[ATM] Re: History of moving mirrors for SCT...

[Vladimir Sacek <vladis.2@juno.com>]

Rutten and Venrooij give as the reason better peformance at close
focusing. Standard focusing would result in significantly more
aberrations, and would require too much of a focuser movement. Also,
since image would be forming farther away from the mirrors, it would also
be more magnified, and wider converging beams would very likely cause
stopping down of the aperture at the tight front end baffle tube opening.
Having a scope capable of handling close focusing makes it more
versatile, and it is likley to reflect in higher sales volume.

One thing that I like about mirror focusing is that it allows you to find
the mirror separation at which the spherical is at its minimum. 

Vlad
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