Cameras and Humidity

[Gollum]

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.

Summary

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.

Or

Happiness is a Warm Body:).

[rebel18]

I found this info very interesting, thank you.:)

[lay-z]

Thanks for providing a (sort of) scientific explanation on how this is caused - so simple!

So let's say if you do end up with condensation in your lens, will it promote the growth of mould / fungus especially if it occurs in a tropical environment?

[Gollum]

Lay-z

Sorry, I know nothing about Mould/Fungus on lenses.

[mikew09]

Lay-z

Sorry, I know nothing about Mould/Fungus on lenses.

Another question. If it does occur, does it just dry off the inside of the lens once the gear has warmed up without leaving an obvious tell tail watermark on the inside of the lens glass?

I have not experienced this yet and nor do I want to - I am one of these owners that takes every precaution due to paranoia about gear damage :-)

[Gollum]

Mikew09

On a recent trip to Vietnam & Cambodia with my walk-around lens EF-S 17-85, the front element fogged up a number of times (not a morning person:(). Once the Camera warned up you could see watermarks on the front element. As for inside the lens I have no idea, it’s impossible to see any inside surface.

On a trip to PNG I took my EF 70-300L and due to more good luck than good management this lens was never on the body when I first wanted to shoot, so it never fogged up. Although I did use this lens pointing up into the canopy, in both tropical and temperate rainforest. The lens hood had to be cleaned after every outing to remove water, dirt, seeds and general debris. The front element itself never had any water marks or dirt (unlike my other lenses). It only needed some dust to be removed with a brush. So far, I have never used the microfiber cloth on the front element. As this is my first L lens I don’t know if this is normal or it’s the new coating referred to in the specs.

As the newer white lenses (1999 or later designs) have better weather sealing there may be less chance of moisture getting inside the lens, but that is only my ill-informed opinion.

Hope this helps.

[mikew09]

Thanks Gollum, I assume the water marks inside the front element - although daunting - don't affect IQ. As I didn't see any loss of IQ on my old kit lens when I had it I did not bother looking at it closely. When I finally did it was filthy so I cleaned it, no IQ difference.