Cleaning SCT corrector plate

[matt]

Hi guys

Need some info on how to clean a SCT corrector plate?

Was out viewing tonight and the breeze carried some kind of gunk from a nearby tree onto the front of my scope.

Removed most of it using a camera lens cloth but there's still a very thin smeared residue.

Any threads/ links anyone's aware of?

Your help much appreciated.

[Stu]

Clean filtered water is probably the safest. But a pure alcohol will work better. Get 100%ethanol if you can. Iso-Propanol is OK but is has more % of heavier alcohols that will hang around after the propanol evaporates. I wouldn't recomend Turps or Metho for exactly this reason. Acetone is too harsh on plastics and will remove paint so I wouldn't use it because of the potential damage to the scope in the surrounding area.

Try water first.

[h0ughy (David)]

do a search on cleaning optics and you will find your answer. we covered the bintel snake oil (which is good stuff) and others in that thread

[beren]

Heres a well known one Matt , take care http://www.arksky.org/asoclean.htm

[Robert_T]

bummer Matt! just thought of another good reason to have a physical dewshield as well as the zapper. Let us know how you go cos's no doubt I'll have to deal with this sooner or later as my backyard viewing is surrounded by big gums.


cheers,

[Dennis]

Originally Posted by Robert_T

bummer Matt! just thought of another good reason to have a physical dewshield as well as the zapper. Let us know how you go cos's no doubt I'll have to deal with this sooner or later as my backyard viewing is surrounded by big gums.


cheers,

Hi Robert

I was in Sirius Optics yesterday and purchased an Orion flexible dew shield for the 10" Meade SCT which I will trim down to fit the C9.25. The inside is a flat black compared to my glossy Celestron dew shield.

Gee, Ron had some nice gear in the shop! He showed me one of the Orion soft, padded cases for the C9.25 OTA. It looked well made and well padded. If I hadn't made my wooden box, I might have purchased one.

I also forgot to turn on my Kendrick system the other night, and ended up getting a little dew before I realised my mistake. Turning the control unit up to max cleared the corrector in about 5 minutes.

Cheers

Dennis

[matt]

Rob

Had a little try last night with "hama" brand Optic cleaner (German) and supplied lens tissues.

Appears to have removed the original crud but I noticed there's some form of dark purple smearing as a result. I'm hoping that's just alcohol residue from the cleaner not being pure enough and ideally suited to SCT optics and that I've not smudged/ moved around the plate's coatings??? I seem to recall they were of a dark purple colour too.

Anyone know if that's possible? Can coatings be dissolved and moved around on the surfacee of the plate or am I just seeing residue from the alcohol-based optical cleaning fluid?

Anyway. There don't appear to be any scratches which was my big concern.

I'm going to have another try with distilled water, isopropyl alcohol (90%+ pure) and some surgical cotton/ unscented kleenex to see if I can get it completely clean.

And then ... if I'm lucky and the problem's fixed, I'm not going to set up the 9.25 in the same spot ever again. That's a promise I've made to the Gods of Astronomy if they let me off the hook this one time

[matt]

Thanks guys

By the way Houghy ... have ordered the Bintel "snake oil" today. They're still at work in Sydney on Xmas Eve.

Talk about Santa's little helpers!

[h0ughy (David)]

Originally Posted by matt

Thanks guys

By the way Houghy ... have ordered the Bintel "snake oil" today. They're still at work in Sydney on Xmas Eve.

Talk about Santa's little helpers!

Thats great Matt, I use it too it was supposed to put hair on my chest but rubbed some on my hands and my face, well you can see the result in the avitar!

[rumples riot]

Matt, NO, no no. Cleaning Corrector plates should only be done once every 3-6 months. Do not use the method you used this time again. You might damage your corrector plate.

Procedure.

1. use hurricane blower over the entire plate first. Do this until all the loose dust is removed.
2. Use a blush brush to remove any fine particles.
3. use a spray of IPA solution, place directly onto a cotton wool bud. Clean a small section at a time going in a circular motion. Do not use a radial pattern from the secondary out to the edge of the tube. Sections should be no great than 3 inches wide. After each wipe replace cotton wool bud with a new one. Dont reuse the same bud.
4. before IPA dries use a facial tissue (must be one without any scents or oils in it. It must be plain tissue paper) to give final clean and polish to cleaned area. Use your breath and clean tissue to take away final smears. Through out each tissue after one area is clean.
5. repeat steps 3-4 until entire corrector is clean.

