Keeping Eyepieces Warm and Dew/Frost-free

Discuss telescope eyepieces.
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Arctic
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Keeping Eyepieces Warm and Dew/Frost-free

#1

Post by Arctic »


There has been a fair amount of discussion on the various astro forums about keeping eyepieces warm and free of dew.

Ideas include:

--Keeping eyepieces in your pocket (a bad idea from my experience due to dirt and dust).

--Keeping eyepiece cases closed to protect eyepieces from radiant heat loss/condensation (this works fine in milder conditions or drier conditions, but not in deep cold, damp nights, or during extended observing sessions.

--Using eyepiece heaters (seems to be a pain -in-the-a** when you are constantly changing eyepieces.

So, this is what I am going to try: I'm purchasing a small (12"x15"), cheap heating pad used for sore muscles/arthritis, etc.--and placing over my eyepieces in the open case. I'm guessing the radiant heat, on a low setting, will solve the problem of dewy, frosty, and foggy glass.
Gordon
Scopes: Meade LX10 8" SCT, Explore Scientific AR102 Refractor on ES Twilight 1 Mount, Oberwerks 15X70 Binos, Nikon Action Extreme 10X50 Binos.
Eyepieces: ES 68* 24mm, ES 68* 20mm, ES 82* 11mm, ES 82* 8.8mm
Observing: Messier Objects--110/110, H1 Objects-- 400/400. Hundreds of additional NGC Objects. Significant Comets: Kohoutek, West, Halley, Hyakatake, Hale-Bopp, McNair, Neowise. Transits of Mercury and Venus.
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#2

Post by notFritzArgelander »


Your idea will work.

I’m dedicated to the use of a pocket though. I have a dedicated observing vest whose pockets are kept clean and lint free.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#3

Post by UlteriorModem »


Nothing wrong with keeping them in your pocket as long as you have the caps on :D

Also consider this.

Tom

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Re: Keeping Eyepieces Warm and Dew/Frost-free

#4

Post by pakarinen »


You could also toss a couple of chemical warmers in the EP case. IME, they don't get hot enough to cause any damage to plastic, etc.
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#5

Post by Lady Fraktor »


When doing cold weather viewing I use a low tech hot water bottle wrapped in a thick towel for keeping the eyepieces warm.
I also tend to have one or two in a specific jacket pocket to retain heat and if it is fairly cold I use Kendrick dewheaters.
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#6

Post by Thefatkitty »


I do a combination of what nFA and UM said... a dedicated jacket under a bigger jacket, and the lenses on the inside pockets with the caps on. The coldest night I have ever been out with a scope was three years ago and it was -42C (-43F), and I had no problems.
Well, visually at least... It was so clear out and I had to try it; I think I lasted 20 minutes :lol:

All the best,
Mark

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Too much Towa glass/mirrors.

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Re: Keeping Eyepieces Warm and Dew/Frost-free

#7

Post by Refractordude »


UlteriorModem wrote: Mon Oct 21, 2019 6:35 pm Nothing wrong with keeping them in your pocket as long as you have the caps on :D

Also consider this.

I put a hand warmer in both pockets. I put my low power eyepieces in the right pocket, and high power eyepieces in the left pocket. When I upgrade to 2" eyepieces, I will put them in a small lunch box cooler with a hand warmer. The hand warmers are great for this problem.
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#8

Post by Don Quixote »


Ok.
I am confused.
Why do you need to keep them warm?
I will learn something here.
I can understand not letting them frost up, but I have never tried to keep them warm.
What am I missing? 😊
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#9

Post by Shabadoo »


I put the caps on and put them in my pockets.
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#10

Post by Arctic »


