Fogged lens

Moisture will condense on the lens if you carry the camera from outdoors into a heated room in the winter, or from an air-conditioned room to the outdoors in the summer. In either case, the moisture in the warm air condenses as dew, when it comes in contact with the cool camera. If you wipe off the lens immediately, more moisture will quickly condense on it again, and the lens will be as foggy as before. The only solution is to wait for the camera to warm up to the ambient temperature.

If you wipe the lens in a panic, the fog will return immediately. Continued wiping of the lens may cause abrasion or other damage. The problem remains until the camera warms to the surrounding temperature, a process that can be slightly speeded up by directing an air current on the camera with a blower. During nighttime shooting sessions, the lens may be fogged by the evening dew, so don't leave it outside for long periods of time. Remember that whenever moisture condenses on the lens, it is probably condensing inside of the camera as well, and you will need to take appropriate measures for its maintenance and storage.

When dew condenses on the lens, the image will be cloudy

Condensed dew on the lens and viewfinder