Brief condensation on inner element of L lens

So, earlier today I went out to get a little sun after lunch with the dog. It was particularly humid today, probably 80f dew point and low 90s temperature. Like a blast furnace swamp basically, very sunny.



Camera (R8 with RF 100mm L macro) had been on the floor in its box as usual, about 20f cooler where it is. I took a few photos after a few minutes outside, and as I shot I noticed blurriness appear. Had to make sure it wasn't glasses or smudgy LCD for a second, but it wasn't.



Rear element had condensation, which went away easily enough, but it was still blurry once that was gone. Front element was fine, but I noticed condensation behind that.



So first thing, I don't expect that even an L lens is airtight and tested against something rigorous like a helium leak test. Please correct me if that's wrong. From a mechanical design and physics standpoint, I expect that the combination of uneven thermal expansion and extreme humidity allowed for greater air leakage and moisture content than normal. This then caused condensation on the cold inner and real elements.



That said, still was a bit alarming in the moment. I'm curious if this is somewhat common? I've taken this setup into similar humidity even recently without any internal element condensation that I know of (just front element). I don't really know how much air leakage should be expected, though rapid heating from the sun and heat of mostly plastic can definitely cause a temporary change in geometry that encourages leakage.



I guess I am just curious: is this seen sometimes with L lenses? Is it a very bad thing to see? Are any of my assumptions above incorrect? I am assuming that the sealing is not super robust, and I think that is probably reasonable.



Here's a picture showing the inner element at the time. It went away not too long after.

View attachment 6f4e5c2b038944c7945d1a6d32a220de.jpg

I think you're correct. Even lenses sealed against the elements aren't completely airtight. If they were, there'd be tremendous pressure from inside the lens when you changed altitude. Even a brief flight in a pressurized airplane would be problematic. Planes are generally pressurized to about 8000 feet altitude. The atmospheric pressure at 8000 feet is about 10.9 pounds per square inch. At sea level it's 14.7 pounds per square inch, so that's nearly 4 pounds of pressure per square inch over the entire interior surface of the lens. Just think of the immense pressure there would be in the front element of a large white lens. I don't think they're built for that sort of pressure.

Back to humidity. The same applies to humidity. At a dew point of 80 degrees F, the partial pressure of water is 35 mb, according to this chart. https://www.engineeringtoolbox.com/relative-humidity-air-d_687.html

That's about 1/2 PSI just for the water. Yeah, that water is getting in there. Just for comparison, this is about half the maximum pressure that a human can blow.

homebodyMacro said:

So first thing, I don't expect that even an L lens is airtight and tested against something rigorous like a helium leak test.

Click to expand...

That is correct. Imagine how hard it would be to operate if it was indeed completely airtight, when operating volume needed to change or Ambient pressure changed after it left the factory

On top of that, the air inside isn't anything special. It has moisture in it just like everything else, and condensation due to extreme temperature shocks just extract out that moisture. In most cases, when things normalize, the moisture should just get back into the air if not more of it is getting added at a high rate

homebodyMacro said:

Please correct me if that's wrong. From a mechanical design and physics standpoint, I expect that the combination of uneven thermal expansion and extreme humidity allowed for greater air leakage and moisture content than normal. This then caused condensation on the cold inner and real elements.

Click to expand...

Can be that, can just be normal air exchange (the seals are more effective at blocking water molecules than vapor in the air), or even just too much cooling of element just exposing the vapor already inside

homebodyMacro said:

That said, still was a bit alarming in the moment. I'm curious if this is somewhat common? I've taken this setup into similar humidity even recently without any internal element condensation that I know of (just front element). I don't really know how much air leakage should be expected, though rapid heating from the sun and heat of mostly plastic can definitely cause a temporary change in geometry that encourages leakage.

Click to expand...

