ICEINSPACE
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28-02-2009, 01:48 PM
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Registered User
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Join Date: Mar 2006
Location: Castle Hill Sydney
Posts: 660
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Substance on lens?
Hi.
My telrad, finder and guide scope sits next to each other on my scope.
Both the finder and guide scope have 15 - 20 cm cardboard dew shields attached.
I found a substance, like very fine sand paper, or , like a fine mist from a spray can, on the front lens of the finder and also on the telrad, but not on the guide scope? Nothing will remove the stuff, not, soap and water, kerosine, turps, metho and glass cleaner??? What's left to try, sand paper???
Any clues?
Ken
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28-02-2009, 02:00 PM
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Waiting for next electron
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Join Date: Mar 2008
Posts: 2,427
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28-02-2009, 02:14 PM
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Join Date: Feb 2009
Location: Renmark, SA
Posts: 2,993
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!!!!!!!!DO NOT USE SANDPAPER!!!!!!
Sounds like this stuff might have etched into the coating of the lens. I've heard a story where a refractor somehow had gotten insect repellant on its lens and the stuff ate into the coating, making it impossible to remove with normal cleaning agents. I think the bloke who owned it had to get it repaired.
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28-02-2009, 02:25 PM
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Registered User
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Join Date: Mar 2006
Location: Castle Hill Sydney
Posts: 660
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JOKE, SILLY, JOKE! But thanks for your reply
Ken
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28-02-2009, 02:33 PM
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Join Date: Mar 2006
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Funny, the stuff is only on the glass surfaces, not anywhere else, like on any plastic body.
Ken
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28-02-2009, 02:39 PM
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Waiting for next electron
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Join Date: Mar 2008
Posts: 2,427
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If the stuff has chemically bound to the surface coatings it may be a case of removing the old coatings and have them re-applied or swopping the lens which ever is cheapest or available. Looking at the solvents you have applied they have probably been compromised in any case. It would be interesting to know what the stuff is so the rest of us can avoid the same fate. Can you remember what you did the last time the scope was used? Or do you think it happened when the scope was in storage?
Ciao Mark
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28-02-2009, 02:59 PM
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Registered User
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Join Date: Mar 2006
Location: Castle Hill Sydney
Posts: 660
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Now that you mention it Mark, during yesterday I reinstalled the Telrad and the stuff was not there then, I have not looked at the front lens of Finder scope for a long time. It can only mean that it happened at the viewing site last night??. Towards the end of the observing session, around 11 PM, I had difficulty seeing through the Finder,I checked, and there it was, mainly on the Finder lens, the stuff, large blobs of it, 2 - 3 mm in diameter, covering the outside front of the lens. I rubbed off most of it there and then.
But also on the ext side glass on the Telrad.
Thanks for bringing that up.
Ken
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28-02-2009, 03:11 PM
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Join Date: Oct 2005
Location: Tassie
Posts: 1,104
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Quote:
Originally Posted by solissydney
JOKE, SILLY, JOKE! But thanks for your reply
Ken
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Yeah, never use sandpaper; sandblasting is way better  
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28-02-2009, 03:24 PM
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Waiting for next electron
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Join Date: Mar 2008
Posts: 2,427
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You were not anywhere near a heavy industrial plant were you? They love to pump out the nasties at night when no one can see them.
Mark
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