ATM A large refractor experience

["David Lonard" <lonard@hotmail.com>]

Dear Group,

I would like to relay my experience concerning the
impulsive purchase of a large Kaiser Electro Optics
surplus objective that I obtained from
Surplus Shed for others that may get their hands on
one of these.  It has 11" clear aperture
and is stated to be a triplet oil spaced f/3.3 objective.
The outward facing side is strongly convex while the
side facing the eyepiece is less strongly concave.
Ronchi star testing revealed very straight lines,
so it appears to be well corrected for viewing
objects at infinite distance.  The down side is
that is displays considerable chromatic aberration
on bright objects, jupiter had a nasty violet halo
around it, although it does resolve detail down to
about as well as southeast Texas skies will allow.

As for its more realistic use as a wide field, ultra
bright, deep space avenger, I noticed some field curvature
with a 25mm plossl and I can barely reach a satisfying
focus accross the whole field of view but it frames
M44 really well.

I have since built up a telescope around the massive
objective.  See:

http://www.geocities.com/lonard3/tele1.JPG
http://www.geocities.com/lonard3/tele2.JPG
http://www.geocities.com/lonard3/tele3.JPG
http://www.geocities.com/lonard3/tele4.JPG

Does anyone know more about these objectives, or
perhaps indulge me with some sort of strategy
to abate its chromatic aberration?  I have already
been told that one of the commercially available
means to do this wont work for me.  Also, excluding
exit pupil concerns, if I wanted to try my luck
with a longer focus eyepiece, what eyepiece would
be better at coping with the field curvature
of a fast f/3.3?  A Nagler, panoptic, plossl...

David


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