Corrector plate coatings flaking off..

[Worzsel]

I have had my scope since May and have used it maybe 10 time. It was immactulate when I got it, no dust in the tube or anything.

I got it out yesterday and noticed that there are a few spots where it would appear that the coating is flaking off the corrector plate.. there are only a few spots and are small but they are there and are new. Is this normal ?

The mirror looks perfect and I cant see any detritus in the tube.

The scope lives in it's original box in a wooden box in my kitchen. I've never touched the corrector plate and apart from the flakes the glass is spotless except for a few dew marks which only become apparent when breathed on. It's not been put away wet or anything

I've not had a chance to look though it as I got called in to work last night and had to put it away.

Advise would be appreciated

Thanks

[barkis]

Are you sure it's the coating and not just small water stains?.

Condensation can form internally, and when it dries, it can leave marks that may prompt you to think it's the anti reflective coating shedding. My Meade SCT has little spots, but I don't consider them to be all that bothersome. Of course, you should keep an eye on yours, in case I mislead you into a false sense of security on this, I could well be wrong, and If it deteriorates further, then contact the dealer who sold you the telescope, before the warranty expires. Better still, contact him to air your worries, and tell him to make a note of your call, and what the problem is. Ask for him to supply a reference number naming the fault you are concerned about. Make a note of the time and date you called, and ask the name of the person you are speaking too.

Ron.

[Worzsel]

Well the marks are like little silvery spots. I need to look at them in daylight really to see and i'll take some photos then too.

I dont think it's water marks. It was dewey they last time i used it and i can see the water marks on it but the marks don't lok the same at all.

Thanks for your reply

[Capricorn]

Is this the anti-reflection coating ?

If so, do you mean "flaking" or "rubbed" away?

I cannot think of how an anti-reflection coating would flake, they are very thin to start with and vaporised on in a vacuum chamber.

Just a thought is it the outside or the inside?

Alternatively do you mean the silvered surface of the corrector plate?

Being honest I am puzzled!

[Worzsel]

Nothing has been rubbed off, i've not touched it at all.

I think it's on the outside but it's hard to tell.

[Capricorn]

If it is on the outside then all I can think of it something like moisture has been on it and if acidic has removed some of he layer.

It may be an illusion in that water moisture has condensed and left a little dirt behind and being non-reflective it looks as if the coating has gone but it is beneath the deposit left by the water.

In which case a clean of the front surface may be called for.

If it is the actual anti-reflection that has gone I would be surprised. However since the coating reduce the light loss from about 4% to 1% I wouldn't worry overly.

I would say that unless you can get the corrector plate out and then back in in the correct position that it is not a viable option to consider recoating it. Do know of one place that may consider it.

To find out exactly you are going to need to examine the front surface. Perhaps a magnifing glass to examine the plate would work. After that it is probably a finger (protected) on the plate to feel it, then a clean to see what if anything changes.

Still think it a bit weird.

[dweller25]

Small water marks on the coating do look a little metallic.

[Worzsel]

Righty, well i've been unable to locate my camera charger so can't post a picture. Ive been looking at it today and have come to the conclusion that it's not flaking off and it's not water marks I think it's resin from a silver birch which overhangs my observing spot

That cant be good can it

How do I clean it ?

[davew]

If this was a USA forum I think they would advise Windex and lens tissues used to dab off the resin. Have a search on cloudy nights.

I don't know if we have a direct equivalent of Windex or not.

Dave

If Peter Drew sees this he may be able to comment.

[Worzsel]

It's windolene over here i think.

I'll have a look in tesco and see. Are there special coatings on the outside of the corrector plate ? I had just assumed there was. Most window cleaners have vinegar in don't they ? wouldn't that take any coatings off ?

Thanks Dave, I'll pop over to CN and see

( and hope Peter Drew sees this!)

[davew]

Hi Sarah,

Here's one to start you off -

Telescope Reviews: Horrors! Drip on inside of corrector plate

See also - Tele Vue Optics: Cleaning Eyepiece and Telescope Optics

Also - http://firstlightoptics.com/proddetail.php?prod=wonderfluid

Give FLO a ring ?

Take care. Of you and it

Dave.

[Worzsel]

Very much appreciated Dave, thanks

I have a read when I get back from the school run.

[dweller25]

Baader optical cleaning fluid ??

[Worzsel]

Yeah I think that's the route I am going to take, I'll ring flo for a chat tomorrow and order it as it doesn't lol like they have any in stock at the moment.. Either that or 'ring for price and availability' means it's hideously expensive..

Say it isn't so!