Don Quixote wrote: Tue Oct 22, 2019 4:31 am Ok.
I am confused.
Why do you need to keep them warm?
I will learn something here.
I can understand not letting them frost up, but I have never tried to keep them warm.
What am I missing? 😊
When it's cold (ie well below freezing), and especially when it's frigid (below 0 F) a cold eyepiece will quickly fog up as soon as your eye gets near it.
Gordon
Scopes: Meade LX10 8" SCT, Explore Scientific AR102 Refractor on ES Twilight 1 Mount, Oberwerks 15X70 Binos, Nikon Action Extreme 10X50 Binos.
Eyepieces: ES 68* 24mm, ES 68* 20mm, ES 82* 11mm, ES 82* 8.8mm
Observing: Messier Objects--110/110, H1 Objects-- 400/400. Hundreds of additional NGC Objects. Significant Comets: Kohoutek, West, Halley, Hyakatake, Hale-Bopp, McNair, Neowise. Transits of Mercury and Venus.
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#11

Post by Arctic »


Thefatkitty wrote: Tue Oct 22, 2019 12:39 am I do a combination of what nFA and UM said... a dedicated jacket under a bigger jacket, and the lenses on the inside pockets with the caps on. The coldest night I have ever been out with a scope was three years ago and it was -42C (-43F), and I had no problems.
Well, visually at least... It was so clear out and I had to try it; I think I lasted 20 minutes :lol:

All the best,
Haha! On the few nights when I have been out observing in that kind of cold it's been with the naked eye, typically a twinkling night with a bright winter Milky Way. The scope stays inside, and I'm soon heading back in as well to sidle up with the woodstove!
Gordon
Scopes: Meade LX10 8" SCT, Explore Scientific AR102 Refractor on ES Twilight 1 Mount, Oberwerks 15X70 Binos, Nikon Action Extreme 10X50 Binos.
Eyepieces: ES 68* 24mm, ES 68* 20mm, ES 82* 11mm, ES 82* 8.8mm
Observing: Messier Objects--110/110, H1 Objects-- 400/400. Hundreds of additional NGC Objects. Significant Comets: Kohoutek, West, Halley, Hyakatake, Hale-Bopp, McNair, Neowise. Transits of Mercury and Venus.
2017 Total Solar Eclipse
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#12

Post by pakarinen »


Arctic wrote: Tue Oct 22, 2019 1:33 pm Haha! On the few nights when I have been out observing in that kind of cold it's been with the naked eye, typically a twinkling night with a bright winter Milky Way. The scope stays inside, and I'm soon heading back in as well to sidle up with the woodstove!


Not quite the same, but the gas fireplace in my living room is a nice astro accessory to have after a cold observing session.
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I drink tea, I read books, I look at stars when I'm not cursing clouds. It's what I do.
=============================================================================
AT50, AT72EDII, ST80, ST102; Scopetech Zero, AZ-GTi, AZ Pronto; Innorel RT90C, Oberwerk 5000; Orion Giantview 15x70s, Vortex 8x42s, Navy surplus 7x50s, Nikon 10x50s
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#13

Post by Arctic »


Small heating pad is on its way, along with an Apertura Red Dwarf LED lamp for reading my IDSA. We'll see how these pan out...
Gordon
Scopes: Meade LX10 8" SCT, Explore Scientific AR102 Refractor on ES Twilight 1 Mount, Oberwerks 15X70 Binos, Nikon Action Extreme 10X50 Binos.
Eyepieces: ES 68* 24mm, ES 68* 20mm, ES 82* 11mm, ES 82* 8.8mm
Observing: Messier Objects--110/110, H1 Objects-- 400/400. Hundreds of additional NGC Objects. Significant Comets: Kohoutek, West, Halley, Hyakatake, Hale-Bopp, McNair, Neowise. Transits of Mercury and Venus.
2017 Total Solar Eclipse
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#14

Post by AntennaGuy »


Interesting. I had already been carrying eyepieces around in one of those little Igloo lunchbox coolers, mostly because it was available and it was a convenient size! But I can see now that it may offer some additional thermal benefits, and presumably would work even better if I add a high heat capacity item to it (e.g., a very well sealed jar of water) prior to taking it outside in the cold.
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#15

Post by pakarinen »


Buy one of those hot-cold microwavable "muscle ache" pads to toss in your cooler.

