telescope getting wet

[ChrisLX200]

i still dont understand what scratches look like.... are they like smudges or are they sharp and precise cuts like regular scratches?

Scratches come in all sizes, a really deep one would look like you describe - sharp and obvious, but then there are the microscopic scratches caused by fine particles of grit, and if you get a lot of those (say, from a a dusty rag) then the glass will just look dull. Look close enough though and you will see myriad scratches (on aluminised mirrors it's called 'sleeking'.) However, coated glass is much harder than an aluminised mirror but the same thing can happen if you rub hard enough. If scratches are just in the coating and not the glass then there is much less of an effect (the coatings just prevent loss of a small % of light due to reflections). I;ve seen lenses with half the coating missing and they still appear to work OK when you look through them.

ChrisH

[keiwein1]

this is what i used to wipe my telescope that night 

http://imgur.com/tqJmPSr

[keiwein1]

Scratches come in all sizes, a really deep one would look like you describe - sharp and obvious, but then there are the microscopic scratches caused by fine particles of grit, and if you get a lot of those (say, from a a dusty rag) then the glass will just look dull. Look close enough though and you will see myriad scratches (on aluminised mirrors it's called 'sleeking'.) However, coated glass is much harder than an aluminised mirror but the same thing can happen if you rub hard enough. If scratches are just in the coating and not the glass then there is much less of an effect (the coatings just prevent loss of a small % of light due to reflections). I;ve seen lenses with half the coating missing and they still appear to work OK when you look through them.

ChrisH

thank u sooo much for the help! i apreciate it! thank you

[astronymonkey]

To be honest id take a pragmatic view in that what is done is done, but in line with the advice here I wouldn't do it again due to the risk of causing small microscopic scratches that can degrade the image.

Coatings are tough , as is the glass used for the corrector plate , but in future just let the corrector plate air dry but wiping the tube will be ok.

Nice scope by the way, so dont fret , just enjoy it.

Cheers

[Uplooker]

What you used and what you did with it really was not a good idea. Depending on how hard you rubbed and how dirty/dusty the cloth was, you may not have done any damage at all. As ChrisLX200 said, the coatings are quite tough. Just don't do it again, you may have got away with it this time. Next time just let it air dry

Sent from my Fone

[keiwein1]

To be honest id take a pragmatic view in that what is done is done, but in line with the advice here I wouldn't do it again due to the risk of causing small microscopic scratches that can degrade the image.

Coatings are tough , as is the glass used for the corrector plate , but in future just let the corrector plate air dry but wiping the tube will be ok.

Nice scope by the way, so dont fret , just enjoy it.

Cheers

thx!

[ChrisLX200]

Don't be frightened of cleaning the corrector when needed, it's something that has to be done sometimes. I clean my Televue refractor objective quite regularly using disposable wipes and Baader cleaning fluid. These are the wipes: http://www.amazon.co.uk/gp/product/B0001M6K24?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00They are kept in a sealed packet and one is only removed when needed, a single wipe using each side of the cloth then toss it in the bin (no re-use). No chance of picking up any grit to scratch the lens.

ChrisH

[redfox1971]

The only problem I have found if you have been caught out by a freak rain shower and who hasunt here in the uk is that ok let it air dry but it leaves a water mark on the mirror,dose this do more harm than gently wipeing clear the mirror especially with pollutants,the mirror coating will not last forever just don't clean to often and enjoy.

[keiwein1]

Don't be frightened of cleaning the corrector when needed, it's something that has to be done sometimes. I clean my Televue refractor objective quite regularly using disposable wipes and Baader cleaning fluid. These are the wipes: http://www.amazon.co.uk/gp/product/B0001M6K24?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00They are kept in a sealed packet and one is only removed when needed, a single wipe using each side of the cloth then toss it in the bin (no re-use). No chance of picking up any grit to scratch the lens.

ChrisH

thx! i will buy these ASAP

[ChrisLX200]

The only problem I have found if you have been caught out by a freak rain shower and who hasunt here in the uk is that ok let it air dry but it leaves a water mark on the mirror,dose this do more harm than gently wipeing clear the mirror especially with pollutants,the mirror coating will not last forever just don't clean to often and enjoy.

