c14 corrector plate destroyed

[icytailmark]

my corrector plate was very dirty so i tried to clean it with a tissue and demineralised water. It has now left massive amounts of smudging.

How much does it cost for a new corrector plate for a c14?

[Hotdog]

It may be a bit premature to write it off just yet. By attempting to clean it using water alone you've probably just smeared out the oily residues that were on the surface. To remove oily contamination you need an organic solvent, I would try again using a mix of isopropanol and water (a.k.a. rubbing alcohol). Be careful not to scratch it though. Celestron have cleaning instructions on their website: http://www.celestron.com/c3/support3/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=1738&nav=0

[casstony]

At this point Mark, I'd recommend using pure cotton balls to clean the corrector with 100% Isopropyl alcohol (can be found at a pharmacy). Then clean again with cottons balls and distilled water and use folded Kleenex tissues to absorb the water droplets off the glass.

Smearing the corrector doesn't do any damage; the coatings can be scratched by dragging particles across the glass, but there shouldn't be any more particles to worry about since you've already had a go at cleaning.

[astroron]

Hi Mark, I think you are giving the Robustness of the corrector plate a bit of a bum rap.
I have had a Schmidt Cassegrain for over twenty years and cleaned it many times, without a mark on it.
I suggest that you get in touch with "BinTel" and get a bottle of their lens and plate cleaner, it works wonders.
I saw it demonstrated at AstroFest by Don Whitman a few years ago and it was just fantastic.
Slight smears on corrector plates do not degrade the image one bit.
The Schmidt 48" plate at Siding Spring get cleaned with Windex.
They get bird **** and other crap on ,and it has been working for over thirty years.
Cheers:thumbsup:

[Rod771]

Mark, sounds like all is not lost :thumbsup:

I must admit, I've been thinking of cleaning my C11 plate but the fear of damaging it makes me feel sick so I keep pretending the dust is not on it :screwy:

Thanks for the tips in this thread, good to know it can be done :)

[icytailmark]

i might just try using the demineralized water in a sprayer then wipe with cotton balls.Let it dry then use some windex and a micro fiber cloth to finish it off.

[multiweb]

Ha... I thought you broke it. Then you'd be up s||t creek. Don't worry if it's only smudges. A soft rag with bit of soapy(dish washing drop) warm water will clean it. It does have a small curve and it is a lens with a profile so don't rub it with a hard material in a concentric manner or it is possible to bugger it. Just wipe it radially from the inside out. If you keep it clean it'll be easier to keep it dew free as well.

[astroron]

Make sure the scope is facing the floor when you spray with liquid as it can seep in through the sides.
The scope is not waterproof.
Cheers:thumbsup:

[multiweb]

Just remove the corrector to clean it.

[astroron]

Mark that is bad advice in my opinion..
You don't need to remove the corrector plate to clean it unless there is dirt or any other stuff on the inside.
Just simply clean it with as little interference to the plate as possible.
If you remove the plate, there is every possibility that you would need to collemate it.
Cheers:thumbsup:

[icytailmark]

it has alot of streaks and smudges will that degrade the performance of the scope?

[multiweb]

Removing the corrector is very straight forward. Just mark where the shims are and put them back in place. If you wet the corrector in place by spraying it's very likely water will get under the retaining ring and may cause more problems in the long run. You won't have to re-collimate your scope. Only if you remove the secondary cell.

[Astro_Bot]

This came up not so long ago, so rather than type it again ... :)

http://www.iceinspace.com.au/forum/showthread.php?t=114896

[astroron]

Would you remove the Rocker cover on your car just because it was dirty:question: Of course not.
If there is NO Need to remove the corrector plate to clean it, Don't.
Three reasons not too
(1) You could drop it, then you have a useless C14 as you cannot replace it.
(2) Even doing what you said there is always the chance that it will need collamating.
3 it is much simpler to just clean it in place and not give yourself extra work.
It is a five minute job to clean it in place.
Cheers:thumbsup:

PS Water doesn't normally flow up hill so if you point the scope facing down when cleaning it the water won't seep through"Simple."

