Re: A Project for Tass

[<aah@nofs.navy.mil>]

We did something similar for ARNE when making the
aperture masks so that I can work down to 2nd magnitude.
Basically took a 1/4" thick aluminum plate and milled
it out to ~1/16" thickness, giving a 3/16" lip to slip
over the end of the lens.  One thing you should be
careful about is that the front lens is strongly
curved and comes *very* close to the end of the tube.
I was conservative and had an extra 1/32" taken off
the center where the front surface comes closest to
hitting the cap.
  If you don't slide the cap down so that its end
hits the end of the 'telescope' tube, then you wouldn't
run into this problem.  Just be careful.
Arne