ATM 18 inch telescope

[Steve Fejes <jsfejes@swva.net>]

Joseph,

  Some people have found a way to bring the eyepiece down to a more
comfortable viewing height in bigger reflectors.  There are two designs
that come to mind other than the Cassegrain design already mentioned.

  One is to use a flat diagonal mirror at an angle other than 45
degrees, say more like 30 degrees.  This will mean that the focuser is
looking at an angle up toward the top of the tube.  It will require a
bigger diagonal mirror, and shielding to block out sky light.

  The other idea uses a flat secondary mirror (bigger than normal) which
reflects the image back toward the primary mirror.  Then a smaller 45
degree angle mirror reflects the image to the side of the tube.  The
tube will look similar to a Newtonian telescope, but the focuser is
closer to the middle of the tube. 

  These two designs only require one parabolic mirror and a flat mirror
or two.  For many amateurs it seems easier to buy the flat mirrors and
then you only need to make one precision mirror.

Steve