ATM Baffle/Aperature Stop Calculations

[BodyByJay@aol.com]

Just curious if anyone had any ideas of how to calculate baffle dimensions for
a Newtonian.  The way that the NEWT25.EXE program does it is it creates
"aperature stops" or baffles whos inner diameter follows the edge of the light
cone.  In calculations for a 12.5" Newt the aperature (at the opening of the
Newt) is about 13.5" and the inner diameter of the baffles gets smaller and
smaller as it approaches the primary.  Someone gave the formula D+(F/100)
where D=diameter of the primary and F=Focal lenght.  Not sure how this is
used.  Any ideas?

Jay D. Anderson