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Leaving your telescope out

beginner equipment observing reflector
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#1 Calla1995


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Posted 16 May 2019 - 09:46 AM

Hi all,


I would like to know what the consequences are of leaving a telescope out during the night. I have a SkyWatcher Explorer 150-P with Goto SynScan built into the equatorial mount. Night time temperatures here reach around 6-9C and moisture regularly builds up on the outside of the scope when I use it. If I leave my telescope out, set up, all night, will anything bad happen to it and if so, what can I do to protect my telescope?


Many thanks!

#2 Alex McConahay

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Posted 16 May 2019 - 09:51 AM

Nope, people leave their scopes out all the time. You are fine. 


I would recommend at least a trash bag (waterproof) over the top, but open enough at the bottom to let moisture out. If dew is a real problem, some people leave a small wattage light bulb underneath to raise the temp. 


There are much better protective devices than the typical trash bag. They include barbecue covers (particularly "smoker" covers which tend to have more vertical coverage). And, of course, there are covers made especially for that purpose that can last years. 



#3 Starkid2u



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Posted 16 May 2019 - 09:59 AM

Uncovered? You're asking for trouble. Covered? Do-able but not indefinitly. Those are the quick and dirty answers.



#4 Couder


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Posted 16 May 2019 - 10:07 AM

Here is a picture of the heavy dew on one of my refractors, taken in 1998 so the quality is not good. but you can easily see what would happen if left uncovered. And this happened while we were observing!



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#5 lee14


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Posted 16 May 2019 - 10:46 AM

A heavy duty trash bag is fine, but if the scope is on a tripod it will be nearly impossible to properly seal the setup. If it's on a pier, or a pier-like extension on a tripod, you can achieve a very good seal. A large can of desiccant would be an extra bit of protection. 



#6 trapdoor2


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Posted 16 May 2019 - 10:47 AM

Considering the mess I found on my windshield this morning, I would get some kind of a cover...


I had no idea we had Condors in Alabama.

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#7 jeffreym


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Posted 16 May 2019 - 10:56 AM

Getting dew (or frost) on equipment is very common.  Just don't put anything away or in a case or a cap or cover when it is still wet.  I will leave my setup out all night (using it) and it will almost always have something on it.  I always cap the eyepiece end immediately.   If the corrector/mirror/lens is clear because the heaters were effective, I will put the lens cover on and leave it uncovered until the rest of the setup dry and then cover the whole works like Alex recommended.  If the lens is not clear, I use a blow drier (low heat) at a good distance to clear the lens before putting the lens cover on.  If that's not available, point the scope north and to the horizon some (lets not let the rising sun shine into the objective end unprotected!) until the glass is clear and then put the lens cover on and cover the rest of the setup when it is clear.  Leaving it out in the sun is fine, no different than solar viewing.  I try not to over do that as the sun will probably impact the paint and plastic over time.   I have also bagged the scope after putting the lens cover on to prevent additional moisture from getting on things, then uncover to dry it off in the sunshine before putting it away or recovering it.  Don't reuse the bag if you cover a wet scope, the inside of the bag will have a lot of moisture on it. 


#8 konrad



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Posted 16 May 2019 - 11:12 AM

I live in a great climate my Dobs (manual) sits outside under cover (lappa in RSA) and has a cover like a webber barbeque   but all electronic stuff is inside  due to condensation which gets everywhere and eventually corrodes the connections , so no dont leave a go to mount outside

#9 Napp


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Posted 16 May 2019 - 11:17 AM

Here in Florida there are nights when the dew is so heavy water drips from the tube and the mount.  When you break everything down in the morning be sure to lay out the equipment in a dry place - preferably under a/c or heat - with all caps and covers removed so all surfaces - especially optical surfaces dry thoroughly.  Once dry cap and case the equipment.  Never put the equipment away wet.

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#10 ShaulaB


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Posted 16 May 2019 - 11:57 AM

Please take heed to all the warnings about moisture accumulation in previous posts.


On a different note, are there any creatures that might mess with your equipment during the night? Four-legged or two-legged? Rodents can chew on plastic and fabric, and leave their wastes behind. Bored teenagers on summer break might visit and mess with your stuff at 3am.


Best of luck with whatever system you choose.

#11 cuzimthedad


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Posted 16 May 2019 - 04:42 PM

TeleGizmos makes really good covers for all sizes and shapes of telescopes and mounts, and for long or short term outdoor storage. If your worried about covering the scope/mount after it's dewed up, you can always put a throw away hand warmer or two under the cover with the equipment. I keep several on hand (no pun intended) while observing and when the night is exceptionally dewy I will put one in my ep case and keep the lid closed. Just enough warmth to keep the eps from dewing up when the lid is left open for several minutes.

#12 crn3371


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Posted 18 May 2019 - 02:16 PM

With a Telegizmo 365 cover I’d have no problem with leaving my scope out all night.
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#13 Sky Muse

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Posted 18 May 2019 - 03:24 PM

Waxing the telescope would offer some protection. 


Our telescopes, are, after all, celestial automobiles.

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