Hi Kevin,
Many thanks for your useful comments.
I had wondered about the design of the focuser and the Starlight 3in Feathertouch with the posidrive motorised add-on does indeed look very interesting.
I gather from what you say that a two mirror system and a focuser that can be collimated independently can be somewhat tedious to tame.
My hope is to mount the 16″ model on a Paramount MEll.
Kind regards,
Ron