The GoPro fogging some people experience is NOT a "GoPro Malfunction" like the heading of the thread suggests, it's a user handling/preparation malfunction.
The fogging is caused by a simple scientific fact known as dew point.
http://en.wikipedia.org/wiki/Dew_point. The GLASS dome lens is the first thing to fog because it is a better heat/cold conductor than the acrylic case material. As a professional user of Gopro products for the last 6 years and also founder of the largest (46,000+ members) GoPro User Forum on the net
goprouser.freeforums.org, i have seen just about every issue people have had with these cameras and the solutions.
Earlier this year we conducted scientific tests with a Professional Diver Photographer and also a Physics Professor (both members) involving humidifier cribs, pressure vessels and scientific measuring devices on the causes of fogging in Gopro waterproof cases. This involved systematically testing at what levels external air/water temp, internal air and camera moisture content caused fogging. We even went to the extremes of heating the internal air in the case to high levels and dunking the case in ice water. With next to zero moisture content inside the case with heated air there was no fogging within 4 hours (test was terminated) when immersed in ice water.
However, anytime the dew point could be crossed with the introduction of tiny water drops or humid air in the case, fogging would occur very quickly on the internal center of the dome glass lens.
So if GoPro housing internal air space is say 100cc , for us in the tropics it will contain 30cc water vapor divided by 1000 = 0.03 cc per 1 liter of air space and divided by 10 ( 100cc ), in 30C ambient and 80% humidity. At sea on the boat, it is close to 100% humidity and the hotter the air is, it can carry/contain more water vapor.
That is approx 0.6 drops of water per 1 liter of air space in typical 30C and 80% humidity.
So 0.06 drops of water alone will fog the lens....crazy hey. ? I don't take much.
Here are the results of "FIXES" that were tested to work and NOT work when introduced into the case interior.
1. Antifog solutions (Cat crap, RainX etc) > Don't bother, works on mirrors and goggles not inside sealed cases.
2. Desiccant balls, Silica Gel, Gopro antifog Strips, Shammy strips, etc. > All Work if they are dried in an open oven for 10mins and stored dry in a sealed container after treatment, and placed in the GoPro case when required, but work best when combined with number 3 below.
3. Introducing dry aircon or SUBA TANK air (Home or Car) blast from a vent into the case for 2mins (INCLUDING the camera) and assembling/closing the case while still over the vent. Store in cool place and DON'T reopen till finished filming. Best combined with No 2 above.
4. Aluminum Tin foil folded and placed at the bottom of the case. As Aluminum is a better heat conductor than glass ANY air moisture will form on the foil first rather than the glass lens. Not an ideal solution as water can run into the camera if upended. But is a good solution if combined with No2 above if no aircon is available.
5. Make and use a Humidity box if aircon is not available (see video) You can also use a simple seal-able plastic bag with a quantity of desiccant or dry rice insert camera and case, squeeze out the excess air, seal, leave overnite and assemble and close the Gopro case while still sealed inside the bag.
TIPS >
A. Completely dry the white seal and inside the case after use, a hair dryer and kitchen paper can help here.
B. Make sure you don't have sweaty fingers when placing the GoPro into the case, one drop will ruin your other efforts at fog reduction.
C. When storing your GoPro and case leave the door ajar and place both in a sandwich bag with a handful of dry white rice. (Moisture can hide inside the camera itself the rice will draw it out)
MY PERSONAL METHOD > Cut shammy strips to fit the gaps on all four sides between the camera and the case and use the aircon method mentioned in 2 above or use my humidity box/bag. I have NEVER experienced fogging with this method with Hero1 or Hero2 (i don't use any bacpac device)
Sample of how some of the tests were done
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