Humidity - temperature changes

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Brian Rutter

Brian Rutter

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Hi all.
I am currently in Thailand and read as much as I could regarding lens fog from humidity, going from air conditioned room to hot outdoors.
I fully understand what is going on scientifically, but I have a question regarding one specific answer on the' issue...

'leave your gear in your camera bag, and place it outside for 15-30 minutes (others say up to 1 hour)'.

So, what we are trying to avoid at all cost, is condensation forming on the lens/camera leading to possible further issues in the future, such as mildew in the lens barrel.

So here's my question ...

If your gear is in a zipped up camera bag, how do we know no fogging up is happening?

For this trip, I am using a 'Gitzo Adventury 30L'

Gitzo statement on the bag ... 'The coated zippers, water repellent fabric and coated bottom enable you to use the bag in humid environments and a rain cover is supplied for very bad weather conditions'.

I would love to hear other peoples views on it, especially from those who will put my mind at rest :D

Gear in the bag ... Nikon Z8. Nikon Z 400mm 4.5
 
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From the world of telescopes where this is something you can deal with twice in a day easily and even all night long… It isn’t about preventing fogging during the temperature transitions. More about acclimating the optics to the ambient temperature before using it and at that point the fogging will be done and over. If you want to be extra sure what you can also do is to get a dew heater strip (many are available with usb inputs) and place that around the lens barrel end and let it heat up while you’re acclimating the lens.

Also you’d be surprised at how effective lens caps are and lens hoods at preventing dew. The condensation will go on those first. And if your lens has acclimated before you take those off then you’ll be fine.
 
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Brian Rutter said:
Hi all.
I am currently in Thailand and read as much as I could regarding lens fog from humidity, going from air conditioned room to hot outdoors.
I fully understand what is going on scientifically, but I have a question regarding one specific answer on the' issue...

'leave your gear in your camera bag, and place it outside for 15-30 minutes (others say up to 1 hour)'.

So, what we are trying to avoid at all cost, is condensation forming on the lens/camera leading to possible further issues in the future, such as mildew in the lens barrel.

So here's my question ...

If your gear is in a zipped up camera bag, how do we know no fogging up is happening?
Click to expand...
If the lens is placed in a sealed bag before going outdoors, condensation will form on the exterior of the bag and not the lens. The lens, and the air inside the bag, will slowly rise to ambient outdoor temperature. The humidity of the air inside the bag is significantly lower than that of the air outdoors. Once the lens has reached outdoor temperature, the bag can be opened with low chance of moisture condensing on the lens.

I am not familiar with it but I assume the Gitzo bag is sealed when zipped.
 
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I'd say the only valid answer is: We don't know.

Unless your camera bag is gas sealed or equipped with a hygrometer that can be read out remotely, you can't know the actual dew point in the bag.
Of course, bags may prevent exposure to humid air - on the contrary, they are also able to enclose humidity.
So, putting your stuff in your bag in the middle of a rain forest and then put it in a cool room might be not the best idea.
 
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Krümelkraft said:
I'd say the only valid answer is: We don't know.

Unless your camera bag is gas sealed or equipped with a hygrometer that can be read out remotely, you can't know the actual dew point in the bag.
Of course, bags may prevent exposure to humid air - on the contrary, they are also able to enclose humidity.
So, putting your stuff in your bag in the middle of a rain forest and then put it in a cool room might be not the best idea.
Click to expand...
When does condensation form? When taking a cold item in a hot humid environment.You take the can of Mountain Dew out of the fridge in full summer in Texas and you shall have condensation on the outside of the can.
Take a lens from your warm hotel room in the cold Wyoming winter and there will be no condensation forming on your lens. Why? Because there is at those cold temperature hardly any humid in the air (the colder the air the less water vapor it can hold, hence you easily get 99% rH in freezing condition but still have dry skin.
Hence I prefer to take my gear from a humid environment with much more confident to my AC room than vice versa ;-)
 
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Brian Rutter said:
I have noticed that there are no obvious signs of condensation going from hot to cold
Click to expand...
As I know from experience, if you expose a warm lens to cold air, some condensation will form, particularly on the glass. There will always be warm air around a warm object. It’s inescapable.

Going from warm air to cold air, to avoid condensation, it’s best to allow the object to “cold soak” before using it. In winter, I’ll place my camera gear in my car (in a garage) for 20 to 30 minutes, usually covered with a microfiber cloth to absorb any moisture which forms. As I’m driving to the shooting location I’ll keep the heater off. I’m ready to go once I arrive. The gear will be cold but that’s the point.
 
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On a trip to Costa Rica earlier this year with 10 other photographers, we put our cameras with lens attached outside for 30-45 minutes before we left to shoot and had no problems. I have no fungus or condensation problems.
 
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