[Stephane]

Thank you both Ray & Raymo.

Raymo, I agree with you and I had noticed it already. I was wondering if the eagle-eyed photographers would notice enough to mention it and I’m glad you did. Any suggestions on fixing this would be most welcome. Interestingly, some subs don’t have this eccentricity, but many do. Elongation rotates with camera. Polar alignement is excellent (no mouvement with unguided test subs). Guide scope image is centered. Guiding occasionally has bumps at irregular intervals that could be causing this. I think I’ll be scratching my head for a while. My main suspicions are either the guide scope “bending” as the OTA rotates and/or the focuser is tilted and bends a little with rotation. Comments welcome.