Re: [ATM] Maksutov vs. Schmidt

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

vladimir sacek wrote:

>Richard,
>
>
>
>Its spots are not nearly as neat, but it is corrected to better than 1/10
>wave
>as it is (I didn't spend much time optimizing, so it likely can be made
>better).
>Color correction doesn't seem considerably inferior. 
>
Actually, you may want to reconsider this.  Although forcing the color
to cross in the ROI does not significantly change the spot size, it would
raise the Strehl from, say, 0.91 to 0.95.  It might just make the difference
that would make you pleased with the result.

>
>As Dominic-Luc suggested, the curve needed for Schmidt corrector would be
>very 
>shallow: ~1/25mm at the 0.866 zone, and less than that everywhere else.
>Is it really
>much harder to make such a slight curve, as opposed to Maksutov
>corrector, which also 
>requires very tight tolerances?
>

Actually, I get about 1/3 of that (but I do like the shift of the
corrector to 2.8 m out quite a bit better)...  but that is
equivalent to parabolizing a 500 mm f/2.4 mirror.  If that is
within your capability, good.  One historic advantage of the
Maksutov has been the spherical surfaces.

>
>
>Vlad
>
>  
>

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