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Fungus on C11 corrector plate?

catadioptric Celestron
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#1 cengell

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Posted 19 September 2020 - 08:04 PM

Hello all, I have a C11 carbon fiber OTA that I got it with my CGE and so used it for a while and so left it in a Pacific zipper bag and left it in my garage for about 6 years not thinking of Mold & Fungus getting on the corrector plate? Stupid me!

 

We last week I opened it and well you guessed it, I found fungus on corrector plate on the side of the facing the mirror? What's off there is nothing on the mirror and very little on the secondary, and nothing on the facing corrector glass, this is not the model that has Starbright coatings, so I googled and found an old post talking about "Fungus on corrector plate? in the Meade listing. So I saw an great post by Dr. Clay on making your own cleaner and so I got everything on the list all but the Kodak Photoflo 200 as it's costly and I would need to wait longer than I wanted and read that Jet Dry would work?? It only needed 2 drops so why not as right now it the corrector plate was worthless in it's current condition and to replace it is about $1K.

 

So I mixed up the list and started. I first removed the holding ring and then removed the corrector plate but it was stuck on good so I used a needle syringe and filled it up with 99% alcohol and injected around the glass in hope to loosen the seal. Well it worked!

 

Also the FastStar mounting ring was loose so need to place it where it needs to be, anyone know where that notch should be at the 12 o'clock position? 

 

So I attached 2 images a before and after pic.

 

So after using Dr. Clay's mixture it's 1000% better but when I fog the corrector plate with my breath please see my pic you can see the fungus has damaged or ate the coatings, but only when I fog the side that had the fungus issues. I even used 99% Alcohol and tried Photographic Solutions Eclipse Cleaning System Solution that has over 90% Methanol supposedly is 90+%. I put some on a cotton ball and spread it in an area and when it dried I fogged it and had no effect, no improvement.

 

So I hope if this is the best I can get it at I hope it will not be a problem unless it fogs up because of dew and plan to use a heater strip. 

 

Does anyone have a suggestion on how I can clean it better, I have some other chemicals like hydrogen peroxide, Acetone (nail polish remover) Apple Cider Vinegar (ACV) and I read that vinegar not good for glass. 

 

But anyone can suggest something else to try or is this the best I can get without stripping the coating off and have it recoated which I won't do, but any advice is very welcome.

 

Thank you

Christopher

Attached Thumbnails

  • C11 Corector Plate fungus 1-2 small.JPG
  • C11 Corector Plate fungus 2-2 small.JPG


#2 KTAZ

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Posted 19 September 2020 - 08:22 PM

Do NOT use acetone unless your goal is to continue the removal of your coatings smile.gif. I would try the 99% isopropyl straight.

 

As long as you got it cleaned up and back in the correct positions, your views should not be affected too terribly much. The best thing is to get it back together and test it.

 

I’ll let somebody else chime in on the correct rotation of the secondary since I don’t want to speculate. I hope you marked the corrector plate so that you can install it back in the same position (rotation).



#3 markb

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Posted 19 September 2020 - 08:25 PM

Is my understanding that the notch as well as the etched number on the edge of the corrector go to the 3:00 position viewed from the corrector end. This should be the side opposite the focus knob.

 

From your photos, it looks like you used hash marks around the edges. Be aware they will disappear if you use alcohol or acetone.

 

Ideally, you should have noted the position of the corrector plate within the cell, as Celestron placed them in the proper alignment position, held by the rubber gasket material, but without spacers. I believe nylon grub screws were added to the HD series design. They are no longer simply centered. If you didn't make a note of it, you'll probably be fine if it's centered.

 

Good luck on the fungus . I use an old suggestion from a photography forum, Ponds Cold cream, followed by the cleaning regimen you already did.

 

I had to clean a growth off a camera lens element and an acetone clean seem to help. There is still a small visible something left from the growth.

 

Although the manufacturers use acetone, I don't normally, since it wicks into every crack and opening, and, even if lenses are separated, evaporates so rapidly it does not seem to remove all the oils and often streaks. Just my personal experience.

 

EDIT don't use nail polish remover under any circumstances, usually has additives including oils.

 

If you're going to use acetone, which is said to be safe on glass and coatings, get pure acetone solvent from a hardware store.

 

Your photos look more like streaking from solvents or cleaners than from any organic material that was removed. Usually that looks like thin tree branches in shape.

 

I don't use drugstore isopropyl alcohol since it seems to leave a residue, I've used a couple of 190 proof ethanols and they vary in quality, 190 proof everclear has also worked well for me. Lab grade isopropyl alcohol will be fine as well, it is used in most of the commercial cleaners including Zeiss cleaning fluid which is 5% isopropyl alcohol and 95% distilled water per the MSDS.


Edited by markb, 19 September 2020 - 08:35 PM.


#4 cengell

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Posted 19 September 2020 - 08:41 PM

Thanks KTAZ, I understand that acetone could remove what's left in the glass coating. I already did tried 99% isopropyl Alcohol and it had no effect

what so ever.

