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Warm Eyepieces

Started by Dan McConaughy , Jan 15 2013 11:46 PM
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36 replies to this topic

#1 Dan McConaughy

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Posted 15 January 2013 - 11:46 PM

What are the benefits of keeping eyepieces warm? Are there any disadvantages?

#2 Scanning4Comets

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Posted 16 January 2013 - 12:06 AM

Keeps dew off them.

Cheers,

#3 Starman1

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Posted 16 January 2013 - 12:07 AM

Well, actually warm might not be a good idea if you're going to pull them out to use at 0F. But warmer than the dewpoint/frostpoint is not a bad idea so the proximity of your warm, moist, eye doesn't cause immediate fogging.
You can accomplish that by merely keeping them in a case until used.

#4 Astrojensen

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Posted 16 January 2013 - 03:47 AM

If you're outside for a few hours or so, you'll need some kind of heat source in the case. I always observe from home and have many eyepieces, so I usually keep a couple inside, on top of the electric heating element. Nice 'n toasty! And stay free from dew for a while.


Clear skies!
Thomas, Denmark

#5 SteveTheSwede

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Posted 16 January 2013 - 03:53 AM

When I observe from home I also keep them idoors (though not on a heater :) ). Also I tend to keep 2 ocular in my jacket pockets which keep them warm enough in the winter. Of course you need lots of pockets if you use lots of eyepieces.

#6 Sarkikos

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Posted 16 January 2013 - 07:01 AM

I've never bothered to heat the eyepiece case. Doesn't seem necessary to me. In fact, I don't think it is necessary. I've never seen an eyepiece fog up in transit from case to focuser. I keep the case closed until I need to take an eyepiece out. When one is in the focuser, I wrap a dew strip around it. If I take an eyepiece out of the focuser but I plan to use it again soon, I put it in the focuser rack with a cap on top of the eyepiece. No dew problem at all.

Mike

#7 Jon Isaacs

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Posted 16 January 2013 - 08:14 AM

I've never bothered to heat the eyepiece case. Doesn't seem necessary to me. In fact, I don't think it is necessary. I've never seen an eyepiece fog up in transit from case to focuser. I keep the case closed until I need to take an eyepiece out. When one is in the focuser, I wrap a dew strip around it. If I take an eyepiece out of the focuser but I plan to use it again soon, I put it in the focuser rack with a cap on top of the eyepiece. No dew problem at all.

Mike


I have never tried heating my case, I just keep it closed. Maybe it would help when it's cold and it's close to the dew point and the eyepieces are fogging up. Generally it is so dry that I see static electricity sparks whenever I touch anything but sometimes eyepiece fogging is a problem, particularly with friends. Seems less cumbersome that a dew heater.

I suspect Thomas on his island in the Baltic sea and Steve the Swede probably see colder conditions that most of us do so maybe they are onto something.

Jon

#8 Dick Jacobson

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Posted 16 January 2013 - 08:51 AM

I keep my eyepieces in a little 6-pack or lunch sized Coleman cooler. This keeps them reasonably warm, dry, and clean without an additional heat source. I made a little rack out of hardboard with six 2-inch holes to keep the eyepieces standing upright. An alternate rack has four 2-inch and three 1.25-inch holes. The rack sits in the bottom of the cooler supported by four bolts. If you need additional heat you could throw in a chemical hand warmer, but I haven't found this necessary.

#9 Sarkikos

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Posted 16 January 2013 - 09:04 AM

A dew heater with dew strips is essential here in dewy Maryland, unless you want to bother with constantly wiping off the lenses or blasting them with a hair dryer. Dew will form eventually most nights on eyepieces when they are in the focuser. That's where the dew forms. I've never had an eyepiece dew up in the case.

In my area, you could go to the trouble of keeping eyepieces nice and toasty in the eyepiece case. But what's the use? You put one in the focuser, and on many nights, that eyepiece will be dewed over within an hour or so anyway. Heating the case seems like an exercise in futility to me. I would not bother with it. You want heat at the eyepiece while it's in the focuser! Heating it anywhere else is a waste of time.

Mike

#10 t.r.

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Posted 16 January 2013 - 09:09 AM

Oh, I thought the topic was about "coffee tones" again! :p :lol:

#11 Sarkikos

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Posted 16 January 2013 - 09:12 AM

That's what I thought, too. Otherwise I might not have bothered.

:grin:
Mike

#12 kevint1

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Posted 16 January 2013 - 09:19 AM

I was out the other night in cold weather. The scope and eyepieces went from about 60 deg F to 20 and the scope needed quite a while to cool down. I set up the scope and went inside to keep warm. When I went back out and opened the eyepiece case the eyepieces were still warm. I was wondering do eyepieces experience the same cool down issues as refractors? If true, wouldn't this apply when keeping them warm inside the house and bringing them outside when observing?

Thanks,

#13 csrlice12

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Posted 16 January 2013 - 09:46 AM

Only here will you find that part of your equipment must be cooled, while other pieces must be heated.... :shrug: :question: :whistle:

#14 dan_h

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Posted 16 January 2013 - 03:23 PM

In my area, you could go to the trouble of keeping eyepieces nice and toasty in the eyepiece case. But what's the use? You put one in the focuser, and on many nights, that eyepiece will be dewed over within an hour or so anyway. Heating the case seems like an exercise in futility to me. I would not bother with it. You want heat at the eyepiece while it's in the focuser! Heating it anywhere else is a waste of time.

