NavList:

"A" is the tube and objective lens of a Galilean telescope. "B" is the tube and objective lens of a so called "inverting" or Keplerian telescope. "C" is the eye lens and tube for either "A" or "B". "D" has no lens and is sometimes called a zero magnification tube, used when the motion of the vessel is great: the more magnification, the faster is the apparent motion of the body in the field of view and the smaller is the field of view. "E" is an eyepiece shade or filter. "D" is an eyelens which screws into "C" - unless it is a "foreigner". The eye lens for the Galilean is a negative or concave lens and everything looks smaller through it. The eyelens for the Keplerian is a positive or magnifying lens and is usually made up of two lenses separated by a spacer of some sort.

Try mixing and matching the eye lenses to see which one goes with which telescope. You are missing an eye tube for one of them.

Bill Morris

Pukenui

New Zealand