Fog proofing question (1 Viewer)

[nightheron28]

I have the maven 7x28 bins that claim to be fog proof yet the left eye piece kept fogging up near the eye. It was pretty cold 30f with windchill making it feel more like 15f. It was just the eye piece that fogged. I guess what I'm asking is this normal? Its been a really long time since I used a binocular in the cold. Thanks!!

 

[Dennis Mau]

"A properly sealed binocular, especially one marketed as "fog proof," should not fog up on the inside due to its airtight design, usually filled with nitrogen gas, which prevents moisture from condensing on the internal lens surfaces; however, moisture can still condense on the exterior lenses of a sealed binocular if there is a significant temperature difference between the outside air and the binocular itself, which can be wiped away."

 

[mekidear]

I have had this problem, I think it is moisture from your eye condensing on the cold lens.
If you keep your binocular under your jacket and just pull it out when needed, it stays warmer and helps prevent this.

 

[tenex]

You are the fourth person in the last week or so to say their left eyepiece fogs more than the right, in anything from Maven to NL. I wonder why.
See recent thread: Fogging oculars...just NL's or all new production Swaros?
(and the earlier thread referenced in it)

 

[Dennis Mau]

You are the fourth person in the last week or so to say their left eyepiece fogs more than the right, in anything from Maven to NL. I wonder why.
See recent thread: Fogging oculars...just NL's or all new production Swaros?
(and the earlier thread referenced in it)

AI and it sounds reasonable.

"If the left lens of your binoculars fogs up more than the right, it's usually because of a slight difference in the distance between your left eye and the eyepiece, causing more moisture from your breath to condense on that lens due to a greater temperature difference between your eye and the colder glass; this can be exacerbated by not properly aligning the eyecups to your eye socket, leading to a more pronounced fogging on the left side."

 

[dorubird]

a hypothesis:
If the right eyepiece is held with the right hand more often by the right tube than the left one (or the left hand has tub contact with a smaller surface than the right one), then the right tube eyepiece is warmer than the left one, so fogging appears first on the left eyepiece that it is colder

 

[Maljunulo]

a hypothesis:
If the right eyepiece is held with the right hand more often by the right tube than the left one (or the left hand has tub contact with a smaller surface than the right one), then the right tube eyepiece is warmer than the left one, so fogging appears first on the left eyepiece that it is colder

Brilliant! (I think)

It doesn’t take much, just enough to raise the eye lens above the dew point. Astronomers use very gentle heat on their eyepieces.

I guess if it’s not even above the dew point, the other (colder) one would indeed fog up first.

My only reservation is how many folks hold their binocular bare-handed, and with their right hand only when the temperature is below the dew point?

 

[Dennis Mau]

Brilliant! (I think)

It doesn’t take much, just enough to raise the eye lens above the dew point. Astronomers use very gentle heat on their eyepieces.

I guess if it’s not even above the dew point, the other (colder) one would indeed fog up first.

My only reservation is how many folks hold their binocular bare-handed, and with their right hand only when the temperature is below the dew point?

I never hold my binoculars with just the right hand. I keep them around my neck with the strap and then raise them with two hands. There are very few binoculars I can use one-handed and focus at the same time comfortably.

 

[tenex]

A binocular may often be held in one hand when not viewing, and most people are right-handed, so there's a potential thermal difference, though I too would expect gloves to cancel it.

 

[mekidear]

I don't seem to get this problem with binoculars - which I try to keep warm inside my jacket as much as possible. But I have a low eye relief rifle scope which fogs up immediately in cold weather. The scope is of course completely exposed to the cold.

So this has to be something to do with the temperature of the lens and proximity to your eyes.

Does the diopter adjuster change the distance from eye to lens? This might explain one side fogging first. Also possibly the deoptre mechanism means the the flow of heat through the binocular is not the same on both barrels.

 

[james holdsworth]

Skynet becomes self aware…post 5

 

[Dennis Mau]

I don't seem to get this problem with binoculars - which I try to keep warm inside my jacket as much as possible. But I have a low eye relief rifle scope which fogs up immediately in cold weather. The scope is of course completely exposed to the cold.

So this has to be something to do with the temperature of the lens and proximity to your eyes.

Does the diopter adjuster change the distance from eye to lens? This might explain one side fogging first. Also possibly the deoptre mechanism means the the flow of heat through the binocular is not the same on both barrels.

"No, when you change the diopter on a binocular, the ocular lens itself does not physically move closer to your eye; instead, it adjusts the internal lens elements within the eyepiece to change the focus for your eye, effectively compensating for any difference in vision between your two eyes without altering the physical position of the eyepiece itself. "