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LX200R - collimation/off-centered secondary proble

Started by amstel78, 03/19/2008 04:21PM
Posted 03/19/2008 04:21PM Opening Post
**I'm snipping this from my post on the LX200GPS Yahoo group. Hopefully though, someone here can also provide some insight.

I posted several days ago about having a lot of trouble achieving fine collimation with a new LX200R. Unfortunately, I did not get a response from this group.

Just to recap; for example if I collimate with a diagonal and the CO is down and to the left on outside of focus, it will be down and to the right on inside of focus. No matter how much I try to center one side, it will be off on the other. I've tried this with three different diagonals.

I also tried collimating with no diagonal, just an EP inserted directly into the visual back. I was able (at least to my eye) get the diffraction rings concentric on both sides of focus. This leads me to believe that perhaps all 3 of my diagonals may be bad. I find that hard to believe though.

After collimating with just an EP and no diagonal, I looked at the front of the telescope to see how well the reflections lined up. They looked a little off, especially the reflection of the secondary mirror housing or baffle. For example, if I aligned my eye so that the center reflections are even, the outermost reflection in the mirror seemed skewed. If I repositioned my eye so that the outermost rings reflections were concentric, then the interior reflection of the secondary seemed skewed.

This brings me to a small experiment I tried last night. I stuck a flash light into the visual back of the OTA and looked at the light and shadow projection on a wall. The shadow of the secondary housing is off-centered.

Now my question is this: would an off-axis secondary cause my collimation issues with a diagonal? Would an off-axis secondary also introduce optical aberrations?

I know that the 6-screw secondary can be removed without touching the corrector. How then can I reposition it so that it is fully centered on the corrector?

Please help, as I'd really like to avoid sending this back to Meade.

Best regards,
James

Regards,
James
[SIZE="Small"]
[COLOR="Blue"]Toys: [COLOR="Red"]2006 Evolution MR, 2005 BMW M3, Meade LX200R[/COLOR][/COLOR][/SIZE]
Posted 03/19/2008 09:53PM #1
Have you tried arksky.org (big website but lots of advice and address for questions) or weasner.com/etx/techtips.html (also available through optcorp.com, then "Weasner's Corner" under information (also gives an email #). I have had good results using both sites on my unusual LX problems. Both seem run by knowledgeable, helpful astronomers. Hope this helps.