[blink138]

mark this a person who thinks he has knackered the corrector just with smudges............ do you really advise him to remove the corrector...... seriously?
pat

[multiweb]

You guys treat your SCTs as if they were some kind of blackbox. It's just like another scope. The corrector is just a big lens. It comes off and on. The only thing to remember:

1_ Put it back in the same orientation.
2_ Put the shims in the exact same spots.
3_ Make sure you have the same side facing inwards (although it's not a show stopper if you reverse it)

If it was a newt you wouldn't think twice about getting the primary out to dust or clean it (without dropping it of course). So? It pays to know a little about your scope and how it works so you don't freak out everytime there's a little smudge on the corrector or something inside. Just basic maintenance.

PS: If you need help PM me for a step by step procedure.

[Astro_Bot]

Not wanting to "take sides", but I've cleaned my corrector both in situ and removed, and it's easier to get it clean when removed. On the other hand, it's quicker to clean in situ. I suppose the choice comes down to how dirty it is (and therefore how much fluid you're likely to use) and how close to the edge you need to clean.

If removing, use common sense and keep in mind that the corrector is heavier than it looks ... but it's not especially hard to do.

[astroron]

Make sure you have the same side facing inwards (although it's not a show stopper if you reverse it)
There is only one way you can put a corrector plate in,
What are you talking about:shrug:
Back to the original point,there was a smudge on the plate, all as he has to do is clean it.
End of story
It is BS to say removing it is Easy, a 14" corrector plate is not a light weight piece of glass.
Leave it alone unless there is a really big need to take it out to clean something off the inside.
BTW I have cleaned both inside and out and the mirror as well in the last twenty odd years.
The poster of this thread sounds as though he has not got a lot of experience with SCT's, so in my opinion would be best just to clean it as normal people would, and not strip it down to clean a bit of a smudge of the front of the corrector plate.
Cheers

[multiweb]

Most Celestrons have the profile only on one side of the corrector, meaning the other side is flat. Having the flat side in or out doesn't matter.

Yes, if it is a small spot on the outside, wet a rag then wipe it off. If you want to spray the corrector It's better to take it off and give it a good wash, keep the cork/paper shims dry in the annulus.

Half a dozen screws and a retaining ring. It's easier than getting the primary off a newt.


Agreed. That's why I said to PM me if he needs any further info. Better ask than sorry.

I have documented work here (http://www.astropic.net/astro/C11/article.sub&productid=1)on my C11 with lots of pictures so you can see the guts of it. C14 is exactly the same. Just bigger and heavier. Although my C11 now is probably heavier and longer than a C14. I think it's about 25kg with the CF tube.

[icytailmark]

thanks guys for all your help. I managed to clean it without taking off the corrector plate. I just used 50% rubbing alcohol and 50% water. I then dried with cotton balls and its all clean now.

I guess i over reacted :lol:

[Merlin66]

Geee
When I read the message heading - I thought you'd dropped it !!!!

[astroron]

The secondary mirror is attached to the curved side in mine, I was not aware you could remove the secondary from the corrector plate. ?
Surely it would defeat the exercise if the curved plate was facing outward.

[Hotdog]

Short answer, no, not really. Slightly longer answer, the smudges would slightly increase scattered light and so reduce contrast but probably not so much that you'd actually notice. In the long term some types of contamination can accelerate the aging of optical coatings but we're talking time scales of years not weeks so don't panic about that.

If you do want to get rid of the smudges I really suggest you put away your spray and the demineralised water (and the Windex!), they're not the right tools for the job.

Water alone will not shift smudges, as others have also said what you need is isopropanol/isopropyl alchohol (same thing), either neat or slightly diluted. This is a gentle solvent that will shift oily marks but not damage coatings, we use it in our labs for cleaning optics all the time. Don't use domestic cleaning products, they may contain acidic/caustic/abrasive ingredients that will cause damage.

When cleaning optics you should use the smallest amount of fluid you can, the more you use the more likely you are to get residues left behind when it dries (or get fluid getting into places you don't want it like inside the tube). So, don't directly wet the corrector, instead lightly dampen a lens tissue/microfibre cloth/cotton ball and then drag that across the surface with zero or almost zero downwards pressure, moving it radially outwards from the centre. If you get the amount of fluid right the surface should dry behind you within seconds. Don't press hard and don't rub in circles. Repeat, replacing and re-wetting tissue/cotton balls as required, until clean.

Edit: And by the time I'd typed this you'd done it already, good on you.

