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


The problem with the eye is that as you go away from the KE, the eye lens
is unable to see all of the cone of light, thus dimming one side of the
zone over the other.  This isn't too bad near the center but as you go away
from the  center of the mirror, the light comes to you at larger and larger
angles which make it easier to vignette some of the light with the edge of
your iris.
Basically, what this means is that you pretty much need to get your eye
closer to the KE in order to see all of the mirror properly. As to the
point of what is nulled, the blink method works fine as you are somewhat
doing where both zones go through their shades of gray at the same time. 
Moving the KE .002-.003" in or out and seeing that one trails the
other, depending upon the direction will also assist in proving where the
null zone is.
Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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