Condensation inside lens

Amadeus21 wrote:

In short: Normally it is not so "dangerous" to fetch the warm camera and optics to the cold outside because cold air does not contain much moisture. Normally no danger of condensation.
You always shout store and let the optics adapt the temperature difference in a moisture-tight bag/housinf if coming from rather cold conditions to warm rooms.

I believe the OP is talking about condensation inside his lens when he takes it outdoors into cold conditions.

So, moist air inside the lens carries that moisture to the coldest part of the lens (the inside of the front element) where it condenses on the coldest part of the inside of the front element, there in the center where that front element is thinnest.

One solution is to store the lens and camera in a dry environment when it is not in use.

Camera stores sell "dry cabinets" for this such as the following:

Ruggard EDC-50L Electronic Dry Cabinet (50L, Black) EDC-50L B&H (bhphotovideo.com)

Here, a de-humidifier controls moisture inside the cabinet so the humidity is low there. This reduces the chances that condensation will occur when the equipment is taken outside into a cold day.

A less expensive alternative is a pouch of dessicant in a sealed enclosure that holds the lens etc. Here is one that contains the recharging heater (heats the silica gel for 4 to 5 hours to drive off collected moisture so it can be used again). Dessicant color changes during use so that you know it is time to recharge it.

Ruggard Renewable Dehumidifier PDC-RD B&H Photo Video (bhphotovideo.com)

If moisture is kept away from the air inside of lens, camera, binoculars, telescope etc, it will not be there to condense on the optics when the temperature cools.

PS there are places inside houses where humidity is high, such as basements in winter and summer, and attics in summer.  Not good places to store optical equipment!