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How to deal with dew ?

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#1 [proxima]


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Posted 24 April 2005 - 11:29 AM

How does one deal with dew, or condensation, on binocular (my 20x80LW) eyepieces? This seems to be a real problem because observation is very annoying when you're obliged to clean the eyepice every 5 minutes or so.
A dew heater heater should work properly but I'm open to other ideas.

#2 Guest_**DONOTDELETE**_*

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Posted 24 April 2005 - 12:14 PM

That's a good question. I'm sure that everyone has there own technique. I carry with me a clean lens cloth to gently wipe the condensation off as needed. Very basic. It's even worse when the condensation freezes. But I don't know of a way to keep it from forming to begin with. There are anti-dew gels and sprays, but I would not use it on my bins or EPs.

#3 Rich N

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Posted 24 April 2005 - 12:33 PM

If you observe without wearing eye glasses, try rolling (moving) the eyecups down as if you did wear glasses. This will let air flow between your eye and the eyepiece.

I guess you could try making a slotted eyecup that would also allow the moist hot air to flow away from the eyepiece lens.


#4 sftonkin



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Posted 24 April 2005 - 01:26 PM

>How does one deal with dew,

I have a 12V "travelling" hair-drier that I use for eyepieces and unit-power finders. (Same thing is twice the price if it's sold as a "dew gun".)

#5 Alby


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Posted 24 April 2005 - 01:53 PM


These work great on scopes!

Stick with a sure thing!

I'm getting the binoviewer pad heaters for my binocs if the need arises.


#6 AJTony


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Posted 24 April 2005 - 07:01 PM

Living in New Jersey, I travel over 300 miles about twice a year to get to really dark skies, then find myself shut down as my 25 X 100 binos dew over. I tried various simple tricks with no good results.

So as every astronomer knows, when you have a problem, throw money into it. Therefore, I got the Hendricks heaters and controller mentioned above, plus the smaller of the two power packs sold by Orion. A lot of money, but as my maps, laptop, tripods, tables and everything else are dripping wet, my binocular lenses are clear and dry all night long.


#7 EdZ


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Posted 25 April 2005 - 08:45 AM

For binoculars, I believe the best solution is a pocket battery powered blower. $15.95 or so. Use it if you have to.


#8 HfxObserver



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Posted 28 April 2005 - 07:55 PM

Try cupping one hand over the eyepiece while the other hand grips the eyepiece, this seems to force air over the lens and provides an increase in temp. which radiates and the dew along with it, or something like that, anyway, I find that works on eyepieces from binos to regular telescope oculars. Once clear, cap and repeat with the second eyepiece.

When not in use, always cap.

This from a guy whose club built their observatory in a watershed!!! But it's dark there and the rent was cheap, not to mention probably the best weather in the province.


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