Re: Re[2]: [ATM] The Hubble mirror goof up.

[Ken Lowther <hermit@outofoptions.org>]

Quoting PK <pkreisle@earthlink.net>:

> Question for the optical engineering types.
> If you were to build a telescope to look at objects say 200 miles away,
> as in orbit looking back at Earth, would you use a parabola or something
> near it with a bit of what we would call spherical aberation?  It seems that
> light from a source this close would not be paralel and thus the true 
> parabola
> would not be the ideal shape of the mirror.
>

20 inches / 200 miles = close enough to infinity

Indeed, several miles was good enough for placing my mirror in the tube 
relative to the focuser.

Ken

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