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

[Dominic-Luc Webb <dlwebb@canit.se>]

On Fri, 9 Feb 2007, Richard wrote:

> Depends what you are after Dominic. It is outside the visible spectrum
> and therefore to me, of no interest. That said, I would never actually
> build a scope without checking the design at extremes and I know my
> design is still good from 300nm (beyond BK7) to over 1um, I just
> didn't think it was relevant to the discussion.
>
> I think the main reason you don't see these extremes from people (and
> certainly why you didn't see them from me) is that moist of the time
> in your optics software you are optimising the design, which can
> involve long run times. The last thing you want to do during
> optimisation is include wavelengths which are not of main interest,
> even if they are in your main wavelengths table. It just so happens
> that the optical design software most commonly used by the pros
> defaults its spot diagram display to the wavelengths that you have
> turned on in the wavelength table for optimisation.


In context of astronomy, relevant wavelengths in my mind for
ground based scope for amateur consideration would be UBVRI
system. Specifically, peaks are 360, 440, 550, 700 and 880 nm,
respectively. I reckoned these were the wavelengths of main
interest, so I always tried to optimize with these.

Dominic-Luc Webb


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