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Aid On Telescope Design

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Posted by Pereira on July 31, 2000 21:48:44 UTC


I was wondering of pros vs cons on the following optical design.
It is similar to a cassegranian telescope but uses a flat secondary and a negative lens.
Think of a parabolic primary say 6" f/4 reflecting to a flat secondary (1.0" diameter).
Because of secondary being flat light folds back just 6" (and still having 18" to primary).
If we have a negative achromat lens (between secondary and primary), the light cone would `open` allowing light to go through a hole (just like a cassegrain) making possible to achive focus outside the tube.
I would like to hear comments upon this.

Thanks in advance,


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