From: "David Lonard" 
To: atm{at}shore.net
Reply-To: "David Lonard" 




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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