c14 corrector plate destroyed

[Merlin66 (Ken)]

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

[astroron (Ron)]

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 (Anthony)]

Originally Posted by icytailmark

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

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"
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

Andrew

[multiweb (Marc)]

Originally Posted by 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.

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 (Ron)]

Originally Posted by 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.

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

[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 (Steve)]

Originally Posted by 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

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 (Steve)]

Originally Posted by 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.

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 (Ken)]

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

[Astro_Bot]

Originally Posted by Harb

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

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 ). 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 (Mardy)]

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 (David Niven)]

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

http://sctscopes.net/ASO_Cleaning_System.rtf