How to Get Fingermarks Off Corrector Plate

[jeff.cotter]

...and continuing my tale of woe with my new Celestron AVX 9.25 (see my other thread on the topic).

Like probably every person first unpackaging their new SCT, I couldn't resist taking the front cover off and admiring the pristine (but not for too much longer) optics. Trouble was, I didn't put the cover back on correctly. So, later as I lifted up the OTA to fix it to the mount, I heard a soft dull thud, which I ignored (probably the cat!). As I soon discovered, this is the typical sound made by an SCT corrector plate cover falling onto the carpet (all this was indoors). After a bit of manhandling I got the OTA mounted successfully, only to then discover that some unknown person had left fingermarks on what, only minutes before, was a beautifully transparent corrector plate.

So my question to everyone is, how should I go about cleaning the corrector plate? I'm a bit worried that if I attack it with industrial-strength floor cleaner, I might damage the coatings. There are only three or four finger marks, so might I be better off just leaving them there?

Thanks everyone.

[erick (Eric)]

Jeff, go to the camera store and buy a lenspen:

https://www.lenspen.com/

Job done!

[Astro_Bot]

Originally Posted by jeff.cotter

... only to then discover that some unknown person had left fingermarks on what, only minutes before, was a beautifully transparent corrector plate.

That guy gets around, doesn't he?

So my question to everyone is, how should I go about cleaning the corrector plate? I'm a bit worried that if I attack it with industrial-strength floor cleaner, I might damage the coatings. There are only three or four finger marks, so might I be better off just leaving them there?

Do not use domestic cleaners! And only clean when you really have to (you probably don't need to right now - a few fingerprints isn't going to spoil your view).

There are some pre-made cleaners out there and some formulas for optical cleaning solutions that you can find online. When absolutely necessary, I use a mix of distilled water and isopropyl alcohol (50:50), a soft microfibre cloth and patience. To finish, I use a fresh microfibre cloth moistened with 100% isopropyl alcohol to gently remove minor streaks left by the other solution. This seems to work fine for most regular film-like build up that accumulates over months of use.

Here's some general advice for Meade, but equally applicable to Celestron. Personally, I'd avoid using Kleenex tissues as they're no softer than many lens cleaning papers, which are slightly abrasive, at least the ones I've seen. (I understand that some tissues in the USA are made with cotton, whereas ours are all-paper and, consequently, harsher). Their formula is a bit different and I've not used it.

SCT Maintenance

I have a lenspen but only use it on eyepieces as it's not as gentle as the method described above - it's easier to replace a buggered eyepiece than a buggered corrector.

Also, I accept no liability if you take my advice and bugger your corrector. The best advice is to try not to get it dirty in the first place.

[Astro_Bot]

Here's another link from my library:

Guide To Removing and Cleaning the SCT Corrector Plate

He mentions in situ cleaning as well and also seems to not mind lens papers and tissues (again, I don't use them).

[Camelopardalis (Dunk)]

+1 for diluted IPA and a microfiber cloth...a couple of my past (and present!) SCTs were bought used and being a bit OCD I cleaned the corrector plates, one of which was quite greasy

I use the Baader Wonder fluid + cloth, but the fluid is just diluted IPA (isopropyl alcohol not a pale ale ) if the prints were fresh on a pristine corrector they should lift pretty easily but don't expect a streak free finish without a lot of dedication...one of mine took several sessions but neither the prints or any streaks won't be visible through the eyepiece.

[jeff.cotter]

Thanks for the info everyone...much appreciated.