Now tips on when the corrector needs cleaning.

Tree oil will not generally damage the coatings, nor will dust or pieces of gunk. Nor will it affect your viewing or imaging. Only clean the corrector when absolutely necessary. Months and months of exposure can occur before cleaning is necessary. The coatings are very resilient but each clean will degrade the coatings and potentially produce scatches on the plate. You can test your plate for scratches by shining a torch on it at an angle. The scratches will show in the light.

For a recipe of IPA solution go to CN's website which has the formula in the articles section.

Sorry I was so terse, but you need to stop cleaning your plate the way you have.

Paul

[astronut (John)]

Or you could use 600 wet/dry paper, just don'T rub too hard, just kidding
Merry Christmas and a Happy New Year everyone. LOVE AND HUG YOUR KIDS AND FAMILY. Cheers, John

[matt]

Paul

As per my prior thread, I had to clean the corrector. I had no choice. Something dropped on it and stuck to it and when I attempted to remove it the obejct simply turned to mush.

It was too large to leave on the plate. Not much smaller than a five cent piece! I would rather I didn't have to, but didn't have a choice Paul.

Next point. As far as I can tell you're the only person who recommends cleaning in a "circular motion"? Celestron's own instruction manual and website recommend cleaning in a straight line from secondary out. So does every website and other "authority" I've read.

They all say avoid circular cleaning because it has the potential to re-contaminate the area you've just cleaned.

Celestron and all the other "experts" totally recommend 60% isopropyl alchohol with 40% distilled water as a cleaning agent.

Apart from that, the process you describe is exactly the same as what I've been doing, although I didn't give you a detailed description of what I've done.

By the way, what's IPA?

Anyway, thanks for all your suggestions

[matt]

Paul

I'm guessing IPA is isopropyl alcohol, which is precisely what I said I'd be using to clean the corrector, and which is contained in the lens cleaning fluid I initally used.

I don't think it was pure enough alcohol, though - hence the streaking.

I never re-used the same cleaning tissue.

The Bintel UHTC cleaning solution I've ordered is the precise recipe laid out by some astro "Dr" bloke in the U-S whose recipe everyone swears by.

Also, as stated in the original post, there fortunately do not appear to be any scratches.

I dunno, but I reckon all bases are covered there, and you and I are on the same page?

[acropolite (Phil)]

Matt, I don't think you'll go wrong with the Bintel snake oil. Dr Clay's recipe works, you can even mix it yourself, although by the time you buy al the ingredients it gets a bit expensive. I made up a batch of Dr Clays all singing all dancing cleaning mix (same as Bintel) and it works as stated, streak free and no damage to the coatings. BTW I think it's the minute portions of photoflo solution that help with the streak free finish.

[rumples riot]

Matt IPA is isopropyl alcohol.

I know that Celestron recommend cleaning form the secondary out, however the last time I saw this done I ended up with a scatched corrector on a brand new scope. That was the dealer's doing on my new scope. I have since had that scope replaced.

In terms of what I was saying, the corrector should never be cleaned with a cleaning cloth, whether it be a lens cloth or not. That was my main objection.

When I say circular, I don't mean in a circle, I mean go in strokes a segment at a time parrallel to the secondary out to the edge of the scope. Every article I have read on corrector plate cleaning recommends this technique. In fact Meade also recommends this process, as do many other SCT manufacturers. The reason being that tine dust particles can and do lodge themselves near the secondary or the edge section and if you were to go in a radial pattern from the secondary out the edge of the corrector you could potentially scratch the plate from one side to the next.

Anyway, my whole point was to prevent you from damaging your coatings. Having seen this done, I don't want to see anyone else do this by accident.

Paul

[matt]

Paul

Appreciate the sentiment, mate. Hope anyone encountering a similar predicament can learn from reading this.

Am still a little confused about your cleaning directions though. What do you mean by strokes which are "parallel to the secondary out to the edge of the scope"????

That sounds like starting at the secondary and moving out to the edge of the corrector? What's the starting point for each of your "parallel" cleaning strokes? Are you working top to bottom, left to right ... or how?

I'm also interested to see some these SCT manufacturer recommended cleaning methods you refer to. Please provide some links.

Thanks

[acropolite (Phil)]

Matt, clean from the inside (secondary) out radially, as in the spokes of a wheel. Look at the link Beren has posted further up the page. All is explained there. That's Dr Clay's site....he... is... the one...