Cleaning SCT Corrector Plate - Mixed Verdict

[DeepSkyMan]

Well... Had a go at cleaning the corrector plate on my 8" EdgeHD today with somewhat mixed results ?.  While the glass is much cleaner than before, worrisome dew stains and what looked like pollen marks removed, I am stil less than happy with the results.  When caught in the light correctly I can see streaks on the surface of the glass, no doubt left from the cleaning mixture and/or my cleaning technique.  Cleaning solution is as recommended by Celestron 60% ISO and 40% distilled water.  Also of concern is a coma shaped mark in the bottom left hand corner that I spotted prior to cleaning, and had hoped would be removed during the cleaning process. The mark can be clearly seen in the attached photo.  Difficult to know whether the mark has been reduced as a result of the cleaning, possibly wishful thinking on my part.  Would welcome some feedback from fellow members who have gone through this process, regarding my results, and also comments regarding the coma shaped mark.  Before and after photos attached.

[Alien 13]

I get marks like that on my frac and lenses, easily removed with a lens pen provided its not fungal damage.

Alan

[Luna-tic]

I notice you replaced the collimation screws on your secondary, too.

 

How many outings did it take for your corrector to get that  grimy?

[DeepSkyMan]

46 minutes ago, Luna-tic said:

I notice you replaced the collimation screws on your secondary, too.

 

How many outings did it take for your corrector to get that  grimy?

I've had the Scope since 2014, and this is the first time that I've cleaned it.  As to how many outings... well considering the abysmal weather and lack of clear skies we've had in central Scotland in recent years, not that many, possibly 10 full observing nights in the past 3 years, and maybe three times that in terms of the odd hour or so of an evening.  Having eventually summoned up the courage to do it, I believe I'll make a point of cleaning the corrector at least once a year, or perhaps more frequently if I think the level of grime merits it.

 

Regarding the collimation screws this is something I've been trying to do since I purschased the scope.  I think it's crazy having to use a pointed steel tool anywhere near a piece of optical glass. Especially if it comes to fine-tuning under dark skies.  When I purchased the Bobs Knobs 3 years ago however I encountered a problem in that the collimation screws were seized tight, can only conclude they were over-tightened by the previous owner.  Happily when I revisited this possibility just last week I found that the screws had 'unseized' themselves so took the opportunity to change them out.  Feel much happier now with the prospect of collimation (which I have yet to do), using the Bobs Knobs.

[ronin]

I have never met any cleaner, and that includes water, IPA, Acetone and others, that does not leave a residue to some extent without you going over the surface a number of times with a less and less "wet" cloth, eventually I generally end up with a dry something - cloth or bud or whatever.

Actually if you think about it a solution will have to leave something behind and whatever is left has some of the grunge in it that you are trying to remove.

Cannot help on the mark, I would actually try a cotton wool bud and pure IPA on that bit alone and see if it improves it. My potential worry is that just maybe it could turn out worse, but I cannot see how. Sort of covering myself. Actually try a simple dry cotton wool bud.

The front is just a corrector and plays some part in the optics but not a great one. So maybe just live with it.

[DeepSkyMan]

40 minutes ago, ronin said:

I have never met any cleaner, and that includes water, IPA, Acetone and others, that does not leave a residue to some extent without you going over the surface a number of times with a less and less "wet" cloth, eventually I generally end up with a dry something - cloth or bud or whatever.

Actually if you think about it a solution will have to leave something behind and whatever is left has some of the grunge in it that you are trying to remove.

Cannot help on the mark, I would actually try a cotton wool bud and pure IPA on that bit alone and see if it improves it. My potential worry is that just maybe it could turn out worse, but I cannot see how. Sort of covering myself. Actually try a simple dry cotton wool bud.

The front is just a corrector and plays some part in the optics but not a great one. So maybe just live with it.

Ronin, that's my gut feeling regarding the mark.  Can't see that it's going to make much difference to the overall optical performance, it's just severely annoying.  Might have a go with a cotton bud.  Thought that a lens pen might be worth a go as well, though not sure whether this would be appropriate on the corrector. 

[DeepSkyMan]

Thank you everybody for your feedback, but all's well that ends well, amazing what a little gentle breath and a microfibre cloth can do.  All the streaks now gone, and as far as I can tell the comma shaped mark from yesterday as well.  If you didn't know about the glass, you could be forgiven for thinking that it isn't actually there.  Procedure noted now for subsequent cleaning sessions, when completely dry, finish with breath and a clean unused microfibre cloth.

 

 

[Dave In Vermont]

My 150mm Maksutov by Skywatcher suffered some nasty, oily hand marks on the corrector-lens. So, having cleaned many optical goods over the decades, I bought Doc Clay's cleaning solution. I bought the liquid one - which can't be posted international as it contains ammonia - and went to town. I'm enclosing instructions below. The dry-type is available to you if you wish. You need to find a couple simple things to complete it.

All I can say is it worked better than anything I've ever tried. It was again 'showroom' clean with zero streaking. Excellent! I went into the operation with skepticism, and emerged thoroughly elated!

https://optcorp.com/products/opt-doc-clay-cleaning-kit-dry-version-spckit-d

The first part of these cleaning instructions is on how to assemble the solution & ingredients, but with the stuff already in hand - it's the directions for use you want:

CLEANING - DOC CLAY ASO fine optics CLEANING SYSTEM.pdf

So I'm a 'Happy Camper.'

Happy Days -

Dave