From: "Bob May" 
To: "atmlist" 
Reply-To: "Bob May" 


There is basically nothing wrong with testing through a camera.  The big
thing is to insure that the camera is not vignetting at the edge of the
field.  If you have vignetting, the shadows will change the end results and
WILL produce a incorrect reading (shadows between the center and edge of
the screen will make for an offset!) for the test. The camera that I use
does have a flat field intensity so that there is not a problem.  Also
testing with the mirror on one side of the screen and then moving the
camera so that the mirror is on the other side of the screen and getting
the same result proves that the position of the image in the screen doesn't
affect the results.
Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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