Today’s Question: I’ve seen lens wipes advertised as preventing lenses from fogging up. Do you have any experience with these to know if they actually work?
Tim’s Quick Answer: No, in my experience the wipes that are promoted as being “anti-fog” do not prevent lenses from getting fogged up. Instead I recommend getting the lens to match the ambient temperature to minimize the risk of fogging.
More Detail: In most cases lens fogging is the result of the lens being cold in a humid environment. In my experience the most typical scenario is coming out of an air-conditioned building into a warm and humid environment. The cold lens (and other gear) causes condensation in conjunction with the humidity in the air.
I generally find that in this type of situation, I’m not really able to plan ahead. For example, if it was possible to leave my camera outdoors safely, that would have ensured the camera was not colder than the ambient air, and thus condensation would be less likely to form.
If you’re able to plan ahead, warming up your camera either by taking it outdoors before you plan to start photographing, or using a hair dryer to warm up your camera gear, can help minimize the risk of fogging.
Otherwise, I will simply wait for my camera gear to warm up, which generally takes about five minutes. In extreme cases it may be necessary to use a lens cloth to wipe excess moisture from the lens elements. But very often simply waiting will resolve the issue.
If anyone knows of lens wipes that actually provide an anti-fog capability, please let me know. All of the wipes I’ve tested were not able to prevent fogging at all.