There have been a number of posts about protecting your camera and equipment from humidity, but all are about storing and transporting your equipment, not how to operate in these environments.
The following has been simplified to make it easy to understand so any Mechanical Engineers reading this please take this into consideration.
How many times have you walked out of your lovely air-conditioned hotel and attempted to take a photo, only to find that the lens and eyepiece are both covered with condensation? If you are anything like me two or three times a trip, and I know better.
First you need to understand why this happens so that you can manage the problem.
This problem is in fact only related to both Temperature and Humidity, what’s more important is something called Dew Point Temperature. This value is provided by every weather service, so look for it.
Dew Point Temperature is the temperature at which the humidity (water Vapor) in the air will condense (become a liquid again). This value is always at or below the current Air Temperature. What happened when you walked out of your hotel, was that the camera temperature was at or below the Dew Point Temperature. This caused the water vapor in the air to condense on the camera.
If the Hotel air Temperature is 22oC, outside air Temperature is 33oC and the Dew Point Temperature is 24oC. In this example any object at or below 24oC will cause condensation to form on its surfaces (fog on the lens).
At the time of writing
Temperature in Bali (Indonesia) is 31oC
Dew Point Temperature 22oC
In the above example I would expect to have a problem with condensation because 22oC is a fairly high temperature and some hotels run their cooling systems down to 18oC.
Temperature in Melbourne is 13oC (clear sunny day but was below freezing overnight in the hills)
Dew Point Temperature 3oC
In this example you may think that you wouldn’t have any problems because the Dew Point Temperature is so low, 3oC is very cold. If I leave the equipment in the car overnight and the temperature went down below freezing, I need to make sure it’s warn first, or condensation will form.
Temperature in Ha Noi (Vietnam) is 29oC
Dew Point Temperature 28oC
This will not be a very happy time to use your camera.
Now to prevent this from happening its simple, all you need to do is keep the temperature of your equipment above the Dew Point Temperature (keep it warm).
Things you can do:
- If you have a P&S keep it against your body
- If you have a DSLR you may attract some strange looks if you have your camera stuffed up your shirt (don’t try this going through customs). What I do is as soon as I can get the camera out of the bag and let it warm up before removing the lens cap. The time required will depend on the size (mass) of your lens but I would typically wait 2 hours. Any direct sunlight will help it warm faster. As soon as your lens is no longer cool to the touch you will be fairly safe.
- Store your equipment in an un-air conditioned room at the hotel like the bathroom and keep any doors to air-conditioned areas closed.
- Make sure that you keep your car air-con set as high as possible.
- Use your camera bag like a blanket to keep your equipment warm by putting it away before going into cool areas.
It doesn’t matter if you are in the Tropics or the Arctic, what’s important is the Current Temperature, Dew Point Temperature and the temperature of your equipment.
Happiness is a Warm Body.