Hi John.
No it's not the focuser. Your offer is thoroughly decent...but the original focuser had off axis issues as well.
I managed to centre/tilt adjust the advanced focuser somewhat to get nice flat field analysis and centred optics..happy with that. Yet the scope still showed coma (actually astigmatism) and chromatic flare.
This German site shows that indeed these issues are due to the lens spacing and adjustments. He appears quite thorough and not superfluous on his words but it does appear he tests scopes for astroshop.de (and vegaoptics.de)... so be careful of commercial relationships and their tests! That said..I'd be happy with an expert backing the scopes I am buying and they appear to be guaranteeing results.
It's indeed a learning curve but I wouldn't have it any other way! The only way to learn is to make mistakes! It makes interesting reading for those who have the scopes.
I'm sending Gilman some info from this site. I don't know Gilman's position in Hioptic/Northgroup..aka is he a technician? So, I don't know if this will be well received nor passed on.
