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Quickly remove condensation from a very cold eyepiece?

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8 replies to this topic

#1 SM881

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Posted 01 February 2024 - 10:28 PM

I am asked once in a while to run outreach for a local group. I happen to live in a cold location. During my last outreach, one of my fear occurred. Someone exhaled on the eyepiece which instantly "fogged up". The condensation had frozen on the eyepiece before I noticed it. Thankfully, it was towards the end of the session. M42 had literally doubled in size... Does any of the experienced "outreachers" on this forum can suggest a quick and effective way to remove frozen condensation (or prevent it) on an objective when the temperature is below the freezing point(by sometimes a lot).

Thank you
Sue

#2 mogur

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Posted 01 February 2024 - 10:43 PM

Just put a frosted-up EP in an interior pocket and your body heat will defrost it fairly fast. If it's just fogged, you can wave it around in the air and it will clear rapidly.



#3 SM881

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Posted 01 February 2024 - 10:55 PM

Just put a frosted-up EP in an interior pocket and your body heat will defrost it fairly fast. If it's just fogged, you can wave it around in the air and it will clear rapidly.


Hmmm, I'd be worried water vapor coming from me would frost it up even more. It was -15° C when that happened. The eyepiece would have taken a long time to warm up enough in my pocket...

#4 calypsob

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Posted 01 February 2024 - 11:01 PM

bring a kerosene heater with you and heat up a towel in a pot on top of the heater, wrap the ep in the towel.   



#5 jeffreym

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Posted 01 February 2024 - 11:41 PM

As Mogur said, you should put it in your pocket and put the extra one you had in your other pocket in the eyepiece holder.  This happens a lot around here.  I keep two backups handy when it's cold out.

 

Have fun,

Jeff


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#6 wrvond

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Posted 02 February 2024 - 01:42 AM

I am asked once in a while to run outreach for a local group. I happen to live in a cold location. During my last outreach, one of my fear occurred. Someone exhaled on the eyepiece which instantly "fogged up". The condensation had frozen on the eyepiece before I noticed it. Thankfully, it was towards the end of the session. M42 had literally doubled in size... Does any of the experienced "outreachers" on this forum can suggest a quick and effective way to remove frozen condensation (or prevent it) on an objective when the temperature is below the freezing point(by sometimes a lot).

Thank you
Sue

I use heat straps controlled by a DewBuster. A strap at the scope objective and eyepiece as well as the finder if I'm using one. The configuration changes depending on the scope being used, etc. But the upshot is, a three or four inch long dew strap is plenty to keep the eyepiece clear.



#7 Astroman007

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Posted 04 February 2024 - 11:38 AM

I set it aside for a few minutes. It will clear on its own before long. Ditto binoculars.



#8 mogur

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Posted 05 February 2024 - 11:57 AM

If it's only fogged and not frozen, I just wave it around in the air for a few seconds and it will clear up.



#9 Paul Sweeney

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Posted 08 February 2024 - 02:49 PM

Put it in a inside pocket. Have spare eyepieces handy. That way your eyepiece can defrost slowly.


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