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View Full Version here: : Meade LX90 - foreign object in OTA


lsimpson
07-01-2017, 11:04 PM
A little metal ring has come off the tube of the focuser, a baffle perhaps, and is rattling around inside the OTA of my 8" Meade LX90 SCT.

It has left a ring of oil on the primary, though from the vantage point of the front of the scope there are no visible scratches, touch wood.

I fear using my scope because sharp metal objects rattling around inside my delicate instrument and scratching the optics can be a little disconcerting.

I've Googled "how to clean Meade LX90 primary" and similar searches and come up with a lot of "do not ever remove and clean the primary mirror of an SCT period!" type answers in forums.

Is this a job for a professional optical technician to fix, or is there a guide I can follow somewhere for how to remove the primary, thus allowing me to take out that little metal ring, and clean it, and recollimate it?

I've got a long history of owning Newtonians and refractors and have a reasonable idea of how to properly clean optics, but this is my first SCT and it's a much more complicated thing than I've ever had to deal with, and those posts I read were a little alarming!

Please help! :sadeyes:

Leani

lsimpson
07-01-2017, 11:16 PM
This is the object!

casstony
07-01-2017, 11:34 PM
That looks like the C clip off the end of the baffle tube, meant to stop the mirror from falling forward off the baffle if the focuser is disconnected. If so it's easy to fit back into the groove, then perhaps do a minimal clean of the spots on the mirror without removing it.

It's not hard to remove the mirror, but kind of a PITA dealing with the grease if you don't really need to.

Remember to keep the same rotational orientation of the corrector plate during reassembly.