There are several separate questions related to your question. Let's look at each one in turn.
Abrupt changes in temperature
When materials are subject to sudden changes in temperature, they can tolerate the change or be irreversibly damaged. Everything depends on the materials involved, the extreme temperatures involved and how fast the change is. Take any heated lens element to something like 300-400 ° F and place it in a bucket of ice water and it will probably crack. That does not mean that leaving your home from 75 ° F to 0 ° F in winter will have the same effect. In fact, it almost certainly will not.
Although 0 ° F is a bit extreme, moving from the ambient temperature to the outside where the temperature is just below the freezing point does not seem to permanently damage the cameras and lenses. What it does do is affect the battery that powers the camera (more on that in a moment). When ideal optical performance is required in cold climates, such as for astrological photography, allowing all optical components to stabilize at room temperature before starting to shoot will avoid temporary minor optical problems due to different parts of lens cooling / camera at different speeds.
Moving from warm to cold environments is usually much easier with the camera equipment, in terms of long-term health, than the opposite. The main culprit is humidity.
Humidity and condensation.
Condensation and moisture can damage your camera and your lenses in various ways.
- Moisture can affect the electronics, especially if a circuit is powered while it is wet. Allowing voltage to be applied to a circuit board while it is wet is a recipe for disaster. Very often fry the electronics instantly.
- Condensation can leave mineral deposits on the optical surfaces when it dries. You can also "weld" dust to the lens elements or to the camera sensor and the filter stack immediately in front of the sensor.
- If moisture is combined with a warm, dark environment, the fungus can grow inside the lens or camera. Keep in mind that fungal spores spread through the air and are everywhere. This is the dust. Even new lenses have dust. Those new lenses also have fungal spores in them. It is a biological fact of life when it is present in the Earth's atmosphere.
The most common cause of condensation in camera equipment is due to the movement of a cold camera and / or lens in a warm, humid environment. If the temperature of the camera or lens is below the dew point of the surrounding air, water droplets will condense on colder surfaces. This should be avoided as much as possible.
The easiest way to avoid condensation is to always place the camera / lens in a sealed bag before moving it from a cold to a warm environment. The cold air sealed in the bag will contain less moisture than hot air inside buildings. Leave the bag closed until the contents have warmed to room temperature. Any condensation that forms will be on the outside of the bag.
Cold and Batteries
Batteries are chemical devices that depend on chemical reactions to supply electricity. Those chemical reactions are affected by temperature. When the batteries cool down a lot, their voltage drops quickly. A battery that will power your camera for hundreds of shots at room temperature can only manage a few dozen frames under freezing conditions. The good news is that just heating the battery restores some of its energy. If you shoot in cold weather, bring spare batteries. Keep them warm inside your clothes. Change the batteries in your camera and the hot batteries inside your clothes often.
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