Nope, I've never been caught in the rain over the last 20 years or so, but I've had my 12" primary and secondary dew up before now (and get a coating of hoar frost come to think of it). An aluminised mirror is a whole different ball game to a lens though and it should never be wiped dry. A dirty mirror will work a whole lot better than a badly-cleaned one, and wiping the surface can easily damage not just the coatings but the mirror surface itself. So don't do it. If it has got wet then leave it so the mirror is standing vertically (so dust is less likely to drop onto the wet surface and stick) and let it dry naturally. There is a specific procedure for washing a mirror when it becomes really dirty but I'm not covering that here. Be assured though that the job needs to be done rarely, if you're a really keen observer maybe once a year. If you have been caught out with the weather and after the mirror is dry there are obvious water marks then yes, you may be forced to wash it eariler than you thought. It's preferable not to let it get rained on though... :-)

ChrisH

[Ruud]

Smaller pieces of optical glass have very hard coatings indeed. That is because they can be coated at very high temperatures. Larger lenses and corrector plates generally cannot be coated at equally high temperatures as it would cause many of them to crack due to thermal stress.

So, eyepieces have really hard coatings and will stand a lot of abuse, but you want to be much more careful with a corrector plate or your telescope's front lens. Clean these only seldom to avoid micro scratches accumulating on their surface because these will eventually dull the image of your instrument.

I regularly blow off the dust from my corrector plate and refractor's objective with a big hand blower.

The only times I need man on glass action is when I need to remove biological stains. You want to get rid of those quickly, particularly finger prints and  drops of tree sap. They are your coating's worst enemies because they contain acids and other nasty chemicals that cause damage over time if you don't remove them.

I like to be careful when cleaning optics, even eyepieces. I'm extra careful with my SCT's corrector and refractor's objective, though.

For them I use a big, forceful hand blower with a filter on the air intake. I use a new, very soft brush to gently push loose any small particles which won't be blown off at first. Then I inspect the glass with a magnifier. When satisfied that all particles are gone, I move on to non-synthetic surgical cotton balls of which I use one for each sweep, with Baader's Optical Wonder on the balls. Any liquid that remains I remove with Kleenex regular, again one sweep per tissue only. If after that, if I see any streaks I remove them by fogging the lens and wiping it dry with more tissues.

A thorough cleaning of my 4" refractor costs me plenty of cottons balls and tissues, a soft cosmetic brush, and 20 minutes or so, but the glass is just as clear as when I bought it 25 years ago, and the lens is 'as new' in every way.

I avoid non-disposable materials because you never know what has ended up in them.

[Dave In Vermont]

There are 2 things one can do about those unannounced rain-showers. One is to find a weather-site on your computer that has a link to a Doppler-radar map showing your area. Keep an eye on this. It saved my neck and anxiety-level before. One a beautifully clear day I checked the radar - and nothing in siight. So I set-up my LX200GPS 12" scope to let it acclimate. This takes a bit of work at the time. It weighs a country-ton - as does my other gear to haul.

All was well. Still clear as a bell. Then - out-of-the-blue - one big black cloud popped-up on the radar. Everything else remained clear. And, sure enough, this single black-mass was making a b-line straight for me! Nowhere else. Of course! So I didn't have time to haul my gear & scope to a dry location - that thing was truly after me at high speed! But I had a little something I had bought in anticipation of such an event: A large, blue roofer's tarp. Mine was 16' by 20' and cost me $20US. Ever price a scope-cover made for a telescope? If they put the word 'telescope' or 'astronomy' in the product-name, get ready to take out a bank-loan! So I tossed this tarp over all my gear. And part of me and my chair as I waited.

It took about 5 minutes for it to hit. Thunder & lightning all around me and buckets of water. It was a nasty, little beast! But nothing of mine got wet in the slightest.

So if you may not have enough enough time to move everything to a dry harbour - a roofer's tarp can be a great ally. And watch the Doppler.

High & Dry -

Dave

[brantuk]

If I see a cloud coming I just chuck a large cover over the gear - you can get those cheap bbq and garden furniture covers from your local garden center which are made of fabric, well ventilated, and waterproof. Or use a toilet tent ready erected and near enough to just lift over and peg down. Then get in the car till it passes - you can't see through clouds anyway lol

[HighHo]

If it helps I had my SCT rained on before, I feel asleep in the nice  warm with my scope outside capturing, there was no rain due according the the weather forecast that night. Luckily for me the object it was tracking had put my scope fairly level so no rain hit the optics (other than maybe a few specks), I just dried the outside and looked cleaner than ever!

Not quite the same story, but just wanted to share that your not the only one to have let your precious SCT occur some rain.