Re: ATM Re: star test

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

The null test is really fairly easy to understand.
You are cutting off the light at a point focus.  Any light from a zone that
is cut off early is pointing its light to a point on the KE rather than the
at the edge of the KE.  If the zonal area is bright, then the light is being
pointed to where the KE hasn't been yet.
Basically, if you have a KE coming in from the left, a zone that is shorter
for FL on the left side will put the light beyond the KE so it will be
brighter and vice versa.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net