Re: [ATM] Flat Field Cass with Hougthon subaperture corrector. WAS:corrected dall-kirkham telescope

[Richard <cnc@cncservo.co.uk>]

Hi Dominic-Luc,

Friday, February 9, 2007, 11:23:59 AM, you wrote:

DLW> seeing. Anyone have an explanation for any of these designs and
DLW> are there are recommended standards?

I've always used the F, d and C lines as being three lines that are
typically near the start, middle and end of the visible spectrum and
happen to be a preset in my optical program of choice. I'll weight
them, too. If I want to really hone results I may go to 5 wavelengths
but that really is gilding the lily a bit. Refractive properties just
don't change suddenly or non deterministically with wavelength. If
it's OK at the ends and the middle, I've never seen a design do
anything odd at intermediate points. To extrapolate off the ends would
be asking for trouble though.

-- 

Best regards,
  Richard in the UK

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