 

I think I can get the corrector very close to where it was before I removed it, I did mark and took pics before I removed it.

 

Maybe some of the coatings experts can help advise me on this? What's funny is when I reflect light on the underside of the corrector glass there is not coloring from coatings, so maybe the standard C11 non-Starbright coatings, so maybe the fungus just ate the surface of the glass but I can't see or feel any surface issues, so maybe there is a thin coating?

 

Thank you all that respond.

 

Christopher



#5 cengell

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Posted 19 September 2020 - 08:57 PM

Thank you markb, those harsh marks are around the outside rim is from the seal and since the outside ring covers that I did not try to clean that, as well it should help me to recenter the corrector back to where it was placed. 

 

Thank you for the "I use an old suggestion from a photography forum, Ponds Cold cream" info what does the Ponds Cold Cream do, I see there is Pond's Cold Cream Cleanser, and I would guess I would put on if it on the corrector plate to clean and moisturizes the coatings? So any more info would be very much appreciated to know more.

 

I agree I will not use acetone even it says acetone only, but I will not use it!

 

When I am ready to reinstall I will use Ziess lens wipes to clean the glass the best I can.

 

Thank you very much markb.

 

Christopher



#6 markb

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Posted 19 September 2020 - 09:14 PM

Pure acetone is okay to use on glass removed from the telescope, just I personally find that I usually follow with an alcohol-based cleaner to avoid streaking issues and to remove residual oil that the acetone may not lift.

 

I have no clue why the pond's Cold cream seems to work, probably has something to do with the organic makeup of the infestation. I've never tried to substitute anything other than the original ponds Cold cream.

 

It's not to moisturize, just to interact with the organic matter and help remove it. I always use as little as possible, and it will require care to remove since it has some kind of oil base. In the past I've used a dilute soap solution followed by the solvents discussed. Any time I use a water-based soap solution, I do a thorough distilled water rinse and I blot dry, without wiping. 

 

I have skipped using the Ponds entirely, and gone with acetone followed by alcohol cleaning. Since the damage left by the infestations can vary, it's hard to compare one experience to another.

 

 

 

Best of luck.



#7 Oregon-raybender

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Posted 19 September 2020 - 09:38 PM

The fungus could have stained the coating enough almost etching it. Chemicals may not clean the surface. Acetone is fine on

overcoating for correctors but won't work on fungus. Based on the images you have the corrector off the cell, hoping you marked

it with a clocked position. So when you put it back it's in the same position.

 

Now for the cleaning, my guess that's it is etched. That being said I have a strange and special suggestion to try. Try using

white toothpaste. Before everyone falls off their chairs, this is the same as using the chalk method. Chalk has been used for

over a 150 years for cleaning surfaces before coating, ( I used it to clean NASA optics) like spray silver (see the Oregon's TM group forum). My suggestion of white toothpaste because has chalk in the mix, calcium carbonate. Tom's of Maine has it listed. I would place a dab of it on a cotton swab. In a area, about a 12mm in from the edge, look at the area visually, in reflection as shown in your images. Remember the amount of the stain. Slowly and with light pressure (try more if needed) make small circles about 5mm to 10mm. Do this for 15-20 secounds, moving about, staying within the zone. Wipe clean with distilled water and cotton cloth. Dry and Inspect the area, look for improvement. If there is none, chances are the surface is etched.  The toothpaste should not effect the overcoating if it's intact. If the coating is damaged, it may flake off.  So I will suggest caution if you decide to go forward with the process, it is difficult to explain enough over the WWW. You are mechanically removing a stain. 

 

Removing a AR (MgF2) is difficult and NOT worth the effort, the process involves harsh chemicals and heat . The corrector will need to be replaced. 

 

I am sure there will some very interesting methods offered, try them.

 

Keep us posted, I am sure folks would like to know what happens.

 

Starry Nightswaytogo.gif



#8 Michael Harris

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Posted 21 September 2020 - 09:18 PM

The alignment notch in the secondary mirror holder aligns at the “3 o’clock” position as viewed from the front of the telescope, with the dovetail at the bottom. This aligns with the little serial number on the corrector plate. At least in older scopes the mirror, corrector, and secondary mirror were all matched with the same number and big marks at that position to facilitate alignment. The Arkansas All Sky Observatory has a nice formula for corrector plate cleaner that is mainly distilled water, Windex, and 90% isopropyl alcohol, all filtered before use.

http://arksky.org/as...cleaning-system


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#9 KTAZ

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Posted 21 September 2020 - 11:11 PM

I asked around a bit and I was mis-informed...acetone will not likely harm your corrector coatings. The problem with acetone is that it will dissolve other stuff; paint, grease, even some plastics.

 

So be darn careful with it if you decide to use it.


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#10 robodan

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Posted 22 September 2020 - 12:23 AM

What I do to prevent fungus is have a dessicant cap and put 2 or 3 Silica Gel Sachets packs in the cap.


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