Re: [ATM] FigureXP

["Bob May" <rmay@nethere.com>]

Just a quick question on FigureXP...  Does anybody have a copy of
it before it became XP only?  I'm not worried about the bugginess
of the older version nor the "enhanced" features that got put
into it which made it for the XP operating system only.
If you do, let me know by private email to arrange the transfer.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net

----- Original Message -----
From: Mitchell R <funnybone101@embarqmail.com>
To: <atm@atmlist.net>
Sent: Tuesday, May 13, 2008 12:28 PM
Subject: Re: [ATM] FigureXP


>
> FigureXP, and Sixtests before it, differ from "older" programs
such as
> Tex in actually finding "best focus", in other words the ROC
that gives
> least RMS error. And let me stress again - the RMS error, not
the "1/10
> wave" etc P-V error is what determines the performance.
"Modern"
> programs can do the rather computer-intense calculations to
find the
> RMS error, while older ones like Tex can't (and that's the only
excuse
> I can think of at all for using P-V error).
>
> But FigureXP lets you experiment - it will give you both the
(also
> obsolete) transverse error and P-V error, and also lets you
fine-tune
> the effective ROC. You might be surprised to see that neither
> transverse nor P-V errors are at minimum at best focus (or even
at the
> same focus)!
>
> Nils Olof
>
>
> Hey Nils,
>
>      I just had a huge message with questions typed up as I was
going
> through Mel Bartels site on mirror rating, then at the bottom
reached your
> comment, that pretty much answered them all.
>
> I see how many things can be contradictory. I have a 10" Mirror
I did. It
> reads at 1/17.5 P-V Wavefront and .99 Strehl. Yet it fails the
M-L plot in
> one zone and has a transverse error of 1.5, which is greater
than the
> acceptable 1. It is within the 20nm RMS limit, coming in at 4.3
nm. So it
> passes with flying colors, p-v, strehl, and rms, but fails
transverse error,
> and M-L plot. Quite interesting,
>
> So it there a basic rule of thumb for the tests discussed? 1/4
p-v = 20 nm
> rms = .80 strehl?
>
> I think Mel's site is an excellent aid but the debate will rage
on forever
> ;)
>
> Funny how P-V is considered useless, and yet it is the primary
criteria used
> by the majority of makers.
>
> Mitchell
>
>
>
>
>
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>

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