[AndrewJ]

In words similar to Croc Dundee, "Thats not destroyed":D
I saw this very unscientific test a while back,
http://kurtmunger.com/dirty_lens_articleid35.html
and whilst its not an SCT, it shows progressively what effects dirt and "minor" scratches have by the time the light gets to the focal plane:shrug:

Andrew

[multiweb]

The deflection in the glass is in the order of 1/1000th of an inch at 80% off the center or so. It's virtually flat. The only way to identify which side is wich would be to put the corrector flat on a turning table and bounce a laser on it. Celestron used to mark the edges of the glass with a ">" sign to indicate which side faces outwards. Years ago I was talking to R.Piekiel and asked the same question, which side in. He said he saw both. Even correctors with profiles on both sides in the early models. I tried both sides on my C11 and it didn't make the slightest difference.

You have to remove the secondary to install an hyperstar cell.

[astroron]

IC, mines an older model which the secondary is as far as I know not removable.:question:
Re Hyperstar,Even more reason to clean the corrector in situe.;)
Cheers:thumbsup:

[Harb]

Just went through a similar thing.....

Just be sure you be very very careful.....

The corrector plate, primary and secondary mirrors are all a matched set, and you CANNOT buy them separately.

Regardless of how easy it is to take the corrector plate off, you are far far better off leaving it on and cleaning it while it is pointed at the ground as previously mentioned.

Whatever you use to clean it it will most likely leave cleaning marks to some degree......

Good luck

[kinetic]

Ron is correct. don't remove it to clean it!
A corrector plate is possibly matched to the mirror so it must go back in
exactly 'on the clock face' as it came out....a fact I discovered when I cleaned my 4" Cass/Mak

Steve

[Astro_Bot]

Just a quick point: correctors from both Meade and Celestron SCTs have alignment marks so that a corrector can be aligned exactly the way it was before being removed. Having done it, it adds about a minute or so to the replacement procedure to align the corrector.

Not everyone may feel comfortable with this, but I found it fairly straightforward.

[kinetic]

Yep, just be careful when tightening the lock rings too, firm but not
overtighten!

[Harb]

The late model Celestrons no longer have the mark....... :(

[Merlin66]

A couple of small pieces of masking tape applied before removal will do the same job.

[Astro_Bot]

That surprises me, unless they've stopped matching up optics, which may be the case as a cost-saving measure (and, who knows, maybe they never did and it was a marketing ploy all along ...).

Next time you have the retaining ring off, look for a small mark on the vertical edge of the corrector, rather than at the edge of the front surface - it might only be a small line drawn by permanent marker. My secondary was marked that way, whereas my corrector was more clearly marked (albeit, in my case, it hard partially worn off).

Anyway, as Ken says, you can make your own easily enough, just to be on the safe side.

[LewisM]

I am with Ron - clean in situ, but spraying is a BAD idea. REALLY bad idea. Just get some cleaner from Bintel (or mix Windex with isopropanol - you can get it at the pharmacy or Bunnings - I get it from the solvent stores at work :D). Radial strokes - centre out to edge - NEVER circular.

I cleaned the plate on the Mak and Mak Newt I had. The Maksutov was a breeze (though cleaning it revealed idiotic Chinese chinagraph/wax pencil serial/assembly number residue ON the corrector plate!), the Mak-Newt a bit of a headache since it is not a well sealed system and there was crud on the INSIDE of the corrector (I damned well don't recommend removing the corrector on a Mak Newt as it is a massively heavy chunk of glass!!!), but I managed to clean it off anyway through removing the focuser.

I have cleaned all my scopes. Never a single issue. I tend NOT to disassemble ANY of them - lesson hard learnt after shearing off a screw on an R200SS once (though I think the prior owner had cross-threaded and forced it in anyway) - drilled that one out.

[BlackWidow]

I also use this product. You can also find it on the Bay http://www.ror.net

ROR was shown to me at scope city in SanFran when picking up some cheap scope stuff when on holidays. Fantastic gear and great on the eyepiece as well. Does not leave marks at all. I use a soft lense cloth that I use once only and then discard.

I have removed my corrector for other issues and feel this should only be done if you really have to. Cleaning the outside really does not need the added risks..

Saying that, each to thier own.. If your fear it and lack confidence....Don't Do It


Mardy

[David Niven]

ASO or Arkansas Space Observatory has detailed instruction on how to clean,

http://sctscopes.net/ASO_Cleaning_System.rtf