Re: [ATM] Question about "Null-testing"

["David Harbour" <scarab2@cox.net>]

Mel, all:

Remember, there is one kind of a null test that REQUIRES NO AUXILIARY
OPTICS. I wrote about this a few posts back. Jan Texereau liked it; it is
idiot proof. If the Hubble people would have used it, there would have been
no trouble with the Hubble telescope's primary. "Qantitatively" it is at
least as accurate as Focault. Jan Texereau said so. (About tenth wave, by
long standing consensus, including Tex.)

Dave
----- Original Message ----- 
From: "Mel Bartels" <mbartels@bbastrodesigns.com>
To: <atm@atmlist.net>
Sent: Monday, July 04, 2005 8:45 PM
Subject: Re: [ATM] Question about "Null-testing"


> > Is-not a Null test Considered a Qualitative test?,,
> > If so, does not the null-lens if say"Guaranteed 20th wave on the
> > wave-front"
> > or better with all other aberration's being equal in quality,,,
> > Does-not the worker have the right to say that he [If he has the skill]
> > has
> > in his hands a "Qualitative"-optic" of better than 20th wave?
>
> Not really.  The Ross Null test has some stringent requirements on lens
> placement.  So at best, you are introducing further error.  Then, there's
> the question of how deep of shadows are acceptable.  It's a qualitative
> test, and as such, can make no quantative statement.  If you have a lens
and
> can get it set up properly, it's a great test.  Just don't transfer the
> quality of the test lens to the work.
>
> Mel Bartels
>
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> ATM mailing list http://www.atmlist.net/
>


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