Re: [ATM] Ball bearing for triangles,spherical aberration caused by thermal gradient in the mirror: theresults...(long)

["vladimir sacek" <v959@msn.com>]

Raphael,

If I understand correctly, you have a 24" f/3.3
Newtonian. If so, the secondary is flat. Banding
a flat would induce much more astigmatism than
spherical aberration; that is definitely not a way
to improve telescope's optics.

You may want to check out the edge quality. TE
can make spherical aberration look worse and, to
unsuspecting eyes, or in compromised conditions,
can even "imitate" s.a.

I will also say that 1/4 wave wavefront level is plenty good
for such a large and fast thin mirror. But I understand
your desire to make it as good as it possibly can be.

Good luck,

Vlad
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