Eyepieces misting up

[DRT]

I had my scope out for about 4 hours a couple of nights ago and by the end of the session the view from most of the eyepieces I have had a cloudly circle in the middle of the field of view. The diameter of the circle was about one quarter of the overall field. I checked the primary and secondary mirrors on the Dob and both we fine so I assume it was dew/mist on the eyepieces themselves.

Should I be keeping the lens caps on the eyepieces I am not using to avoid them collecting moisture from the air? I have an aluminium case with a foam insert that I use to store them. Should I keep them in that with the lid closed?

Any tips for keeping them mist-free would be much appreciated.

[Space Dragon]

Yep, keep them capped and in the case when not in use, some build heated EP cases.

If you keep them in an inside pocket to keep them warm that will help.

I ended up getting some dew heater strips for EPs as well, or a quick blast with a hair dryer will do it.

Basically it's the warmth and moisture from your eyeball forming on the cold glass.

[DRT]

Thanks. I was mistakenly working on the assumption that all of the optics, not just the mirrors, had to be at ambient temperature in order to perform at their best so have been leaving the caps off and having them lying in the open for hours on end, even when I am indoors having a coffee to warm up!

[brantuk]

Whilst I'm using one eyepiece, I have the next one sitting in a warm pocket till required. The one in use comes out and goes back in the case with caps on and lid closed, the pocket one goes in the focuser tube, and the next one comes out of the case into the pocket. You can rotate eyepieces all night like that so long as you plan what will be used on which object in an observing list.

If the air gets too moist and starts misting the optics, then dew bands are the solution - you can also get eyepiece dew bands. Sometimes though it gets so heavy even dew bands don't work - then I just have to pack up till the next clear spell.

[DRT]

Thanks.

Dew Bands are a new one on me. It seems that every time I ask a question here it ends up costing me money

I'll try my case and pockets first

[Space Dragon]

Thanks.

Dew Bands are a new one on me. It seems that every time I ask a question here it ends up costing me money

I'll try my case and pockets first

I thought owning a car was a money pit.....until I discovered astro gear.

[itmo]

I rotate the eyepieces through my pockets and the ones i keep in the mount's holder i keep capped. 

[Tinker1947]

Give the EP's a bit of love with a hairdryer, try not to do it on damp ground but some place dry if its a main powered dryer.....

[DRT]

I keep my scope and bits and bobs in my garage, which has the benefit that the scope is always at almost ambient temperature when I want to use it. Should I keep the eyepiece case indoors so that they start off being warm?

[itmo]

I havent seen any difference in image quality between warm and cold eyepieces, so i keep them inside and in my pocket to keep them from dewing. 

[Bart]

If you have a tray for holding eyepieces on your Dob. Try attaching a piece of camping mat foam or something similar across the top leaving enough space to accommodate your tallest EP. It has worked for me and is so simple. If you're interested I'll try to post a pic. It was a bit of a eureka moment for me

Barry

[Bart]

If you look carefully at the left hand side of the base on the 10", you'll see the EP dew shield I use. Lasts all night, no problem. You might have to enlarge the photo to see it!!

Barry

[DRT]

Thanks, guys, I'll try using that advice

[Christopher Davenport]

I find that the warmth from my eyes fogs up my EP.

So I leave them indoors while my scope cools down outside.

Then I keep them capped in my pockets.

Last resort is a blow dry'er if they get really bad.

I have seen some use hear strips on there EP's, but this costs.

Hope these tips and the ones above help.

[itmo]

Not the warmth from your eyes but the coldness of the eyepiece and moisture from your skin and eyes. 

[robhatherton]

I keep my scope in the garage so closer to ambient temperature and eyepieces in the house in a case like yours with a foam insert. I just take each eyepiece from the case when using the scope, putting the lid down on the others and swap eyepieces replacing them in the case and never have a problem with them dewing up. If I go inside fir a while I point the scope down and cap the objective lens and cap the diagonal leaving all the eyepieces in the case. The foam keeps them higher than the outside temperature and it's rare I have any dew problem.

But I do have a refractor!

[m37]

I've found a gap in the market - some sort of eye-cooling system...

[Mr Spock]

Pockets work just fine

[AstroJOE]

I've found a gap in the market - some sort of eye-cooling system...

Lol like the cooling gel eye packs you can get to wear at night that go in the fridge and help to reduce the bags under your eyes (apparently)!

[Christopher Davenport]

I've found a gap in the market - some sort of eye-cooling system...

For the DIY enthusiast out there who doe not want to spend on the ever expanding new eye-cooling systems, you could use those dry ice cooling packs from your freezer and attach it onto your face with some rubber band ... much like the expanding market in Africa for Bluetooth. 

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRKc_saj8dhsXiWRNDsOaPy8w4fumTMzmHGg-VKvLIwiSrY1AdjVA