Elongated Stars – Focuser problems

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Elongated Stars – Focuser problems

| Troubleshooting | October 25, 2012

Last night, in order to try to reduce the differential flexure problem that have been plaguing me, I replaced the guiding camera 2″ extension tube I was using with the ED80T CF  with a 1.25″ diagonal with the hope to be able to move the draw-tube more into the focuser. With the 2″ extension tube, my draw-tube was 60mm out of the focuser; With the diagonal, I was able to reach focus with the draw-tube only at 35mm). This is because the optical light patch of the diagonal is longer than 2″. I was thinking that in this position, the draw-tube would less suffer from sagging under the weight. However…

While trying to test this new guider/diagonal configuration, I was standing near the telescope running a focus run on the imaging camera when I heard a “ding” coming from the focuser area. I started to examine the focuser (i.e. Motorized Moonlite SCT) more closely and realized that one of the stainless steel bearing looked damaged (i.e. some sort of metal spring was sticking out of the bearing).

I then took the telescope inside for a closer inspection. When I unscrewed the bearing, it fell apart in my hand…

It also looked like the faulty bearing damaged the focuser drawtube…

Since my focuser is not even 18 months old and still under the 3 years warranty, I have written an email to Moonlite Telescope Accessories to request assistance. I am waiting for the reply.

This might be the cause of the differential flexure problem I’ve been experiencing.

  1. Obviously, the draw-tube was probably not correctly collimated (which would explain the results I was getting with CCD Inspector in previous posts);
  2. I was possibly loose in the focuser (creating flexure).

I’ll provide more information as soon as I have answers from Moonlite.


About the author

You can call me Frank. I've been an amateur astronomer since 1988. In 2004, I purchased my first astrophotography equipment. In 2008, I built my own observatory. I cannot count the number of hours I have spent building, learning and trying. It as been a humbling experience that I hope will continue for a lifetime.

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