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Speaking of restoring equipment temperature...bringing stuff in from the cold.

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#1 JimFR

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Posted 19 November 2017 - 08:03 PM

I have a rule with all of my astro equipment, and my cameras and electronics too.  Before I bring them in from the cold, everything gets bagged in plastic and I let it reach room temp in the bag to prevent condensation.  If I left them exposed, moisture would find it’s way onto and into them and condense on all the external and internal parts. If I bagged them indoors, even the short transition would be enough to get a lot of moisture on them, I wouldn’t want them bagged in that condition.

 

Once they’re in I’m not using them anyway so I have no reason to have them open.  Maybe it’s a bit anal but I figure the extra few minutes I spend is worth it in terms of maintenance.

 

Are others this picky?


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#2 DLuders

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Posted 19 November 2017 - 08:10 PM

Um, no -- mainly because in the Western U.S., the Relative Humidity inside houses is usually very low in the winter.  Sometimes there is static electricity buildup from carpeting, and skin becomes dry.  It doesn't take very long for any indoor condensation to evaporate.

 

I was born and raised in Connecticut, where the Relative Humidity is a lot higher year-round. 


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#3 Don W

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Posted 19 November 2017 - 08:36 PM

Just the opposite. Bring them in and let them warm up to the inside temperature uncovered! That way the moisture that has accumulated on them will evaporate into the air in your house instead of into your plastic bags. You have it backwards, my friend.


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#4 Gipht

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Posted 19 November 2017 - 08:37 PM

I have a stocking cap over my camera right  now which is taking pictures just northeast of Prescott, Arizona. Just to guard  against any frost forming.  I leave the camera and the telescope in the garage if its cold, rather then bringing them into the warm house.   We have not had measurable rain since mid September, but just the moisture in the air when it gets cold is enough to concern me.   Last night it got down to 12 degrees F. here.  I  only lasted to about 20 degrees F.



#5 james7ca

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Posted 19 November 2017 - 08:40 PM

This gets discussed every few months here on CN and opinions differ. Probably no need to rehash this topic, it's been done many times already (search can be your friend).

 

If the humidity is high and the temperature difference is also significant (meaning cold outside) then I will "bag" my scopes in plastic before taking them inside and then I open the bags on the next morning to allow outside air to reach the optics. On other nights I just place a good dust cap over any of the exposed ends of the scope. On really bad nights I may throw a couple of packs of desiccant into the bag before it is sealed.

 

Of course, this requires that the scope is already dry before you place it inside of the bag. In the latter case you won't/can't get any more condensations inside of the bag once you bring it inside because the temperature can only go up, since the relative humidity inside of the bag can only go down as the temperature of the "bagged" air gets higher. However, if the scope is already wet when it is outside then you need to get it dry as quickly as possible and that may require different treatment.

 

As for having low humidity inside the house during the winter, during a winter Santa Ana condition in California you may have higher humidity in the house than outside, so bringing a cold scope inside may cause moisture to form on the tube and optics.


Edited by james7ca, 19 November 2017 - 09:20 PM.

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#6 M11Mike

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Posted 19 November 2017 - 08:51 PM

I agree with bringing them in UNbagged.  Bagging them in plastic confines and maintains the moisture - if can't evaporate.

 

I have a hygrometer in my upstate ny 40 year old home - have a natural gas powered boiler furnace / base board hot water heat and the humidity level in the dead of winter is like 20-25% tops!!!!  (IE. THAT'S like a desert)   VERY DRY.

 

In super low humidity levels like that - any moisture quickly evaporates into the room.

 

MP Ballston Lake, NY

 

  



#7 msl615

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Posted 19 November 2017 - 09:07 PM

I live in Fairbanks, Alaska and if it is dark outside, then it is cold. So, I need to face this all the time.  However, it is also usually bone dry here and I would love it if we could get the humidity in the house all the way up to 25% as in the previous post! 

 

So, my routine is to wrap the  OTA in a polar fleece blanket before bringing it into the house. Any moisture on the tube will slowly evaporate, and no moisture will form on it. I also use large, heavy cotton "game bags" to bag the scopes in other cases, before bringing them it.  Most of the time, it is dry both inside and outside the house, so simple bags work well.   In the shoulder seasons (Oct and April), when it is cold but the humidity is a little higher, then I more carefully wrap the OTAs with polarfleece/ cotton so that they can warm up inside without issues. 

 

Eyepieces go into their cases, warmed up and then opened up a few hours later. 

 

 

Mike



#8 GoFish

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Posted 19 November 2017 - 09:31 PM

Relative humidity is irrelevant. What we care about is dew point versus the temperature of telescope surfaces. 

 

Dew point and relative humidity are related, but dew point is the metric that counts here. 



#9 Sketcher

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Posted 19 November 2017 - 09:44 PM

Wow!  Our "experts" appear to be everywhere on this one!

