(ATM) RE: How much quality?

[clark@witch.mitra.com (Clark MacDonald)]

> Classical Cassegrains have far too much off-axis abberations to make
> very good wide angle scopes. The small field of view and long focal
> ratio hide the flaws of the classical Cassegrain design.  Any design
> would work great at f/20 with a small field of view.]
> Chuck
> 

OK. What is it that I do not understand? What off-axis abberations
are we talking about? Other than curvature of field introduced by
the secondary magnification factor, typically 4X - 5X, what is the
flaw in this design.

        The secondary obstruction is usually < 20%
        Coma is that of a newtonian of same f#
        Long FL is in a small package

Perhaps the thing to mention here, is that the Classical Cassegrain
was never designed to be a low power, wide field instrument. This
means that adequate baffleing should not be a problem, because
FOV is not a problem.

A Classical Cassegrain has a parabolic primary. My scope has
an F4 primary making it a Very Fast, Very wide angle 
newtonian scope.

I do not know of a more flexible instrument.
        

-- 

        Best regards,
                clark@mitra.com
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