Cleaning rc mirror

[pjphilli]

Hi
Advice would be appreciated on how to clean the mirror of my 200mm f8 Ritchey Chretien scope.
Cheers Peter

[gregbradley]

I can't comment on your particular scope beyond I recall someone here posting they pulled theirs apart for some reason and had a lot of trouble getting it all back together as it had packing shims etc.

I cleaned my Planewave CDK mirror. In my case its a truss design so I can stick my head inside and get access to the mirror quite easily.

I parked the OTA so it was pointing slightly downhil.

I then put a towel at the base of the mirror to catch excess water and another towel on the floor so it didn't make a mess.

I bought a garden pump up sprayer from Bunnings - something like $15.

I bought some bottles of distilled water I think from Bunnings or perhaps just even Coles.

I sprayed the mirror with the water and the air pressure spray tends to wash off loose stuff.

Now its damp. I am not sure now but I may have sprayed some Windex on it and washed it off.

Now the fine grit and dust is off, I got some clean white unscented tissues and wet them with Bintel lens cleaning fluid (its around $10 a bottle and is a very good cleaner).

I then cleaned a small section of the mirror with tissues. Then I changed the tissue. Turn the tissue over, don't wipe twice with the same spot in the tissue in case it gets grit on it.

I did this to the whole mirror. I cleaned each area as I went from the top down (so runs don't go over an area you just cleaned, start from the top and work to an area below not the other way around).

I did a bit of touch up where the cleaner wasn't fully cleaned off. I dried off any residual water.

Mirror is as clean as when I bought it except maybe one or two very minor spots.

One tip, don't image when its really windy. Its not so much the effect on your images its the amount of dust that gets on your optics. Most of the dust gets on the optics from just a few windy nights.

Try to clean it in place - not so easy with an 8 inch but if you can get your hand in there try it.

Another tip, don't work over a mirrored scope with the OTA pointing up. If you drop anything it'll hit the mirror.

Greg.

[pjphilli]

Thanks Greg for your thorough reply. I have printed your advice off for inclusion in my records and will follow it. Last Thursday I had a bigger
problem when a possum set up house in my unattended scope. See later
post! I had to take the front reflecting mirror and spider off the scope
to extract the possum which also allows me to get access to the mirror for cleaning.
Cheers Peter

[gregbradley]

Yes I saw that. It seems cleaning the mirror was the least of your problems there.

You'll have to stop putting apples in your telescope tubes:lol:

Greg.