 

I've given my procedure and supporting story in the past, but it does little good when others have given and will continue to give contradictory advise.

 

Frankly, many if not most on this forum (by their own admission) either live in regions where it doesn't get "cold" or they simply refuse to get out and observe when it's "cold".  How could they possibly know how to deal with "the cold"?

 

Listen to those who observe under the same (or close enough) conditions that you observe under.  Ignore the others.


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#10 JimFR

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Posted 19 November 2017 - 10:02 PM

Frankly, many if not most on this forum (by their own admission) either live in regions where it doesn't get "cold" or they simply refuse to get out and observe when it's "cold".  How could they possibly know how to deal with "the cold"?

I’m thinking in terms of sub freezing.  Like said previously, it’s about dew point, and it’s going to condense when it comes it when it’s like -10C outside so I’m asking whether others think it’s worthwhile to take the extra steps to avoid it.  I agree dew formation when outside has it’s own handling and basically a ‘hazard of the trade’.



#11 EJN

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Posted 19 November 2017 - 10:25 PM

I put everything in the oven, it gets them nice and warm and drives off all the moisture.



#12 emflocater

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Posted 20 November 2017 - 12:23 AM

I just leave all my equipment outside uncovered (if during the winter cold season) until spring usually April when it gets warmer! JK. seriously though I have always for years brought my equipment in the house uncovered with no caps etc. I let then naturally evaporate for at least 30+ minutes until I can see all my glass and or mirrors with no moisture/fog on them. Cameras a bit longer. Never had an issue or build up of of streaks due to dew/moisture. Once the glass or mirror is ambient and surface is free of moisture, I give them a good blow of air from a Rocket Bulb and then cap. I then also with a soft cotton towel wipe down the mount and tube gently and store away until next time.

Cheers

Don


Edited by emflocater, 20 November 2017 - 12:23 AM.


#13 Paul G

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Posted 20 November 2017 - 07:06 AM

I have a rule with all of my astro equipment, and my cameras and electronics too.  Before I bring them in from the cold, everything gets bagged in plastic and I let it reach room temp in the bag to prevent condensation.  If I left them exposed, moisture would find it’s way onto and into them and condense on all the external and internal parts. If I bagged them indoors, even the short transition would be enough to get a lot of moisture on them, I wouldn’t want them bagged in that condition.

 

Once they’re in I’m not using them anyway so I have no reason to have them open.  Maybe it’s a bit anal but I figure the extra few minutes I spend is worth it in terms of maintenance.

 

Are others this picky?

You're doing it right, assuming the equipment isn't already wet. I put everything back in its Pelican case, sealed like the plastic bags you use, before bringing it in. The scope I wrap in a blanket (Edit: I cap the glass outdoors before bringing it in), keeps moisture from condensing and if the tube is wet (optics are always dry since I use dew prevention heaters) it will dry off.

 

The key for the glass is to prevent dew formation to start with and then put the objective cover on before bringing the scope indoors. Cold outdoor air contains a lot less moisture than warm indoor air. For example, if the outdoor temp is 30 F with RH of 20%, the amount of water in the air is 0.39 grains per cubic foot. Indoor air at 70 degrees F, RH 40%, moisture in the air is 3.8 gr/ft3, 10x as much water vapor volume as the outdoor air. Another example, same indoor air with outdoor air at 0 degrees F 10% RH -- indoor air contains more than 75x the water vapor volume as the outdoor air.


Edited by Paul G, 20 November 2017 - 08:15 PM.


#14 geoffl

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Posted 20 November 2017 - 12:04 PM

I save the little "Silica Gel - do not eat" bags from purchased items, and store them in a screw-top jam jar. If I use my DSLR outside, a few of these go with the DSLR in a zip-lock bag, overnight. The "used" bags go in another screw-top jam jar. When the jar is full, I place the bags, spread out, on a baking tray in an oven at about 120 deg. C (250 deg. F) for about an hour to drive out the water. They go back into the first jar again, ready for re-use. If the heating is done in an oven after it has been used for cooking at a higher temperature, the cost is minimal.

 

Geoff



#15 DoctorNoodle

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Posted 24 November 2017 - 03:39 PM

We always have a humidifier going in the winter so stuff brought in from the cold would get covered in moisture quickly. I won't go as far as bagging my equipment but I will make sure all scopes and eyepieces are capped and everything is in its case before being brought inside.



#16 highertheflyer

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Posted 05 December 2017 - 01:50 PM

My favorite scope of 20 years ago was a Meade EXT 125 having an aluminum "man hole" screw-on cover.

I would allow the cover to warm over a living room lamp and when ready to bring the scope indoors, crew the cover back on.

Presto, no moisture formed indoors!

Wish they still made these jewels,

Jim


Edited by highertheflyer, 05 December 2017 - 02:07 PM.



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