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DPChallenge Forums >> Tips, Tricks, and Q&A >> Underwater Housing Fog
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Showing posts 1 - 9 of 9, (reverse)
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 06/02/2007 09:12:41 AM · #1
I have a Nikon S6 with a Fantasea FS-6 Housing that I have been using as a temporary set up for underwater photography. It seems that after about five minutes of being in the water, the lens port on the housing fogs up. The rest of the housing stays nice and clear because of the silica (sp?) gel crystals in it, but there is no room for that in the lens port. Anyone have a suggestion or tip on how to keep it from fogging up?
 06/02/2007 09:43:41 AM · #2
well a technique I've always seen and used with swimming and snorkel goggles is to spit in the googles and wipe it around in the lens, then rinse it with the water, but I'm not sure if doing that and then drying it out would work. Almost certain there are wipes for that if you check dive shops or maybe even pool supply places.
 06/02/2007 09:49:54 AM · #3
Try this. After cleaning the lens face with whatever you use, take ordinary newspaper (black ink) and rub it lightly over the surface. This has worked on a bathroom mirror that tends to fog when a hot shower is taken. There is something in the ink that doesn't allow the moisture to build up.
 06/02/2007 10:01:16 AM · #4
//www.adorama.com/NKFE.html

R.
 06/02/2007 10:14:47 AM · #5
If you are near salt water, dive equipment shops sell a lens antifog solution for diving mask lenses. It works.
06/02/2007 10:47:08 AM · #6
Assuming that the lens port does in fact share air with the rest of the housing, here's what's probably happening:
- The glass of the lens port conducts heat better than the plastic of the housing, so cools faster
- The temperature of the lens port falls below the dew point of the air in the housing
- Condensation forms on the lens port
If this is the scenario, then you'll have some issues, especially in very cold water. You may have success just by making sure that you put the camera into the housing a few hours before the dive, with plenty of freshly-dried silica. Let the silica pull the water out of *all* of the air as completely as possible (it may take a while for diffusion to do its work, but the camera and lens are not sealed, so *will* exchange air).
For reference, if the surface conditions (when you put the camera in the housing) are 20°C and 50% RH, then you have to reduce the RH in the housing to 24% to achieve a dew point of 0°C. A 0°C dew point will ensure condensation-free operation in all but the coldest ocean waters. But you have to ensure that the *entire* air volume in the housing has equilibrated at that dew point.
FWIW, anti-fog solutions will only work temporarily and incompletely. They are really not the solution to the problem.

Message edited by author 2007-06-02 10:48:40.
 06/02/2007 11:21:06 AM · #7
Originally posted by kirbic:
Assuming that the lens port does in fact share air with the rest of the housing, here's what's probably happening:
- The glass of the lens port conducts heat better than the plastic of the housing, so cools faster
- The temperature of the lens port falls below the dew point of the air in the housing
- Condensation forms on the lens port
If this is the scenario, then you'll have some issues, especially in very cold water. You may have success just by making sure that you put the camera into the housing a few hours before the dive, with plenty of freshly-dried silica. Let the silica pull the water out of *all* of the air as completely as possible (it may take a while for diffusion to do its work, but the camera and lens are not sealed, so *will* exchange air).
For reference, if the surface conditions (when you put the camera in the housing) are 20°C and 50% RH, then you have to reduce the RH in the housing to 24% to achieve a dew point of 0°C. A 0°C dew point will ensure condensation-free operation in all but the coldest ocean waters. But you have to ensure that the *entire* air volume in the housing has equilibrated at that dew point.
FWIW, anti-fog solutions will only work temporarily and incompletely. They are really not the solution to the problem.


That was probably the most complete, concise, informative, and scientific response to a question that I have ever seen on DPChallenge. I would never have thought that exact temperatures and relative humidity would be suggested within a couple of hours of the question being asked. Sometimes answers like this are offered days or weeks later after people have had to time to mull it over and do some research.

Amazing.
 06/02/2007 11:23:34 AM · #8
Something oily or waxy would do the trick, but I don't know if you want to put something like that in an underwater housing because it's really hard to wash out..
 06/03/2007 11:54:01 AM · #9
Originally posted by kirbic:
Assuming that the lens port does in fact share air with the rest of the housing, here's what's probably happening:
- The glass of the lens port conducts heat better than the plastic of the housing, so cools faster
- The temperature of the lens port falls below the dew point of the air in the housing
- Condensation forms on the lens port
If this is the scenario, then you'll have some issues, especially in very cold water. You may have success just by making sure that you put the camera into the housing a few hours before the dive, with plenty of freshly-dried silica. Let the silica pull the water out of *all* of the air as completely as possible (it may take a while for diffusion to do its work, but the camera and lens are not sealed, so *will* exchange air).
For reference, if the surface conditions (when you put the camera in the housing) are 20°C and 50% RH, then you have to reduce the RH in the housing to 24% to achieve a dew point of 0°C. A 0°C dew point will ensure condensation-free operation in all but the coldest ocean waters. But you have to ensure that the *entire* air volume in the housing has equilibrated at that dew point.
FWIW, anti-fog solutions will only work temporarily and incompletely. They are really not the solution to the problem.

The lens port is sealed by a large rubber gasket from the rest of the housing. I was considering cutting the gasket, or something like that, to allow the entire housing to share air, but I wasn't sure if that would be good. It is a point and shoot camera, so the lens port is created only by a rubber ring and shouldn't be a big deal if I do that. I live in Okinawa, Japan, so the temperature of the water and the air temperature are very hot. I will try putting everything together a few hours before I get in and see if that does help. Thank you very much.
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