Re: ATM How good is good enough?

[Adrian Toledano <atoledan@prodigy.net.mx>]

Life is wise, you see...

Total erros is the sum of optic induced errors( eyepice, optics alignement,
diagonal and your own eyeball!!!!),  plus viewing conditions induced error
(mainly atmospheric conditions, heat currents, etc.). So unless you are
going to use top quality eyepices, perfectly flat secondary and view from a
place with normaly good viewing conditions, odds are that the image
degradation induced by a mirror corrected around 1/4th wavelength are
marginal.

Unless you are a seasoned observer and familiar with what you are looking
through the telescope, odds are that you dont even notice the difference.

Mirror testing is an art (A very subjective art indeed), so unless you eye
is educated and familiar with mirror testing and the equipment you use for
testing has the adecuate stability, odds are that your "Judgement" induced
error limits your ability to meassure mirror error with precission.

Do some star testing, if you like it go, with it. No mater what the numbers
tell you.

So this is the questions you should ask yourself.

1.- What is the overall quality of the telescope you are aiming. A better
mirror, needs a better mount, better diagonal,better eyepices, beter
foucault tester, better everything ..., and the work and expenses (specially
TIME) needed to achive more quality is not linear, its exponential.


I'm not telling you that you shouldn't look for building the best mirror you
can build, but a 1/4th wave mirror is a millon times more usefull than a
will be 1/30th mirror. Just put limits, ask yourself in what part of the
road you are.


My two cents

Adrian