Cold, glass, and condensation


in Canada, Daily updates, Geek stuff, Ottawa, Photography

Users of cameras and eyeglasses will be familiar with the phenomenon of fogging, which occurs when one goes from a cold and dry place into a warm one. This occurs because air can hold about 7% more water per unit of volume for each ˚C of additional temperature. That means that air in warm places is naturally more laden with water than that in cold ones. When the water-laden air hits cool glass, it condenses into a fog that confounds the bespecktacled and shutterbugs.

The other night, I witnessed a special elaboration of this phenomenon unique to conditions including (a) a very cold and dry night (b) a fairly large volume of glass and (c) an instant transition to a warm and relatively humid coffee shop.

The normal fogging occurred, but it would not dissipate after several minutes of waiting. It was then that I noticed that the glass on which the fog had formed was cold enough to freeze it – leaving a thin sheet of ice of the lens. The remedy was a few minutes of huffing to melt the ice, followed by a few more waiting for evaporation.

I am a bit surprised not to have experienced this working with cameras in Finland or Estonia. Like getting mild frostbite walking home from a party, it seems to be an Ottawa experience.

{ 5 comments… read them below or add one }

. November 21, 2008 at 9:48 am

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. November 21, 2008 at 9:50 am

“A major problem facing camera users in cold weather is condensation. Condensation occurs when warm moist air encounters a cold surface. Warm air can hold a lot more water vapour than cold air, so when the cold surface causes a localised reduction in temperature, this water will condense out of the air and form droplets on the surface. If you use your camera outdoors, it will become cold. If you then bring it indoors into a warm room, condensation will form not just on the outside, but possibly also on the inside, where the moisture can cause damage to the electronic components. Even weather-sealed cameras such as the Olympus mju or Pentax K10D are at risk.

The best and easiest way to avoid this is to find a large airtight Ziplock plastic bag, pop in one of those silica gel packs that come with any new electrical equipment, and carry it with you when you go out taking photos. Before you come back indoors, put your camera and any moisture-sensitive accessories such as lenses into the bag and seal it up. This way, when you come inside the condensation will form on the outside of the bag rather than on your camera. Leave the camera in the bag for at least ten minutes, until it has returned to normal room temperature. The silica gel should be enough to absorb any moisture that gets inside the bag.”

Litty November 21, 2008 at 12:29 pm

The eventual upshot of living in Ottawa should be elegant snowy landscapes to photograph.

Emily November 21, 2008 at 2:23 pm

Oh Ottawa. The joys you afford so freely!

Milan January 5, 2009 at 11:02 am

I made myself a special anti-condensation bag. It’s just a ziploc bag large enough to hold my dSLR and largest lens, but it also has a couple of packets of silica gel duct taped inside to absorb moisture.

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