SC Owners

[alan potts]

Anyone with an LX 200 or 90 and Celestron SC's. I have come to the conclusion that my secondary seems to have a yellowish colour caste without being what I would call dirty. It has a few bit of small dirt here and there as does the main mirror but no way would anyone call them dirty.

I am guessing but I think to clean this I have to remove the front cell and may as well do all of them while it's open, open scope surgery so to speak.

Any tips would be welcome as I have never done this before, what to clean them with or should I just leave it?

Alan

[Zakalwe]

Does it have a fastar secondary? If not, then yes, you will have to remove the corrector plate.

[paul mc c]

Remember to put a mark on the corrector cell and the tube so as the corrector is put back on the exact position when putting it back together.

[YKSE]

Alan,

There is an old thread here on SGL with tips from Tim and others:

http://stargazerslounge.com/topic/34629-how-do-i-clean-an-sct-optics/

[alan potts]

Zak,

No it is not fastar so it is off with the front part.

Yong,

Tim talks about Baader fluid and is cleaning the corrector plate which I will do as well but what do I clean a secondary with, I think you use a type of alcohol mixed with a little water. I have a load of micro fiber cloths are these any good for this work or should I use cotton wool?

Please bear in mind where I am, things are not that easy to get, alcohol is plentiful but the drinking type.

Alan

[Zakalwe]

Here's a good guide to doing a Celestron:

http://astronomer.proboards.com/thread/2760?page=1

[YKSE]

Alan,

There're some suggestions about fluids and cleaning material here:

http://www.lcas-astronomy.org/articles/display.php?filename=cleaning_lenses_and_mirrors&category=telescopes

http://starizona.com/acb/basics/using_cleaning.aspx

[alan potts]

I am beginning to think this is a leave alone for moment, however i would really like to hear from any members that have this or have heard of this yellowing that seems to have occured to the secondary.

It is not as if the scope has been either over used or kept in the damp or something like that, I have only really noticed it in the last six weeks or so. I just can't imagine what is happening as there is no sign what so ever of any other damage to any mirror edge and the scope is always covered in the horizonal plain. If I didn't kow better it could almost be said that it was from heavy smoking near to the surface of the mirror, I don't smoke.

Alan

[Digger1895]

You say you have only noticed it in the last 6 weeks. In that time has it got steadily worse or stayed the same?

[alan potts]

Digger sorry I didn't see you reply.

I only noticed it when I was cleaning the outside of the scope from dust, I was wearing a white shirt, it could have been like it for ages but it just don't sound or look right to me. It has not got worse and it has always been well cared for under cover and prior to indoor in a lowish humidity Country compared to England.

I have moved it to the observaory now but for about 2-3 years it has only been used from time to time, I have a good few scopes that are not as heavy.

Alan

[ollypenrice]

How are you observing the secondary? Its reflection in the primary or through the baffle tube? I'm just wondering about a possible illusion caused by reflections.

I suppose you might have some kind of fungal growth.

I took my Meade corrector off and put it back again. There was nothing to it.

Olly

[m.tweedy]

I have a similar "issue" even though it is not an issue on my 1979 C8. To be honest i have left well alone as it is not affecting any views. Nor is the small amount of foxing on the mirror.

I doubt if i could remove the corrector safely on a scope of that age anyway. The screws are probably rusted into place by now. Help keep it collomated  (how do you spell collomated?) i suppose.

[alan potts]

Olly,

It seems no matter which way I look at it it seems the same. The inside of the observatory doors are white and i looked direct down the focusing tube and I could see a slight yellowing. The odd thing is there is no other marks or even really any dust on the secondary. Trouble is I am looking for it now, I'm sure you know what I mean.

I am having difficulty getting the correct alcohol for cleaning so I know it is not too much of a job with care but I will wait until I have all the tools so to speak.

Michael,

It is nice to know i am not alone but mine is only 2007 I would have expected it to last a bit longer, still they don't make'em like they used to.

Alan

[m.tweedy]

Michael,

It is nice to know i am not alone but mine is only 2007 I would have expected it to last a bit longer, still they don't make'em like they used to.

Alan

I only acquired mine recently so don't know how long its been like that.

It had been in an observatory fork mounted for a long time before i got it.

[ollypenrice]

Isopropyl alcohol isn't essential. Distilled water and a vanishingly small droplet of detergent will do. But yellowing sounds more like oxidation of the aluminium to me. Peter Drew is a top class man on SCT issues.

Ollyu

[alan potts]

Thanks Olly,

I have not seen Peter on line for a while but I may well PM him. Not that I can do much about it but I will be a bit miffed if it is oxidation after reading and believing all the Meade advertising about their coatings. If it needs a re-coat I have no idea where to send it but I am sure there must be somewhere. When you say detergent do you mean wash powder like Persil.

Alan

[faulksy]

Thanks Olly,

I have not seen Peter on line for a while but I may well PM him. Not that I can do much about it but I will be a bit miffed if it is oxidation after reading and believing all the Meade advertising about their coatings. If it needs a re-coat I have no idea where to send it but I am sure there must be somewhere. When you say detergent do you mean wash powder like Persil.

Alan

i striped my cpc 9.25 it was a walk in the park, just mark everything up especially the corrector, whilst its striped flock it makes quite a difference. if your mirrors need re coating, this might be your excuse to get that big dob

[alan potts]

I opened her up today and gave secondary and corrector a clean, as Olly suggested it was an optical illusion it looked fine in daylight. There was not so much as a speck on the main mirror so I let it be, the seconary had a few bits on it though, so put it on a delicates wash cycle with no spin, looks pretty now.

Alan

[alan potts]

I don't believe my luck, as reported above, took the front corrector off and cleaned everything put it back and would you believe it didn't even need collimating after, that really was the last thing I expected.

Alan