Condensation

[unclebuddha]

I was just reading over the guidelines on the EOS pages of the Canon Website and

I'm a little puzzled (NOT the first time!). When taking the camera from a Cold

environment (hotel room) to a Warm environment (the beach) you should put the

camera in an airtight bag "to allow condensation on the bag, not inside the

camera". Why? Doesn't the condensation occur anywhere the cold camera is in

contact with the humid air as the air cools down? I can see how the bag would

get wet, why doesn't the airspace inside the camera (e.g. between the lens and

sensor)? Thanks, Snake

[JohnMWright]

In general, warm air is more humid than cold air. When you seal the camera inside a bag, you've sealed it with drier air. So the condensation occurs on the outside of the cold bag instead of the camera. I've found that just having the camera inside a camera bag (not totally airtight) seems to be enough to prevent condensation, as the camera is insulated and warms more slowly.

[alec_myers]

As the previous poster states, when coming in from the cold, the air inside the camera is cold and dry. Without a bag, warmer moister air will diffuse into the camera body and condensation will form on the still-cold surfaces inside the camera body. By sealing the unit inside an air-tight bag the moist air cannot enter the camera body and so no condensation will occur inside it.

[unclebuddha]

Thanks!