[MarkJerling]

One needs to let the camera assume the same (warmer) temperature as the humid air before exposing it to the humid air. For instance, putting the camera into an airtight bag, and letting it acclimatise (i.e., reach the same temperature) before removing it from the bag will prevent condensation.

I don't think that's going to work that well. Happy to be corrected, but the science does not stack up - and neither does experience.

So, lets say outside environment is 32degC, with 90% humidity. That makes the dew point 31degC.
Inside, probably 20degC, with, perhaps, 70% humidity.

So, no matter what you do, if you take a 20degC object outside into 32degC, with 90% humidity, you can't avoid the dew point of 31degC. Unless you can bring the camera up to 31degC prior to going out, condensation will form. So, what happens if we put the camera in a plastic bag? There is, after all, air in the bag. Even if we argue that the air in the bag is at 70% RH, (because the air in the room was at 70% RH) that still makes the dew point 26degC. So, you'll need to heat your camera to a minimum of 26degC before taking it outside to not have any condensation forming on the camera in the bag or on the cold lens elements between the body and the rear of the lens. Because, it's highly likely that the inside lens surfaces will be a cold 20degC too, after potentially spending the night in the hotel room. (Which is where your advice about storing in an unconditioned space comes in handy)

Which brings me back to my original point of this being largely unavoidable. Unless you have a heater in the room, or you can adjust the aircon (and often you can't) it will be difficult if not impossible to get the camera to 26 degrees before going outside and then removing it from it's plastic bag.

Hopefully, the camera bag has some insulating properties and, let's presume that the camera (and camera internals) stays at a toasty 24 degrees. Lets further presume that the RH is 75: That would mean the dew point is 27 degrees. So, to avoid condensation forming, we'd still need to get the camera up to 27 degrees, before venturing out. And, the moment we open that plastic bag, and hit 90% RH, that dew point moves up to 30 degrees.

So, you're back to square 1. You need the camera at 30-31degC minimum before you'll avoid condensation, even with a plastic bag. So, going outside and waiting for it to heat up is not going to avoid the condensation in the bag and inside the camera. You need to get the camera to a higher temperature before you venture out. And therein lies the difficulty.

[MarkJerling]

With a sealed body (KP) and WR lens, will the condensation occur on inner elements?

Yup. There's air in there.

[NZ_Ross]

With a sealed body (KP) and WR lens, will the condensation occur on inner elements? I know it is to prevent liquid water and dust ingress, but will it be "air tight" or sufficiently so? I suppose as soon as I need to change lens I'm letting it in anyway, but I suspect the 18-135WR will be on the camera most of the time.

I have travelled frequently enough into that situation with a sealed body and lens (K-3, 20-40 Ltd). Where I get condensation it tends to be on the viewfinder first, which is easily fixed with a quick wipe with a cloth, and very occasionally on the front elements of the lens. A little bit of time, generally 15mins or less seems to take care of it.

[MarkJerling]

I have travelled frequently enough into that situation with a sealed body and lens (K-3, 20-40 Ltd). Where I get condensation it tends to be on the viewfinder first, which is easily fixed with a quick wipe with a cloth, and very occasionally on the front elements of the lens. A little bit of time, generally 15mins or less seems to take care of it.

The water vapor is in there, there's just not very much of it. At room temperature, at RH of 75%, the amount of water in the air is 0.017ml per litre of air volume. So, the mirror-box is probably less than 1/10th of a litre air volume, so the amount of water in there will be a miniscule 0.0017ml. Or thereabouts.

[richandfleur]

I was super annoyed at myself for my one. Fogged up the view finder and was present on the test images I took too, so was throughout the camera.
Basically you'll get condensation on any cold surfaces (metal/glass) when you go from cold to hot. Think taking a can out of the fridge and sitting it on the bench on a warm/muggy day.
Cold air can't hold much water, but warm humid air has a lot of water in it, just perfect for condensing out onto cold surfaces.

Do check the bathroom of your accommodation. I'm not normally one for putting your camera gear in a wet location, but in this case it helped me a lot. Not the whole bag etc, just the body and lens I'd be using the next day.
In my case there was about a 20 min drive and some sitting around for discussion and tea before we headed off. Was all good to go by the time I needed it.

Look forward to the shots

[zkarj]

Most locations will be at least 10-15 minutes away from the hotel so hopefully that will solve most of the problem. But, as Rich said, careful observation of the camera on first use will be the key — one advantage to TTL is that most of the elements concerned will be visible simply by looking through the viewfinder at a suitably contrasty scene. I guess the sensor could even be checked by whipping the lens off, though I tend to keep that exposed to the outside world as little as possible. And I would also assume that a hunting auto-focus where I wouldn't expect it would be another sign that something is amiss.

