SCT corrector plate crud - when is crud too cruddy?

[Robert_T]

Calling all SCT owners. Despite my best efforts at keeping it relatively dew free and applying a bit of gentle hair dryer action after wet observing sessions, I appear to be developing some fine spotty "film" of crud on the corrector. This is also where the dew first begins to condense whenever I bring the scope out. I really have little experience of SCT's and don't know how much crud is normal, acceptable, and how often a clean is recommended. It's about the same I guess as that which collects on a typical exposed mirror surface after 6-12months of use, so I suppose it's just what happens:shrug: .

I miss my pristine slightly purple tinted corrector - sniff... should I clean or follow my own advice re mirrors that unless it's very very bad, don't touch it?

cheers,

[asimov]

I'm in the same boat as you mate. My gut feeling tells me not to touch it; it won't effect a darn thing, just like a mirror (with what happened to Daves 10" mirror in the back of my mind) backing that feeling up.

[acropolite]

http://www.arksky.org/asoclean.htm This may help.

[h0ughy]

take an image of it, post that and buy some SCT corrector cleaner snake oil from bintel:thumbsup: ! I swear by it its great stuff, and if you have arthritis rub a bit on:whistle: :P

seriously do take an image of it so that you can see the difference later. buy some microfibre cleaning cloths from OPSM or similar stores (i have 3) and use then to clean the plate. it makes a huge difference and do not press hard of rub hard either. gentle centre-out movements not circular motion.:D

[Lester]

Hi,

Don't know how cruddy is cruddy. But my 8" SCT Celestron new in mid 1970's I have cleaned it only once in all that time. Never touched either mirror, only the corrector. And you have all seen what that scope is capable of on Jupiter with Asimov.

[asimov]

Yup all bull-twang this cleaning optics every 12 mths...I'll think about it in 10 yrs time :lol:

[Robert_T]

thanks fellas. I did try and get a pic, but I haven't been able to get the right angle to really show the crud. What do you guys actually see when you look at your correctors close up and personal?

[asimov]

hard to get a good shot of the extent of dust etc. This is pretty well how I see it though.

[Robert_T]

thanks Asi, appreciate you making the effort to photo and post that. I feel better now as that looks pretty well what I see, at least the large spotting... do you see a more uniform spread of very very fine spotting when you shine light on it too?

cheers

[asimov]

Yes I do mate. Nothing to worry about yet. It looks even worse when the scope is out as the dew is forming. It's human nature to reach for that cloth or whatever to clean it I know. But my experience with terribly dirty newt mirrors tells me to not worry about it, it is not affecting my imaging. Logic prevails.

[asimov]

The worst thing an astronomer can do is shine a torch on his optics..:doh:

Throw the thing away! :lol:

[matt]

That, my friend, is one of the truest things ever said about scope optics.

Never... ever ... use a torch shining on a corrector/mirror as a guide to your optics.

I only use it (at an angle, mind you) to tell me if I'm all dewed up and it's time for bed:thumbsup:

[Robert_T]

thanks guys,much appreciated, just needed some reassurance to still my hand... it's take me a long time and bitter experience to learn to ignore in on my mirrors, corrector plates are a bit new to me and less hidden down a dark tube... I'm getting over it already:D

[matt]

Totally understand Rob.

I'm in exactly the same boat. New to SCTs and always looking at the cleanliness of the corrector.

I had my cleaned (by Bintel) early on because some serious sticky crud fell on to my corrector a week or 2 after getting it home, you might remember.

I've not touched it since. However, I do use a Hurricane blower to regularly blow off any large dust particles or small bits and pieces. But no contact with the corrector.

[acropolite]

Pollen and fingerprints can etch the coatings on your corrector plate, so if you think it's pollen, or get a fingerprint on the plate, you are better off safe than sorry. Apparently fingerprints left for longer than a few days can permanently mark your optics, the same goes for oil from eyelashes on EP's.

[Robert_T]

Aw Phil, why dya have to go and say that, just when I was getting comfy:rolleyes:

appreciate the tip though;)

[Roger Davis]

Usually I say:
If you think it's dirty leave it for a year or two, if you still think it's dirty leave it for another year, if you then think it's really dirty then ask someone else and if they think it's dirty leave it for another year.
That does not mean leave it alone if it is growing mould!!!
Your corrector looks fine! Give it another year.

[astro_nutt]

I got caught out a few months ago when I spied something oily looking on the primary mirror of my 10" dob..:eyepop: I tried to see if it was just dust...wouldn't blow off..indavertanly sneezed!!:mad2: ...had to wash the mirror..oily stuff still there..washed and rinsed about 6 times.:help: .got fed up and reinstalled the primary...:( ..thinking the worst I called Bintel...the "oily stuff" is just oxidization between the aluminium and overcoating...and it hasn't affected the image quality!!:D ...how did I find the "oily stuff"?..Yup..shined a torch on the mirror!!..So if I think it's dirty..........:whistle:
Many thanks again Roger:thumbsup: