Re: ATM 3 or 4 vane Spider

["Thomas O'Hara, PhD" <ohara@azstarnet.com>]

Art,

To paraphrase General Philip Sheridan, the only good spider is a dead
spider. How about zero vanes?  Texereau shows how to make a front window
in the chapter on Cassegrains. Six inch window of BK7, drilled at center
for a secondary holder like a Schmidt Cass -- presto! NO SPIKES!  Works
even better on long focal ratios, for the planets.

Otherwise, all your fine work will have been in vane!

Tom