[MarkJerling]

Most locations will be at least 10-15 minutes away from the hotel so hopefully that will solve most of the problem. But, as Rich said, careful observation of the camera on first use will be the key — one advantage to TTL is that most of the elements concerned will be visible simply by looking through the viewfinder at a suitably contrasty scene. I guess the sensor could even be checked by whipping the lens off, though I tend to keep that exposed to the outside world as little as possible. And I would also assume that a hunting auto-focus where I wouldn't expect it would be another sign that something is amiss.

I was super annoyed at myself for my one. Fogged up the view finder and was present on the test images I took too, so was throughout the camera.

Indeed. If you want to test what happens, walk into the Begonia House in the Wellington Botanical Gardens on a cold day with your camera. It's severe! (As I discovered)

[MarkJerling]

This TM auction: Ricoh-Pentax SMC-D FA 100/2.8 Macro WR | Trade Me
Have a read of the Questions and Answers section.

[NZ_Ross]

Have a read of the Questions and Answers section.

It will be interesting to see if the lens sells, and for what price

[GUB]

Hopefully I'll be back!! Heading off for a trek to Base Camp. See ya in 3-4 weeks.

[NZ_Ross]

Hopefully I'll be back!! Heading off for a trek to Base Camp. See ya in 3-4 weeks.

Look after yourself, and enjoy the climb and the photography

[MarkJerling]

Hopefully I'll be back!! Heading off for a trek to Base Camp. See ya in 3-4 weeks.

Enjoy! Safe travels!

[MarkJerling]

It will be interesting to see if the lens sells, and for what price

It's a nice lens, I think, but not at that price.

[Class A]

So, no matter what you do, if you take a 20degC object outside into 32degC, with 90% humidity, you can't avoid the dew point of 31degC.

Of course not.

My point was to avoid the exposure to 90% humidity before the camera has caught up to the 32°C outside temperature.

Even if we argue that the air in the bag is at 70% RH, (because the air in the room was at 70% RH) that still makes the dew point 26degC. So, you'll need to heat your camera to a minimum of 26degC before taking it outside

Luckily, you have the outside temperature to warm up your camera to 32°C, i.e., even beyond 26°C.

I'm working on the assumption that initially the camera is not in an environment where condensation would form on it. I think that's a reasonable assumption to make.

Obviously, if your camera temperature indoors, for some reason, is below the dew point for the indoor air then you'll get condensation on it, whether you go outside or not. However, provided the conditions are such that no condensation forms on the camera, by preventing the camera from being exposed to higher levels of humidity, you can let it adjust its temperature to the outside temperature, making it safe to take it out of the container once it has warmed up beyond the dew point for the outside conditions.

FWIW, some people appear to add silica gel packets to sealed bags. That would make sense when you take a camera that was sealed in a bag with warm, humid air, into a colder environment. However, I think it would probably be better to allow limited air circulation. A reliable way to achieve condensation is to suddenly expose the camera to different conditions. An approach that allows temperature to only change slowly while supporting the exchange of air so that humid air can be swapped out for less humid air before it can start condensating on the camera seems best when proceeding from a warm humid environment into a cold one.

[MarkJerling]

Of course not.

My point was to avoid the exposure to 90% humidity before the camera has caught up to the 32°C outside temperature.


Luckily, you have the outside temperature to warm up your camera to 32°C, i.e., even beyond 26°C.

I'm working on the assumption that initially the camera is not in an environment where condensation would form on it. I think that's a reasonable assumption to make.

Obviously, if your camera temperature indoors, for some reason, is below the dew point for the indoor air then you'll get condensation on it, whether you go outside or not. However, provided the conditions are such that no condensation forms on the camera, by preventing the camera from being exposed to higher levels of humidity, you can let it adjust its temperature to the outside temperature, making it safe to take it out of the container once it has warmed up beyond the dew point for the outside conditions.

FWIW, some people appear to add silica gel packets to sealed bags. That would make sense when you take a camera that was sealed in a bag with warm, humid air, into a colder environment. However, I think it would probably be better to allow limited air circulation. A reliable way to achieve condensation is to suddenly expose the camera to different conditions. An approach that allows temperature to only change slowly while supporting the exchange of air so that humid air can be swapped out for less humid air before it can start condensating on the camera seems best when proceeding from a warm humid environment into a cold one.

I've often wondered whether it would be good to have a whole lot of desiccant in the camera bag anyway. But, you're right, air circulation seems to work best - for the exterior of the camera gear at least. For the inside, I prefer to not think about the moisture in there!