Suppose you keep your camera at, say, 20 degrees C at a relative humidity of 60%. This means that the air inside the camera will have the same humidity at the same temperature, the relative humidity will increase if the camera cools down. Then you go outside for several hours where it is -20 C, put your camera on a tripod. After some time the camera will cool down and you will get condensation inside the camera.

The only thing I can think of is to go outside with the camera a day or so earlier, remove the lens and let it sit there for a while, making sure no dirt or snow enters the camera. Then you put the lens back on and put the camera in an airtight bag filled with the outside air. You only get the camera out of the bag the next day when taking pictures outside. However, removing the lens while outside seems to me like a dangerous thing to do, you are bound to get dust inside the camera...

  • \$\begingroup\$ I switch lenses outside all the time, in Arizona, the dustiest state in the union. It's not a problem, the camera is designed to be used that way. You'll get dust in there but it won't ruin your day as long as you maintain your camera appropriately in between outings. Rocket blower into the mirror is all I ever need. Otherwise, this question is a duplicate... photo.stackexchange.com/questions/3730/… and photo.stackexchange.com/questions/25191/… \$\endgroup\$
    – Jasmine
    Dec 9, 2014 at 22:22
  • \$\begingroup\$ O btw... one thing that has ruined my day is dust on the front element. If a helicopter is landing nearby, clean your camera after that event is over, and don't switch lenses until a while after the helicopter lands. Helicopters have ruined my day three times. Shots of the landing were great, but the shots after that were bad until I realized the dust coating that it deposited on the front. Again, simple to fix with a rocket blower - amazon.com/Giottos-AA1900-Rocket-Blaster-Large/dp/B00017LSPI \$\endgroup\$
    – Jasmine
    Dec 9, 2014 at 22:25
  • \$\begingroup\$ Are you sure that you have 60% humidity inside in the winter? A more normal value would be around 30%. I currently have 23% indoors, and it's not even proper winter here yet... Normally in the winter the humidity indoors is even lower than outdoors, as the air comes from outside and you heat it up. \$\endgroup\$
    – Guffa
    Dec 9, 2014 at 23:24
  • \$\begingroup\$ @Jasmine I guess I have to get over my anxiety of things getting damaged, I actually haven't changed the lens for more than a year now! \$\endgroup\$ Dec 10, 2014 at 0:15
  • \$\begingroup\$ @Guffa At my current location it isn't very cold, the humidity here is about 55%, but I'm going to travel to a cold place soon, and in the hotels there they have air conditioning. \$\endgroup\$ Dec 10, 2014 at 0:22

2 Answers 2


I don't think you need to do anything special - the problem is much worse going in the opposite direction (from -20c back into a warm humid room).

When going outside, you have a very small volume of humid air within the camera/lens. The camera/lens will initially be at room temperature and will cool relatively slowly, all the while the small amount of humid air will be diffusing out and dryer air diffusing in.

When going back inside you have a very large volume of humid air within the room, and the camera will warm up slowly, so for a long time you'll have lots of humid air moving past cold glass surfaces producing large amounts of condensation.

The standard advice applies to moving indoors, bag the camera/lens until they reach ambient temperature. This doesn't work when moving outdoors as you'll be keeping the moist air in!

  • \$\begingroup\$ You may also want to take a second bag for the card. You can remove the card from the camera while still in the cold and bag it separately. It will acclimate much faster than the camera, like in 10-15 minutes vs. over an hour. This will allow you to view your photos much quicker. \$\endgroup\$
    – Robin
    Dec 10, 2014 at 17:21

Just try to make this transition (from +20 to -20) as smooth, as possible and as long as time allows. When I have experienced such conditions, I kept camera in its bag in a car for some time and then in the bag outside the car. And same process to bring it back to warm room. Had no problem with condensation. Also you may want to use special camera cases for cold conditions. Check bhphotovideo.com for this.

  • \$\begingroup\$ I have never had an issue going into the cold, but I always bag my camera (large ziploc) before coming back in. \$\endgroup\$
    – Robin
    Dec 10, 2014 at 17:23

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