[APML]: Lumicon 2.5X CCD telecompressor

["Jim Pennington" <penningtonj@email.msn.com>]

Has anyone ever had problems getting their "ducks lined up"?

After getting 4 cassegrain easy guider adapter rings and trying to find one
that would screw onto my scope, I finally came up with one that is usable
but still not perfect.  At this point, I am considering THAT problem solved
and now am faced with other questions and problems.

I didn't like the idea of having to use my ST-4 with a star diagonal in
order for the autoguider to be able to reach focus.  Anyone with an ST-4
knows how heavy the guiding head is and when it is stuck out on the end of
the star diagonal, it looks like it can exert a lot of torque on the guider
body and possibly cause something to slip during an exposure especially if
the guider head is orientated off to the side.  Another consideration is
that the assembled apparatus looks like flexure could be a problem
especially with 2 hour exposures when imaging at F/10.  That's a lot of
weight and it's hanging a long way from the optical axis of the camera and
scope.  As of yet, I haven't had a change to image with the cassegrain easy
guider due to the first problem mentioned above.  My concern at this point
is that the setup "looks" like trouble.  Am I being unduly concerned about
this?

I discussed this with Dr. Marling at Lumicon and he suggested that I might
be able to shorten things up a bit by using their 2.5X CCD telecompressor
lens with the ST-4 and at the same time get smaller sized guidestars for the
ST-4 to work with.  After getting the telecompressor lens, I find that it
does not fit the threads of the ST-4.  The lens will screw onto a regular
eyepiece barrel but not to the barrel of the ST-4 which is a bit smaller on
the inside.  In Lumicon's catalog, it states that this lens is made for use
on the ST-4 autoguider.  Am I missing something here?

Another question:  Will this lens (assuming that I can get one to fit the
ST-4) shorten the guiding focal length of the ST-4?

Thanks for any feedback on this.

Jim
http://www.geocities.com/capecanaveral/lab/6529