"Bill Becker" wrote in message
...

"donutbandit" wrote in message
...
I ran into a great deal on a 6" f/4 parabolic mirror. All the stats on
it
look good, except that it is a 1/4 wave mirror.

I was raised believing that no less than 1/8 wave will suffice, but how
about a low power rich field scope? The magnification would never be
greater than 40.

I don't know but....if the total correction for the "system" was 1/4 wave,
that wouldn't be too bad at all but...
for the primary itself to be 1/4 wave, it doesn't sound very promising.

Best regards,
Bill

Take these surface accuracy claims with a grain of salt! Test the
mirror yourself. Unfortunately in most cases, it is up to you to prove the
claim incorrect. Even a good 1/8 wave mirror will act poorly if the surface
is not properly polished. Also what does the claim mean. Is it
peak-to-peak or wave front????
Ed
Ed