Information needed on cleaning fungus of corrector plate

[[1ponders]]

Just recently I volunteered for the job of maintaining the C11 and Losmandy G11 mount at the Mapleton School Community Observatory. This week I completed a brief maintenance survey of jobs to do and this big one jumped out at me.

Both the inside and the outside of the corrector plate have considerable "fungal" contamination. I don't have a problem dealing with the external cleaning, but I would like to get some ideas on getting to the internal problem. The preference, of course would be to not to send the OTA away to be cleaned if this is possible.

Any ideas welcome.

Thanks

BTW the fungus is also visible on the interior walls of the OTA (doesn't seem to be as much as on the corrector) and I wasn't able to see if there was any on the the mirror due to the lighting conditions. I'll check the mirror during day light this weekend.

[acropolite]

Paul I would suggest first take the corrector plate off, noting it's orientation. Then I would try Dr Clays cleaning mixture which is safe for corrector plates, if that mixture doesn't work I'm not sure what to suggest. Dr Clays mix has Windex, IPA, Demineralised water and photoflo solution to achieve good cleaning without streaking. I've had the corrector plate of my LX90 and its a simple task, I assume it would be the same for the Celestron. Corrector removal is covered in Jan's LX90 pages http://m1.aol.com/kewtasheck/corrector.html Dr Clays cleaning recommendations are at http://www.arksky.org/asoclean.htm I'd also make 100% sure all the fungus is removed from the inside of the OTA. Good Luck.. Once you have done the job I think I have seen some SCT backplate caps that incorporate dessicant holders, might be worth hunting one up. :thumbsup:

[casstony]

You also need to note the position of any shims under the corrector that can fall out of place during removal of the corrector if you're not careful.

Tony

[allan gould]

Fungal contamination will need the application of a strong detergent and possibly containing a bleach to remove this. However the bleach may remove some coatings. Immersion in strong detergent should do it with gentle washes [copious] with distilled water

[[1ponders]]

I hear what your saying guys and I've done a bit of research as well. It appears you have to kill the fungus first or it will come back again quickly. And then you have to try to remove the dead fungi which can hang on quite tenaciously. I'm going to have a bit of a chat to the local camera repair shop as well. If i find out anything definate or if there is an industry standard I'll make sure I post it here.

I wish it did just wash off Phil. :sad:

[johnno]

Paul,

I Think I read somewhere,That direct sunlight will kill Fungus,
Perhaps a little exposure may help.

And it DEFINATELY will come back,if it is not killed totally.

Regards.
John

[Johno]

UV light will kill it. Best if you can get hold of a UV fluoro tube and give it a good long burst. That will give you a higher UV intensity per unit area than you'll get from the sun. Try getting a 40cm tube. I used to use one for erasing EPROMS many years ago.

Also note that the glass will attenuate the UV so it will only be effective on the surface facing the source.

[acropolite]

I wonder if the dead fungii will soak off after a long period of immersion and if so is it advisable to soak the corrector for long periods. It may also be worth contacting Celestron to see if they have any recommendations for removal.

[MiG]

The usual way to clean fungus off lenses is to use a 50:50 solution of ammonia and hydrogen peroxide and a cotton bud. I assume that people mean supermarket ammonia (2%) and supermarket/pharmacy peroxide (3%) :) Pure peroxide is rocket fuel, wheeee!
I used this mix today on an old multicoated Pentax lens and it is definitely coating safe.

Apparently concentrated fungus comes off like butter with this solution. I did it as a bit of a precautionary measure because I couldn't tell whether it was fungus or not. Hydrogen peroxide kills fungus and bacteria, you can use it on yourself too.

If you do use UV, make sure you use a germicidal UV tube, not just a blacklight. And stay the heck away from it.

[acropolite]

If Mig's solution works Paul you could try it on a test area where the corrector mounts cover the corrector to see if it worries the coating.

[[1ponders]]

Thanks for that Mig. I'm trying to contact YorkOptical in Brisvegas atm but they don't seem to want to answer their phones :shrug: I had another good look on Saturday and there is definately fungus down the insides of the OTA and on the mirror. Looks like a full pull apart and clean.

I've has a positive response from the Observatory Committee that it needs to be done they realise that this is part of ongoing maintenance costs of a scope in the humid subtropics so if I can find a company that will do the job at a reasonable cost that will be our preferred way.

If I can't find a company to do it (and I'm sure YO will if they can answer their phones) then it will have to be an inhouse job. As I don't have access to a UV light it looks like the Ammonia/peroxide option may be the way to go. I'm still going to try to contact YO, as I'd much rather they or someone similar do it than me. Maybe Roger D will see this thread and offer his feelings? I'm sure he's had to do it a time or two.

[gaa_ian]

Hey Paul, how did you go with this job ? We have a very mild fungal problem on the outside of our Meade LX-90 corrector plate & need to give it the treatment too.

[[1ponders]]

We ended up sending the scope away to Bintel be cleaned Ian. It needed a complete clean up of both inside and outside of the corrector and mirror. It was in a very sad state.

[gaa_ian]

So was the treatment a success ?
Is it just like new now ?

[[1ponders]]

The treatment was a success. The fungus was so bad though that there ended up being a couple of small etched patches here and there. I'm glad I sent it away, much less nerve wracking.

[gaa_ian]

Glad to hear it went well
That is such a good set up there in Mapleton, good to see it back in working order !

[astro_nutt]

Just a question..would placing a small bag with "silica gel" inside the focuser while the scope is pointing upwards help absorb any moisture while the scope isn't used??

[Roger Davis]

Sorry I missed the discussions, have been busy in areas other than astronomical!
The silica gel can be placed into an old film cannister (remember them? you know - film) after you've drilled a few holes in the bottom of the cannister and then slide it into the focuser and lock it up. You can also place some of the smaller bags onto the inside of the front dust cap with velcro so that it just misses the corrector plate. You would have to be fastidious about baking out the moisture every couple of weeks though.