RE: ATM secondary cage size

["Frank Ward" <thewards@mindspring.com>]

That answer depends first of all on the distance of the
eyepiece from the side of the secondary cage. If it is
at the side or close to it the view will be many degrees
more than if it is two inches back from the side. That's
why most folks make the secondary cage large enough to
support the spider and diagonal and use a light shield
to protect and baffle the eyepiece from stray light.

Frank Ward
Atlanta, GA

-----Original Message-----
From: owner-atm@shore.net [mailto:owner-atm@shore.net]On Behalf Of James
Taylor
Sent: Tuesday, June 25, 2002 11:35 PM
To: ATM
Subject: ATM secondary cage size



I suppose I could map this out myself, but I thought I would ask and see if
there is a quick/easy answer.

If my upper (secondary) cage has an inside diameter of 15", how "tall" would
I want the secondary cage to be so that the cage itself acts as an adequate
light shield for the focuser if the focuser is centered top to bottom in the
cage (assuming I line the inside diameter of the cage with something dark)?

My focuser will be for a 1.25" eyepiece.

James Taylor