Breathing on eyepieces

[JoeP]

Recently I've found that while looking through the eyepiece, a thin layer of condensation appears, even when I'm not breathing directly onto the lens. When I move away from the eyepiece, it gradually disappears, so it can't be dew. I've found myself holding my breath while observing, which really isn't comfortable. Is there anything I could do to stop it, ideally without dew heaters? Thanks.

[Galen Gilmore]

How are you putting your eye up to the eyepiece? Keep your nose and mouth below the eyepiece. If there is still a problem than a fan blowing onto the eyepiece can help.

[John]

If your eyepieces get too cold the heat from your eye can cause them to mist up.

Try to keep your eyepieces just a bit warmer than the outside temperature such as in a pocket or in a foam lined case ?

 

[Galen Gilmore]

2 minutes ago, John said:

If your eyepieces get too cold the heat from your eye can cause them to mist up.

Try to keep your eyepieces just a bit warmer thant the outside temperature such as in a pocket or in a foam lined case ?

 

Really? That's kinda crazy actually.

[John]

Just now, Galen Gilmore said:

Really? That's kinda crazy actually.

But it works

Scopes need to be cooled. Eyepieces work fine at slightly a warmer temperature and won't mist up when you look through them.

[Charic]

I've had a similar issue with head under a towel, and not sure if its breath or just heat from the eye/socket that can  cause the issue.
To be honest I just use the towel to clear any issue, but some folk pocket their eyepieces, which keeps them a tad warmer, which might help. All my eyepieces that are in use are un-capped, and scattered around the base of the scope, as the shelf only holds three.
I need a better storage rack for the scope?

[Charic]

..I type tooooooooo slow, three before me, but nothing when I started?

And as John mentions, I too for ages found it weird that we need to cool our scopes and warm the oculars? 

[Knighty2112]

I'm currently trying this observing aid out on EP's to see if it helps them from getting misty when in the scope. Built primary to reduce LP in the eye, it seems to work for both things very well so far. Although spec'ed for 2" EPs I'm using it OK on my 1.25" ones Ok so far. One of the benefits of it too is that when using it it keeps the breath from your nose and mouth clear of the lens on the EP. 

https://www.telescopehouse.com/soft-eye-shield-for-50mm-diameter-eyepieces.html

[JoeP]

9 hours ago, John said:

If your eyepieces get too cold the heat from your eye can cause them to mist up.

But surely the heat from your eye heats the eyepiece and stops it being as cold? Why would heat from a towel or case cause any less mist than heat from your eye?

I think the problem is, at least partially, breathing. Whenever I breath out, I can see stars dim slightly, and when I then shine a torch on the eyepiece I can see mist. I'll try keeping the EP warm and see if that makes a difference.

[John]

16 minutes ago, JoeP said:

But surely the heat from your eye heats the eyepiece and stops it being as cold? Why would heat from a towel or case cause any less mist than heat from your eye?

I think the problem is, at least partially, breathing. Whenever I breath out, I can see stars dim slightly, and when I then shine a torch on the eyepiece I can see mist. I'll try keeping the EP warm and see if that makes a difference.

Breathing on them will not help of course. If the eye piece is cold it will have a tendancy to mist whenever a warmer source is near. The heated bands keep the eyepiece above ambient temperature so they don't mist. Keeping them a little warmer than outside temp has the same effect.

Eyepiece with short eye relief ( eg: plossls and orthos less than 12mm in focal length) show this more because your eye gets glose to the glass.

My shortest eye relief eyepiece has 10mm of eye relief and is a littl prone to this on cold nights.

 

[Nyctimene]

Whilst most of my scopes live in the shed at almost ambient temperature, I keep all of my eyepieces indoors, to keep them warm and dry. During breaks when observing, I always put a cap on the eyepiece (eye side) to avoid fogging and keeping the lens slightly warmer (rest heat). Sometimes in winter I carry an eyepiece or two in my coat pockets. Trying to avoid breathing at the lens surface is very important; learn to breathe downward or to the sides, or to hold your breath (some diving techniques, in my case, are helpful).

I have no experience with warming eyepieces up (by means of heat pads, electric baby bottle warmers, electric heated pet blankets....)

The famous Australian comet hunter William Bradfield used this device with success:

Stephan

[John]

The above plus an eyepatch. And hope that nobody sees .........

[Nyctimene]

The equipment of Bradfield, this very successful comet hunter (18 comets; and always the single discoverer) is shown in the video below; just for the techno guys on here. Enjoy these scopes, that might have been used in the world of "Riven"!

Stephan

 

[Paul73]

Think of condensation on glasses when you walk into a warm room from outside on a cold day.?

Stick eyepieces in a lint free pocket when not in the focuser. Eyepiece trays are a waste of time on a cold night.

I leave mine in a closed foam lined box when not using them. This works 90% of the time.

Paul

[Stub Mandrel]

Don't forget, eyeballs aren't just warm, they are moist too.

[Alien_Photons]

I wear glasses and for me I worked out that Its condensation caused by warm air being expelled from my nose. As I am basically at rest the expelled air is not forced away and rises around my nose towards the eyepiece.

I generally try and breath through my mouth as if I am exhaling cigarette smoke. For the record I gave up smoking some twelve or more years ago and put the money saved into astronomy.

[Stu]

In anything other than warm dry conditions I have taken to using an eyepiece dew strip. I normally wrap it around the top end of the diagonal including the eyepiece holder and this seems to keep the dew off whilst allowing me to change eyepieces easily.

[Louis D]

I always wear eyeglasses at the eyepiece and have never had fogging issues with any eyepiece.  I guess the eyeglass lens acts as a moisture barrier.  I also never have to clean the eye lenses of any of my eyepieces except to blow off dust particles.

If you don't like electric dew strips, you could try wrapping a chemical hand warmer around the eyepiece.  There's also microwaveable heating packs that could serve the same function.

[BeerMe]

10 hours ago, JoeP said:

But surely the heat from your eye heats the eyepiece and stops it being as cold? Why would heat from a towel or case cause any less mist than heat from your eye?

I think the problem is, at least partially, breathing. Whenever I breath out, I can see stars dim slightly, and when I then shine a torch on the eyepiece I can see mist. I'll try keeping the EP warm and see if that makes a difference.

Put a drinking glass in the freezer for an hour or two, then pour a room temperature beer in to the glass.  Condensation will form on the outside of the glass to the extent that you think it has sprung a leak.  Putting your eye close to a freezing cold eyepiece has the same effect, as the warmth from your eye is concentrated very close to the frozen glass of the eyepiece. 

Putting them in to a case or coat pocket however, introduces them to an area of air that is uniformly only slightly warmer than the ambient temperature, meaning the optics cool at a slower rate that will stop condensation from forming.

I'm guessing that eyepieces are treated differently from scope optics for that very reason - they are constantly being introduced to different variations in temperature through handling, eyes, etc.