IFFFF your only gonna use the mirror as a rich field scope....1/4 wave is
fine......


particularly if your not using extremely well corrected eyepieces like naglers
and coma correctors like a paracoor....

I could go into all kinds stuff regarding the eyes resolving power, airy
(hairy) disks, MTFs etc etc....

but the bottom line is....for rich field (ie lower power/large exit pupil)
viewing, unless you got eyes like superman...you AINT GONNA see any difference
between a 1/16 wave mirror and one as worse as possibly a FEW waves of
error....

Ive actually toyed with the idea of making a poor mans high performance rich
field scope that would give very NICE views on a pretty good budget....

make the mirror F8 (sorta) or so.....use a 50mm plossl or perhaps one of the
higher performance eyepieces at a slighter shorter focal length (and drop the F
ratio accordingly)...

make the mirror spherical....AND let the secondary diagonal mirror be
undersized so that IT defines the aperture ....

So, for example....you would use an 8 F6 spherical mirror with an UNDERSIZED
secondary so that anywhere across the eyepieces field of view it acts like a 6
inch F8.....so there would also be a fully illuminated field for a 50mm
plossl....

Actually, for nice rich field viewing....proper /well done baffling of the
telescope tube, a scope that is easy and comfortable to use, and low scatter
eyepieces are probably WAY more important than mirror accuracy....

take care

Blll