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


Jack, sometimes you have to sit back and see what is important to the
process.  In this line, making the optical surface concentric to the mount
isn't anywhere near as important as making sure that the mechanical stuff
is fully hidden behind the shadow of the secondary.  The front surface of
the secondary is the important part of the job and getting it so that it is
centrally located to the focuser so that the axis of the motion of the EP
is pointing at the center of the ellipse of the secondary and the
reflection thereof points to the center of the primary.  This method is the
old centered secondary.  The "new" system is to offset the
secondary so that it captures the whole cone of light from the primary
equally which will make the point at which the focuser axis hits the
secondary slightly off (towards the near side of the secondary to the
focuser) from the center of the secondary.  The point at which the focuser
points to still doesn't move on the secondary and this is a very important
point. Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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