6,000 km Corrector Plate Service Advice Needed

[wayne anderson (Wayne)]

Over the last few years the LX200 has travelled over 6,000km on the back seat of the car strapped in with the seat belts and inside a padded JMI case but it seems the vibrations and gravity have had an effect on the corrector plate.

I removed the corrector plate retaining ring to inspect and noticed the corrector has slipped down by 2mm and rotated by 3mm clockwise and the bottom cork shim has been compressed by 0.5 mm.

I am now seeking advice on how to fix this, do I just rotate it back and re collimate or do I need to replace the crushed cork shim to lift the corrector back up as well. Any helpful advice would be appreciated. ( the photo shows what happened)

Thanks, Wayne.

[multiweb (Marc)]

Just rotate it back then center the corrector glass and pack the gaps between the cork and glass on each side with bits of paper or cardboard shims. You'll be alright.

[jenchris (Jennifer)]

I'd go with Marc's suggestions.

[DarkArts]

Having owned an LX200 and having had exactly the same problem, yes, re-centre and re-shim, and re-collimate on completion.

You may have to be a bit iterative as it's a fiddly job inserting shims, not to mention getting or making shims of the right thickness.

I found having the LX200 in the mount and oriented so that the OTA was pointing straight upwards (so that the corrector was flat and at a comfortable working height) made the job easier.

You should notice an improvement in image quality - an off-centre corrector causes a sort of permanent astigmatism (at least that's what it looks like to me).

[multiweb (Marc)]

Originally Posted by DarkArts

You may have to be a bit iterative as it's a fiddly job inserting shims, not to mention getting or making shims of the right thickness.

Get a big flat screwdriver and jam it in between the glass and the corrector cell. Rotate it until you compress the shim opposite the glass and drop your cardboard shim in between the corrector and the cork shim. Repeat opposite, then do the quarters, then do the eights, always one in opposite pattern, like when you bolt a big flange in a star pattern. Do this flat scope pointing up. Do not drop anything on your primary and make sure your secondary is secured and in position. Most importantly do not overtighten the retaining ring when you're done, and screw it back in a star pattern again before securing it. Touch not tighten.

[wayne anderson (Wayne)]

Thanks everyone for the detailed advice it is very much appreciated, this weeks project will be to fix it using the information you provided.