Mike


In this area, if you stick a cold eyepiece in the focuser and place a dew strap on it, you will have to wait for the eyepiece to warm up before you can look through it or it may very well fog up with first peek. Won't happen if the eyepiece case is heated. I get similar problems with my binos on many nights if I don't store them in a heated location. They may stay nice and clear right up to the moment I put them close to my eyes. Then they fog up almost instantly.

(The secret to successful ice fishing? Keep your worms warm!)

dan

#15 stevetaylor199

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Posted 16 January 2013 - 05:42 PM

I have the same problem as Dan, and it's really annoying me. I'm willing to use a dew heater for my objective, finder, hand controller, etc, but I find them a bit cumbersome on many eyepieces. I've got to find a way of keeping them warm - vest pockets aren't good enough in the winter, and I guess be disciplined enough to wrap them in dew heaters. (Because you can never have enough cables hanging around. ;) )

The only other thing I can think of that could help reduce eyelens fogging under my eye is to use eyepieces with large eyelenses and/or lots of eye relief.

#16 Starman1

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Posted 16 January 2013 - 06:26 PM

And remove the eyecups to keep air circulating between your eye and the eyepiece.

#17 rfic1

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Posted 16 January 2013 - 06:33 PM

For years I have been placing hand warmers in my eyepiece case. Works great.I put one or two in the case depending which size case I use. They are cheap, usually $1 for a pair and can be found at lots of stores. You can also buy them in bulk.

#18 Sarkikos

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Posted 16 January 2013 - 08:14 PM

I attach dew strips to three points on my scope: Telrad, optical finder eyepiece and the eyepiece that's in the focuser. You can get different widths of dew strips for eyepieces and even a special double-pronged attachment to fit under the Telrad's window. I don't find them cumbersome at all, just a bit of a bother to set up in the evening. But if I'm going to be at my dark site for five or six hours, dew control is a necessity.

For the finder's objective, I've made a dew/light shield out of black foam sheeting, ProtoStar and Velcro. Doesn't make sense to wrap a dew strip around a refractor's objective when passive dew control is sufficient. That simple dew shield keeps the dew off my finder's objective all night.

I tried something similar for my Telrad, but it obstructed the view. IME, active dew control is needed for a Telrad.

Mike

#19 stevetaylor199

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Posted 16 January 2013 - 09:31 PM

Thanks for the tips gents!

#20 bigdob24

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Posted 18 January 2013 - 10:17 AM

I agree with the hand warmers.
I put two in my eyepiece box and keep the lid closed when not grabbing an eyepiece.
Its good for the whole night , I also have a dew strap at the scope for when they are in the scope.
Dan

#21 csrlice12

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Posted 18 January 2013 - 10:50 AM

So far have not been bothered with dew and have no dew strips/equipment. Not that we don't get dew here, we do occasionally. But it is usually not until just before daybreak...and I'm just not up that late (actually, I am, but only after I've been asleep, as I'm usually up before it gets light to go to work.)

#22 Scanning4Comets

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Posted 18 January 2013 - 11:17 AM

I wonder if it would help putting a hand warmer on the eyepiece by using an elastic band to secure it on the eyepiece, (the side of course), ?? Hmmmmm....Has anybody tried this?

#23 csrlice12

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Posted 18 January 2013 - 12:10 PM

That would probably cause thermals as it would be too much heat. Now, throw that handwarmer into a closed eyepiece case......

#24 Sarkikos

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Posted 18 January 2013 - 12:53 PM

All of this depends on where you observe. If you are in a dewy area - the East Coast of the USA, for instance - you really need dew control on the eyepieces when they're in the focuser. Whether or not you warm the eyepieces while they're still in the case is pretty much irrelevent. I wouldn't waste my time with it. In fact, I don't. :shrug:

Maybe farther north, heating the eyepiece case would make more sense. And out west, in the drier states of the USA, maybe dew control for the eyepieces is not needed at all.

Any observer with a little experience should know what they need or don't need in their area in terms of dew control. There's no sense having observers from different climates debate what's needed - that's going to vary from area to area.

But I know for a fact that in my area, you really need dew control at the telescope, not in the equipment box. Dew can be prevented actively or passively. For most nights here - if you're going to observe longer than just an hour or so - you better have active dew control on an eyepiece in the focuser, the eyepiece of the finder, and the Telrad.

Here in Maryland, a hand-warmer or two in the eyepiece case won't cut it. You best keep those hand warmers in your pocket. That's just the way it is.

Mike

#25 dan_h

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Posted 18 January 2013 - 01:51 PM

And remove the eyecups to keep air circulating between your eye and the eyepiece.


You can buy high end goggles for alpine skiing that have tiny little fans built into the sides to blow a gentle stream of air in front of your eyes to keep the goggles from fogging. Maybe that's what we need for our eyepieces!

dan
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