I think humidity is just one part of it. Rapid cooling if elements is a bigger factor. Maybe the back of the lens saw a bigger differential somehow

Can be a failing seal too, but I won't jump to that conclusion yet

Victor Engel said:

I think you're correct. Even lenses sealed against the elements aren't completely airtight. If they were, there'd be tremendous pressure from inside the lens when you changed altitude. Even a brief flight in a pressurized airplane would be problematic. Planes are generally pressurized to about 8000 feet altitude. The atmospheric pressure at 8000 feet is about 10.9 pounds per square inch. At sea level it's 14.7 pounds per square inch, so that's nearly 4 pounds of pressure per square inch over the entire interior surface of the lens. Just think of the immense pressure there would be in the front element of a large white lens. I don't think they're built for that sort of pressure.

Back to humidity. The same applies to humidity. At a dew point of 80 degrees F, the partial pressure of water is 35 mb, according to this chart. https://www.engineeringtoolbox.com/relative-humidity-air-d_687.html
That's about 1/2 PSI just for the water. Yeah, that water is getting in there. Just for comparison, this is about half the maximum pressure that a human can blow.

Click to expand...

Thanks for the response! Certainly for large lenses, typical pressure changes could cause issues. And as I was getting at, I thought there was nearly 0% chance that there was good sealing in lenses, as it is impractical and would be almost impossible for large lenses with moving internals.

As far as air and gas dynamics, partial pressures are a nice accounting tool, but ultimately there's just a lot of water in the air as far as the weight fraction, and the air mix is quite homogenous and leaking continuously. Hence I mentioned the 80f dew point - there's a very nonlinear increase in weight fraction i.e. doubling from inside to outside (60f vs 80f: https://extension.psu.edu/psychrometric-chart-use ).

PicPocket said:

That is correct. Imagine how hard it would be to operate if it was indeed completely airtight, when operating volume needed to change or Ambient pressure changed after it left the factory

On top of that, the air inside isn't anything special. It has moisture in it just like everything else, and condensation due to extreme temperature shocks just extract out that moisture. In most cases, when things normalize, the moisture should just get back into the air if not more of it is getting added at a high rate

Click to expand...

I agree, like I said I have no expectation of good sealing on these. And indeed with common pressure changes it would be an incredibly impractical design envelope, particularly with moving internal elements.

Victor Engel said:

Can be that, can just be normal air exchange (the seals are more effective at blocking water molecules than vapor in the air), or even just too much cooling of element just exposing the vapor already inside

part of it. Rapid cooling if elements is a bigger factor. Maybe the back of the lens saw a bigger differential somehow

Can be a failing seal too, but I won't jump to that conclusion yet

Click to expand...

There wasn't any cooling, just a lot of warming. I actually expect that the front element fogged earlier and dissipated without me seeing, since it heated up before I started shooting a bit.

The rear element and internal element(s) would take much longer to heat up and hence I saw them fogged; the extreme 80f swamp blast was a very sudden moisture increase, meaning the cool glass caused condensation.

Given that condensation can probably cause some capture of particulate (pollution, pollen, mold) in the air, which would remain on the surface after drying, I'll try to warm up my gear more gradually in the future. I definitely don't want to encourage any mold growth over time, especially since I'm in a very humid climate.

It is quite a new lens (have had it less than 5 months), so I doubt the seal is failing. I guess I assume in this case that the conditions were just particularly bad. Also, thanks for the response, much appreciated.

What I have read in the past:

No camera lens by itself is airtight. Humidity dissolved in the air has droplets much smaller than water. It is also not an uncommon problem. Generally, it is not serious if you let the lens dry out.

The preventative way is to keep the camera/lens in an air-tight (Zipplock or similar, and they make bags for larger lenses). Wait for the lens to heat up (the problem always is going from cold to hot - you can get the reverse problem you had in winter), and then it will not act like a water magnet (like a cold drinking glass).

Usually, letting the lens stay in the warm sun for a while will fix the problem if it occurs. Another solution is to bag the lens with desiccant or warm towels from the dryer to help dry it out, but it can take hours (and several sets of towels or a lot of desiccant). Some say to add old (pre-1982 in the US) warm pennies as copper is a fungicide/algaecide. Whatever you do, let it dry out before putting it away, or you risk algae/fungus, which may require professional cleaning.