Now that I think about it, those might be better than chemical handwarmers for dew busting at home. The chem packs are supposed to last 6-8 hours though. Not sure a zappable pad would last long.
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I drink tea, I read books, I look at stars when I'm not cursing clouds. It's what I do.
=============================================================================
AT50, AT72EDII, ST80, ST102; Scopetech Zero, AZ-GTi, AZ Pronto; Innorel RT90C, Oberwerk 5000; Orion Giantview 15x70s, Vortex 8x42s, Navy surplus 7x50s, Nikon 10x50s
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#16

Post by stewe »


I'm wondering why none of the inventive vendors has come up with heatable eyepiece cases. I'm smelling an empty market niche here...

Last time I went out to observe (about two weeks ago, since then it has been constant overcast) my Baader Hyperion Aspheric 36mm eyepiece got somehow fogged up internally. It either could not dry up ever since (even though I heated it up) or the dew left some residue because there is a round(ish) shaped area in around the center that definitely was not there before. I do not know if/how it affects the view, but it makes me really disappointed.

So my plan is to invest only in waterproof eyepieces in the future. However, I do not yet own one. Do they really work as advertised?
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#17

Post by Arctic »


stewe wrote: Mon Nov 11, 2019 8:19 pm I'm wondering why none of the inventive vendors has come up with heatable eyepiece cases. I'm smelling an empty market niche here...

Last time I went out to observe (about two weeks ago, since then it has been constant overcast) my Baader Hyperion Aspheric 36mm eyepiece got somehow fogged up internally. It either could not dry up ever since (even though I heated it up) or the dew left some residue because there is a round(ish) shaped area in around the center that definitely was not there before. I do not know if/how it affects the view, but it makes me really disappointed.

So my plan is to invest only in waterproof eyepieces in the future. However, I do not yet own one. Do they really work as advertised?
I think they do work. I have several argon-filled Explore Scientific eyepieces, and none has ever fogged up internally, despite a WIDE range of temperatures I've used them in.
Gordon
Scopes: Meade LX10 8" SCT, Explore Scientific AR102 Refractor on ES Twilight 1 Mount, Oberwerks 15X70 Binos, Nikon Action Extreme 10X50 Binos.
Eyepieces: ES 68* 24mm, ES 68* 20mm, ES 82* 11mm, ES 82* 8.8mm
Observing: Messier Objects--110/110, H1 Objects-- 400/400. Hundreds of additional NGC Objects. Significant Comets: Kohoutek, West, Halley, Hyakatake, Hale-Bopp, McNair, Neowise. Transits of Mercury and Venus.
2017 Total Solar Eclipse
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#18

Post by patrickdives »


I have a nice eyepiece box my dad gave me for Christmas last year that has heated drawers in it. I plug it into my dew controller. It holds all of my accessories. It's not the cheapest option but I do enjoy it. https://www.wood-wonders.com/eyepiece/
Equipment: Obsession Classic 15, Televue Ethos (13, 21, 6) Televue Nagler (22, 31), Explore Scientific (6.7, 18),
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#19

Post by AntennaGuy »


patrickdives wrote: Wed Nov 13, 2019 3:02 pm I have a nice eyepiece box my dad gave me for Christmas last year that has heated drawers in it. I plug it into my dew controller. It holds all of my accessories. It's not the cheapest option but I do enjoy it. https://www.wood-wonders.com/eyepiece/
Some impressive items at that site.
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
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Re: Keeping Eyepieces Warm and Dew/Frost-free

#20

Post by patrickdives »


They have very nice items with excellent workmanship.
Equipment: Obsession Classic 15, Televue Ethos (13, 21, 6) Televue Nagler (22, 31), Explore Scientific (6.7, 18),
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