Fogging inside scope

Frank Ryan · Post by **Frank Ryan** » Sun Jan 03, 2010 10:52 am

The last few nights I've used the club 10"
the inside as well as the outside of the
Ota is fogging up.
I brought it in and let it dry out but
There now appears to be beads of dried in
water left behind.
Will this need to be cleaned?
I'm sure it wont effect the viewing
that much but I am concerned with
The build up of moisture on the inside
Because of what it might do to the mirrors.

Dave Lillis · Post by **Dave Lillis** » Sun Jan 03, 2010 4:37 pm

Where is the dried in beads?, the water in itself isnt dangerous but what it can do is trap contaminant acids on the mirrors and very eventually etch it, this is why open tube dobs need recoating every 10 years or so, for SCTs its a much rarer occurance.
If its on the corrector plate, then watch out for mildew, if it forms it will etch the anti-reflective coating off it when you go to remove it.
BUT, a once off like this isnt worth worrying about, unless it was completely destroyed, how about putting up a pic of it...

Frank Ryan · Post by **Frank Ryan** » Sun Jan 03, 2010 7:01 pm

The inside is now 100% dry.
I'm concerned though with this new development.
Maybe it was always the case , just the scope has not been used
as much by the same person.
It's plainly obvious a dew shield / heater is needed for this.

Oh, and the scope was cooled sufficiently before placing outside
so it wasnt a case of taking direct from warm to freezing.
Either way, quick fogging at near 0 degrees is a pain in the A**.
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John O'Mahony · Post by **John O'Mahony** » Sun Jan 03, 2010 8:48 pm

It could be mould. Is it definitely on the inside of the corrector?

Dave Lillis · Post by **Dave Lillis** » Sun Jan 03, 2010 9:13 pm

Go to a pharmacy, get some isopropyl alcohol and surgical cotton and wipe the corrector, use allen keys to take off the corrector but for god sake make sure you put it back on in the same rotational orientation or the scope will be kyboshed!
Use a marker+stickers to mark the orientation.

Frank Ryan · Post by **Frank Ryan** » Mon Jan 04, 2010 2:13 am

Can do.
Have you done this before Dave?
I'll do it no probs but it might be
a good idea to have a second pair of hands
and someone that has done this before to get
the job done.

Dave Lillis · Post by **Dave Lillis** » Mon Jan 04, 2010 11:05 am

I've done it to my own scope numerous times and it was the second thing I did to the club scope when I got it.
I can come out during the week if you like.

Frank Ryan · Post by **Frank Ryan** » Mon Jan 04, 2010 4:56 pm

Grand thanks, I'll give you a buzz.