Re: Rules of Evidence (S&T January Editorial)

Now I am hopelessly confused. I have read the summons delivered to
Meade from RCOS and others about how evil Meade is in their advertizing
etc etc and now when I do just a bit of research on RC Telescopes I
find ..... on WIKI - Ritchey-Chrétien telescope
From Wikipedia, the free encyclopedia


"The Ritchey-Chrétien telescope or RCT is a specialized Cassegrain
telescope with a hyperbolic primary and a hyperbolic secondary mirror.
It was invented in the early 1910s by American astronomer George Willis
Ritchey (1864-1945) and French astronomer Henri Chrétien
(1879-1956). Ritchey constructed the first successful RCT, which had
a diameter of 0.5 metres, in 1927. The second RCT was a 1-metre
instrument constructed by Ritchey for the United States Naval
Observatory.

The Ritchey-Chrétien design is free of third-order coma and spherical
aberration, NOTE ---although it does suffer from fifth-order coma,----
END NOTE severe large-angle astigmatism, and comparatively severe
field curvature (Rutten, 67)."

As one reads the RC Design suffers from 5th order Coma, and all along I
believed the advert on RCOS's web site (Home page mark you) ---

" Ritchey-Chrétien is a specialized Cassegrain reflector utilizing
true hyperbolic surfaces. All reflectors typically have an aberration
called coma - all except for the Ritchey-Chrétien. The hyperbolic
mirrors of the Ritchey-Chrétien make this design coma free"

Just when I was thinking RCOS was our knight in shining armour, I find
that they also are careful with the truth.
No coma is no coma. No coma does not mean no 3rd order coma and only
5th Order coma, I don't care if I can see it or not, No coma is No
coma.

I have an RCX 400 14" and I know it is not a pure RC but strangely, it
performs beautifully with no visible coma. Even buying it stretched my
budget and I would never think of an RCOS priced telescope. Thanks
Meade.


Hope you got my drift.

John

.

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