Fogging.....

[wildbill9]

Fairly new to underwater photos.... only my 5th trip using a dive camera and only the last dive my case fogged up it sucked. I don't have a high $$$$ system, a tg3, case and strobes). But this was the first time my case fogged up and wasn't usable. I soaked it before the dive but alas no joy. I did clean and assemble out on the deck (we were in Roatan) and the night before we had the camera in the pool. So enough background.... how do you keep your case from fogging up?

 

[herman]

"I cleaned and assembled on the deck"....there is your problem. Fogging is caused by moist air inside the housing and Roatan sure fills that bill. You have to keep the moisture out of the housing. Blowing the housing out with tank air helps since it has a very low moisture content and the moisture absorbers help as well. My solution is this. I NEVER open the case outside of an air conditioned room. I open, assemble and close the case in the room. Just before closing the case, I make sure the A/C is cooling and hold the housing with the camera installed in front of the air, let it run for a few minutes then close the housing. There are those who will disagree with this but I have had great success doing it this way. Contrary to what some believe, A/C air is much dryer than the room air although it feels the opposite. I use to have fogging issues but ever since I started this procedure I have had none. The exterior of the housing WILL fog when you do this but that is washed away as soon as you hit the water or the housing warms to ambient....exterior fogging is not a problem.

 

[DA Aquamaster]

I follow the same practice as Herman, provided an air-conditioned room is available.

The critical issue with moisture is that once you get in the water, the air inside the housing cools to the temperature of the water, and if that temperature is below the dew point for the air inside the housing will condense on the housing walls and on the port (since they cool to ambient temperature first). Most cameras generate some heat, so it's less common to have condensation remain on the camera itself, but the camera will also not normally be able to warm the housing enough to remove the condensation.

Dew point is dependent on the relative humidity of the air - the more water in the air, the higher the dew point, so the colder the water, the drier the air needs to be in order to have a dew point low enough to avoid condensation.

In addition to only opening the housing in an environment with comparatively cool, dry air, I also use desiccant strips inside the housing to remove whatever moisture is present. They sell them for use in GoPro housings and they will fit in some other housings as well as they are very small. Larger housings use small bags of silica gel. Both the strips and the gel packets can be recharged in an over at low heat (around 150 degrees) for a few hours.

If you're trying to use a housing in very cold water, some form of desiccant is an essential item.

 

[Larry C]

Also, don't leave the camera and housing sitting in the direct sunlight on deck between dives. The moisture in the hot air will go to the first place that cools when you hit the water, usually your port glass.