Karl_Guttag said:

What I have read in the past:

No camera lens by itself is airtight. Humidity dissolved in the air has droplets much smaller than water. It is also not an uncommon problem. Generally, it is not serious if you let the lens dry out.

The preventative way is to keep the camera/lens in an air-tight (Zipplock or similar, and they make bags for larger lenses). Wait for the lens to heat up (the problem always is going from cold to hot - you can get the reverse problem you had in winter), and then it will not act like a water magnet (like a cold drinking glass).

Usually, letting the lens stay in the warm sun for a while will fix the problem if it occurs. Another solution is to bag the lens with desiccant or warm towels from the dryer to help dry it out, but it can take hours (and several sets of towels or a lot of desiccant). Some say to add old (pre-1982 in the US) warm pennies as copper is a fungicide/algaecide. Whatever you do, let it dry out before putting it away, or you risk algae/fungus, which may require professional cleaning.

Click to expand...

Thanks for the tips - I may use a bag or just some other pre-warming method to try to avoid it.

As far as drying it out - I actually went back out shortly after and took some photos that appear totally normal. As far as I can tell the slight amount of condensation resolved mostly within 10-15 minutes. Hours sounds like a much more extreme problem ... That sounds a bit more concerning.

homebodyMacro said:

Victor Engel said:

I think you're correct. Even lenses sealed against the elements aren't completely airtight. If they were, there'd be tremendous pressure from inside the lens when you changed altitude. Even a brief flight in a pressurized airplane would be problematic. Planes are generally pressurized to about 8000 feet altitude. The atmospheric pressure at 8000 feet is about 10.9 pounds per square inch. At sea level it's 14.7 pounds per square inch, so that's nearly 4 pounds of pressure per square inch over the entire interior surface of the lens. Just think of the immense pressure there would be in the front element of a large white lens. I don't think they're built for that sort of pressure.

Back to humidity. The same applies to humidity. At a dew point of 80 degrees F, the partial pressure of water is 35 mb, according to this chart. https://www.engineeringtoolbox.com/relative-humidity-air-d_687.html
That's about 1/2 PSI just for the water. Yeah, that water is getting in there. Just for comparison, this is about half the maximum pressure that a human can blow.

Click to expand...

Certainly for large lenses, typical pressure changes could cause issues. And as I was getting at, I thought there was nearly 0% chance that there was good sealing in lenses, as it is impractical and would be almost impossible for large lenses with moving internals.

As far as air and gas dynamics, partial pressures are a nice accounting tool, but ultimately there's just a lot of water in the air as far as the weight fraction, and the air mix is quite homogenous and leaking continuously. Hence I mentioned the 80f dew point - there's a very nonlinear increase in weight fraction i.e. doubling from inside to outside (60f vs 80f: https://extension.psu.edu/psychrometric-chart-use ).

Click to expand...

I only mentioned partial pressure because it helps to consider it as an actual pressure. What I failed to mention was that what counts is the difference in partial pressure between what's inside the lens and what's outside the lens. This difference in partial pressure is a good representation of how hard that water is trying to cross the boundary.

homebodyMacro said:

homebodyMacro said:

Can be that, can just be normal air exchange (the seals are more effective at blocking water molecules than vapor in the air), or even just too much cooling of element just exposing the vapor already inside

part of it. Rapid cooling if elements is a bigger factor. Maybe the back of the lens saw a bigger differential somehow

Can be a failing seal too, but I won't jump to that conclusion yet

Click to expand...

There wasn't any cooling, just a lot of warming.

Click to expand...

If there was condensation, there was cooling of the water vapor (balanced by the resulting warming of the glass the condensation is happening on).

homebodyMacro said:

I actually expect that the front element fogged earlier and dissipated without me seeing, since it heated up before I started shooting a bit.

