Re: ATM 100% illumination and secondary sizing

["John Lynch" <john_p_lynch@hotmail.com>]

David,

One other thing I forgot to mention:  With a 2.6" minor axis diagonal
mirror and 12.5" primary, Newt indicates, as you have stated, that
the obstruction of the diameter of the primary mirror by the diagonal
is 21%; however, the obstruction of the primary mirror surface area
by the diagonal is only 4%.  I would consider this very small, and
the gains you get by using a 2.6" diagonal versus a 2.14" diagonal
considerably outweigh the minimal increase in obstruction.  By the
way, using 2.14" in Newt gives 17% and 3% obstruction for diameter
and surface area, respectively.

John

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