LensFog - Camera Fog Forecast

The first thing on the screen is one word for whether your lens will fog when you walk outside: Fog, Close call or Clear. Under it is a line on what to do about it, like "Set the zipped bag outside 50 minutes before you head out." Glass fogs when it's colder than the dew point of the air around it. So each verdict comes from two figures: how cold your gear is, and the dew point from Apple Weather. You'll see the gap between them with the verdict, like "Gear 8°F below the dew point." There are two trips. Going out is gear carried outside from an AC room (70°F), an AC car (64°F) or a temperature you set. Coming in is cold gear carried back into a quiet room or a crowded one. A packed reception with a dance floor has wetter air, so cold gear fogs more easily there. Whichever trip is more likely to fog is on top. On a Fog verdict, the advice is a head start: how long to leave the zipped bag…