue on. What I notice is that the further away the centering error is form my requested 78 pixels the higher chance on the next try it will reach it. It's acting just like some folks here are saying in that it never converges but just a random chance that I hits the 78 pixels. I've never seen anything less then 70 pixels with my system and it never converges.
Just thought I would share my experience.
mahaffm