The rear element and internal element(s) would take much longer to heat up and hence I saw them fogged; the extreme 80f swamp blast was a very sudden moisture increase, meaning the cool glass caused condensation.

Click to expand...

But that sounds like a scenario I experienced during my first 48 Hour Film project. We had completed our first day, and I was the first person to get up in the morning, at the crack of dawn. I took my camera outside to get some b-roll until everyone else got up. Immediately, the lens fogged up. The air conditioning inside was quite effective, and my camera was likely cooler than room temperature inside from radiative cooling, so probably around 70 degrees F or so. Meanwhile, there was a touch of fog outside, and the temperature was about 80, so the dew point was probably close to 80, so instant foggy lens.

But the condensation was on the outside of the lens, because the dew point of the air inside the lens was probably about 50 degrees F, thanks to the drying effect of the air conditioning where the camera was stored overnight.

I pointed the camera toward the rising sun to let it warm up in anticipation of filming when the rest of the crew woke up. So much for the b-roll.

homebodyMacro said:

Given that condensation can probably cause some capture of particulate (pollution, pollen, mold) in the air, which would remain on the surface after drying, I'll try to warm up my gear more gradually in the future. I definitely don't want to encourage any mold growth over time, especially since I'm in a very humid climate.

Click to expand...

It's a good idea to store it in a relatively dry place (and by relative, I mean relative humidity, heheh).

Hmmm - some errors here, I think.

Karl_Guttag said:

What I have read in the past:

No camera lens by itself is airtight. Humidity dissolved in the air has droplets much smaller than water.

Click to expand...

Water vapor has no droplets. It is a gas. The droplets come only when the relative humidity approaches the dew point and there are condensation nuclei in the air (or camera lens).

Karl_Guttag said:

It is also not an uncommon problem. Generally, it is not serious if you let the lens dry out.

The preventative way is to keep the camera/lens in an air-tight (Zipplock or similar, and they make bags for larger lenses).

Click to expand...

That's only a preventative if the relative humidity inside the bag is low.

Karl_Guttag said:

Wait for the lens to heat up (the problem always is going from cold to hot

Click to expand...

Actually, it is not going from cold to hot. It is going from low dew point to high dew point. If brining the camera from cold to hot air with the same dew point, any moisture that may have been on the camera would evaporate.

Karl_Guttag said:

- you can get the reverse problem you had in winter), and then it will not act like a water magnet (like a cold drinking glass).

Usually, letting the lens stay in the warm sun for a while will fix the problem if it occurs.

Click to expand...

A wet lens in a ziplock bag sitting in the sun will not benefit from the sun. The ziplock bag works only if the air inside the ziplock bag has a lower dew point than the ambient temperature.

Karl_Guttag said:

Another solution is to bag the lens with desiccant or warm towels from the dryer to help dry it out,

Click to expand...

Hmmm - when I think of warm towels from the dryer, I think of towels that have just been through a wash cycle. Such towels are likely to have some residual moisture in them unless the cycle was a longer, less-efficient cycle.

Karl_Guttag said:

but it can take hours (and several sets of towels or a lot of desiccant). Some say to add old (pre-1982 in the US) warm pennies as copper is a fungicide/algaecide.

Click to expand...

Add the pennies to what? Copper is an effective fungicide/algaecide in aqueous environments, but I doubt it has much effect in air.

homebodyMacro said:

I guess I am just curious: is this seen sometimes with L lenses? Is it a very bad thing to see? Are any of my assumptions above incorrect? I am assuming that the sealing is not super robust, and I think that is probably reasonable.

Click to expand...

It's something that happens under the right conditions and is completely normal. You can learn to anticipate it and act accordingly. I had to wait for my 100-500 to clear up just this past weekend. There's a difference between being airtight and being weather-sealed. The (air) venting is designed in.

R2

Victor Engel said:

I only mentioned partial pressure because it helps to consider it as an actual pressure. What I failed to mention was that what counts is the difference in partial pressure between what's inside the lens and what's outside the lens. This difference in partial pressure is a good representation of how hard that water is trying to cross the boundary.

