Re: [ATM] Figuring question

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

Lance, if you are getting 10 results for the mirror, it doesn't
matter whether you're using a 10 zone mask, two 5 zone masks or
10 single zone masks. you're using 10 zones to judge the mirror!
If you really want to make the judging of the mirror a lot
easier, take a video camera and place it behind the KE and use
that to see the returned light.  The whole testing will become a
lot more stable and easier to read.  I'll also note that when you
do the testing, you want to use the same brightness level for all
of the zones or you will be getting different results for each of
the zones.  The actual brightness is pretty much irrrevelant
provided that the brightness selected is less than 1/2 of the max
brightness - the slitless tester has a much more gentle slope of
darkening in the upper half of the brightness curve than a slit
tester but the darker regions are a lot more accurate.
Bob May
bobmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
Replace the obvious words with the proper character.

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