after a few calculations with an octagonal central and distance to primary from newt.
I know the octagonal will be more difficult to construct given truss angle to optical axis will no longer be 90 deg, but my hunch is that the truss arranged along the surface of a cone would provide better rigidity than along a cylinder.
Moonlite has ball and socket truss connectors, might have to look at alternatives as trusses will be fibre.
newt output says there will be vignetting at focuser of 75% ray if I use a standard 2" focuser with a 51mm ID and 51mm for eyepiece focal plane to camera sensor. I need a minimum of 57mm ID to correct this.
not sure what the practical impact would be.
is the 51mm allowance for a camera nominal?
this is from the newt help page
http://stellafane.org/tm/newt-web/ne...l#UsingACamera
"If you will be using a camera, enter the amount of additional height for the focal plane above the focal plane used for eyepieces. This is usually about 2 inches for 35 mm Single Lens Reflex cameras. You should also add any height required for an off-axis guider. This is usually three quarters to one inch."