Click to expand...

There's definitely some diffusion going on, but if it's leaking air, it's mostly just replacing the air in the lens inner volume with new air that's mixed uniformly @ the current outdoor conditions.

Victor Engel said:

There wasn't any cooling said:

Victor Engel said:

Given that condensation can probably cause some capture of particulate (pollution, pollen, mold) in the air, which would remain on the surface after drying, I'll try to warm up my gear more gradually in the future. I definitely don't want to encourage any mold growth over time, especially since I'm in a very humid climate.

Click to expand...

It's a good idea to store it in a relatively dry place (and by relative, I mean relative humidity, heheh).

Click to expand...

Yep, I definitely try to keep my gear cool and dry inside. My air filtration is quite good, so there's also essentially 0 particulate to accumulate over time as well.

Victor Engel said:

Victor Engel said:

Wait for the lens to heat up (the problem always is going from cold to hot

Click to expand...

Actually, it is not going from cold to hot. It is going from low dew point to high dew point. If brining the camera from cold to hot air with the same dew point, any moisture that may have been on the camera would evaporate.

Click to expand...

It not really an either/or thing. The condensation happened because the lens was ~70F (on the floor, cool room), and it went into an 80F dew point. Condensation on the lens is generally just "is the lens surface temperature below the ambient dew point", and the answer was yes. The lens temperature is directly tied to the indoor temperature, so it is basically indoor temperature vs. outdoor dew point. The outdoor temperature is less relevant, unless it is roughly at the dew point and everything is in a fog.

Victor Engel said:

Victor Engel said:

Another solution is to bag the lens with desiccant or warm towels from the dryer to help dry it out,

Click to expand...

Hmmm - when I think of warm towels from the dryer, I think of towels that have just been through a wash cycle. Such towels are likely to have some residual moisture in them unless the cycle was a longer, less-efficient cycle.

Click to expand...

Yeah agree on that - there is definitely residual moisture.

Victor Engel said:

Victor Engel said:

but it can take hours (and several sets of towels or a lot of desiccant). Some say to add old (pre-1982 in the US) warm pennies as copper is a fungicide/algaecide.

Click to expand...

Add the pennies to what? Copper is an effective fungicide/algaecide in aqueous environments, but I doubt it has much effect in air.

Click to expand...

Yeah I don't think pennies are somehow presenting an aerosolized antimicrobial effect. There's nothing aerosolizing them.

Thanks for your responses!

R2D2 said:

homebodyMacro, post: 67843254, member: 132846"]
I guess I am just curious: is this seen sometimes with L lenses? Is it a very bad thing to see? Are any of my assumptions above incorrect? I am assuming that the sealing is not super robust, and I think that is probably reasonable.

Click to expand...

It's something that happens under the right conditions and is completely normal. You can learn to anticipate it and act accordingly. I had to wait for my 100-500 to clear up just this past weekend. There's a difference between being airtight and being weather-sealed. The (air) venting is designed in.

R2

Click to expand...

Yeah, the venting definitely makes sense. If it was too well sealed, 1. it would still pretty much leak, but 2. it could have a more stagnant inner air volume that could be very conducive to microbial growth, as in a beaker with a long looped opening or just some large container with slight openings but no through-leakage.

Thanks for the response!

Click to expand...

Colder lens going to warmer, more humid air = condensation. Nothing unusual here. Try to keep your lens and camera at the ambient temperature. You can also get similar condensation inside the viewfinder optics, which usually aren’t well sealed. In theory you could get it on the sensor too, but that is usually mitigated by the electronics/sensor heating up. Specifically, in the tropics, going from a cold air conditioned room to the outside air causes immediate condensation. The cure is to leave your camera outside the room, or keep it in a heated cabinet - we had a cupboard with a light bulb inside for this purpose when in Fiji/Solomons.

The opposite can happen when skiing/hiking in the high mountains. Cold mountain air is very dry. Going inside, to your warm moist room, condensation is inevitable.