Hi Richard,

the U.O. HD Orthos plus 2.8x Klee Barlow might be an interesting combination for your 10" Newt.
The Klee Barlow compensates the off-axis coma of the Newt.
I use it with m 8"f/6 Newt with some U.O. clasical and HD Orthos and I am very pleased by the views.
On axis it is contrasty and sharp. When I focus a star in the center of the field of view and let him
drift towards the edge the star stays off-axis pinpointlike until it hits the field stop.
Only downside of the 2.8x Klee is that it does not work well with long focal length eyepieces.
With a 25mm Ortho it moves the exit pupil too far out.
With the 18mm Ortho it works nicely, but the eye needs to be precisely on-axis.
With a 12,5mm Ortho it is nothing but stunning.

If you get the opportunity to use the Klee with a good jepenese ortho do not hesitate to try it.

Cheers, Karsten