--- In C14@y..., "W. Gondella" <gondella@s...> wrote:
The corrector is a very, very weak lens. It doesn't sound right
that a
small tweek in alignment would noticably alter the color of the
system.
Does color get worse and worse as you go further off axis?
I will check that.
Is the fringe
concentric to the Airy disc, and have you tried different
eyepieces?
No not yet.
What
eyepiece are you using?
Nagler series usually 7,9 or higher depending on seeing.
Further, there is little chance the primary could
be tilted or off-center, as the mirror stay forces the glass into
alignment
with machined metal surfaces. However, the corrector *could* be
off-center,
and can be easily remedied.
I'll take some measurements.
Wayne, Thanks for the reply. Ed
Wayne E. Gondella
AFA Engineering Company
Pittsburgh, Pennsylvania
Date: Sat, 02 Mar 2002 18:29:50 -0000
From: "ejoganic" <astron1@m...>
Subject: alignment of optical surfaces
I am new to this group and find the discussion on component
alignment interesting. My C14 is a little unusual. When I
collimate
I start with touching up the secondary alignment by centering the
secondary shadow. When I bring a star into center field there is
a
slight but noticeable color fringe. Finally I make a very slight
correction to eliminate the fringe. This gives the sharpest image
and smallest stars. It is intereting when I defocus because the
secondary shadow is then very slightly but noticeably eccentric.
It
would seem that one of the elements is tilted. Has anyone
noticed a
slight red to blue fringe at star edges or anything like this?
Check
the next time you are observing. It would be interesting to know
what you find. Any ideas on where the misalignment is? I would
guess
you could shim the corrector to make it parallel to the primary
but
would have to offset the center to keep the optical axis aligned.
Doesn't sound easy. Any ideas? Ed
