[ATM] Re: Couder Masks and Zone Testing

["Byron" <byron@astronomygeek.us>]

Now that is an innovative idea, I just need to get a web cam that I can both
use for Focault testing and for Astrophotography!  Any recommendations?

----- Original Message -----
From: <artbianconi@blast.net>
To: <atm@atmlist.net>
Cc: <richas@earthlink.net>; <mikell@optonline.net>; <byron@astronomygeek.us>
Sent: Sunday, April 18, 2004 7:38 PM
Subject: Couder Masks and Zone Testing


>
> > I don't know how you can make a Couder mask with software.   I always
used
> > black paper or cardboard and an X-acto knife.
> >
> > Note that it is best when testing to isolate the mask from the mirror.
> > That way you can adjust the mask position without disturbing the
distance
> > from the mirror to the knife edge.
> >
> > . . . Richard
>
> Bob May shows some photo's on his website of him using an inexpensive PC
linked "eye-
> ball" camera to capture the reflected image of the mirror at COC. He then
projects the image
> to a conventional CRT (TV set). Whether you are doing a Faucault test or a
Ronchi, you
> have the option of capturing the image, saving it to appropriate media and
then using the
> string of photos for checking your progress and adjusting your strokes.
>
> Gordon Waite and Mike Lindner have taken the idea a little further. At the
risk of
> misrepresenting their creativity, I believe it goes something like this. .
. . . .
>
> they cut the mask not to the  mirror but to fit the TV screen! Then they
simply zoom in and
> out until the mirror image on the screen is sized to fit the mask! Then
they do their tests.
>
> Presto! One mask fits all !
>
> Neat Huh?
>
> Art

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